Influence of pore architecture on bone regeneration in atelocollagen scaffolds

We aimed to compare the bone regeneration capacity of two atelocollagen sponges with distinct porosity, pore size, and pore morphology: Atelocollagen Sponge MIGHTY^® (MIGHTY) and the three-dimensional Honeycomb Boosted^® scaffold (Honeycomb). Scanning electron microscopy revealed that Honeycomb exhibited a continuous linear pore structure with a uniform honeycomb-like architecture, higher porosity, and larger pores than MIGHTY. Each sponge was placed in a high-density polytetrafluoroethylene dome and fixed to the rat calvaria. X-ray micro-computed tomography showed that Honeycomb increased bone volume fraction approximately 2.4-fold and 2.3-fold at 4 and 8 weeks post-implantation, respectively, compared with MIGHTY. At 12 weeks post-implantation, bone volume fraction was comparable; however, trabecular number in Honeycomb remained approximately two-fold higher. Histological and immunohistochemical observations confirmed enhanced bone formation, suggesting relatively early angiogenesis and progressive mesenchymal stem cell involvement. Overall, these results indicate that the Honeycomb scaffold supports early bone regeneration.