Effects of Autologous Platelet-Rich Plasma on Cell Viability and Collagen Synthesis in Injured Human Anterior Cruciate Ligament

BACKGROUND: Platelet-rich plasma is a fraction of plasma in which platelets are concentrated. It is reported to represent a source of multiple growth factors that promote tissue repair. In anticipation of the eventual testing of platelet-rich plasma in anterior cruciate ligament (ACL)-deficient patients, we examined the effect of autologous platelet-rich plasma on human ACL cell function in vitro. METHODS: Fresh blood and ACL remnants were obtained from four patients who underwent ACL reconstruction surgery. Platelet-poor plasma and platelet-rich plasma were prepared from the blood samples. The concentrations of various growth factors in each preparation were tested with use of enzyme-linked immunosorbent assays. Isolated ACL cells were cultured in the presence of 5% fetal bovine serum, 5% platelet-poor clot releasate, 5% platelet-rich clot releasate, or 10% platelet-rich clot releasate. Platelet-rich plasma and platelet-poor plasma releasates were applied to the ACL cells from the same patient autologously. Cell viability and collagen synthesis in each group were analyzed, and semiquantitative gene-expression assays for type-I and III collagen were also performed. RESULTS: The concentrations of the main growth factors (transforming growth factor-beta, platelet-derived growth factor, epidermal growth factor, and vascular endothelial growth factor) were much higher in platelet-rich clot releasate than in platelet-poor clot releasate. In vitro treatment of ACL cells with platelet-rich clot releasate resulted in a significant increase in cell number compared with platelet-poor clot releasate. Total collagen production by the platelet-rich clot releasate-treated cells was significantly higher than that of the platelet-poor clot releasate-treated cells only because of enhanced cell proliferation. There was no significant effect of platelet-rich clot releasate treatment on gene expression for type-I collagen, but expression of type-III collagen was significantly enhanced by the treatment with platelet-rich clot releasate. CONCLUSIONS: These results suggest that autologous platelet-rich plasma can enhance ACL cell viability and function in vitro.