We humans are stuck with bodies that are far from the ideal of regenerative prowess: we are very frail in comparison to a great many other species. We don't regrow limbs or organs to any meaningful degree, we scar, lose functions, and die to a range of injuries that are easy enough to fall into. Break that poorly protected sack of innards and you won't be around for long enough to greatly regret it. So all told, evolutionary success is something of a low bar when it comes to resilience to wear, tear, and aging - and as a recent popular science article reminds us.
"The trouble is that humans and other mammals do not have a very good means of responding to loss of heart muscle. They cannot repair the heart as other creatures, such as zebrafish, can. There is no intrinsic mechanism to get cells to migrate into the heart to replace those that have been killed off by a heart attack."
Fortunately, we will soon be able to work around or remove human limitations of this nature through the application of biotechnology. Evolutionary pressure has done little for our robustness, but technology can do much more in the decades to come:
Unlike the approach taken by the team led by Paul Riley, which is concentrating on trying to simulate a patient's own stem cell population, Emanueli is working on techniques to deliver stem cells derived from other sources. The ultimate aim is to find a way to create sets of cells that can be put inside heart attack patients in order to stimulate the growth of new blood vessels. These cells are known as vascular endothelial cells and vascular smooth muscle cells and both play a crucial role in the construction of blood vessels that are destroyed in the heart in the wake of a myocardial infarction.
By contrast, Dr Anastasis Stephanou, at University College Hospital, London, is using a grant from the BHF to work - with his colleague Suwan Jayasinghe - on a technique aimed at "patching-up" a damaged heart. Their work exploits a form of spray technology that allows them to impregnate sheets of protein with biological material including aerosol suspensions of cells. The protein acts like a skeleton in which the cells can settle.
Several research groups round the world have recently reported success in using stem cell technology first to isolate fibroblast cells found in the skin and then to transform these into cardiac cells using various chemical interventions. "We envisage a person going into a hospital and being diagnosed with a serious heart problem. Once a diagnosis is made, a section of his or her skin would be removed and its fibroblast cells would be isolated. These cells would then be treated with chemicals and transformed into cardiac cells which can be used to create one of our sheets. This in turn would be taken by a surgeon and inserted into the damaged part of the patient's heart in the expectation that cardiac cells will be taken up and the heart's function restored."
These are small steps, but there are many different similar lines of work for the heart, and again more groups working on regeneration of other organs. Ultimately, this will all lead in to ways to address the damage of aging at earlier stages than a heart attack - incrementally restoring and maintaining the heart such that it never comes to that point of catastrophic failure, and doing the same for other organs and biological systems in the body.