I have not been able to run for about 3 years. I looked into the stem cell therapy approaches, but could not get one of the providers to supply me with one case of showing that after the treatment, the recipient was able to run. There are two approaches, as I can tell. One extracts the stem cells from bone marrow and incubates them in a petri dish for 2-3 months then inserts those into the joint cavity. The second takes adipose tissue (fat cells) eliminates the non-stem cells and injects the stem cells into the joint cavity.
My guess is that the marrow based stem cells will be "stronger" and the adipose cells will not survive as long. But the operation that did the stem cell approach wanted me to sign up for extensive "therapy" before I would actually start the process. It was $5k for the "therapy" and ~10k for the stem cell work. I spoke with my orthopedist, a Leadville 100 finisher and sub 2:45 marathoner, who told me that if there was any "validity" to this stuff you would see the pro-athletes doing it all the time. He said, check out the type of doctors performing the treatments, typically they are estaticians or plastic surgeon types, with little bone, joint background. We was spot on with that comment.
One runner I coached, went in for the marrow treatment here in Colorado for his hip. Severe arthritis to the point his hip hurt to stand. They did the full treatment $15k later, he has no relief and cannot even ride a bike without pain, let alone run.
Obviously, I would love for there to be a "recreate cartilage" therapy, but I do not think it has been developed as yet. I hope there will be soon.