Stem cells are cells that are similar to embryonic cells that have the capacity to be transformed in multiple tissue types. There’s been considerable interest in recent years in using stem cells to support healing of joint and tendon/ligament problems. There are even stem-cell kits commercially available to vets, but they don’t have strong research to support their use.
A Colorado State study presented at the 2006 American Association of Equine Practitioners (AAEP) meeting used a surgically created model of arthritis to test the results of treatment with stem cells derived from either bone marrow or fat vs. no treatment. They found no difference between groups in degree of lameness, radiographic appearance, gross or microscopic appearance or synovial fluid prostaglandin E2 (an inflammatory marker), making the prospects for treating arthritis with stem cells not that encouraging.
A Cornell study released in the April 2007 issue of the Journal of Orthopedic Research compared healing of surgically created full-depth cartilage defects in horses after injecting them with fibrin alone or fibrin containing connective tissue-type (mesenchymal) stem cells. At 30 days, there was significantly improved healing in the stem-cell-treated defects, but by eight months there were no differences between groups for either degree of healing or the characteristics of the healed defects. Note: Fibrin is a protein produced by enzymes acting on fibrinogen that forms the structural backbone of clots. There are also anecdotal reports of stem cell or bone marrow aspirate (contains small numbers of stem cells) being useful in helping to heal difficult tendon and ligament problems. However, no well-constructed, controlled studies comparing treated to untreated horses have been published.
It remains to be seen if stem cells turn out to be of use for soft-tissue problems. There’s no harm in trying this if your horse has a tendon or ligament problem that isn’t responding to other therapies, as long as you realize that this pricey approach is still unproven.