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- Cornelis (Cees) Wortel, Ichor Therapeutics Chief Medical Officer, on Rejuvenation Research and Its Engagement with the Established Regulatory System
- Dementia Risk Trends Downward and Later in Life, Due in Part to Cardiovascular Health
- Recent Research on the Benefits of Exercise in Later Life
- Another Example of a Marginal Senolytic Drug Candidate
- The Fable of the Dragon-Tyrant, and the Courage to Speak Out in Opposition to Aging
- A Set of Marginal and Alleged Senolytics Show No Meaningful Benefits in a Cell Study
- DNA Demethylase Activation via Klotho Reduces Arterial Stiffening in Mice
- Glial Cell Behavior Critical to Proficient Central Nervous System Regeneration
- Towards a Better Epigenetic Clock
- Extracellular Vesicles Used to Promote Heart Regeneration in Rats
- Two Faces of Macrophages in Cancer Tissue
- Exercise Increases the Rate at Which New Heart Cells are Produced
- More Supporting Evidence for the "Amyloid then Tau" View of Alzheimer's Disease
- Does Immune System Decline Determine the Contribution of Senescent Cells to Aging?
- Significant Improvements to Chimeric Antigen Receptor T Cell Therapies Lie Ahead
Cornelis (Cees) Wortel, Ichor Therapeutics Chief Medical Officer, on Rejuvenation Research and Its Engagement with the Established Regulatory System
Ichor Therapeutics is the most mature of the US-based companies that have emerged from the SENS rejuvenation research community in recent years. You might recall a number of interviews back in the Fight Aging! Archives with founder and CEO Kelsey Moody. He has his own take on how our community should proceed from laboratory to clinic: he is very much in favor of demonstrating (a) that the formal regulatory path offered by the FDA can work for the treatment of aging, and (b) that - given the right strategic approach - rejuvenation therapies can attract the attention, collaboration, and backing of Big Pharma entities in the medical development marketplace. Indeed, he holds that this is a vital transition for the community to make.
As a step towards this goal, Ichor has recently gained the support of long-standing industry veteran Cornelis (Cees) Wortel, who is aiding the company in the role of Chief Medical Officer. He has advised on and guided near two hundred clinical trials in his career, and is now focused on helping Ichor's therapies to achieve success in the regulatory pipeline. Here, he writes on some of the subtleties inherent in the complex regulatory systems of the FDA in the US and EMA in Europe, and the priorities that companies must develop in order to be successful - particularly those that newcomers to the regulatory environment might find surprising or unexpected. I think you'll find it a most interesting and informative read, regardless of your position on the current regulatory system for medical research and development. You might look at some of my recent comments on nuanced opposition to the FDA as a companion piece to the article here.
Most products provided to people, which may impact their safety one way or another, undergo some form of regulatory review and approval before they are allowed on the market. Medications and devices undergo a very extensive development, review and approval process, as they can have a significant short term and very long term impact on a patient's safety and quality of life. The regulatory bodies, including the FDA and analogous regulatory authorities in other parts of the world, are not perfect. The premise of regulation in medical development however is good and very necessary: to ensure that people are safe and that therapies work. These regulatory agencies focus on consumer protection and aim to prevent serious harm such as that which came to patients when medical research was not done properly, such as the thalidomide disaster which caused countless women to give birth to babies with extremely deformed limbs and other birth defects. Treatments also have to have the effect they promise, as patients pay for them and tolerate the side effects that often come with the treatments. The overall risk-benefit balance needs to be known and acceptable.
The execution of the regulatory development path can be flawed in all the usual ways present in any structure built by fallible human beings, however. I would imagine everyone who has spent significant time working with regulators has a list of items they'd like to change or improve upon. That said, the regulatory systems available are the only viable way to put safe, new treatments into the clinic, and make them ultimately available to large numbers of people. Once we realize and embrace this, we can engage with the regulatory agencies in an informed and purposeful manner and work towards the best common path forward across different parts of the globe.
I have just recently engaged with the rejuvenation research community and it seems that it has been firmly focused, and rightly so, on the early stage research portion of progress, but it may have had comparatively little experience with later stage clinical development of agents for this new frontier. This is the natural progression of a new and exciting frontier in clinical development. I understand the existence of a certain amount of regulatory phobia, as the first view of the enormous cost and complexity of the path of clinical trials for a new therapy is very intimidating. Having been engaged in many clinical trials developing potential treatments for life-threatening diseases such as pediatric brain tumors, I also understand the enormous frustration and the need for access to new potential solutions. But as long as drug candidates are under clinical study, there is still a real inherent risk that one does more harm than good (which is exactly what the trials are intended to find out) and thus the regulations are designed to protect the trial participants first and foremost. In too many cases potential treatments have turned out ultimately harmful or have a much more modest effect impacting the risk-benefit balance negatively. Thus engaging the current regulatory systems is the road we have to travel in order to get treatment options in the hands of medical professionals and patients.
Not all study drugs in development make it; in fact most drugs turn out to be toxic or do not have an acceptable risk-benefit balance. I have been lucky enough to be part of a few innovative drug development projects which dramatically improved the medical outlook for some serious diseases (Remicade, the very first anti-TNF monoclonal antibody was the first successful drug development project I became deeply involved in). It is very gratifying to know that so many patients with Rheumatoid Arthritis, Crohn's Disease and other serious ailments are benefitting from treatment with biologicals, far beyond the reach of any single doctor's direct patient focused capabilities.
For drug development, there are ways to de-risk the complex development path. The development pathway is broken up in separate pieces, which makes the phases more manageable and the development risks (and safety risk for the trial participants) are decreased along the way. Doing this translational step from science to the clinic poorly however, often results in very promising technologies 'dying on the vine' and therefore deprives us all of potential worthwhile solutions. One of the reasons I joined Ichor Therapeutics is to help build this development bridge for the team across its varied projects, to build on and validate the scientific focus by constructing a robust infrastructure for the clinical development of innovative new options to treat aging and its conditions.
A Pharmaceutical Developer's Initial Considerations
As a company founder and pharmaceutical developer, with a specific implementation of new technology in mind, what should one be thinking about? An important initial step is to build a living model of the path ahead, and the first and most important consideration is which indication or indications to pursue. An indication is the reason to use the treatment under development, meaning the specific medical condition and class of patients that will be treated to produce the intended benefits. For example, a therapy that enhances muscle growth might be applied, depending on the technical details, to muscular dystrophy, frailty syndrome, sarcopenia, cancer cachexia, and so forth. Selecting the best initial indication can be based on different departing points: the indication with the best regulatory approval pathway versus an indication which reaches the most patients in a common disease, for instance. Choosing an indication also depends on the initial funding available and timeline constraints. There are almost always far more choices than can reasonably be tackled in the near future by any one company, and understanding the development ramifications of each top contender is key.
Interactions with regulators over the initial development years of any drug candidate will be focused on preparing for, building, and conducting a series of experiments - clinical trials - to rigorously prove that the therapy is safe and effective for the selected indication. This will involve a sizable amount of time and effort; the following costs are middle of the road estimates for indications with a high medical need and a modest sample size studying a chemical drug and might be halved or doubled for any specific company and therapy. Much will depend on the cost of manufacturing the therapeutic, implementing the pre-clinical programs, the regulatory filings, the type of disease and therapy, the medical assessments needed to prove safety and efficacy, the required length of follow up for patients, the geographical location of the trials and so forth.
a) Getting ready for the pre-trial engagement with regulators: design the overall development plan, rigorously develop the manufacturing process and implement the animal studies for initial safety assessment and other scientific building blocks such as mechanism of action and drug exposure. The doses in the animal models are much higher and exposure much larger than will be given to people and thus provide a safety margin. Costs depend on many factors, including whether the drug in development is a chemical or biological drug, the duration of intended treatment and number of patients dosed for instance. This initial work can easily cost 4-6 million, of which about half goes to the manufacturing.
b) Phase I trials: the purpose is to establish safety in a limited number of people (first in man and thus limited exposure of number of individuals) and obtain a baseline set of mainly safety data across escalating doses. Expect at least 2.5-4 million for the trial alone, and then an additional 2.5-3 million for ongoing support and all of the other work necessary to run the development team and activities in a company.
c) Phase II trials: the purpose of phase II is to 1) expand the safety database on recipients of the study drug and to start understanding how the trial endpoints are changed due to exposure to the study drug, meaning the specific measurements of the disease needed to prove safety and effectiveness, and 2) obtain information on the optimal dosage. It takes often at least 300 patients to obtain a rigorous set of data for these items. Much depends on the magnitude of the difference in an endpoint between treated and control participants. This builds the necessary data to design a Phase III. Often multiple Phase II studies are needed. This will cost 10-15 million for a single Phase II trial, and expect the average pharmaceutical company to spend another 10-15 million on ongoing operations and related costs.
d) Phase III trials: the purpose of Phase III is to determine the treatment benefit to a specific population. It also provides most of the safety data. Two such trials are typically needed, and these are the big, expensive, high-publicity projects. The cost will often run 25-50 million for the trial alone.
e) Often other specialized Phase II trials are needed to study the effects on the heart, metabolic breakdown of the study drug, and interactions with other drugs already on the market, for instance, adding to the cost. Also not included are the ongoing manufacturing costs for the study drug needed for the trials, which for each Phase grows in size of number of patients included in the trial, as well as all the regulatory costs (for instance safety reporting). Later stage trials also often require expanded pre-clinical safety work.
