Biologist Harold Katcher (see this) claims that the epigenetic age (there are several measures for it such as methylation level of DNA) of rats has been reduced up to 50 percent. The theory goes that epigenetic age of molecules would be controllable by hormonal signalling globally.
I have been just working with the view about state function reduction in zero energy ontology of TGD providing a theory of quantum measurement free of its basic paradox and having profound implications in the understanding of mysteries of life and death.
For ordinary "big" state function reductions (BSFRs) the arrow of time changes. BSFR would mean death of conscious entity and its reincarnation with opposite arrow of time. The system would rejuvenate in the transition starting a new life in opposite time direction from childhood so to say- rejuvenation would be in question. Doing this twice would lead to life with original arrow of time but starting in rejuvenated state.
Returning cells to the stem cell state inducing de-differentiation as reversal of differentiation would be one example of rejuvenation. The claims of the group suggests that living matter is doing this systematically using hormonal control.