Some nagging uncertainties remain on progress in stem cell medicine - and especially progress in reprogramming easily obtained somatic cells into patient-specific pluripotent stem cells. These uncertainties will be answered and addressed in the years ahead, but this one springs to mind today: it is possible that cells from older people may be altered or damaged in ways that prevent their effective use as-is in the sort of autologous stem cell therapies presently envisaged. That would be a setback for the first generation therapies: an entire additional industry would be required to fix or generate cells for use. We'd like to be able to repair arbitrary issues in stem cells anyway, but to have to do it to even get therapies running at all in the elderly would be a blow.
So it is reassuring to see papers appearing to show that cells from the old are as good by some measures as cells from the young, once reprogrammed:
Human induced pluripotent stem cells (IPSCs) have enormous potential in the development of cellular models of human disease and represent a potential source of autologous cells and tissues for therapeutic use. A question remains as to the biological age of IPSCs, in particular when isolated from older subjects. Studies of cloned animals indicate that somatic cells reprogrammed to pluripotency variably display telomere elongation, a common indicator of cell 'rejuvenation.'
We examined telomere lengths in human skin fibroblasts isolated from younger and older subjects ... While these results reveal some heterogeneity in the reprogramming process with respect to telomere length, human somatic cells reprogrammed to pluripotency generally displayed elongated telomeres that suggest that they will not age prematurely when isolated from subjects of essentially any age.
Good to know. Again, though, this is all a non-issue in the long term. In the long term, cells, genomes, and cellular components will be built entirely from scratch and altered in any arbitrary way to accomplish the task at hand. In the long term, we'll all be man-made machines. The real issue is how things go in the near term: whether those of us who will have to benefit from the therapies available two decades from now will have an easier or a harder time of it.
Suhr, S., Chang, E., Rodriguez, R., Wang, K., Ross, P., Beyhan, Z., Murthy, S., & Cibelli, J. (2009). Telomere Dynamics in Human Cells Reprogrammed to Pluripotency PLoS ONE, 4 (12) DOI: 10.1371/journal.pone.0008124