This is interesting. Not only outside stem cell injection, but the stem cells that are made within the bone marrow. At 20 years old 100% compared to 65 year old at 10% of active stem cells in the blood stream. I put this under the Parkinson's post because he specifically talks about it in a couple of places. But it applies to all kinds of disease and injury and how the stem cells replace damaged cells. He gives some very interesting facts about how often cells in different organs get replaced in general and how often in days or years that enough cells get replaced to replace the entire organ.

Stuff I had not heard before. It is kind of dry the first 12-15 minutes because it is about his background and his own health issues. Can skip forward if you want. It gets lots more interesting after that.

https://www.youtube.com/watch?v=EN6asTGOArw&t=1845s

At around minute 38 he gives pictures of cartilage being re-grown in a knee in about 7 months.