Optimization of the Platelet-rich Plasma Concentration for Mesenchymal Stem Cell Applications.

Platelet-rich plasma (PRP) and mesenchymal stem cells (MSCs) are promising tools for muscular-skeletal regeneration. However, increasing evidence has demonstrated controversial effects of PRP on the tissue regeneration. To obtain optimum PRP concentrations for MSC expansion and to accurately control osteogenic, adipocytic, and chondrogenic differentiation, MSCs were exposed to PRP alone or in combination with induction medium. We found that PRPs with the platelet concentration beyond 1500 x 10(9) pl/L were preferable to promote MSC proliferation. In addition, PRPs ranging from 200 x 10(9) to 3000 x 10(9) pl/L were capable of augmenting MSC osteogenesis, and PRP with 1500 x 10(9) pl/L was most effective for MSC osteogenic differentiation. Furthermore, PRPs in low platelet concentration range just slightly promoted MSC adipogenesis, and only when the platelet concentration was beyond 1800 x 10(9) pl/L, the promoted effects were evident. Moreover, PRP range from 1000 to 3000 x 10(9) pl/L significantly enhanced chondrogenesis of MSCs in the absence and presence of chondrogenic induction medium, and PRP with 2000 x 10(9) pl/L was more effective for MSC chondrogenesis. Furthermore, we explored the mechanisms of PRP-induced MSC differentiation, showing that the growth factors played a major role in this process while other unknown factors may also be involved in it. At last, we measured the levels of cytokines to learn that PRP treatment suppressed the secretion of interleukin-1 beta (IL-1 beta), IL-6, and tumor necrosis factor-alpha, but favored the production of IL-10 by MSCs. In summary, our findings demonstrated that PRPs with different concentrations of platelets exerted different effects on proliferation and differentiation of MSCs, which indicated that preparing appropriate PRPs may be a precise and efficient strategy for improving MSC-based tissue regeneration.