Enhancing cranial defect repair in rats: investigating the effect of combining Total Flavonoids from Rhizoma Drynariae with calcium phosphate/collagen scaffolds

Objective To investigate the therapeutic efficacy of total flavonoids of Rhizoma Drynariae (TFRD) in conjunction with a calcium phosphate/collagen scaffold for the repair of cranial defects in rats. Methods The subjects, rats, were segregated into four groups: Control, TFRD, Scaffold, and TFRD+Scaffold. Cranial critical bone defects, 5 mm in diameter, were artificially induced through precise drilling. Post-surgery, at intervals of 2, 4, and 8 weeks, micro-CT scans were conducted to evaluate the progress of skull repair. Hematoxylin-eosin and Masson staining techniques were applied to discern morphological disparities, and immunohistochemical staining was utilized to ascertain the expression levels of local osteogenic active factors, such as bone morphogenetic protein 2 (BMP-2) and osteocalcin (OCN). Results Upon examination at the 8-week mark, cranial defects in the Scaffold and TFRD+Scaffold cohorts manifested significant repair, with the latter group displaying only negligible foramina. Micro-CT examination unveiled relative to its counterparts, and the TFRD+Scaffold groups exhibited marked bone regeneration at the 4- and 8-week intervals. Notably, the TFRD+Scaffold group exhibited substantial bone defect repair compared to the TFRD and Scaffold groups throughout the entire observation period, while histomorphological assessment demonstrated a significantly higher collagen fiber content than the other groups after 2 weeks. Immunohistochemical analysis further substantiated that the TFRD+Scaffold had augmented expression of BMP-2 at 2, 4 weeks and OCN at 2 weeks relative to other groups. Conclusions The synergistic application of TFRD and calcium phosphate/collagen scaffold has been shown to enhance bone mineralization, bone plasticity, and bone histomorphology especially during initial osteogenesis phases.