Biocompatibility comparison of novel soft tissue implants vs commonly used biomaterials in a pig model.

Kolb, Caroline M; Pierce, Lisa M; Roofe, Scott B

OBJECTIVE To develop a model to evaluate biocompatibility, integration, and substrate independence of novel porous bioscaffolds for maxillofacial and plastic reconstruction using sphere-templated angiogenic regeneration technology compared with currently available synthetic and biologic soft tissue implants. STUDY DESIGN A prospective pilot study using animals. SETTING Military medical center. SUBJECTS AND METHODS Five pigs underwent dorsal subcutaneous implantation of a polypropylene-based material coated with precision pore silicone granules (sphere-templated scaffold), expanded polytetrafluoroethylene, human dermis, and porcine dermis. Sham and undissected sites were also used as controls. Specimens were harvested 7, 21, 90, and 180 days after surgery and evaluated histologically for inflammation, neovascularization, and collagen deposition. RESULTS All materials and sham sites induced a mild to moderate inflammation that decreased over time, except for human dermis, which elicited a moderate to severe inflammatory response. The responses were varied and measurable using subjective scoring methods. The sphere-templated scaffold demonstrated numerous foreign body giant cells adjacent to the silicone granules, which were not seen in any of the other specimens. CONCLUSION Subjective scoring of pathology slides and measurement of capsule thickness appeared to show differences between the materials, but these differences require a larger number of subjects and proper statistical analysis to assess. The robust foreign body reaction elicited by the polypropylene/silicone-based scaffold argues against the use of this material in future studies. The authors advocate using inert biodegradable substances for future bioscaffold constructs.