Adverse Reactions to Stem Cell Therapy

Stem cell therapy is one of the most discussed regenerative therapies in the horse health community today, and both peer-reviewed and anecdotal evidence indicates that these tiny tools have been relatively successful in assisting injury healing. But as with most therapies, despite some great success things don't always go as planned. At the 2011 North American Veterinary Regenerative Medicine Conference held June 2-4 in Lexington, Ky., a researcher from the University of California (UC), Davis, discussed a recent study that evaluated the adverse reactions associated with stem cell injections.

"Stem cell therapy has become common in equine practice," explained Larry Galuppo, DVM, Dipl. ACVS, professor and chief of equine surgery at UC Davis' William R. Pritchard Veterinary Medical Teaching Hospital and lead researcher on the study. "There are two different types of stem cell therapy. The first involves collecting and injecting an injured horses' own stem cells back into the site or injury--a process referred to as 'autologous'--and using 'banked' stem cells from one horse to treat an injury in a second horse. This latter technique is referred to as allogeneic,"

Using the allogeneic method requires having a large dose of stem cells readily available to treat injured horses (think of it as stem cells available "off the shelf"), rather than collecting new stem cells from the injured horse and waiting several weeks for the cells to proliferate (since a large number of cells are needed for each treatment) before injecting them into the injury site.

"To determine if there was a difference in the frequency of adverse effects when autologous versus allogeneic stem cells were used, we closely observed 36 horses after stem cell therapy and recorded our findings," explained Galuppo.

Key findings of the study were:

  • Eight of the 19 horses (42%) treated with allogeneic stem cells had an adverse reaction characterized by inflammation in the stem cell injection area, either with or without lameness;
  • Significantly fewer (2 of 19 horses, or 10.5%) horses treated with their own stem cells had an adverse reaction;
  • More horses reacted if the stem cells were injected into a joint rather than a soft tissue injury; and
  • All horses responded to medical treatment, and no detrimental effects were noted between nine and12 months post-injection.

"Contrary to our prediction, a higher occurrence of adverse reactions occurred following the use of allogeneic stem cells," concluded Galuppo.

It's important for owners to remember that all medical treatments have risks and stem cells shouldn't be avoided as a result of the study, however Galuppo noted that "further evaluation of allogeneic stem cells is needed before recommending this treatment" to clients on a regular basis.

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.