Sinclair et al. using the eye as a model CNS tissue, showed that ectopic expression of Oct4, Sox2 and Klf4 genes in mouse retinal ganglion cells restores youthful DNA methylation patterns and transcriptomes, promotes axon regeneration after injury, and reverses vision loss in a mouse model of glaucoma and in aged mice. The beneficial effects of OSK-induced reprogramming in axon regeneration and vision require the DNA demethylases TET1 and TET2.
However, I have been arguing in papers (see Treatment-resistant schizophrenia: focus on the transsulfuration pathway and A disease-modifying treatment for Alzheimer’s disease: focus on the transsulfuration pathway) and on this blog that TET enzymes are the very enzymes that are dysregulated in many chronic illnesses, which results in various chronic illnesses possessing a range of phenotypic expressions. Ectopic expression of OCT4, KLF4 and SOX2 alone would not work in aged humans and/or ill humans as TET enzymes are dysregulated in aged and/or ill humans.
TET enzymes are iron and 2-oxoglutarate dependent dioxyegenases. Fixing TET enzymes could be a key part of the treatment of a range of chronic illness and would be a lot simpler and safer than systematic ectopic expression of OCT4, KLF4 and SOX2 in humans. A lot of methylation changes acquired during aging must be beneficial. Systematically turning back the clock to 18 or so would not be desirable .’Just’ fixing TET enzymes would allow desirable methylations to occur but would allow DNA demethylations of undesirable DNA methyations. Clearly fixing TET enzymes would be a required first step prior to any genetic engineering of humans to restore youthfulness given that such genetic engineering was feasible and desirable.