Abstract
BACKGROUND: Platelet-rich plasma (PRP) is a treatment option for tendon injury because of its effective tendon-healing properties. At the early stage of tendon repair, paratenon-derived cells (PDCs) are thought to play a more important role than tendon proper-derived cells (TDCs). However, there has been no study investigating the effects of PRP on PDCs. HYPOTHESIS: PRP promotes the migration, proliferation, and differentiation of PDCs in vitro. STUDY DESIGN: Controlled laboratory study. METHODS: TDCs and PDCs were isolated from the tendon proper and paratenon of rat Achilles tendons and were cultured to the third passage. PRP was prepared from the rats using the double-spin method. Third-passage TDCs and PDCs were cultured in Dulbecco's modified Eagle medium with 2% fetal bovine serum (control group) or 2% fetal bovine serum plus 5% PRP (PRP group), and cell migration, proliferation, and differentiation were evaluated. The relative mRNA expression levels of scleraxis (Scx), tenomodulin (Tnmd), collagen type I alpha 1 (Col1a1), collagen type III alpha 1 (Col3a1), and vascular endothelial growth factor A (VEGF) were examined by quantitative real-time reverse transcription polymerase chain reaction. RESULTS: The cell migration rate was significantly higher in the PDCs of the PRP group than in the control group (1.4-fold increase; P = 0.02). Cell proliferation was significantly higher in the PDCs of the PRP group (2.2-fold increase; P < 0.01). In the PDCs, the gene expression levels of Scx, Col1a1, and VEGF were significantly increased by PRP (Scx: 2.0-fold increase, P = 0.01; Col1a1: 5.3-fold increase, P = 0.01; VEGF: 7.8-fold increase, P = 0.01), but the gene expression level of Tnmd, a factor for tendon maturation, was significantly reduced by PRP (0.11-fold decrease; P = 0.02). CONCLUSION: In vitro PRP promoted migration, proliferation, and tenogenic differentiation with the upregulation of Scx in PDCs. PRP also upregulated the expression of the angiogenic marker VEGF. CLINICAL RELEVANCE: Our results suggest that PRP treatment in vitro may enhance the tendon-healing properties of PDCs at the initial stage of tendon repair.