BACKGROUND: Autologous platelet-rich plasma (PRP) application appears to improve tendon healing in traumatic tendon injuries, but basic knowledge of how PRP promotes tendon repair is needed. HYPOTHESIS: Platelet-rich plasma has a positive effect on cell proliferation and collagen production and induces the production of matrix-degrading enzymes and endogenous growth factors by human tenocytes. STUDY DESIGN: Controlled laboratory study. METHODS: Human tenocytes were cultured 14 days in 2% fetal calf serum medium complemented with 0%, 10%, or 20% vol/vol platelet-rich clot releasate ([PRCR] the active releasate of PRP) or platelet-poor clot releasate (PPCR). At day 4, 7, and 14, cell amount, total collagen, and gene expression of collagen I alpha 1 (COL1) and III alpha 1 (COL3), matrix metalloproteinases ([MMPs] MMP1, MMP3, and MMP13), vascular endothelial-derived growth factor (VEGF)-A, and transforming growth factor (TGF)-beta1 were analyzed. RESULTS: Platelet numbers in PRP increased to 2.55 times baseline. Growth-factor concentrations of VEGF and platelet-derived growth factor (PDGF)-BB were higher in PRCR than PPCR. Both PRCR and PPCR increased cell number and total collagen, whereas they decreased gene expression of COL1 and COL3 without affecting the COL3/COL1 ratio. PRCR, but not PPCR, showed upregulation of MMP1 and MMP3 expression. Matrix metalloproteinase 13 expression was not altered by either treatment. PRCR increased VEGF-A expression at all time points and TGF-beta1 expression at day 4. CONCLUSION: In human tenocyte cultures, PRCR, but also PPCR, stimulates cell proliferation and total collagen production. PRCR, but not PPCR, slightly increases the expression of matrix-degrading enzymes and endogenous growth factors. CLINICAL RELEVANCE: In vivo use of PRP, but also of PPP to a certain extent, in tendon injuries might accelerate the catabolic demarcation of traumatically injured tendon matrices and promote angiogenesis and formation of a fibrovascular callus. Whether this will also be beneficial for degenerative tendinopathies remains to be elucidated.

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Keywords *Platelet-Rich Plasma, Cell Proliferation, Cells, Cultured, Collagen Type I/*biosynthesis/genetics, Collagen Type III/*biosynthesis/genetics, DNA/analysis, Gene Expression, Humans, Matrix Metalloproteinases/biosynthesis, Tendons/*cytology/metabolism, Transforming Growth Factor beta1/biosynthesis, Vascular Endothelial Growth Factor A/biosynthesis, Wound Healing/*physiology
Persistent URL dx.doi.org/10.1177/0363546508314430, hdl.handle.net/1765/15197
Citation
de Mos, M, van der Windt, A.E, Jahr, H, van Schie, J.T.M, Weinans, H.H, Verhaar, J.A.N, & van Osch, G.J.V.M. (2008). Can platelet-rich plasma enhance tendon repair? A cell culture study. American Journal of Sports Medicine, 36(6), 1171–1178. doi:10.1177/0363546508314430