The overall development costs vary per study drug and indication and often run in the hundreds of millions or more. Once a drug is approved for one indication, one can build on the existing file to develop follow-on indications, saving significantly on additional development costs.
A full Gantt chart for the end to end process of all the development tasks might take 3 months to assemble and be 3 meters long when printed out. Given that, and the escalating costs during the development timeline, the more that can be done early on to consider and design the best path ahead, the better off one is. No-one wants to have to raise the funding to repeat a later stage trial which came up short, but this happens! In many cases, better planning and choices made far earlier could have avoided such costly outcomes.
An Initial Model of Indications
Many therapies will have multiple possible indications, which can be developed in interactions with regulators. Some will be better than others from the perspective of establishing a foothold in the clinic, and some will be better than others from the point of view of helping more patients (suffering from a disease which affects more people). It is usually the case that these two concerns are opposed as far as size of the required dataset for approval: the intent of the regulator is to protect the public, and applications for approval that lead to the most widespread use will generally require more evidence, time, and funding to reach a sufficient standard of proof of safety and efficacy.
Thus the preferred strategy (if possible) for clinical development professionals is to put forward an initial application for a narrow, critical usage that solves a focused, high medical need problem, one that can be evaluated and proven more easily. Then, once this is well underway, the company can expand their work with regulators to cover other, larger uses of the therapy. This sort of incremental approach to development also allows for applying what one has learned along the way, letting it be more readily incorporated into the ongoing development of the product. A second regulatory application will usually be able to build on the manufacturing and pre-clinical dataset developed for the first indication.
When looking over possible indications, one should consider the following:
a) The medical need - the greater the better. Are patients suffering severe disease effects? Is there no existing therapy? This goes a long way towards determining the degree to which all involved (patients, professionals, doctors, and regulators) will work with you and proactively support your application through the process.
b) The patient population size. This is important in several ways. Firstly, a small population size can lead to an orphan designation, which can offer a number of advantages to development, though maybe now less so than used to be the case. On the other hand, a population that is too small will require more time to enroll the number of patients needed and will render the company unable to produce data that is rigorous enough to pass muster in a reasonable timeframe. A very large population is good as enrollment may be much easier and it supports the ultimate goal of a company to help more people, but as noted above it will lead to greater demands for stringent proof of safety from the regulators - it is often not the optimal first step, but better attempted as an expansion of an indication with a smaller patient population, once the study drug manufacturing is accepted and the drug is proven to be safe in at least one indication. Larger disease indications also may have more competing treatments under development and thus also compete for patient enrollment in these studies.
c) The disease severity. A more severe disease makes it easier to obtain strong data, because the size and speed of onset of the intended benefit resulting from a successful therapy is proportionally larger. It is much easier and less costly to prove effectiveness given large and relatively rapid changes in patient health than it is for more subtle effects which appear over time. Large and rapid beneficial changes are generally only possible to achieve in severe disease conditions.
d) Plausible endpoints that can be measured, and the cost of measuring them. Mortality is a definitive and good endpoint because it is less expensive to assess, but a hard to reach endpoint because patients will have to be followed for many years, unless the disease is rapidly fatal and amenable to intervention. Endpoints based on simple biomedical assays or measurements that can run soon after a therapy is administered, such as presence of a persistent virus, or blood pressure, or blood lipid levels, are much more cost effective where they have been well established in the field and are already accepted by regulators for an indication. Where they have not been established, be aware that the process of introducing a new surrogate endpoint is a long and expensive struggle. Further, some endpoints, such as imaging endpoints, can increase the cost of a trial significantly.
e) The duration of a trial. The cost of a trial is as much determined by its duration as by the number of patients enrolled. Diseases for which there is much competition to enroll patients can be also hard, as all companies and academic groups are looking for the same patients. Some indications will be ruled out for a company at earlier stages simply because there is no practical way to raise sufficient funding given a very long timeline for trials to lead to concrete results.
In most cases, the best approach will either stand out, or be the one left standing after others are eliminated. Here, eliminated can mean "put off for later" as all companies will try to expand their indications as they move forward with more successful data and proven confidence in their approach.
Orphan designation can be obtained for an indication that has a has a small population size and great medical need. The intent on the part of regulators is to incentivize companies to work on therapies for what would otherwise be financially impossible diseases. This is achieved through a combination of fast-tracking, vouchers to speed later development, and a greater willingness on the part of regulators to work with companies to smooth the passage of a therapy for an orphan indication. Success in an initial orphan indication has in the past been a more reliable road to initial approval for many companies, even though on the whole it doesn't make the process significantly less expensive. As a consequence, a complex structure and industry has sprung up around the orphan designation, which has arguably veered into attempts to game the system.
On this topic, it is important to realize that the system is not just the rules as written. It is the intent of the regulators, the interpretation of the regulations, and the relationship built with regulators. I have sat in numerous meetings over the years listening to people engage with the regulators to try to design short cuts, where in the end they would have been far better off trying to work within the regulations while building the relationship with regulators in different jurisdictions around the world. Regulators are people just like the rest of us, and being open, earnest, and intent on producing a good outcome for patients receiving the treatment goes a lot further than aggressively trying to cut corners and rules-lawyering. The degree to which the regulatory teams you interact with are engaged with you can be an important determinant of the pace of the regulatory progress. For instance, once I have been happily surprised to receive a phone call from an FDA doctor overseeing the complex important trial I was running, asking how the agency could help us to increase the difficult enrollment and help getting the trial finished.
On starting with an orphan indication, consider, for example, that most gene therapies will be applicable to some form of genetic disorder. If a gene or protein is being manipulated, then there is probably a population of patients who have loss of function mutations in that gene resulting in an inherited disorder. But what if there are only ten such patients ever recorded, all of whom die young, and none presently known? It simply isn't practical to try to address this super rare condition at the outset of development as an orphan indication. Even if a patient is found in the next few years, the results from one intervention are not rigorous enough to proceed with. I'm aware of a trial for a rare condition that lasted for more than 25 years in order to find 90 or so patients, for example, and that is far beyond any timeline a startup company should be considering.
Further, is a proposed orphan designation biologically defensible? For example, one could look at the very large HIV patient population and try to designate a small orphan population of individuals who show adverse reactions to the common antiretroviral drugs, and thus cannot find effective treatment without bothersome side effects. But is that designation of a biological population, and the measures or metrics used, widely accepted by the research community and by regulators, or does it look more like an entirely novel slicing and dicing of the patient population to enable the aforementioned gaming of the system to try to gain advantage? If the end goal is to treat all HIV patients, then the regulators will see that and treat the application accordingly.
At the end of the day, the final safety database resulting from the clinical trial work available for submission should provide sufficient protection to the population of patients who will receive the treatment in the real world. And if that population would be much larger than the one studied, side effects that are less common (and thus not likely observed in the smaller population) will impact the larger population and only be found after exposure of many more individuals. It is because of this that regulators are stringently doing their reviews. Consider work on an orphan indication, but don't take it as a mandatory step and plan to build a safety database commensurate with the intended patient exposure.
Off-label usage interacts with orphan indications and other incremental approaches to providing a therapy to an ever-large patient population over time, and can be viewed through a similar set of lenses. In principal, any approved medical technology can be prescribed for off-label use - for use with another, different medical condition, unrelated to the approved indication. The manufacturer cannot advertise that use, but physicians and patients can follow their own judgment. In practice, consider that the intent of the regulator is firstly to minimize possible harm to patients, and secondly for all use to be tested and proven to accepted and sufficiently high standards. Small amounts of off-label use will typically fly under the radar, as regulators have limited resources. If off-label use expands greatly for any particular therapy, then regulators are bound to intervene and with good reason.
Thus it isn't wise to adopt a restricted or orphan indication and expect off-label use to take the therapy to the broader patient population. Ethically one should be going through the formal and full regulatory process to bring a therapy to that larger population in order to do no harm (primum non nocere, as the first principle). Doing things the right way in the end also works far more effectively than trying to find loopholes and does justice to the risk taken by the study participants and the recipients of the drug when on the market.
