Osteogenic capacity of diluted platelet-rich plasma in ectopic bone-forming model: Benefits for bone regeneration.

Platelet-rich plasma (PRP) with normal and below-normal physiological concentrations of platelets is designated as diluted PRP (dPRP). The aims of this study are to evaluate whether bone mineral matrix in combination with dPRP possesses osteogenic capacity; and whether the differences in dynamics and osteogenic process pattern depend on different platelet concentrations, to what extent, and also what could be benefits for bone regeneration in clinical practice. Three types of implants were made: BMM-bone mineral matrix alone; dPRP/10-bone mineral matrix mixed with dPRP (concentration of platelets 10 times lower than physiological level) and dPRP/3-bone mineral matrix mixed with dPRP (concentration of platelets 3 times lower than physiological level). A subcutaneous implantation model in Balb/c mice was used. The implants were analyzed using expression analysis of bone-related genes, histochemical, immunohistochemical and histomorphometrical analysis. All types of implants induced creation of necessary preconditions for supporting osteogenic processes, but did not induce visible young bone growth. Implant types dPRP/10 and dPRP/3 showed very similar and significantly better stimulatory effects on osteogenic processes than bone matrix alone. In this study, significant ectopic osteogenic potential of concentration of platelets in PRP that are lower than physiological level in blood plasma in combination with bone mineral matrix was demonstrated. Diluted platelet-rich plasma could be a promising and useful adjuvant therapeutic agent in bone regeneration.