I think they did the experiment in the 50's with mice, but they didn't understood transplantation and rejection so well back then, so many mice had serious prob

I think they did the experiment in the 50's with mice, but they didn't understood transplantation and rejection so well back then, so many mice had serious problems.Now we can prevent those. Also i think you'd have a hard time to get money for any "anti aging" research up until recently.