There is another factor to consider, as well. A common joke in the development community is that "it is easy to obtain approval, but hard to obtain reimbursement." It is of course not at all easy to obtain approval, which is where the humor lies. In recent years, the payer institutions, such as insurance companies and government medical entitlement programs, have become a gatekeeper and very important factor in the drug development planning of pharma/biotechnology companies. It used to be the case that one could largely put this off as a concern in the earlier stages of company development, but now it has become the case that one can have a therapy approved, but find that no insurance company or other payer will pay for it. Thus in addition to proving worthiness to regulators, when planning trials one must also take into account the evidence that payers will require in order to accept the treatment in their plans. This also serves to suppress any significant off-label use.
Aiming to be a Worldwide Company
It is a good strategy, and well established in practice, to work on application for approval of an indication with multiple regulatory bodies. The goal is to make a successful therapy available to patients globally and a larger eventual market also provides a more realistic scenario to recoup the significant developmental costs and eventually may provide profits for corporate growth, return of investment for early (high risk) investors and further development of additional drug and indications. For example, the US FDA and the European EMA and others, have a solid set of guidelines for harmonized submissions under the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH). In the course of talking to both the US and EU, one can craft a plan for trials that will satisfy both agencies, at a similar cost to just one filing. The trials are designed to have the standard components and answer all specific questions for each party, are run once, and provide data for multiple applications, in order to gain approval to access two or more large markets.
My experience is largely with the FDA and EMA. I prefer Europe, as in my experience the Netherlands and Belgium are the best and the fastest locations for the initiation of the initial Phase I study. In general, studies can be conducted at a lower cost and the regulations are more accommodating in Europe. Currency exchange rates can influence these cost differences dramatically, of course.
If Europe is cheaper and faster, then why submit to the FDA early on? A counterpoint is that the US has deep clinical research experience for many diseases in its academic centers and hospitals, and a very sophisticated disease tracking system. This helps in designing clinical trial protocols and predicting enrollment. It also has an extremely large patient population. Compared to Europe, one does not have to deal with quite so many language barriers in the execution of clinical trials. So each continent has its own advantages and certainly the indication should be driven by the geography: certain diseases are not found in the highly developed countries for instance and others are predominantly found there due to lifestyle issues. Certain diseases can only be found in certain geographies or populations.
In summary, the regulators will accept clinical trial data that is developed under ICH guidelines from many parts of the world as long as the clinical trials are implemented appropriately and it is worthwhile to engage with multiple regulatory agencies once one enters later stage trials. As the regulations and local issues constantly change, it is important to keep up to speed or receive the latest information from professionals in the field.
Developing for Quality is Vital
As I mentioned, one of the important parts of the early work in a company that leads up to engagement with regulators is to develop a highly robust development plan and manufacturing and toxicity assessment process. This is the item that surprises many founders, both in terms of the stringency required by regulators, and in terms of the cost of achieving this goal.
It is comparatively easy to produce research grade products on an ad hoc basis, with a moderately wide variation in quality of the output. The core demonstration in cells or mice in any gene therapy paper can be recreated in a laboratory for 100,000 or less, and much of that cost lies in setting up the protocols, not actually running them or assessing the mice. That is far from good enough for a study drug entering the clinic, however. It does in fact cost a few million to assemble a suitable infrastructure to narrow down the product quality to a level suitable for medicine. Appropriately manufactured drug product needs to be used in the definitive pre-clinical toxicity tests as well (non-GLP experiments can provide early stage guidance to select drug candidates and inform the toxicity models).
The focus on developing the overall development plan and required infrastructure and embracing its necessity from the start is one of the distinguishing marks between successful and likely-to-fail startup companies. Smaller startups are able to make enormous advances with relatively little initial funding nowadays, often stimulated with local seed investments. The next phase during the "valley of death" selects the ones which will continue to grow, as they are able to obtain follow-on funding for the more financially challenging phases of the development path. In order to obtain such follow-on funding, a solid and living development plan and meticulous execution of the steps (and if needed, adjustments to the plan!) are key. It pays to be data driven. So is making sure one always has a little extra financial buffer before the next round of funding is thought to be needed, as milestones are always harder to meet and may take a little bit longer. Having to go back for more money before a value inflection milestone is a hit will cost dearly.
Regulation is Complex, and Guidance is Necessary
I would not advocate start up founders attempting to navigate the drug development pathway and regulatory system by themselves. While founders as a category are obviously capable of rapid self-education, in the case in which they are not yet trained and have access to expertise, this isn't in the same category of difficulty as, say, raising the first round with a lead investor (and we all know how difficult that is). It is a much more complex, living, constantly dynamic system that changes in its nuances year to year, and is as much about actual practice (interpretation of regulations), good people, and knowledgeable resources, as it is about the regulations as written.
Find a guide who understands drug development and the regulatory systems you intend to work with very early in the life of the company, soon after founding, and preferably before even starting on the development work - as that work will be strongly shaped by the nature of the indications you choose. Talk to several such people to obtain different views of the development path and regulatory field, and engage one as a consultant and truly integral part of your team. Use smart outsourcing for those activities, which are much better done in specialized (large scale) vendors, and use their highly specialized expertise in a true team like fashion. Never lose oversight though, and manage for success with your associated expert partners as extended team members.
In summary, drug development is a challenging road - don't let anyone tell you differently. The reward at the end is building an extended team with highly specialized complex expertise, now successfully applied, and resulting in the ability to meaningfully improve the lives of patients. Once the core engine is built and running, many projects can be taken through the pipeline and new medical frontiers can be forever changed.
Dementia Risk Trends Downward and Later in Life, Due in Part to Cardiovascular Health
Research papers and popular science articles noting the ongoing decline in dementia risk have become a regular occurrence. Since dementia is driven in part by cardiovascular aging, it is tempting to suggest that this is a side-effect of the improvements in control over blood pressure and treatment of cardiovascular disease obtained in recent decades. From studies that have run the numbers, that incremental progress is as much due to reductions in smoking as it is to the deployment of successful medications such as statins. We do not yet live in an age in which medical technology has reliably outpaced lifestyle choice in the matter of aging and age-related disease. Interesting, those researchers who run the numbers on dementia suggest that improvements in cardiovascular health cannot explain all of the reduction in dementia risk.
Cardiovascular decline contributes to dementia in a number of ways. Firstly, capillary networks spread throughout tissues become less dense, and so less able to deliver sufficient nutrients and oxygen to cells. Declining fitness and heart failure achieve a similar outcome, in different ways. Blood vessels become less elastic with age, causing the increase in blood pressure known as hypertension. Blood vessel walls become compromised by the fatty plaques of atherosclerosis, initially seeded by an excessive inflammatory reaction to oxidized lipids in the bloodstream, but eventually growing to distort, narrow, and block blood vessels. The combination of increased blood pressure and weakened blood vessels is damaging to sensitive tissues, causing cell death and structural harm. In the brain, aging is accompanied by many tiny, silent strokes, each destroying a minuscule section of brain tissue - but it adds up over time.
Considering the damage done by the above processes, what might account for the missing benefits that do not arise from either slowing or compensating for cardiovascular degeneration in aging? Age-related dysfunction of the immune system might be a candidate. All neurodegenerative disease appears to have an inflammatory component, and the immune system of the central nervous system is arguably far more complex and far more involved in correct function of tissue than is the case elsewhere in the body. Further, better lifestyle choices and better control over infectious disease may well lead to, all other things being equal, a slower decline into immunosenescence. This is speculative thinking, however, and a thesis that would have to be proven from the data.
Dementia trend shows later onset with fewer years of the disease
A recently released study indicates that dementia's impact might be compressing a bit. That is, people might be developing dementia later and living with it for a shorter period of time. In data from four different time periods over a period of 30 years, the mean age at dementia onset increased, while the length of time living with dementia decreased. Is it because prevention and care of stroke today is superior compared to decades ago? Stroke is a major risk factor for dementia.
"Prevention of stroke and reduced impact of stroke are great advances, but neither completely explains the trend we are seeing. We are looking at other causes, such as lower burden of multiple infections because of vaccination, and possibly lower levels of lead or other pollutants in the atmosphere. Early education and nutrition might also play a role. Stroke risk has decreased because of greater control of blood pressure. In the past, if you had a stroke you were at 90 percent greater risk to develop dementia. Today, you have a 40 percent greater risk."
Are Trends in Dementia Incidence Associated With Compression in Morbidity?
A total of 5,205 participants from the Framingham Original and Offspring cohorts were studied. Four epochs were considered from 1977-1984 to 2004-2008. Gender and education adjusted 5-year mortality risks were estimated using delayed entry Cox models with the earliest epoch as reference category. Stratified analyses by sex, education, and age were undertaken. A nested case control study of 317 dementia cases and 317 controls matched on age, gender and epoch was initiated.
