Comparative Evaluation of Biocompatibility Data from the Subcutaneous and the Calvaria Implantation Model of a Novel...

This study compares the biocompatibility of a novel hybrid bone substitute material based on biphasic granules in a type I collagen scaffold using both subcutaneous and calvarial implantation models, in accordance with DIN EN ISO 10993-6. Given the distinct biological environments, materials may exhibit different behaviors in connective versus bone tissue. The aim was to evaluate irritation scores and cellular tissue responses to better understand the material's performance in both settings.

This study evaluated the biocompatibility and host tissue response of test materials in male Wistar rats through subcutaneous and calvaria implantation models, following DIN EN ISO 10993-6, assessing cellular responses, material degradation, and bone regeneration at 10-, 30-, and 60-days post-implantation.

Subcutaneous implants elicited a stronger inflammatory reaction with higher counts of polymorphonuclear cells, lymphocytes, multinucleated giant cells, and plasma cells at day 10, alongside consistently elevated irritancy scores. In contrast, calvaria implants showed increased neovascularization, reflecting bone-specific regenerative processes. Although capsule formation and cellular infiltration were similar between models, material degradation and phagocytosis were significantly greater subcutaneously at day 60.

These results highlight the critical impact of implantation site on immune activation, vascularization, and biomaterial resorption, underlining the importance of model selection in preclinical biomaterial assessment.