An analogous manifestation can be triggered by drilling holes in the kneecap allowing blood to move into damaged cartilage (say, below a kneecap). In the new environment, some of the red blood cells apparently transform into cartilagenous cells and repair the cartilage. Some doctors in sports physiology were doing this decades ago. No significant pressure can be put on the knee for 3-6 months but the solution was well worth it to the individual with whom I spoke.

So it seems that it is likely a natural/normal method of repair although it may be very slow w/o some prompting (drilling the holes, in this example).

A newer technique that sounds very similar but more general is P.R.P. (Platelet Rich Plasma) therapy:

New Yorker: "The Blood Injections That Might Transform Orthopedics"(2013)

https://www.newyorker.com/tech/annals-of-technology/the-bloo...

Yes, it happens all the time, but at a low enough rate that for a long time it wasn’t observed

* who knows if it is beneficial