Healing in Horses: Concentrating Bone Marrow Aspirate Increases IRAP Levels

A biologic product called bone marrow aspirate concentrate (BMAC) is significantly enriched in interleukin-1 receptor antagonist protein (IRAP), far exceeding levels of IRAP measured in bone marrow aspirate (BMA) and platelet-rich plasma collected from the same patient. This finding suggests that BMAC may be a clinically relevant autologous regenerative therapy to support tissue healing.

In theory, BMAC can be used for similar clinical applications as BMA, including:

• Intra-articularly for joints with osteoarthritis;
• Intralesionally for enhanced healing of ligament and tendon injuries; and
• Intracystic injection for osteochondritis dissecans (OCD) lesions.

BMAC can be easily produced from BMA, typically collected from the horse’s sternum or breastbone. The procedure is considered “stall-side” and is believed to produce a biologic product containing cytokines and growth factors as well as IRAP and other signaling molecules that affect musculoskeletal tissue healing.

To better understand the composition of BMAC, veterinary researchers collected bone marrow and blood samples from 25 horses, which were subsequently processed stall-side to generate BMA, BMAC, and PRP. Growth factors and cytokines, including IRAP, were measured in each biologic and compared.

“The most exciting finding was that IRAP was 21 times higher in BMAC compared to BMA, and 117 times higher than platelet-rich plasma,” relayed Ashley Fowler, Ph.D. a Kentucky Equine Research nutritionist.

The potent pro-inflammatory cytokine interleukin-1 beta (IL-1â) was also slightly concentrated in BMAC compared to BMA. However, the biological and clinical significance of this remains unclear. Further studies investigating and comparing the IRAP levels in BMAC to those in the commercial IRAP product and autologous protein solution are also indicated.

“BMAC can be rapidly produced stall-side and therefore expedite treatment of various musculoskeletal conditions, including osteoarthritis,” explained Fowler.

Even with BMAC, osteoarthritis is best managed using a multimodal approach that may also include nonsteroidal anti-inflammatory drugs, intra-articular corticosteroids, and oral joint health supplements.

“Glucosamine and chondroitin sulfate are two ingredients that can help support healthy joints by maintaining joint integrity, minimizing inflammation, and reducing cartilage damage,” explained Fowler.

Kentucky Equine Research offers an array of joint supplements, including glucosamine, chondroitin sulfate, hyaluronic acid, and omega-3 fatty acids.

^*Long, S., G. Maleas, Z.A. Belacic, V.G. Quam, and S. Durgam. 2025. Equine bone marrow aspirate and bone marrow aspirate concentrate are enriched with interleukin-1 receptor antagonist protein. American Journal of Veterinary Research 86(5):ajvr.24.12.0380.