In the whole sample, 5-year mortality risk has decreased with time, it was 33% lower in the last epoch compared to the earliest. In the 317 persons who developed dementia, age at onset increased (1.5 years/epoch), and years alive with dementia decreased (1 year/epoch) over time. We observed however, a decreased adjusted relative mortality risk (by 18%) in persons with dementia in 1986-1991 compared to 1977-1983 and no significant change from then to the latest epoch. The nested case control study suggested in matched controls that 5-year mortality relative risk had increased by 60% in the last epoch compared to Epoch 1.
In conclusion, in the Framingham Heart Study population, in the last 30 years, disease duration in persons with dementia has decreased. However, age-adjusted mortality risk has slightly decreased after 1977-1983. Consequences of such trends on dementia prevalence should be investigated.
Recent Research on the Benefits of Exercise in Later Life
A sizable body of work points to the ability of older individuals to continue to obtain benefits through regular physical activity, and particularly in the case of strength training. A perhaps surprisingly large fraction of what is commonly regarded as an inevitable decline in physical fitness and muscle quality with age is in fact the result of lifestyle choices - in particular the choice to exercise less, and the failure to work on maintenance of strength in muscles. We live in an age of comparative comfort, surrounded by low cost transportation machinery, calories, and tools to substitute for physical effort. The result is a growing number of people who are weak and overweight in comparison to their ancestors. Those ancestors still had a much worse time of it, of course, given the absence of modern medicine and sanitation, but we sabotage ourselves nonetheless.
Today I'll point out a few recent papers on activity and strength (or lack thereof), and the benefits realized (or lost). They may for interesting reading, but I think it is important to bear in mind that this is only of interest because exercise is essentially free, and is a reliable source of the benefits it provides. These benefits are not large in the grand scheme of things: 75% of the fittest people fail to reach 90 years of age. It is impossible to add decades to human life spans through exercise. When looking ahead to the future, the quality and length of our lives will become ever more determined by the state of progress in rejuvenation therapies, treatments capable of repairing the cell and tissue damage that causes aging, and ever less by modestly effective approaches to good general health, a few of which can slightly slow the progression of that damage. Large gains can only arrive through the right sorts of progress in medical science.
Resistance training enhances recycling capacity in muscles
Autophagy is a major catabolic route in cells responsible for the clearance of proteins and organelles. Pathological levels of autophagy are associated with muscle wasting, but physiological levels are important for cellular recycling. In the present study, indicators of autophagy and unfolded protein response (UPR), which is another system for maintaining cellular homeostasis, were investigated from the muscle biopsies after a single bout of resistance exercise and after 21 weeks of resistance training in previously untrained young and older men.
Aging may blunt some of the positive effects of resistance training when it comes to improvement in muscle quality, but the researchers reported that UPR that is induced by the accumulation of misfolded proteins in endoplasmic reticulum (ER) was activated by a bout of unaccustomed resistance exercise regardless of age. Skeletal muscle appears to adapt to resistance exercise similarly in young and older people in many ways.
Exercise after a heart attack. It could save your life
Becoming more physically active after a heart attack reduces the risk of death. A study that followed more than 22,000 patients found that those who became more physically active after a heart attack halved the risk of death within four years. Levels of physical activity were reported 6-10 weeks and 12 months after the heart attack. The difference between answers was considered a change in physical activity over the year following the heart attack.
On both occasions, patients were asked how many times they had exercised for 30 minutes or longer during the previous seven days. Patients were categorised as constantly inactive, reduced activity, increased activity, or constantly active. A total of 1,087 patients died during an average follow-up of 4.2 years. The researchers analysed the association between the four categories of physical activity and death, after adjusting for age, sex, smoking, and clinical factors. Compared to patients who were constantly inactive, the risk of death was 37%, 51%, and 59% lower in patients in the categories of reduced activity, increased activity, or constantly active, respectively. "Our study shows that this advice applies to all heart attack patients. Exercise reduced the risk of death in patients with large and small myocardial infarctions, and for smokers and non-smokers, for example."
Sitting is bad for your brain - not just your metabolism or heart
Researchers recruited 35 people ages 45 to 75 and asked about their physical activity levels and the average number of hours per day they spent sitting over the previous week. Each person had a high-resolution MRI scan, which provides a detailed look at the medial temporal lobe, or MTL, a brain region involved in the formation of new memories. The researchers found that sedentary behavior is a significant predictor of thinning of the MTL and that physical activity, even at high levels, is insufficient to offset the harmful effects of sitting for extended periods.
This study does not prove that too much sitting causes thinner brain structures, but instead that more hours spent sitting are associated with thinner regions, researchers said. In addition, the researchers focused on the hours spent sitting, but did not ask participants if they took breaks during this time. The researchers next hope to follow a group of people for a longer duration to determine if sitting causes the thinning and what role gender, race, and weight might play in brain health related to sitting.
Study highlights need for strength training in older women to ward off effects of aging
"Frailty progresses with aging, but older women who engage in a high level of daily physical activity can reverse certain characteristics related to aging, such as slow walking and decreased function. But for women over the age of 75, muscle strength and endurance declines. Starting resistance exercise when they are young and continuing it is important so that when they reach a very advanced age they have already built up their strength and endurance reserves."
The study looked at 46 women across two different age ranges, 60-74 and 75-90, to learn how physical activity affects frailty differently in the two groups. Researchers found that there was a larger difference between the two groups in terms of muscle strength and endurance among those who were very physically active. With mobility - as measured by the length of a person's step - and basic functional ability, there was a gap between the two age groups among women who engaged in minimal physical activity. However, that gap disappeared if they did a high level of physical activities. "Their main physical activities consisted of light gardening, light housework and stretching. Is this because they are still working and don't have time for exercise, or do they think they are healthy and don't need to? It appears that committing to regular exercise is not yet a standard part of older women's lifestyles and is instead a reactive behavior to, for example, falls or illness."
Another Example of a Marginal Senolytic Drug Candidate
Today, let us consider what happens when a new area of medical development arises, attracts a great deal of research funding, and then and one or more companies raise even larger amounts of venture funding to take the first therapies to the clinic. This is the case for senolytics, the development of therapies - mostly pharmaceuticals - that can selectively destroy senescent cells. Good evidence for these cells to be a root cause of aging has existed for decades, but it wasn't until 2011 that research and scientific funding institutions were presented with animal study data that they couldn't continue to ignore. The years since have been a steady avalanche of ever more funding, evidence to link senescent cells to specific age-related conditions, and demonstrations of reversal of aspects of aging in mice through clearance of senescent cells.
What happens is that people take notice. Any group able to write a credible grant proposal in the aging research community has probably by now written several on the topic of cellular senescence. Grant writing follows the state of funding, and all academic organizations tend to steer themselves towards the better funded areas of their field. Equally, anyone in a position to start a pharmaceutical company or spin off a new program in their existing company is certainly giving strong consideration to senolytic research given the 300 million or so that Unity Biotechnology has raised to date. The upshot of all this is that a great deal of discovery work is taking place, both inside and outside the scientific community; people are sifting drug databases and the compounds of the natural world in search of gold. Of course, the median result is much less valuable.
In any sort of drug discovery research, the outcome of the average well-informed project is usually many dead ends and a marginal lead or two if luck is with the researchers. Good results are rare. This means that the present few effective senolytics will soon be vastly outnumbered by marginal and alleged senolytics, the latter being those for which the research community struggles to replicate results. That in and of itself usually indicates that the effect size is small, or that reported positive effects are due to experimental error. Going forward, as the public at large gains a greater awareness of senescent cells and senolytics, supplement makers will seize upon any plant extracts claimed to have (likely tiny) effects on senescent cells, and start marketing to the gullible. The first thing you should look at for any newly claimed senolytic is the size of the effect. Most can be safely ignored on this basis alone, as is the case in the cell culture study noted here.
Blocking negative effects of senescence in human skin fibroblasts with a plant extract
Cellular senescence is involved in the development of age-related diseases and the loss of tissue functionality with age. Senescent cells accumulate in vivo and their selective elimination increases the healthspan of mice. While transiently present senescent cells have beneficial functions in wound healing, their chronic persistence and accumulation with age negatively affects the surrounding tissue by the senescence-associated secretory phenotype (SASP). This consists of pro-inflammatory cytokines and chemokines, extracellular matrix (ECM) remodelling proteases and growth factors and results in a vicious cycle of progressive functional loss in tissues and organs.
Negative effects of cellular senescence can be counteracted by: (i) delaying the loss of cell type specific functionality mediated by senescence-associated de- or trans-differentiation, (ii) interfering with the negative effects of SASP or by (iii) selectively eliminating senescent cells. Indeed, several clinically approved drugs including glucocorticoids, metformin, rapamycin, and JAK inhibitors attenuate the SASP. In addition, senolytic substances have been identified including quercetin, dasatinib, navitoclax, piperlongumine, fisetin, A1331852, A1155463 and FOXO4 inhibiting peptides.
