Every year a group of exceptional young scientists come to work on projects at the SENS Research Foundation in California and in allied laboratories around the country. Producing the rejuvenation therapies of tomorrow is a project that will last for decades: the researchers who will lead companies and academic laboratories into the final stretches to produce the first comprehensive rejuvenation toolkit are still undergraduates and postgraduates today, just starting their careers. It is a very exciting time to be in biotechnology.
It is of great importance that today's leaders in the field of aging research do better than their predecessors when it comes to presenting their field as the groundbreaking, revolutionary, exciting place that it will be over the next twenty years. The world is changing, biotechnology is advancing at a breakneck pace, and the medicine of ten or twenty years from now will look like science fiction already. Radical new possibilities are on the horizon, and doors are opening. Today's scientists must cultivate a next generation of researchers who see aging as the most important medical condition yet be treated in earnest, and who find the new tools for producing those future treatments to be exciting: worth devoting a career to. Hence advocacy and progress isn't just about getting the job done today and raising the funds for today's researchers, but it is also about creating the research community of tomorrow.
A series of posts at the SENS Research Foundation profiles this year's summer scholars and the work they are carrying out relevant to aging and rejuvenation:
At the SENS Research Foundation, I work in the OncoSENS department with Dr. Haroldo Silva. My project will study a specific pathway used by cancer cells called the Alternative Lengthening of Telomeres (ALT) pathway with the use of the ALT-associated promyelocytic leukemia (PML) nuclear bodies (APB) assay.
I will be performing Dr. Silva's version of the APB assay on two specific cell lines: an ALT cell line, called U2OS, and a telomerase control cell line, called 143B. I will be treating each of these cell lines with four drugs provided to us by Dr. Robert J. Shmookler Reis of the University of Arkansas for Medical Sciences, which are all known inhibitors of different proteins in homologous recombination-mediated pathways. My project will assess the effect of these drugs on the ALT pathway. The results generated by the APB assay will provide new data to better assess the potential of these drugs for cancer therapy, particularly for tumors associated with the ALT mechanism.
This summer, at the Buck Institute For Research on Aging, I will be working on a project in the laboratory of Dr. Heinrich Jasper. I will be examining the effect of unfolded proteins in fruit fly mitochondria on stem cell maintenance. Previous studies have shown that fruit fly gut stem cells tend to divide and generate new cells more frequently in stressful environments. Coincidently, the stress of numerous unfolded proteins in the mitochondrion triggers the mitochondrial unfolded protein response.
Recently, the response to mitochondrial unfolded proteins has been shown to control the aging rate of various organisms and has been associated with many renowned aging modulators. We also know that activating the response in certain body parts can have global effects, and these effects could greatly impact the aging process. Yet, there remains uncertainty regarding which proteins initiate the active pathway that alters aging, as opposed to those that are just associated with the process, and also the exact difference between mitochondrial unfolded protein response and other stress responses that seem to have no influence on aging. Thus, this project aims to provide some clarity concerning these aspects of the response.
Cellular senescence is a state of irreversible growth arrest that serves to protect against cancer. Senescent cells are accumulated with age or induced by anti-cancer therapies, such as chemotherapy and irradiation, in the tissue microenvironment. Senescent cells experience deep morphological and functional changes, and they activate a secretory program known as the senescence-associated secretory phenotype (SASP). The SASP includes several pro-inflammatory factors for which levels are increased during aging and cancer treatment.
The secretory program is regulated by multiple molecular events. Among those, the transcription factor hypoxia-inducible factor (HIF)-1a has been linked to many pathways and factors involved during senescence. HIF-1a responds to oxygen levels to promote the formation of new blood vessels in hypoxic conditions. During my internship, I will address the following questions: 1) Which chemotherapy drug or irradiation dose currently used for treatment of cancer patients induces senescence in the tissue microenvironment? and 2) How does the phenotype of senescent cells respond to HIF-1a regulation and to different oxygen concentrations?
This summer I will be working with Dr. Mark McCormick in the laboratory of Dr. Brian Kennedy at the Buck Institute for Research on Aging. We are working in the budding yeast Saccharomyces cerevisiae and the nematode worm Caenorhabditis elegans. These model organisms live for only a few weeks, making it possible to quickly study changes in their lifespan. Because they have long been used to study many other biological processes, there are many existing tools available to us when working with these organisms, such as genome-wide deletion collections. Finally, it has been shown repeatedly in many diverse biological processes that fundamental mechanisms first uncovered in simple model organisms are often conserved in higher organisms, such as humans. In the case of aging, changes in yeast genes in the TOR (target of rapamycin) signaling pathway, including the yeast gene TOR1 itself, were shown to extend lifespan, and subsequent work has shown that treatment with the TOR targeting drug rapamycin extends lifespan when fed to middle-aged mice, leading us to hypothesize that this drug target or others we uncover may allow us to extend human lifespan as well.
Recent progress in whole organ engineering techniques based on decellularization of organs and recellularization of the resulting collagen-based matrix suggests that this method could eventually be used in transplantation. The Wake Forest Institute for Regenerative Medicine team has developed a combination cell seeding system for efficient and functional re-endothelialization of the entire vasculature of an acellular renal scaffold.
In their previous study, the team developed a surface modification method to reinforce endothelial cell attachment onto renal vasculature via CD31 antibody conjugation. CD31 antibody binds to an antigen found on endothelial cells. Encouraged by their promising results using an endothelial cell line, the WFIRM team has recently attempted to re-endothelialize the kidney scaffolds using autologous cell sources for long-term porcine kidney implantation. This approach could potentially be applied to a translational clinical trial.
For my project, I plan to isolate and characterize primary endothelial cells from pigs to determine if the conjugation of CD31 antibody on vasculatures of kidney scaffolds will enhance primary endothelial cell attachment.
This summer, I am working on a thymus regeneration project in Dr. John Jackson's lab at the Wake Forest Institute for Regenerative Medicine. The thymus is a specialized organ in the immune system, and it is involved in the maturation of T-cells. T-cells recognize and attack foreign substances, called antigens, thus protecting the body from developing infections. In old age, the thymus starts to lose its functional abilities, rendering the immune system ineffective. One approach to restore the immune system in aged individuals is the regeneration of the thymus. Thymic tissue regeneration and T-cell maturation also have application in the treatment of autoimmune diseases, immunodeficiencies, and transplant rejection.
During the summer, I will work on one part of this larger project. I plan to decellularize a small piece of pig thymus, which entails getting rid of all the cells in the thymus, leaving behind the extracellular structure called a scaffold. After decellularizing the thymus, I will reseed the thymus scaffold with thymus epithelial cells and bone marrow cells from mice, providing a 3-D environment to the cells that resembles their natural environment in the body. I will then analyze the proliferation of these cells in the scaffold and look for the production of mature T-cells. The success of this project will be an important step forward towards the overarching goal of whole thymus regeneration.