Eggshell membrane supplementation stimulates angiogenesis and promotes bone healing in a rat drill-hole injury model

The development of new adjunct therapies to support bone healing remains an important clinical challenge. Eggshell membrane (ESM), a natural biomaterial derived from chicken eggs, has recently attracted attention for its safety, biocompatibility, and cost-effectiveness. We aimed to evaluate the effects of ESM supplementation on bone healing in a rat tibial drill-hole injury model. Seven-week-old male Wistar rats, acclimated for one week prior to the experiment, were divided into three groups: control, bone injury only, and bone injury with ESM supplementation (EM). Micro-computed tomography and histological analyses revealed a significant increase in new bone volume in the EM group at days 14 and 21 post-drill hole injury. On day 21, reduced toluidine blue staining, a lower osteocyte count, and the maturation of collagen fibers. Moreover, Sp7 mRNA expression and the number of osteocalcin-positive cells were increased. The expression of Nfatc1 and the number of tartrate-resistant acid phosphatase-positive osteoclasts were also significantly elevated. In addition, the vascular area and Vegfa expression were markedly increased in the EM group throughout the observation period. These findings suggest that ESM supplementation promotes bone healing by stimulating angiogenesis and enhancing osteoblast and osteoclast activity, offering a promising nutritional adjunct to support and accelerate fracture healing.