Solidago virgaurea, also known as goldenrod, is traditionally used as an anti-inflammatory herbal medicine. A recent study identified 3,4,5-tri-O-caffeoylquinic acid as the constituent with the highest reduction of tumour necrosis factor-alpha and interleuin (IL)-1β concentrations. However, the effect of extracts from S. virgaurea on cellular senescence and fibroblast subpopulations have not been studied so far. Here we report an alcoholic extract of Solidago alpestris (1201) with the ability to block negative effects of senescence in human skin fibroblasts including the SASP in vitro. We screened seven different plant extracts. 1201 showed the clearest effects in terms of changing cell morphology and of reducing SA-β-galactosidase activity and was therefore selected for further studies.
The extract 1201 exhibited weak senolytic activity and delayed the acquisition of a senescent phenotype. When administered to stress-induced premature senescent fibroblasts, this extract changed their global mRNA expression profile and particularly reduced the expression of various SASP components, thereby ameliorating the negative influence on nearby cells. The caffeoylquinic acids with their anti-inflammatory property are likely to be candidates for the SASP-attenuating property of 1201, whereas the three derivatives of quercetin, one of the three naturally occurring senolytics reported so far, could be the driving force behind the slow selective elimination of senescent cells. Thus, the investigated plant extract represents a promising possibility to block age-related loss of tissue functionality.
The Fable of the Dragon-Tyrant, and the Courage to Speak Out in Opposition to Aging
It has been thirteen years since Nick Bostrom published The Fable of the Dragon-Tyrant, a clear call to action regarding our relationship with aging and medical technology. The world has come to treat aging and the vast tide of death and suffering it causes as something set in stone, and so it was, for in past generations even the best of medicine could do little to influence the course of aging. Yet today we stand in the midst of revolutionary progress in biotechnology, and all of the old limits and incurable conditions might be addressed given sufficient funding and will. Unfortunately, a majority of people continue to hold that old belief that aging cannot be changed, even as we move into an era in which it is possible to create real, working rejuvenation therapies.
Our community is one of patient advocacy, philanthropic support of science, research into aging, and medical development, aimed squarely at the defeat of aging and the deployment of means of human rejuvenation in the clinic. Over the years, philanthropic funding and research programs have produced results, and the first rejuvenation therapies, those based on clearance of senescent cells, are entering clinical trials. Our numbers have grown considerably since the Fable of the Dragon-Tyrant was first written, and many of the newer faces might not even know of this important work. So is pleasant to see the sizable audience and effort put into this adaptation by the same YouTube creators who produced the excellent Why Age? Should We End Aging Forever? last year. Take a look and see what you think.
The Fable of the Dragon-Tyrant
Once upon a time, the planet was tyrannized by a giant dragon. The dragon stood taller than the largest cathedral, and it was covered with thick black scales. Its red eyes glowed with hate, and from its terrible jaws flowed an incessant stream of evil-smelling yellowish-green slime. It demanded from humankind a blood-curdling tribute: to satisfy its enormous appetite, ten thousand men and women had to be delivered every evening at the onset of dark to the foot of the mountain where the dragon-tyrant lived. Sometimes the dragon would devour these unfortunate souls upon arrival; sometimes again it would lock them up in the mountain where they would wither away for months or years before eventually being consumed...
Stories about aging have traditionally focused on the need for graceful accommodation. The recommended solution to diminishing vigor and impending death was resignation coupled with an effort to achieve closure in practical affairs and personal relationships. Given that nothing could be done to prevent or retard aging, this focus made sense. Rather than fretting about the inevitable, one could aim for peace of mind. Today we face a different situation. While we still lack effective and acceptable means for slowing the aging process, we can identify research directions that might lead to the development of such means in the foreseeable future. "Deathist" stories and ideologies, which counsel passive acceptance, are no longer harmless sources of consolation. They are fatal barriers to urgently needed action.
The quality and length of the rest of our lives depends on the degree to which the world at large - its research and development institutions, its public voices, its funding institutions - choose to bring an end to aging. It can be accomplished, but it will only be accomplished if a sufficiently large number of people first desire that goal, and then act on that desire. In an environment of widespread passive acceptance of a terrible status quo, persuasion is just as important as scientific progress.
A Set of Marginal and Alleged Senolytics Show No Meaningful Benefits in a Cell Study
Senolytic compounds are those that selectively destroy senescent cells. As the accumulation of senescent cells is one of the root causes of aging, and senescent cells contribute directly to many specific age-related diseases, there is some interest in the development of effective senolytics. As is the case for any field of medical development, however, there are as many marginal and possible senolytic drugs as there are useful and proven senolytic drugs. The size of effect, the nature of the side-effects, and the quality of the evidence all matter greatly - indeed, this is the whole of the point when looking at whether a particular compound is viable or not.
The researchers here report on a few of the marginals and the possibles, compared against navitoclax, and observed no useful effect in a cell study. This is useful confirmatory work, even through the outcome is to be expected based on past evidence, particularly for quercetin. That said, it is important to note that different types of senescent cell have been shown to have quite different degrees of vulnerability to various classes of senolytic. It isn't quite as straightforward as failure in one cell type disqualifying a potential senolytic completely, but more a consideration of the balance of evidence from multiple studies.
Senolytic drugs hold the perspective to specifically target senescent cells and thereby to rejuvenate tissues or organisms. Several compounds have been suggested to possess senolytic effects, including navitoclax (ABT-263), quercetin, danazol, and nicotinamide riboside. ABT-263 inhibits BCL-2 protein family members, which are crucial regulators of the apoptosis pathway. ABT-263 was shown to deplete senescent cells of human umbilical vein epithelial cells (HUVECs), IMR90 human lung fibroblasts, and murine embryonic fibroblasts, but not human primary pre-adipocytes. Danazol is a synthetic androgen with telomere elongating capacity, which has been used to target accelerated telomere attrition - a hallmark of aging and senescence. Quercetin is a proteasome activator with anti-oxidant properties that triggers apoptosis via the BCL-2 pathway. Nicotinamide riboside increases levels of nicotinamide adenine dinucleotide (NAD+). Aged mice supplemented with nicotinamide riboside revealed increased lifespan and rejuvenated muscle stem cells.
Primary cells undergo a limited number of divisions before entering the state of replicative senescence. The process of senescence induces changes in morphology, metabolism, secretory phenotype, and differentiation potential of cells, thereby having a significant impact on experimental outcomes and affecting their therapeutic potential. This applies particularly to mesenchymal stromal cells (MSCs), which raise high hopes in tissue engineering and are concurrently tested in a multitude of clinical trials. MSCs comprise a multipotent subset of cells, capable of differentiation towards osteogenic, chondrogenic, and adipogenic lineages. The selective removal of senescent MSCs from cultures might improve standardization and effectiveness of cell preparations for cell therapeutics in regenerative medicine. We have therefore directly compared the senolytic capacity of ABT-263, quercetin, danazol, and nicotinamide riboside in human MSCs during long-term culture.
The effects of these compounds were analysed during long-term expansion of MSCs, until replicative senescence. Furthermore, we determined the effect on molecular markers for replicative senescence, such as senescence-associated beta-galactosidase staining (SA-β-gal), telomere attrition, and senescence-associated DNA methylation changes. Experiments revealed that ABT-263 had a significant but moderate senolytic effect. This was in line with reduced SA-β-gal staining in senescent MSCs upon treatment with ABT-263. However, none of the drugs had significant effects on the maximum number of population doublings, telomere length, or epigenetic senescence predictions. Of the four tested drugs, only ABT-263 revealed a senolytic effect in human MSCs - and even treatment with this compound did not rejuvenate MSCs with regard to telomere length or epigenetic senescence signature. It will be important to identify more potent senolytic drugs to meet the high hopes for regenerative medicine.
DNA Demethylase Activation via Klotho Reduces Arterial Stiffening in Mice
Age-related hypertension is largely a consequence of arterial stiffening, as the loss of elasticity causes the evolved feedback mechanisms that control blood pressure to run awry. For the causes of blood vessel stiffening, we can look at, for example, cross-linking in the extracellular matrix, and senescent cells and other sources of inflammation producing calcification in blood vessel walls. Other sources of dysfunction appear to involve more complex and poorly understood changes in cell behavior, however. This includes the failure of vascular smooth muscle tissue to contract and dilate appropriately, and alterations in the activities of cells responsible for maintaining the structure of the extracellular matrix that determines the physical properties of blood vessel walls.
Changes in cell behavior are more complicated than purely chemical processes such as cross-linking, but also more comfortable for researchers used to the present dominant approach in medical research, which is to deliver new instructions to cells, in an effort to partially override their reaction to damage and the aged environment. The open access paper here is an example of the type. Benefits can be achieved in this way, as the stem cell research community has demonstrated over the past few decades, even though it is not the most optimal path forward for the treatment of aging. Override one narrow reaction to underlying damage, and the damage is still there, still causing all of its other secondary and later problems.
