Comparison of the biocompatibility and osteogenesis potential of whitlockite and an activin A/BMP2 chimera using a rat calvarial defect model: a pilot study

The aim of this study was to evaluate bone regeneration using whitlockite (WH) nanoparticles, collagenated bovine bone mineral, and an activin A/BMP2 chimera (AB204) on calvarial defects in rats. This study was conducted using 8 rats. Five-millimeter circular defects were formed on each side of the calvaria. The defects were randomly assigned to 3 groups (BO group: BioOss collagen, BO/WH group: BO + WH, and BO/WH/AB204 group: BO + WH + AB204). After healing periods of 2 and 4 weeks, histological and histomorphometric analyses were performed after sacrifice. The BO/WH/AB204 group showed superior bone healing compared to the other 2 groups (BO and BO/WH). In the BO and BO/WH groups, new bone formation was found in the defect margin. However, in the BO/WH/AB204 group, new bone was observed on the upper and lower surfaces of the grafted area. The new bone area of the BO/WH/AB204 group at 4 weeks was significantly higher than that of the same group at 2 weeks. At 4 weeks, the total augmented area and material area in the BO/WH/AB204 group were significantly lower than the corresponding values at 2 weeks. The BO/WH/AB204 group showed superior results of bone regeneration at 2 and 4 weeks compared to the BO and BO/WH groups. AB204 seems to play an important role in bone regeneration.