This is a Nov 2017 Literature review re: stem cell and PRP treatment of the knee. Knee injury is one of the most common orthopedic causes of disability. And it's growing with the aging and obesity epidemics. There are 2 major competing techniques: PRP and BMAC.

PRP is Platelet Rich Plasma is common with new standards of over 5 mil platelets/ml of plasma. The attraction of platelets is actually the growth factor contained by the platelets.

BMAC is Bone Marrow Aspirate Concentrate. This is usually obtained from the backside of the pelvic bone in a sterile environment. It is minimally processed, simply spun down.

They repeat the general theme. There is a lot of promise, but research seems to be going too slow. Here are some reasons: 1. outcomes are subjective (pain ); 2. their processes are changing (taking out WBC and adding scaffolding); and 3. failure to standardize and document procedures.

https://www.tandfonline.com/doi/full/10.1080/17453674.2017.1368899