Evaluation of a Sphere-Templated Polymeric Scaffold as a Subcutaneous Implant

Objective: To evaluate the performance of a sphere-templated poly(2-hydroxyethyl methacrylate) (poly-[HEMA]) tissue scaffold as a subcutaneous implant by comparing it with widely used high-density porous polyethylene (HDPPE) implant material. Design: We implanted sphere-templated porous poly(HEMA) and HDPPE disks into the dorsal subcutis of C57BL/6 mice for 4 and 9 weeks. Excisional biopsy specimens of the implants and surrounding tissue were assessed for host inflammatory response, tissue ingrowth, and neovascularization using trichrome, picrosirius red, and anti-endothelial cell antibody staining. Results: The poly(HEMA) and HDPPE implants showed resistance to extrusion and elicited a minimal inflammatory response. Both implants supported cellular and collagen ingrowth, but ingrowth within the HDPPE implant was thicker owing to the larger porous structure (>100 mu m) of HDPPE, whereas the poly(HEMA) implant had much thinner collagen fibrils within much smaller (40-mu m) pores, suggestive of less scar-type reaction. Neovascularization was supported by both implants. Blood vessels were identified within the fibrous ingrowth of the HDPPE and within individual pores of the poly(HEMA). Conclusions: Sphere-templated poly(HEMA) implanted as a subcutaneous tissue scaffold stimulates a minimal inflammatory response and supports cellular infiltration, collagen formation, and neovascularization. Because of its tightly controlled porous structure, poly(HEMA) appears to induce less scar-type ingrowth compared with HDPPE. JAMA Facial Plast Surg. 2013;15(1):29-33. Published online October 8, 2012. doi:10.1001/2013.jamafacial.4