When professional athletes began taking trips overseas for experimental treatments, patients began to inquire more frequently about these non-surgical therapies. I now have conversations daily with patients eager for an injection that can alleviate pain, improve function, and delay surgery. Platelet-rich plasma (PRP) and Stem Cell injections have come to the forefront of sports medicine. Research has shown that these modalities offer significant promise when used in an appropriate way, especially with cartilage lesions and knee arthritis. My hope with this post is to explain the differences between PRP and stem cells, their purported benefits, as well as evidence-based benefits.
In very general terms, PRP is a collection of growth factors, platelets, and white blood cells suspended within the plasma layer of the blood. These growth factors help promote cartilage health and help inhibit the factors that cause cartilage breakdown. PRP actually leads to a natural increase in hyaluronic acid production in the knee (versus modalities such as “lubrication” injections which inject hyaluronic acid into the joint). Platelets themselves contain numerous proteins that have positive effects on cartilage and can also destroy bacteria and fungi. Overall, PRP plays a role in enhancing the body’s natural ability to heal by reducing inflammation in tendons and arthritic joints as well as speeding up recovery.
Stem cells, on the other hand, are basically non-differentiated cells. Think of them as unlabeled seeds that can grow into any fruit or vegetable, if the right care is given. The hope is that stem cells injected into an area of damaged cartilage, in combination with the proper growth factors, can form into actual new cartilage. One of the reasons that I prefer PRP over stem cells in my practice is that unfortunately, stem cells can also turn into less desirable cells, and on rare occasion have turned into rapidly proliferating tumors [NY Times Article]. For this reason, most stem cell treatments are not currently FDA approved, including the majority of applications in orthopedic sports medicine.
PRP and Stem Cells also differ in the way the samples to be injected are obtained. Obtaining PRP consists of a few ounces of a patient’s own blood drawn by simple venipuncture to the arm. Stem cell harvest involves a bone marrow aspiration, typically from the pelvis, involving a much larger volume of blood. It is also possible to obtain the sample through fat aspiration where the fluid extracted is manipulated in order to extract stem cells. In our local area, however, a high volume of “stem cell” treatments do not involve actual harvesting of your own bone marrow, and instead come from amniotic fluid—the protective fluid surrounding a baby harvested at the time of a c-section. Though reported to contain a large volume of stem cells, testing has revealed that the vast majority of these injections actually contain NO ACTIVE STEM CELLS! Unfortunately many clinics are happy to extract your money in exchange for the hope that you have not done your homework in advance. Therefore, the best way to tell if any of these reported stem cell treatments/clinics are legitimate is to inquire about their source for the fluid. Bone marrow or fat aspiration contain active stem cells; so if the clinic does not obtain their samples in one of these ways, ask questions.
I hope it is clear that at this point in time, PRP and bone marrow or fat aspirate stem cells are the more legitimate options for knee arthritis. Neither is covered by insurance, so you can expect to pay out of pocket for both options. PRP tends to be $500-$1000, whereas most stem cell treatments are over $4000 per treatment. In the current orthopedic literature, there is little evidence to support paying that extra money for stem cell treatments over PRP. PRP has gone up against placebo, steroids, and lubricant injections in numerous studies, including Level 1 research concluding that PRP usually provides longer and better pain relief. At this time, there is little high quality evidence to support stem cell treatments. I do believe both options have a role in orthopedics currently, and as more research is done, I suspect the evidence will support both stem cells and PRP as legitimate therapies to assist in non-operative management of arthritis as well as assisting in the healing of cartilage after surgery.