Effects of intra-articular injection of an acellular equine liquid amniotic allograft in healthy equine joints.

Abstract

OBJECTIVE: Evaluate effects of acellular equine liquid amnion allograft (ELAA) injected into healthy equine joints. STUDY DESIGN: Randomized, blinded, controlled experiment. ANIMALS: Eight healthy adult horses. METHODS: One intercarpal joint (ICJ) of each horse was randomly assigned to be injected with 1.5&#xa0;ml of ELAA (treatment) while the contralateral ICJ was injected with 1.5&#xa0;ml of 0.9% NaCl (control). Subjective lameness evaluation, force plate analysis, and synovial fluid analysis, including interleukin-1 receptor antagonist (IL-1ra) analysis, were performed before (day 0) and at days 1, 3, 5, and 10. Synovial fluid analysis was also performed on days 20 and 30. RESULTS: No difference in subjective lameness (P&#xa0;=&#xa0;.75) and no decrease in peak vertical force or vertical impulse were seen in any limb on any day. Total nucleated cell count (TNCC) was increased in treatment joints on days 1 (P&#xa0;=&#xa0;.0007; T: 6039 cells/&#x3bc;l, C: 240 cells/&#x3bc;l) and 3 (P&#x2009;<&#x2009;.0001; T: 1119 cells/&#x3bc;l, C: 240 cells/&#x3bc;l). Log-10 transformed values for IL-1ra were higher in treated joints on days 1 (P&#xa0;=&#xa0;.0005; T: 3553.7&#xa0;pg/ml, C: 1890.1&#xa0;pg/ml) and 3 (P&#xa0;=&#xa0;.01; T: 2283.2&#xa0;pg/ml, C: 1250.7&#xa0;pg/ml). CONCLUSION: Injection of ELAA into the ICJ caused an increase in synovial fluid TNCC in comparison with saline control but no lameness was observed. There was increased IL-1ra on days 1 and 3 after ELAA injection. CLINICAL SIGNIFICANCE: Intra-articular injection of ELAA into healthy equine joints results in no significant safety concerns. The observed increase in IL-1ra may provide beneficial effects in inflamed joints.