In the News
Stem Cells, PRP, and Regenerative Medicine
June 5, 2017
There is a great deal of interest and research in the field of regenerative medicine especially as it relates to sports performance and the treatment of sports injuries. The term regenerative medicine and the use of “biologics” broadly refers to natural products that are harvested and used to supplement healing. In orthopedic sports medicine, the use of biologics entails the use of growth factors, cells, or tissue.
Researchers have performed over 500 clinical trials evaluating mesenchymal stem cells (MSC’s) and there have been over 180 trials evaluating platelet rich plasma (PRP), which is a testimony to the level of interest in biologics and the hope of treating or modulating various disease processes. Unfortunately, the scientific approach to studying these therapies and interventions has been quite disordered, with little standardization of the biologic preparation being studied. This lack of standardization has made it difficult to compare study outcomes and validate conclusions of disparate studies.
The use of biologics is regulated by the FDA. The greater the perceived risk to patients, the more highly regulated a given product is. In my field of orthopedic sports medicine, PRP or bone marrow aspirate containing MSC’s is not highly regulated as these products are minimally manipulated. However, the FDA currently does not allow orthopedists in the US to harvest mesenchymal stem cells from bone and expand these cells in culture for injection into an arthritic knee for example.
With PRP, platelets are concentrated from a blood draw, the platelets are concentrated and can be injected into an arthritic knee or onto an inflamed tendon. The growth factors in the platelets are released at these injury sites and there is evidence that the growth factors can attract mesenchymal stem cells (MSC’s), and other types of cells, and in turn, stimulate local protein production that can hasten healing in that local environment.
Stem cells have 4 defining qualities: (1) they can reproduce, (2) they can differentiate into a number of different cell types, (3) they can mobilize, and (4) they can turn on or off other cells in their local environment. MSC’s can be obtained from bone, fat, synovial tissue, and periosteum.
There are several types of stem cells: embryonic, which are omnipotent and can give rise to an entire organism, and adult stem cells, which are multipotent and can differentiate into certain types of cells. The use of embryonic stem cells is highly regulated, there is ethical considerations, and there is some risk of tumor growth. For these reasons, adult stem cells are currently used in orthopedic sports medicine treatments.
As for current orthopedic applications, PRP injections have been shown to be more effective than hyaluronate injections for the treatment of mild to moderate arthritis in younger and middle aged patients. Unfortunately, insurance companies still consider PRP injections experimental and therefore do not cover them. There have been numerous studies assessing whether there is a benefit to injecting PRP at the time of rotator cuff repair and most studies to date have not shown a functional benefit or better healing rates. There are even fewer studies looking at injecting BMA at the time of rotator cuff repair and again no benefit has been demonstrated to date. However, there have been some animal studies in which stem cells have been further manipulated and utilized (which the FDA does not currently allow in humans) that have shown some improved bone tendon healing. As for meniscal repair, the results of animal studies have been mixed. Some studies have shown that BMA loaded onto a scaffold can even regrow meniscal like repair tissue, but others have not demonstrated a difference in healing in animal models.
The future of regenerative sports medicine is bright and its usage and indications are bound to expand.
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