It has a pretty interesting history in the US. America has dramatically limited research because of moral objections and fears of creating dangerous mutations. Regenexx is the company that has dominated the field and had a significant legal battle a couple of years ago.
Right now, in the US, you can get same day stem cell treatments. What they do is draw stem cells out of your pelvic bones and use them to repair partially torn or non-retracted ligament damage. If your ligament is fully retracted then you're SOL. In the cayman islands, they withdraw your cells and multiply them in a petri-dish which is not legal in the US.
I did some research and really can't find significant, sold data to support their treatments. The data the present is total crap and due to restrictions, there have been few true studies about stem cell repairs.
The biggest thing to consider is that OUTCOMES ARE NOT ALWAYS PERFECT! Yes, healing time is faster. Yes, there have been success stories. This is not always the case.
Hopefully in some time there will be more research allowed in the US or big Euro breakthroughs.
Good Outside article:
http://www.outsideonline.com/1921886/no-more-knife-stem-cell-shortcut-injury-recovery
For you other medical peoples:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4634187/