Synergistic effect of fluorapatite and platelet-rich plasma on cell proliferation and differentiation: A novel strategy to enhance dental implant osseointegration

This study investigated the synergistic effect of fluorapatite (FA) coatings and platelet-rich plasma (PRP) on cell adhesion, proliferation, differentiation and mineralisation with a view to the use of this combination in enhancing osseointegration of dental implants. Stainless steel (SS) discs tilted at 45° were hydrothermally coated with FA crystals. PRP was extracted from human blood and the release of platelet growth factors (IGF-1 and PDGF-AB) from non-activated and activated PRP loaded on FA coatings into PBS was measured. Cytotoxicity of FA/PRP combinations and their effect on G292 cell proliferation was tested. Osteogenic differentiation of human dental pulp stem cells (hDPSCs) cultured on FA/PRP was investigated using osteogenic marker expression and histochemical stains. The results showed that FA crystals were disorganised on upper disc surfaces and organised on the under surfaces. Organised FA coatings stimulated greater and more sustained release of IGF-1 from non-activated PRP compared to the control (SS/non-activated PRP). The greatest release of PDGF-AB was triggered by thrombin from PRP loaded on organised FA. FA crystals showed good biocompatibility that was enhanced by PRP. Organised FA coatings induced a high cell proliferation when combined with PRP gel compared to the control (SS/FBS). There was a clear PRP donor variability in ALPL and RUNX-2 gene expression by hDPSCs when PRP used in combination with uncoated SS or FA coated surfaces compared to the control (SS/FBS). Organised FA when combined with FBS or PRP didnot enhance OCN expression but increased OPN expression compared to the control. Organised FA induced less ALP activity but high calcium deposition by hDPSCs compared to uncoated SS when both were combined with FBS or PRP, indicative of osteogenic differentiation. Therefore, it can be concluded that PRP in combination with organised FA coating may offer a promising strategy for bone regeneration around the dental implants.