Semester of Graduation

May 2020


Master of Science (MS)


Veterinary Clinical Sciences

Document Type



INTRODUCTION- The use of biologic therapies like platelet rich plasma (PRP) has a potential benefit for the treatment of osteoarthritis in horses. However, key parts of it are still unknown. The objective is to evaluate the degree of platelet activation achieved when in contact with exogenous activators. As well as the long-term effect in the anabolism and catabolism of cytokines involved in equine osteoarthritis.

MATERIAL AND METHODS-In one in vitro study PRP was collected from 6-horses using a commercially available kit. Platelets were exposed to PBS as negative control or to varying concentrations of CaCl2. Activation was determined via cell surface expression of CD41α and CD62p measured via flow cytometry. Data was reported as the percentage of platelets expressing CD41α or CD62p and assessed using ANOVA. In the in-vivo study, PRP collected from 8 horses with grade 1 of osteoarthritis in both carpi. PRP was injected in one carpal joint and sterile saline in the control joint. At each time point, lameness evaluation was assessed, and joint fluid analyzed for hematology parameters as well as cytokine detection by fluorescent microsphere immunoassay and PDGF-ββ with ELISA techniques.

RESULTS- In the in vitro study, platelets incubated with 23mM CaCl2 (30.57±4.82) demonstrated a significantly higher percentile of activated platelets (p=0.0136) compared to control (13.84±4.82) when stained with CD62p. In the in vivo study, repeated injections of LP-PRP do not cause inflammation of synovial fluid parameters like total protein(p=0), nucleated cells (p=0.149), at any time point. Similarly, no changes in lameness from horses in control and treatment legs from day 1 to day 51 (p=0.625). No significant changes were detected in IL-10 (p=0.155), IL-13 (p=0.511), IL-4 (p=0.659), IL-1β (p=0.387), IL-6 (p=0.4135), TNF-a (p= 0.4135), PDGF-ββ (non-detected).

DISCUSSION: The Flow cytometry protocol described here can be used to evaluate and quantify the PRP interaction with joint fluid, allowing the possibility of optimization of platelet activation and, therefore, growth factor release. In our second study we concluded that repeated intra-articular injections with LP-PRP do not cause a long-term inflammation.

Committee Chair

Laura, Riggs.