Does Stem Cell Therapy Work?

Medical professionals debate whether or not stem cells therapy is an effective treatment for sports injuries, such as ACL tears and chronic tendonitis. It is a controversial subject and research is ongoing.

See Anterior Cruciate Ligament (ACL) Tears

The theories behind stem cell therapy
Researchers theorize that when applied to a sports injury, stem cells might:

  • Develop into needed musculoskeletal cells, such as tendon, ligament, cartilage, or bone cells
  • Facilitate better healing (e.g. encourage the growth of new blood vessels)
  • Decrease or prevent inflammation that make conditions such as tendinopathy worse
  • Release proteins (cytokines) that slow down tissue degeneration and/or decrease pain

See Knee Cartilage Repair, Regeneration, and Replacement


Future research will help show if none, all, or a combination of these processes is at work. In the meantime, doctors debate whether or not stem cells are a good treatment option for sports injuries.

  • Supporters of stem cell therapy point to animal and human studies that have shown generally positive results.
  • Critics do not believe stem cell therapy works any better than a placebo. They point out that there have been no large-scale, prospective, double-blind research studies—the kind of clinical studies that medical professionals consider the gold standard—to support stem cell therapy for sports injuries.

The challenge facing researchers
There is no standard “recipe” for stem cell therapy. The stem cell therapy in one study is not necessarily the same as the stem cell therapy in another study. The differences can include:

  • Where the stem cells originated—For example, did cells come from the patient? If so, were they derived from the patient’s blood, bone marrow, or fat?
  • How stem cells are separated and isolated from the harvested tissue
  • The concentration of stem cells (how many cells per treatment)
  • The health and age of patients
  • How the stem cells are delivered to the injured area—For example, are they injected or applied during surgery?

Because of these differences, it is difficult for researchers to draw conclusions or make generalizations based on existing studies.


Mixing Stem Cells with PRP

Many sports medicine doctors use stem cell therapy in combination with another regenerative medicine therapy, platelet rich plasma (PRP). These physicians believe that PRP can make the most of the stem cells potential effects.1,2

See Types of Regenerative Medicine for Sports Injuries

PRP is derived from a sample of the patient’s blood. In the bloodstream, platelets secrete substances called growth factors and other proteins that:

  • Regulate cell division
  • Stimulate tissue regeneration
  • Facilitate healing

See Are PRP Injections Effective?

PRP can be used alone to treat sports injuries, such as elbow tendinopathy.

See What Is the Difference Between Tendonitis, Tendinosis, and Tendinopathy?

Like stem cell therapy, PRP therapy is a not a standard therapy and may not be covered by insurance.

See Pros and Cons of Using PRP for Tendon Injuries


  • 1.Teng C, Zhou C, Xu D, Bi F. Combination of platelet-rich plasma and bone marrow mesenchymal stem cells enhances tendon-bone healing in a rabbit model of anterior cruciate ligament reconstruction. J Orthop Surg Res. 2016;11(1):96.
  • 2.Wang C, Iversen MD, Mcalindon T, et al. Assessing the comparative effectiveness of Tai Chi versus physical therapy for knee osteoarthritis: design and rationale for a randomized trial. BMC Complement Altern Med. 2014;14:333.