David Frisbie, DVM, PhD, of the Gail Holmes Equine Orthopaedic Research Center at Colorado State University, continued the discussion on new therapeutics at the AAEP Focus meeting in Ft. Collins, Colo., on July 29.

He discussed the use of autologous conditioned serum (ACS), also known as interleukin-1 receptor antagonist protein (IRAP). Whole blood is cultured with glass beads to upregulate interleukin-1. This material is put directly back into a horse’s ailing joint in a series of three injections, followed up at monthly intervals with another dose or two. In nonsurgical joints that are at least partially responsive to HA and steroids, IRAP treatment elicits less lameness and less synovitis up to 40 days following treatment.

Another therapy discussed by Frisbie was stem cells injected either directly into damaged tissue or peripherally (IV). There seems to be some trophic properties to the stem cells to increase mitotic activity in surrounding cells and to recruit and mobilize other stem cells from other areas o the body to the injured tissue site. Currently there are two sources of stem cells: bone-marrow-derived or fat-derived. Bone marrow comes from an aspirate of a horse�s sternum or ileum (hip bone), while adipose tissue is harvested from the fat of the tailhead or peritoneum (abdominal lining). The source from which these tissues are taken has an effect on the results, i.e., sternum-derived bone marrow gives better results than ileum-derived. In addition, bone marrow stem cells are more effective in treatment than using adipose-derived stem cells.

Recent studies in goats indicate that 50-75% of medial meniscal injuries could regenerate. However, in horses the research indicates no decrease in lameness seen with stem cell treatment of equine osteoarthritic joints. Although there was some evidence of decrease in prostaglandins and inflammatory mediators, there was no reduction in cartilage erosion. In summary, Frisbie maintained there is no notable improvement in experimental osteoarthritic joints when treated with stem cells, but based on the goat studies, there could be potential value for helping soft tissue injury in an injured joint