DNA demethylation is an important process that maintains transcriptional activity of genes. An increase in methylation in the promoter region of a gene diminishes the promoter activity and gene transcription. Numerous studies showed that DNA methylation is increased with age. Coincidently, the prevalence of arterial stiffness and hypertension also increases with age. Arterial stiffening is an independent predictor of cardiovascular outcomes, such as hypertension, myocardial infarction, cognitive decline in aging, stroke, and kidney diseases. However, the relationship of DNA methylation and aging-related arterial stiffening is unclear. Whether increased methylation led to arterial stiffening has never been determined. Physiologically, an appropriate methylation level is maintained by the balanced methyltransferase and demethylase activity. In this study, we assessed if activation of the demethylase affects arterial stiffening and hypertension in aged mice.
The Klotho gene was originally identified as a putative aging-suppressor gene in mice that extended lifespan when overexpressed and caused multiple premature aging phenotypes when disrupted. The Klotho level decreases with age, while the prevalence of arterial stiffness and hypertension increases with age. At age 70 years, the serum level of Klotho is only about one half of what it was at age 40 years. Moreover, the serum Klotho level is significantly decreased in patients with arterial stiffness in chronic kidney diseases. Our recent study showed that haplodeficiency of Klotho gene caused arterial stiffness. We found, in cultured renal tubule cells, that a small compound (compound H) may be a potential inducer of Klotho gene expression. Whether compound H promotes Klotho expression and release in vivo has never been determined. In this study, we investigated whether compound H increases Klotho levels and attenuates aging-associated arterial stiffening and hypertension.
Our results demonstrated that aging-related arterial stiffening and hypertension are attributed, at least in part, to the increased DNA methylation. Compound H activates demethylases and attenuates arterial stiffening and hypertension in aged mice likely via increasing the Klotho levels. Aging-related arterial stiffness was associated with accumulation of stiffer collagen and degradation of elastin. These changes were effectively attenuated by compound H, suggesting rejuvenation of aged arteries.
Glial Cell Behavior Critical to Proficient Central Nervous System Regeneration
Why can species such as salamanders regrow organs and limbs while mammals cannot? This proficiency even extends to portions of the central nervous system, such as the spinal cord. In recent years, researchers have made good progress in understanding exceptional regeneration, finding that, for example, differences in the behavior of immune cells called macrophages are essential to regrowth. In the central nervous system, glial cells are somewhat analogous to macrophages in other tissues, and in the research noted here, scientists report on evidence for an equivalent importance in mammalian versus salamander regenerative capacities.
Given the macrophage and glial cell connection, this area of comparative biology is moving of late from speculative to relevant to clinical development. Numerous research groups are investigating the alteration of macrophage and glial cell behavior in order to spur greater regeneration in mammals. These cells can be classified by their behavior, either aggressive and inflammatory while seeking out pathogens, or more focused on aiding regeneration. Both behaviors are needed, but in mammals, and in the old, there is too much of the first type and too little of the second type of behavior. In learning to adjust cell behavior to change this imbalance, the foundations may be laid for more profound enhancements of regeneration in the years ahead, building on what is learned from salamanders.
One of the most vexing problems with spinal cord injuries is that the human body does not rebuild nerves once they have been damaged. Other animals, on the other hand, seem to have no problem repairing broken neurons. Researchers have studied an amphibian known as the axolotl or Mexican salamander. Captive-bred axolotls are frequently used in biological research, both to learn from the animal's remarkable ability to regenerate body parts and to help inform conservation efforts.
When an axolotl suffers a spinal cord injury, nearby cells called glial cells kick into high gear, proliferating rapidly and repositioning themselves to rebuild the connections between nerves and reconnect the injured spinal cord. By contrast, when a human suffers a spinal cord injury, the glial cells form scar tissue, which blocks nerves from ever reconnecting with each other.
Researchers traced the molecular mechanisms at work in each case. They found a particular protein called c-Fos, which affects gene expression, is essential to the processes axolotls use to repair injured nerves. While humans also have c-Fos, in humans the protein functions in concert with other proteins, in the JUN family, that cause cells to undergo reactive gliosis, which leads to scar formation. In axolotls, this molecular circuitry is carefully regulated to direct axolotl glial cells toward a regenerative response instead.
"Our approach allows us to identify not just the mechanisms necessary to drive regeneration in salamanders but what is happening differently in humans in reposes to injury. In addition to spinal cord regeneration, our work also focuses on other forms of regeneration including scar-free wound healing and limb regeneration."
Towards a Better Epigenetic Clock
Researchers here report on an improved version of the epigenetic clock. A few carefully defined patterns of DNA methylation, including the original epigenetic clock, correlate quite closely with age. The current commercial implementation of the epigenetic clock, MyDNAge, has a margin of error of two years or so. While the consensus is that the clock reflects biological age, it is still the case that we might ask what exactly is being measured. The answer to that question remains to be established. It is plausible that DNA methylation changes with age are a reaction to all of the forms of cell and tissue damage that drive aging, but this is by no means certain - it could be more specific than that, tied to only some of the causes of aging.
One of the major goals of geroscience research is to define "biomarkers of aging", which can be thought of as individual-level measures of aging that capture inter-individual differences in the timing of disease onset, functional decline, and death over the life course. While chronological age is arguably the strongest risk factor for aging-related death and disease, it is important to distinguish chronological time from biological aging. Individuals of the same chronological age may exhibit greatly different susceptibilities to age-related diseases and death, which is likely reflective of differences in their underlying biological aging processes. Such biomarkers of aging will be crucial to enable evaluation of interventions aimed at promoting healthier aging, by providing a measurable outcome, which unlike incidence of death and/or disease, does not require extremely long follow-up observation.
One potential biomarker that has gained significant interest in recent years is DNA methylation (DNAm). Chronological time has been shown to elicit predictable hypo- and hyper-methylation changes at many regions across the genome, and as a result, the first generation of DNAm based biomarkers of aging were developed to predict chronological age. The blood-based algorithm by Hannum and the multi-tissue algorithm by Horvath produce age estimates (DNAm age) that correlate with chronological age for full age range samples. Nevertheless, while the current epigenetic age estimators exhibit statistically significant associations with many age-related diseases and conditions, the effect sizes are typically small to moderate. One explanation is that using chronological age as the reference, by definition, may exclude CpG sites whose methylation patterns don't display strong time-dependent changes, but instead signal the departure of biological age from chronological age. Thus, it is important to not only capture CpG sites that display changes with chronological time, but also those that account for differences in risk and physiological status among individuals of the same chronological age.
Previous work by us and others have shown that "phenotypic aging measures", derived from clinical biomarkers, strongly predict differences in the risk of all-cause mortality, cause-specific mortality, physical functioning, cognitive performance measures, and facial aging among same-aged individuals. What's more, in representative population data, some of these measures have been shown to be better indicators of remaining life expectancy than chronological age, suggesting that they may be approximating individual-level differences in biological aging rates. As a result, we hypothesize that a more powerful epigenetic biomarker of aging could be developed by replacing prediction of chronological age with prediction of a surrogate measure of "phenotypic age" that, in and of itself, differentiates morbidity and mortality risk among same-age individuals.
Using a novel two-step method, we were successful in developing a DNAm based biomarker of aging that is highly predictive of nearly every morbidity and mortality outcome we tested. Training an epigenetic predictor of phenotypic age instead of chronological age led to substantial improvement in mortality/healthspan predictions over the first generation of DNAm based biomarkers of chronological age. In doing so, this is the first study to conclusively demonstrate that DNAm biomarkers of aging are highly predictive of cardiovascular disease and coronary heart disease. The new measure, DNAm PhenoAge, also tracks chronological age and relates to disease risk in samples other than whole blood. Finally, we find that an individual's DNAm PhenoAge, relative to his/her chronological age, is moderately heritable and is associated with activation of pro-inflammatory, interferon, DNA damage repair, transcriptional/translational signaling, and various markers of immunosenescence: a decline of naïve T cells and shortened leukocyte telomere length.
Extracellular Vesicles Used to Promote Heart Regeneration in Rats
First generation stem cell therapies largely achieve their results through brief signaling changes, not through any lasting work on the part of the transplanted cells. Those cells in fact die quite rapidly, but the signals they secrete while still alive change the behavior of native cells. This produces benefits such as reduced inflammation or improved regenerative capacity. Given this, why not deliver the signals instead of the cells? It could in principle be an easier, less complex task. Much of cell signaling involves the exchange of extracellular vesicles, tiny membrane-bound packages of molecules. Numerous groups are presently engaged in animal studies of vesicle-based approaches to regenerative therapy, and the one noted here is representative of the type.
