A couple of comments:
First, I understand the need for using a primate as an experimental animal model. However, restoring ‘youthfulness’ to an aged primate, then returning the primate to an aged state (and there is the possibility of accelerated aging) is not ‘humane’ and would be considered cruel in any court of law – and there WILL be lawsuits, as there are already lawsuits by animal rights groups to stop bio-medical chimpanzee experiments (involving ‘personhood’ of said primates, but this distinction is not necessary to prove 'animal cruelty).
Secondly, use of iPSCs to stop or slow aging (the latter being more likely) was all the rage back in 2012/13…but since then, while research has continued…breakthroughs – on the systemic level – have been slow in coming. Cell re-programming took a hit with the Riken Institute scandal (falsified results from a ‘simplified’ cell reprogramming process, dubbed STAP), but work continues, albeit more cautiously. There is some promising work out there regarding arresting stem cell differentiation (involving intervention of TF complex activity and cis-regulatory elements, and even some epigenetic alterations) and even ‘reversing’ cell fate. Challenges exist in fully controlling cell fate and stopping unchecked proliferation (which can produce unwanted immune responses and neoplasia/cancer).
Also, there are the ‘parabiosis’ (rat) experiments from a few years ago in which the circulatory system of a healthy young rat was coupled to that of an older rat; after a period of time, the older rat appeared to have restored muscle tone and memory performance ability. This experiment became sensationalized, and also became the inspiration for the ‘Silicon Valley’ episode ‘Blood Boy’ (with one perversely hilarious scene). The problem is that these experiments did not demonstrate the specific cause of the ‘restored’ youthful vigor and cognition in the aged rat. Meanwhile, the few reproducibility experiments have not been conclusive. However, Snyder et al recently (2019) showed that resident memory T cells localized to and remained in targeted lung tissue for longer periods after parabiosis and that this was associated with “better clinical outcomes”
That said, I do believe that blood circulation – specifically, maintaining micro-circulation* in the brain – is key to preventing the cognitive deficits and decline associated with aging (including preventing common forms of dementia). So, perhaps developing a micro-circulation animal model (or an advanced organoid, as a animal model surrogate) would be highly beneficial in Aging research.
*Recent work by Cruz-Hernandez et al has found that immune (‘sentinel’) cells known as neutrophils pile up in the micro vasculature (capillaries), causing blockages and atrophy (due to oxygen and nutrient deprivation) of both capillaries and tissue.