Mesenchymal stem cell injections and PRP injections are the only non-surgical approaches to arthritis that attempt to regenerate damaged cartilage. All other approaches to treating arthritis focus on pain control. Even knee and hip replacement surgeries reduce pain rather than provide you with new cartilage.

Having said that, there is a lot of controversy on whether stem cell and PRP injections promote cartilage healing and regeneration. For PRP injections, there are some studies that suggest that PRP injections slow down further cartilage deterioration. For stem cells, there are some studies in animals and humans that suggest that stem cell injections help cartilage repair while others suggest that they just slow down deterioration just like PRP. There are also many studies that do not show any evidence of cartilage regeneration after a stem cell or PRP injections in spite of improvement in pain and function.

While we are still not sure whether or not stem cell injections stimulate cartilage repair, we have learned some new things about how they work. The idea that stem cells injected into the joint turn into cartilage cells and are incorporated into the joint cartilage does not seem to be true. Instead, they die within days or weeks of being injected. So, the current hypothesis is that they work by releasing chemicals that reduce inflammation and perhaps stimulate stem cells of the knee joint.

So, to sum up, most studies in humans look at pain and function post-injection rather than cartilage regeneration and repair. Of the studies which do look at cartilage, the results are contradictory with some supporting hypotheses that these injections stimulate cartilage repair while others show no effect at all.

Source:

• https://pubmed.ncbi.nlm.nih.gov/35019764/
• https://www.oarsijournal.com/article/S1063-4584(20)30882-7/fulltext
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7937409/