Comparative analysis of bone regeneration in critical-sized defects using self-assembling peptide hydrogel-178, bone morphogenetic protein-2, and calcium phosphate scaffolds in a rat femur model.

Bone regeneration is a highly demanded but challenging clinical endeavor in orthopedic surgery, necessitating the development of alternative bone grafting materials. This study aimed to evaluate the bone regenerative potential of self-assembling peptide hydrogel (0.8%), bone morphogenetic protein-2 (50 ng/μL), hydroxyapatite, and β-tricalcium phosphate, both individually and in combination with bone chips, in a rat femoral defect model. Ten-week-old female Wistar rats underwent surgical implantation of a polyetheretherketone cage into a 5-mm bony defect within the left femoral mid-shaft, maintained by an external fixator. Polyetheretherketone cages were filled with bone substitute materials alone in the first experiment and with bone substitute materials combined with bone chips in the second experiment. Radiographic and histological analyses were conducted following sacrifice at 56 weeks. While self-assembling peptide hydrogel alone exhibited moderate bone formation, with a bone-volume-to-total-volume ratio of 0.34 ± 0.09, this value was not significantly higher than that of the control group with an empty polyetheretherketone cage. Conversely, the combination of bone morphogenetic protein-2 with bone chips produced the highest level of bone regeneration, with a bone-volume-to-total-volume ratio of 0.78 ± 0.05, significantly surpassing bone chips alone (p < 0.01) and self-assembling peptide hydrogel with bone chips (p < 0.05). These findings suggest that while self-assembling peptide hydrogel holds potential as a scaffold material, particularly in minimally invasive applications, its efficacy in promoting robust bone regeneration may benefit from the inclusion of osteoinductive factors, such as bone morphogenetic protein-2.