@msstoppainnagginme PRP is Plate Rich Plasma, an injection. More info here:
https://www.healthline.com/health/prp
I personally know nothing about it, I have had two TKRs. Are you considering a TKR or something else for knee arthritis? I have been very happy with my TKRs, particularly with the second one which was done with a Conformis knee. From what I hear the robotic method, MAKOplasty, is extremely successful also. Stem cell therapy and PRP are not generally covered by insurance.
JK