Potential of platelet-rich plasma-derived exosomes for bone-defect repair: in vitro and in vivo study

Skeletal progenitor-enriched cells, also referred to as skeletal stem cell (SSC)-like cells, are multipotent progenitors that underpin advancements in bone bioengineering and regenerative therapy. Platelet-rich plasma-derived exosomes (PRP-EXOs) exhibit promising capabilities for enhancing osteogenic repair and addressing bone-defect challenges. Nonetheless, whether PRP-EXOs promote bone regeneration and repair by affecting SSC-like cells remains unclear. This study aimed to investigate the effects of PRP-EXOs on SSC-like cells and bone-defect regeneration and repair. PRP-EXOs were purified from rat-derived PRP, and SSC-like cells were obtained via collagenase digestion of femoral and tibial bone tissues. PRP-EXOs were identified by transmission electron microscopy, nanoparticle tracking analysis, and western blotting. The effects of PRP-EXOs on cell viability, proliferation, migration, and osteogenic differentiation were also assessed. Femoral bone-defect models were constructed in rats and evaluated for bone regeneration and repair using microcomputed tomography, bone parameter analysis, and histological assessment. We successfully extracted PRP-EXOs and isolated SSC-like cells from Sprague Dawley rats. Incubation with PRP-EXOs increased cell viability, promoted cell proliferation and migration, and strengthened the osteogenic differentiation of SSC-like cells. Furthermore, PRP-EXO treatment reduced weight loss and accelerated new bone formation and repair in rats with femoral bone defects, accompanied by improvements in bone mineralization and collagen formation. The promotion of bone-defect repair by PRP-EXOs may depend on their promoting effects on the proliferation, migration, and osteogenic differentiation of SSC-like cells, suggesting that PRP-EXOs may be important in bone-defect treatment.