Platelet-Rich Plasma Stimulates Cell Proliferation and Enhances Matrix Gene Expression and Synthesis in Tenocytes From Human Rotator Cuff Tendons With Degenerative Tears

Background: Platelet-rich plasma (PRP) contains various growth factors and appears to have a potential to promote tendon healing, but evidence is lacking regarding its effect on human tenocytes from rotator cuff tendons with degenerative tears. Hypothesis: Platelet-rich plasma stimulates cell proliferation and enhances matrix gene expression and synthesis in tenocytes isolated from human rotator cuff tendons with degenerative tears. Study Design: Controlled laboratory study. Methods: Tenocytes were enzymatically isolated and cultured. To evaluate cell proliferation, tenocytes were cultured with 10% (vol/vol) platelet-poor plasma (PPP), PRP activated with calcium, and PRP activated with calcium and thrombin at platelet concentrations of 100, 200, 400, 800, 1000, 2000, 4000, 8000, and 16,000 x 10(3)/A mu L for 14 days. Cell number was measured at days 7 and 14. To investigate matrix gene expression and synthesis, cells were cultured with a PPP or PRP gel (10% vol/vol) at a platelet concentration of 1000 x 10(3)/A mu L for 14 days. Quantitative real-time reverse transcriptase polymerase chain reaction was performed to determine the expressions of type I and III collagen, decorin, tenascin-C, and scleraxis, and measurements of total collagen and glycosaminoglycan (GAG) synthesis were conducted at days 7 and 14. Results: Platelet-rich plasma significantly increased cell proliferation at days 7 and 14 in a dose-dependent manner, and the addition of thrombin moved up the plateau of proliferation. Platelet-rich plasma significantly induced the gene expression of type I collagen at day 7 but not at day 14, while it significantly promoted that of type III both at days 7 and 14. The ratio of type III/I collagens did not change at days 7 and 14. The expressions of decorin and scleraxis significantly increased at day 14, whereas that of tenascin-C significantly increased at days 7 and 14. Platelet-rich plasma significantly increased total collagen synthesis at days 7 and 14 and GAG synthesis at day 14. Conclusion: Platelet-rich plasma promoted cell proliferation and enhanced gene expression and the synthesis of tendon matrix in tenocytes from human rotator cuff tendons with degenerative tears. Clinical Relevance: These findings suggest that PRP might be used as a useful biological tool for regenerative healing of rotator cuff tears by enhancing the proliferation and matrix synthesis of tenocytes from tendons with degenerative tears.