Differences in platelet-rich plasma composition influence bone healing.

Aim Platelet-rich plasma (PRP) is autologous blood-derived material that has been used to enhance bone regeneration. Clinical studies however reported inconsistent outcomes. This study aimed to assess the effect of changes in leucocyte and PRP (L-PRP) composition on bone defect healing. Materials and methods We prepared L-PRPs using different centrifugation methods and assessed their regenerative potential in an in vivo rat model. Bilateral critical size tibial bone defects were created and filled with either: single spin L-PRP, double spin L-PRP, or filtrated L-PRP. Empty defects and defects treated with collagen scaffolds served as controls. Rats were euthanized after two weeks, and their tibias were collected and analysed using micro-CT and histology. Results Double-spin L-PRP contained higher concentrations of platelets than single-spin L-PRP and filtrated L-PRP. Filtration of single-spin L-PRP resulted in lower concentrations of minerals and metabolites. In vivo, double-spin L-PRP improved bone healing by significantly reducing the size of bone defects (1.08±0.2 mm3 ) compared to single-spin L-PRP (1.42 ±0.27 mm3 ) or filtrated- L-PRP (1.38±0.28 mm3 ). There were fewer mast cells, lymphocytes, and macrophages in defects treated with double-spin L-PRP than in those treated with single-spin or filtrated- L-PRP. Conclusion The preparation method of L-PRP affects their composition and potential to regenerate bone.