The adult human heart cannot regenerate itself after injury, and the death of cardiac muscle cells, known as cardiomyocytes, irreversibly weakens the heart and limits its ability to pump blood. Researchers have turned their focus to stem cell transplantation for cardiomyocyte replacement and recovery of heart function, but studies have shown that implanted stem cells have difficulty surviving and differentiating into cardiomyocytes to repair the damaged muscle. When stem cells were differentiated into cardiomyocytes before implantation, heart function improved, but with a complication: the implanted cardiomyocytes did not contract synchronously with the heart, thus causing potentially lethal arrhythmias (abnormal heart rhythm).
A team of researchres has designed a creative new approach to help injured hearts regenerate by applying extracellular vesicles secreted by cardiomyocytes rather than implanting the cells. Cell-secreted microvesicles are easy to isolate and can be frozen and stored over long periods of time. Such an "off-the-shelf" product has several major advantages over cell therapy-1) it can be used immediately in an acute-care setting, unlike cells that can take months to isolate and grow; 2) it does not cause arrhythmia (which often occurs when cells are transplanted); and 3) the regulatory path towards clinical application is much simpler than for a cell-based therapy.
It is well known from numerous clinical studies that most of the implanted stem cells are washed away within hours of the treatment, but there still are beneficial effects. This has led to the informal "hit-and-run" hypothesis, meaning that the cells deliver their cargo of regulatory molecules before leaving the site of injury. "Consistent with this hypothesis, we postulated that the benefits of cell therapy of the heart could be coming from the secreted bioactive molecules (such as microRNAs), rather than the cells themselves. So we explored whether the benefits of cell therapy of the injured heart could be achieved without using the cells. This way, we would largely simplify the translation into the clinic, and avoid the burden of arrhythmia associated with implantation of contractile cells."
The team derived cardiomyocytes from adult human stem cells and cultured these cells to allow them to secrete extracellular vesicles. The vesicles secreted by undiffereniated stem cells were used for comparison. The researchers then used next-generation sequencing to read their messages and instructions. They found that the extracellular vesicles from cardiomyocytes - but not from stem cells - contained cardiogenic and vasculogenic microRNAs that are very powerful regulatory molecules. The team encapsulated the vesicles in a collagen-based patch that slowly released them over the course of four weeks when implanted onto the injured heart in rat models of myocardial infarction. "We were really excited to find that not only did the hearts treated with cardiomyocyte extracellular vesicles experienced much fewer arrhythmias, but they also recovered cardiac function most effectively and most completely. In fact, by four weeks after treatment, the hearts treated with extracellular vesicles had similar cardiac function as those that were never injured."
Two Faces of Macrophages in Cancer Tissue
This popular science article looks at opposing views of the role of macrophages in the development of tumors. Some groups see macrophages as aiding the cancer, and want to suppress them, while others are engaged in turning macrophages into an effective weapon to destroy cancer cells. This two-faced nature echos a range of unrelated work on macrophage behavior. These cells can be classed by their activities into what are known as polarizations. The M1 polarization is aggressive and inflammatory, willing to attack cells and pathogens, while the M2 polarization aids tissue growth and regeneration. The balance between the two shifts according to circumstances. Both are necessary, but M1 is too prevalent throughout the body in older individuals, hindering tissue maintenance. In cancers, the problem is reversed: too many M2 macrophages are present to help the cancer, while too few M1 macrophages actively attempt to destroy its cells.
In the late 2000s, researchers found that leukemia cells highly expressed a gene encoding CD47, a surface molecule known for its role on normal, healthy cells as a "don't eat me" signal to phagocytosing macrophages. Researchers demonstrated in cell culture experiments that macrophages only engulfed leukemia cells that did not display CD47 on their surface, and since then have found CD47 on every type of cancer they've been able to get their hands on. "It was shocking. We knew that we were on the track of a potential therapeutic." At least three biomedical companies have raised and invested tens of millions to test drugs that block CD47.
But back in 2008, when the researchers first tried to publish work on how macrophages engulfed leukemia cells lacking CD47, reviewers didn't buy it. Since the 1980s, cancer researchers have linked macrophages and macrophage-stimulating genes to tumor growth and poor outcomes for cancer patients, and the cells had been pegged as nothing but bad news when it came to cancer. In 1996, for example, researchers reported that women whose breast cancer biopsies contained a high density of macrophages were much more likely to succumb to the disease over the subsequent five years than those with low densities. The same correlation was later confirmed in a dozen other types of cancer. These cells earned the name tumor-associated macrophages, or TAMs, and research focused on where they came from and how to block or deplete them. The data suggesting that macrophages could help defeat cancer just didn't fit.
TAMs, which can make up as much as 50 percent of a tumor's mass, had been found to repress other immune cell activity, encourage blood and lymph vessel development to support growing tumors, and help cancer cells metastasize to new sites in the body. But over the past decade, some research has surfaced to support the conclusion that TAMs may have an upside. "Several years ago, the idea was, 'Let's deplete these cells because they are bad.' I think now we are back to saying, 'Maybe it's just very complex.'"
Even as therapies that block TAM activity or prevent macrophage recruitment to tumors reach clinical trials, many researchers are not ready to give up on what macrophages may have to offer in the fight against cancer. There's no question that macrophages can participate in antitumor responses, "it's just that the tumors develop a way of polarizing or educating those macrophages to help the tumors rather than destroy them." Many researchers are now taking advantage of macrophages' plasticity to re-educate the cells to work for the patient. One way to switch TAMs from what's known as the M2 phenotype, which promotes cancer growth, to the immune-boosting M1 phenotype is to provide the cells with proinflammatory stimuli, such as interferons or ligands for Toll-like receptors. Alternatively, researchers can directly target molecular switch proteins responsible for driving M2 characteristics, such as PI3-kinase and the transcription factor STAT3. In animal models, drugs that inhibit these molecules have successfully skewed TAMs toward M1 phenotypes and shrunk tumors.
Exercise Increases the Rate at Which New Heart Cells are Produced
To follow on from yesterday's set of exercise related research, here is an interesting note on what exercise does to the basis for heart tissue maintenance. The heart is one of the least regenerative organs in mammals, not capable of repairing itself to any significant degree following injury. Nonetheless, within those limited bounds, exercise makes a sizable difference. This is supported by the evidence showing that heart disease patients have a better prognosis when they maintain a program of exercise, even to the lesser degree that they are capable of sustaining.
In a new study performed in mice, researchers uncovered one explanation for why exercise might be beneficial: It stimulates the heart to make new muscle cells, both under normal conditions and after a heart attack. The human heart has a relatively low capacity to regenerate itself. Young adults can renew around 1 percent of their heart muscle cells every year, and that rate decreases with age. Losing those cells is linked to heart failure, so interventions that increase cell formation have the potential to help prevent it.
"We wanted to know whether there is a natural way to enhance the regenerative capacity of heart muscle cells. So we decided to test the one intervention we already know to be safe and inexpensive: exercise." To test its effects, the researchers gave one group of healthy mice voluntary access to a treadmill. When left to their own devices, the mice ran about 5 kilometers each day. The other healthy group had no such gym privileges, and remained sedentary.
To measure heart regeneration in the mouse groups, the researchers administered a labeled chemical that was incorporated into newly made DNA as cells prepared to divide. By following the labeled DNA in the heart muscle, the researchers could see where cells were being produced. They found that the exercising mice made more than 4.5 times the number of new heart muscle cells as did the mice without treadmill access. After experiencing heart attacks, mice with treadmill access still ran 5 kilometers a day, voluntarily. Compared with their sedentary counterparts, the exercising mice showed an increase in the area of heart tissue where new muscle cells are made. The researchers now plan to pinpoint which biological mechanisms link exercise with increased regenerative activity in the heart.
More Supporting Evidence for the "Amyloid then Tau" View of Alzheimer's Disease
Alzheimer's disease is a complex condition because the brain is a complex environment. Neurodegeneration is caused by the accumulation of two forms of protein aggregate, amyloid-β and tau. There is evidence to suggest that each can spur the generation of the other, and that they act in synergy to cause worse harm to the brain than either would alone, but the present consensus is that amyloid-β precedes tau in the development of the condition. It may even turn out to be the case that tau causes the majority of the damage in the later stages of the condition, not amyloid-β.
Whether this means that amyloid-β causes tau aggregration is another question entirely, and one that is unlikely to be adequately answered without the development of reliable means to clear amyloid-β from the brain. That has so far proven to be more challenging than was originally hoped, and even those clinical efforts that did remove amyloid-β to some degree failed to show benefits in patients. Varied factions within the research community have their theories as to why this might be the case, and scientists here note one of them - that by the time clinical symptoms manifest, it is past the point at which removing amyloid-β would be helpful, as tau has become the major issue.
