Updated: December 2020
As the field of regenerative medicine has advanced in recent years, athletes have increasingly turned to therapies that utilize biological substances, such as stem cells, to heal sports injuries faster. Researchers are still investigating the use of biological treatments, and their potential efficacy, but given the complicated and rapidly evolving nature of regenerative medicine, the questions below have been compiled to address some of the most important information that athletes need to know about stem cell therapies.
What are stem cells?
Sometimes called the body’s “master cells,” stem cells are the cells that develop into blood, brain, bones, and all of the body’s organs. They have the potential to repair, restore, replace, and regenerate cells, and could possibly be used to treat many medical conditions and diseases. Today, doctors routinely use stem cells that come from bone marrow or blood in transplant procedures to treat patients with cancer or disorders of the blood and immune system. Stem cells can originate from various sources, such as blood, bone marrow or fat (adult), amniotic fluid or umbilical cord blood (perinatal), and early stage human embryos (embryonic).
Do stem cell therapies work to accelerate healing?
In theory, the presence of stem cells at the site of injury could assist in healing because of the potential that stem cells could “turn into” the tissue that is injured and needs to be healed. Some patients have reported less pain and better function in joints or injuries injected with stem cells. However, many objectively measured, controlled studies have failed to find a difference in a tissue before and after treatment. Currently, there are no proven, FDA-approved stem cell treatments for muscle, joint, or tendon injuries.
Are stem cell treatments prohibited in sport?
It depends. Non-transformed stem cells that are extracted from the athlete and then reinjected in the same surgical procedure, with no growth factors or other prohibited substances added after harvesting, are not prohibited as long as they only return the functioning of the affected area back to normal and do not enhance it. In addition to freshly harvested stem cells taken directly from the athlete, there are a number of commercial preparations using donor tissues or cells which may or may not be prohibited depending on various factors.
Stem cell injections are prohibited if they are modified in a way that causes the stem cells to be performance enhancing, or if prohibited substances such as growth factors or hormones are added to the stem cell preparation after it has been harvested (whether from the athlete or another donor). It is very difficult to know the contents of various commercially prepared stem cells or stem cells derived from a donor that are then kept alive or otherwise modified for a procedure.
It is not possible for USADA to evaluate such products or provide an anti-doping status in every case. Use of these products or procedures is at the athlete’s own risk of an anti-doping rule violation and health effects.
Are all stem cell therapies legal?
There are some FDA-approved stem cell therapies solely for treating certain blood disorders, but there are also many stem cell treatments that have not been evaluated or approved by the FDA.
Some uses of stem cells are exempt from pre-market approval by the FDA, such as procedures where stem cells are extracted and then reinjected into the patient during the same surgical procedure when they are not modified and nothing is added to them. But some health clinics perform stem cell procedures that do not meet the above criteria. The FDA has issued warnings to consumers about stem cell therapies because, for almost all these products, the safety and benefits are unproven.
The FDA recommends that you ask your doctor for proof that a stem cell procedure or product is FDA approved, or that the FDA has issued an Investigational New Drug Application number. If the latter, you should ask for that number and review the contents of the application before getting treatment. If you wish to participate in a clinical trial or any kind of experimental treatment, your doctor should also offer you a consent form that identifies an Institutional Review Board (a group of experts that ensures the clinical trial is reasonably safe and ethical) and lays out the risks of the treatment.
More advice from the FDA on this topic is available here.
Are there risks associated with using stem cells?
Yes. The FDA has received reports of serious problems as a result of stem cell use, including a patient who became blind after a stem cell injection into the eye, and a patient who developed a tumor after a stem cell injection into the spinal cord.
The FDA also points out other safety concerns, including injection site reactions, the ability of stem cells injected into one part of the body to migrate to another part, failure of cells to work as expected, and the growth of tumors.
Athletes should also be aware that some physicians or clinics may not follow FDA guidelines on safety. The FDA has identified many clinics that are misusing stem cells or using them in ways not allowed for under current regulations.
Is a TUE required for stem cell therapy?
Maybe. Athletes with a blood disorder who require an FDA-approved stem cell therapy should contact USADA to learn about the most up-to-date anti-doping rules.
Athletes wishing to participate in a registered clinical trial that involves stem cell therapy should also contact USADA, as a TUE may be required.
Stem cell procedures where the athlete’s own cells are harvested and then reinjected in the same day/same surgical procedure, and where no prohibited substances are added to the preparation, are not prohibited and do not require a TUE.
If in doubt, athletes and athlete support personnel should discuss the prohibited or permitted status of a procedure by calling USADA’s Drug Reference Team at (719) 785-2000 option 2, or emailing drugreference@USADA.org.
For questions about specific products, substances, and methods, contact USADA’s Drug Reference Line at drugreference@USADA.org or call (719) 785-2000, option 2.