Stem cells are found in various tissues throughout the body, such as bone marrow and fat. They are capable of renewing themselves through cell division. Mesenchymal stem cells (MSC) are pluripotent, meaning they have the ability to differentiate into many types of tissues. This ability has generated promise of potential treatment for chronic injury, specifically for cartilage cells (chondrocytes).
Bone marrow aspirate concentrate (BMAC) is the safest and most feasible source of MSC. It can be extracted from various sites, most typically from the posterior superior iliac crest. This can be done painlessly in the office under only local anesthesia. Once collected, it is concentrated through centrifugation, similar to PRP, and injected back into the injured area.
There are studies for arthritic disease reporting improvements in pain and function, but few controlled trials. Similar to PRP, it has proven to be safe and well-tolerated (without serious side effects) in multiple studies, including patient-blinded, placebo-controlled trials. FDA draft guidance advises that same day concentration of BMAC without additives is safe, as it constitutes only minimal manipulation (code of federal regulation 361).
That being said, this treatment is considered experimental, as the efficacy and mechanism of action are still to be completely understood. As of now, the Federal Drug Administration (FDA) has not deemed it effective and thus, it is not covered by any insurances. This is a treatment option for those who have failed all other conservative first-line treatments and/or are not ideal surgical candidates.