Polydopamine-functionalized nanohydroxyapatite coated exosomes with enhanced cytocompatibility and osteogenesis for bone regeneration

Background Mesenchymal stem cells-derived exosomes, crucial in regenerative medicine, have been explored for their potential for the functional modification of bone scaffolds. Objective To design a functionally modified biomimetic nanohydroxyapatite using exosomes and explore its effects on bone regeneration. Methods A biomimetic nanohydroxyapatite (named as tHA) was fabricated as previous methods using a polydopamine (pDA) structure as a template, and exosomes (Exo) derived from periodontal ligament stem cells (PDLSCs) were used to functionally modify the tHA scaffold material through pDA. The effects of functional composite scaffold (tHA-Exo) on cells proliferation and osteogenic differentiation were investigated. Furthermore, their effect on bone regeneration was also evaluated in vivo. Results Exosomes can be loaded onto the tHA via pDA and the tHA-Exo releases exosomes in a sustained and stable manner. tHA-Exo showed improved cytocompatibility compared to controls. Additionally, tHA-Exo significantly enhanced the proliferation and osteogenic differentiation of PDLSCs. More importantly, animal experiments have shown that tHA-Exo could dramatically promote bone regeneration. Conclusion The tHA nanoparticles, functionally modified by the PDLSCs-Exo through pDA, significantly promoted bone regeneration by improving its cytocompatibility and osteogenic potential, which could serve as a promising material for promoting bone regeneration.