Veterinarians Discuss Stem Cells for Equine Joint Therapy

Veterinarians Discuss Stem Cells for Equine Joint Therapy

Equine athletes commonly need supportive care for their musculoskeletal system, particularly their joints.

Photo: Anne M. Eberhardt/The Horse

Equine athletes commonly need supportive care for their musculoskeletal system, particularly their joints. Joint therapies were the topic of discussion at a packed table topic at the 2014 American Association of Equine Practitioners Convention, held Dec. 6-10 in Salt Lake City, Utah. Lane Easter, DVM, Dipl. ACVS, of Performance Equine Associates, in Thackerville, Oklahoma; and Ashlee Watts, DVM, PhD, assistant professor at Texas A&M's College of Veterinary Medicine, in College Station, led the conversation.

Initially, Watts had prepared to talk about the evergreen topic of treating injured or arthritic joints with hyaluronic acid and corticosteroids. Instead, one of the key topics was the use of stem cells in joints.

The audience first discussed how stem cell injections to treat joint pain or damage have improved. When veterinarians first began using this treatment method, they noticed profound joint flare reactions. However, current preparation of autologous (from the horse's own body) stem cells instead of fetal bovine serum (the old approach) has markedly reduced flare reactions.

Watts explained that stem cells actually stimulate IRAP (interleukin-1 receptor antagonist protein) production in the joint (which blocks inflammatory protein products that stimulate pain, inflammation, cartilage degradation, and lameness associated with osteoarthritis), as well as growth factors similar to what is achieved with plasma-rich protein (PRP), so they give multiple benefits.

David Frisbie, DVM, PhD, Dipl. ACVS, ACVSMR, professor at the Colorado State University (CSU) Orthopaedic Research Center, said, “Stem cells are best used once active inflammation has settled down, usually four-plus weeks postoperatively.” Frisbie, who helped pioneer stem cell use in horses, also remarked that recent research has shown that using stem cells in the presence of inflammation does not achieve a long-term effect.

On a similar note, audience members agreed that infectious arthritis should not be treated with regenerative therapy until at least two months after infection and inflammation have resolved.

The veterinarians in attendance also recommended that corticosteroids not be injected into a joint that will be treated with stem cells soon. These cells are exquisitely sensitive to their environment and “need to be told what to do.” However, because corticosteroids are toxic to stem cells and interfere with their activity, the presenters recommended using autologous-conditioned serum (IRAP) instead to lessen joints' inflammatory reaction.

Most often veterinarians said they use stem cells to treat stifle injuries, with 60-70% resolution in damage of the meniscus (the cartilaginous tissues between bones in the stifle joint). Frisbie described how CSU researchers demonstrated that 65% of horses returned to function with stem cell joint injections, as compared to 35% of horses not receiving stem cells but treated with other intra-articular therapies.

Combining hyaluronic acid (HA), a joint treatment mainstay, with stem cells or autologous-conditioned serum (IRAP) might well offer an advantage. Frisbie commented that HA has been known to increase the time stem cells stay in the joint and might elicit better “sticking” of stem cells to articular cartilage. He said PRP might be counterproductive for use with stem cells because it could signal the body to make bone instead of cartilage. Further, veterinarians participating in the discussion recommended against using the antibiotic amikacin with joint injections of stem cells because it adversely affects them. However, veterinarians can use systemic gentamycin—another antibiotic from the same class--safely without adversely affecting stem cells.

As a reminder, attendees suggested using amikacin with intra-articular polysulfated glycosaminoglycans to reduce the chance of bacterial growth in joints that sometimes accompanies this product's use. Many horse owners ask to have their horse’s joints injected with HA in advance of a known joint problem as a protective measure. However, veterinarians said that HA can be helpful for acute synovitis (inflammation of the joint lining), but they pointed out that there is no evidence of any prophylactic (preventive) advantage to injecting HA into a non-inflamed joint. Lastly, the group briefly discussed treating joints affected by osteoarthritis (OA), which is nonreversible. In these cases, regenerative medicine is not necessarily the method of choice if the OA is stable; in those cases, corticosteroids are the best strategy. Regenerative medicine has its best application in acute, new injuries.

About the Author

Nancy S. Loving, DVM

Nancy S. Loving, DVM, owns Loving Equine Clinic in Boulder, Colorado, and has a special interest in managing the care of sport horses. Her book, All Horse Systems Go, is a comprehensive veterinary care and conditioning resource in full color that covers all facets of horse care. She has also authored the books Go the Distance as a resource for endurance horse owners, Conformation and Performance, and First Aid for Horse and Rider in addition to many veterinary articles for both horse owner and professional audiences.

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