Hello Mike and all,
Well that is somewhat disappointing – it may we be that some tissues/organs are refractory to rejuvenation. It has been noted in some studies that co-culturing young and old cells seems to revitalize the old cells – and there’s significant evidence that cells can communicate their state of repair throughout the body – so fresh young cells can help rejuvenate old cells – and that might well account for that revitalization phenomenon you mention. The important thing to note here is that age changes can be affected by the body’s internal milieu. So that points us, in both the case of young plasma and the case of young cells, towards the conclusion that aging is not a cell autonomous process, not even cellular aging as it appears reversible. The case of a young woman being colonized by her unborn’s stem cells is interesting – the mother becomes a chimera? How does her immune system feel about that? In the case of a young woman – her plasma is in her favor -would the same approach work with old people?
I also wonder how much is really controlled via the blood – for example in the thymus transplantation experiments showing restoration of structure and function, there was none-the-less no increase in size (the involuted organ decreases in size) – so what I’m wondering is if the plasma from a person in which the thymus was growing (from a fetus) wouldn’t cause the growth of that thymus? Of course all this is primitive – but if it works to any degree it points to way to rejuvenation or at least demonstrates proof of principle. If this is a primitive attempt I’d liken it to the first zeppelins and blimps that preceded heavier-than-air ships – at least demonstrating that it can be done. And that would be a tremendous psychological breakthrough if nothing else. I’m of course hoping for more than that.