Equine autologous blood-based products contain variable quantities of transforming growth factor-β1, interleukin-1 receptor agonist, and α2-macroglobulin.

Abstract

Objective: Quantify the concentration of α2-macroglobulin (A2M), immunomodulatory cytokines, and TGF-β1 factors in 4 commercially available autologous blood-based products including conditioned A2M (CA2M; Alpha2EQ; Astaria Global), autologous protein solution (APS; Pro-Stride; Zoetis), platelet-rich plasma (PRP; Restigen; Zoetis), and autologous conditioned plasma (ACP; Arthrex ACP). We hypothesized that CA2M would have higher concentrations of A2M and lower concentrations of cytokines and growth factors compared to APS, PRP, and ACP.

Methods: Blood was obtained from 6 healthy, adult horses and processed into CA2M, APS, PRP, and ACP. The concentration of immunomodulatory cytokines, including IL-1β, IL-4, IL-6, IL-10, IL-17a, and TNF-α, and the concentration of the growth factor TGF-β1 were quantified using immunoassays. The concentration of the IL-1 receptor antagonist was quantified using ELISA. The concentration of A2M was quantified using mass spectrometry.

Results: No differences in the concentrations of IL-1β, IL-4, IL-6, IL-10, and IL-17a were found. Median TGF-β1 was significantly higher in APS (10,801 pg/mL; P < .05), PRP (6,219 pg/mL; P < .05), and ACP (5,263 pg/mL; P < .05) compared to CA2M (2,090 pg/mL). The IL-1 receptor antagonist was significantly higher in APS (58.78 ng/mL) and PRP (40.45 ng/mL). Median A2M concentration was significantly higher in APS (4.08 mg/mL; P < .001) compared to CA2M (1.99 mg/mL).

Conclusions: Autologous blood-based products have notably different immunomodulatory and growth factor profiles. These differences likely reflect variable concentrations of platelets and WBCs, as well as processing methods.

Clinical relevance: Equine veterinarians should be aware of the constituents of the different orthobiologics available before use.