The rate at which the protein amyloid-β accumulates into the sticky plaques associated with Alzheimer's disease (AD) is already slowing by the time a patient would be considered to have preclinical AD, according to a longitudinal study of healthy adults. The research suggests that anti-amyloid therapies would be most effective before individuals reach the threshold for preclinical AD, long before the first signs of memory issues. Determining how early to intervene is a central challenge in slowing the progression of AD. Clinical trials of drugs for lowering amyloid levels typically involve individuals who do not yet have symptoms but are considered "amyloid positive" and at risk for developing AD. These trials have been largely unsuccessful, perhaps because they begin too late.
To untangle the relationship between amyloid-β, the AD-associated protein tau, and memory impairment over time, researchers studied healthy men and women between the ages of 61 and 88 over a five-year period. Brain scans revealed that even trace amounts of amyloid-β predicted future levels of tau, and both preceded memory decline. The researchers found that greater baseline levels of amyloid-β were associated with a faster rate of accumulation, but only to a point, after which higher amyloid-β levels were associated with slower accumulation. "It appears rates of amyloid accumulation already begin to slow in preclinical AD, suggesting it is a relatively late stage of AD progression. Thus, it is crucial to examine older adults early, before amyloid levels have saturated, to intervene to slow disease progression."
Does Immune System Decline Determine the Contribution of Senescent Cells to Aging?
The self-experimentation rumor mill has it that presently available senolytic pharmaceuticals, repurposed chemotherapeutics that can selectively destroy some fraction of senescent cells, can show results for inflammatory conditions in elderly individuals. Equally, they don't appear to produce evident benefits in basically healthy 40-somethings. While senescent cells are indeed a source of chronic inflammation, one should never act on whispers: wait until data from the present or near future clinical studies is published and ratified. We can certainly debate and hypothesize, however, where anecdotes overlap with existing animal data and supporting evidence from other lines of research.
My thinking runs much as follows: the immune system is responsible for destroying cancerous cells and those senescent cells that fail to self-destruct. Immune cells are very efficient when it comes to this task, and thus the risk posed by both of these classes of harmful cell remains low for much of life. This is the case until immune function has declined significantly with age; one can look at the models that correlate cancer risk with atrophy of the thymus, and therefore reduction in T cell generation, for example. It fits well. Peak cancer risk lies between 60 and 80, which is also, more or less, where one starts to see incidence of inflammatory age-related conditions linked to cellular senescence increase greatly.
No-one has yet run the studies needed to build a decent picture of senescent cell burden by age. I will go out on a limb and wager that when this is accomplished, the numbers will closely mirror both cancer risk and loss of immune function. Some researchers have been thinking along these lines for a while now, and I noticed this commentary in the middle of a recent interview conducted by the Life Extension Advocacy Foundation volunteers:
Research suggests that "inflammaging" plays a key role in aging; many publications also suggest that of the various sources of this chronic age-related inflammation, senescent cell accumulation and the senescence-associated secretory phenotype it produces is the primary culprit. What might we expect to see if therapies to remove these problem cells are used in people?
I have a different view from the majority. I was one of the big fans of senescent cells, and I was 100% inspired by the idea of finding them, eradicating them, and using that for rejuvenation. However, after we spent several years very focused on an extensive study of senescent cells in vivo, we realized that for a major portion of the mouse lifespan, we simply cannot find these cells. This is not because they don't exist; I think they appear pretty frequently during our lives and mice's lives, but they are being very efficiently eradicated by the immune system.
Whether the changes in inflammation in vivo with age are due to the activity of senescent cells is a big question, because when we tried to find these cells in, for example, an irradiated organism, most of the cells that people thought were senescent before the existence of conventional biomarkers appeared to be just parts of the immune system, which is malfunctioning in aging and created the appearance of senescent cells. Macrophages frequently become positive for biomarkers of senescent cells, and people using these biomarkers without looking carefully call them senescent. You might say that does not matter because the whole concept did not change that much; who cares what you name these cells? If certain cells with certain properties accumulate with life and if they secrete something bad, the concept is still intact, and I agree with that.
However, knowing the nature of these cells, we can choose the right weapon against them, and as long as we try to kill the cells that we can make senescent in culture and think we are killing the same cells in vivo, I think that we are on the wrong path. This is my first problem; my second problem is that the accumulation of senescent cells means a malfunction of the immune system because the normal immune system gets rid of them very efficiently. If you kill a cell that cannot be removed by the immune system, you are not getting rid of this potential garbage; you turn it into a different type of garbage. Because to eradicate a senescent cell, something needs to find it and eat it, swallow it, such as a macrophage.
If this function is not working very well and you simply help the immune system by killing these cells, they still remain in the same place where they were; they're just dead. Maybe this is good or not; maybe this will indeed help another branch of the immune system to clean up. I think, in general, that this is not obvious; first, it's not obvious to me that senescent cells are unique in creating the "smell" of garbage that leads to inflammation or if it's only one of many types of cells that become damaged and accumulate with age. I'm not sure that killing them physically really helps to improve the situation, because you are creating a wave of remains that has to be taken care of, too.
I personally chose an approach to invest in the immune system and repair its function so that it can do its job better, instead of us thinking that we can substitute it. So far, in medicine, substitution of lost function has only worked well in orthopedics but not in other areas. Therefore, I think that we need to either invest in a mechanism that blocks the appearance of senescent cells or invest into the mechanism of natural eradication to make the immune system work better. For example, if the part of the immune system that is responsible for clearing senescent cells gets exhausted, you can always try to redirect adaptive immunity against them by vaccination; I would see that as a more appealing thing.
Significant Improvements to Chimeric Antigen Receptor T Cell Therapies Lie Ahead
Chimeric antigen receptor T cell (CAR-T) therapies have proven to be a promising advance in the state of the art when it comes to cancer immunotherapy, though there are certainly challenges remaining to be overcome. The real promise is not only the improved effectiveness, however, but rather that this technology platform offers the ability to treat many different cancers with only an incremental cost in adaptation to each new target.
Over the long term, economics is the driver of success in cancer research. Given that there are hundreds of types of cancer and only so many scientists and only so much funding, the most important lines of research and development are those that can be cost-effectively turned to address many or all cancers. The defeat of cancer in our lifetimes requires universal therapies. CAR-T as a technology platform is now well enough known and proven to be attracting a great deal of interest in its evolution and improvement. This is now beginning to manifest in proof of principle results such as those noted here.
There have been few cancer treatments with such a promising future as using the patient's own immune system. Known as chimeric antigen receptor T-cell therapy, or CAR-T, this treatment uses re-engineered killer T-cells to attack cancer cells, but it also causes potentially deadly side effects. Now, research is opening doors to making such therapy safer and more effective. The researchers see the current CAR-T system as having three major flaws: target specificity; strength of response; and lack of adaptive capability, which is essentially the issue of relapse. "Our system has the ability to address those three problems."
Traditional CAR-T is a treatment engineered for one specific patient to treat one specific type of cancer cell. The new refined system - called split, universal and programmable (SUPRA) CAR-T - can be continuously altered to target different types of cancer cells, turned on and off, and overall offers a significantly more finely tuned treatment than the current therapies. "Instead of thinking about CAR-T as engineering cells that kill cancer, the way I think about it is as an antibody that drags a killer T-cell with it. What's amazing about it is that once the CAR T-cell binds and activates, it will recruit more T-cells and make copies of itself. Drugs don't do that."
This overwhelming immune response is also what causes the severe side effects. And there have been advances in drug therapy to mitigate these side effects by blocking unnecessary portions of the immune response while still allowing the CAR-T to attack the cancer cells. And the greater number of cancer cells means a stronger immune response. But the SUPRA CAR-T system would let doctors deactivate the entire treatment in case the side effects became too severe. The normal immune system requires T-cells to sense two targets coming from an invader cell before it attacks it and SUPRA CAR-T works in the same way. Before SUPRA CAR-T attacks cancer cells, it needs to sense that both targets are present on the cell. If only one is present, the system isn't activated.
SUPRA CAR-T also splits the T-cell from the target-sensing portion of the system. The target on cancer cells is called an antigen and whichever antigen is chosen is sought out by an antibody on the CAR T-cells. The new system breaks apart the T-cell from the antibody and allows for the ability to switch targets. The ability to switch targets is what can prevent relapse in patients. Cancer cells are smart and will mutate to no longer display the target when they sense the T-cells attacking after attaching to it. The SUPRA CAR-T system allows the T-cells to attack a new target by simply injecting the patient with a new batch of antibodies rather than having to re-engineer the T-cells, which is the most expensive portion of the treatment.
The third feature this split system produces is the ability to finely tune how active the T-cell response, which helps mitigate the dangerous side effects of previous CAR-T systems. By introducing a third component that can block the bonding of the T-cell and the antibody, the SUPRA CAR-T system can be deactivated. The level of deactivation can be tuned by choosing the strength to which this third component binds to the antibody.