4) Reversing Stem Cell Aging

The stem cell research field is on a collision course with the issue of stem cell aging. Most of the medical conditions that are best suited to regenerative medicine, tissue engineering, and similar cell based therapies are age-related, and thus most of the patients are old. In order for therapies to work well, there must be ways to work around the issues caused by the aged biochemistry of the patient. To achieve this end, the research community will essentially have to enumerate the mechanisms by which stem cell populations decline and fail with age, and then reverse their effects.

Where stem cells themselves are damaged by age, stem cell populations will have to be replaced. This is already possible for many different types of stem cell, but there are potentially hundreds of different types of adult stem cell - and it is too much to expect for the processes and biochemistry to be very similar in all cases. A great deal of work will remain to be accomplished here even after the first triumphs involving hearts, livers, and kidneys.

Much of the problem, however, is not the stem cells but rather the environment they operate within. This is the bigger challenge: picking out all the threads of signalling, epigenetic change, and cause and effect that leads to quieted and diminished stem cell populations - and the resulting frailty as tissues are increasingly poorly supported. This is a fair sized task, and little more than inroads have been made to date - a few demonstrations in which one stem cell type has been coerced into acting with youthful vigor, and a range of research on possible processes and mechanisms to explain how an aging metabolism causes stem cells to slow down and stop their work.

The stem cell research community is, however, one of the largest in the world, and very well funded. This is a problem that they have to solve on the way to their declared goals. What I would expect to see here is for a range of intermediary stopgap solutions to emerge in the laboratory and early trials over the next decade. These will be limited ways to invigorate a few aged stem cell populations, intended to be used to boost the effectiveness of stem cell therapies for diseases of aging.

Any more complete or comprehensive solution for stem cell aging seems like a longer-term prospect, given that it involves many different stem cell populations with very different characteristics.

5) Clearing Advanced Glycation Endproducts (AGEs)

AGEs cause inflammation and other sorts of mischief through their presence, and this builds up with age. Unfortunately, research on breaking down AGEs to remove their contribution to degenerative aging has been a very thin thread indeed over the past few decades: next to no-one works on it, despite its importance, and very little funding is devoted to this research.

Now on the one hand it seems to be the case that one particular type of AGE - glucosepane - makes up 90% or more the AGEs in human tissues. On the other hand, efforts to find a safe way to break it down haven't made any progress in the past decade, though a new initiative was launched comparatively recently. This is an excellent example of how minimally funded research can be frustrating: a field can hover just that one, single advance away from largely solving a major problem for years on end. All it takes is the one breakthrough, but the chances of that occurring depend heavily on the resources put into the problem: how many parallel lines of investigation can be followed, how many researchers are working away at it.

This is an excellent candidate for a line of research that could move upward in the order of arrival if either a large source of funding emerged or a plausible compound was demonstrated to safely and aggressively break down glucospane in cell cultures. There is far less work to be done here than to reverse stem cell aging, for example.

6) Clearing Aggregates and Lysomal Garbage

All sorts of aggregates build up within and around cells as a result of normal metabolic processes, causing harm as they grow, and the sheer variety of these waste byproducts is the real challenge. They range from the amyloid that features prominently in Alzheimer's disease through to the many constituents of lipofuscin that clog up lysosomes and degrade cellular housekeeping processes. At this point in the advance of biotechnology it remains the case that dealing with each of the many forms of harmful aggregate must be its own project, and so there is a great deal of work involved in moving from where we stand today to a situation in which even a majority of the aggregates that build up with age can be removed.

The most promising lines of research to remove aggregates are immunotherapy, in which the immune system is trained or given the tools to to consume and destroy a particular aggregate, and medical bioremediation, which is the search for bacterial enzymes that can be repurposed as drugs to break down aggregates within cells. Immunotherapy to attack amyloid as a treatment for Alzheimer's is a going concern, for example. Biomedical remediation is a younger and far less funded endeavor, however.

My expectation here is that some viable therapies for some forms of unwanted and harmful metabolic byproducts will emerge in the laboratory over the next decade, but that will prove to be just the start on a long road indeed. From here it's hard for me to guess at where the 80/20 point might be in clearing aggregates: successfully clearing the five most common different compounds? Or the ten most common? Or twenty? Lipofuscin alone has dozens of different constituent chemicals and proteins, never mind the various other forms of aggregate involved in specific diseases such as Alzheimer's.

But work is work: it can be surmounted. Pertinently, and again, the dominant issue in timing here is the lack of funding and support for biomedical remediation and similar approaches to clearing aggregates.