Fenestration Improves Acellular Dermal Matrix Biointegration: An Investigation of Revascularization with Photoacoustic Microscopy

Background: Acellular dermal matrices have revolutionized alloplastic breast reconstruction. Furthering our knowledge of their biointegration will allow for improved design of these biomaterials. The ideal acellular dermal matrix for breast reconstruction would provide durable soft-tissue augmentation while undergoing rapid biointegration to promote physiologic elasticity and reduced infectious complications. The inclusion of fenestrations in their design is thought to promote the process of biointegration; however, the mechanisms underlying this theory have not been evaluated. Methods: Biointegration of standard and fenestrated acellular dermal matrices was assessed with serial photoacoustic microscopic imaging, in a murine dorsal skinfold window chamber model specifically designed to recapitulate the microenvironment of acellular dermal matrix-assisted alloplastic breast reconstruction. Photoacoustic microscopy allows for a serial, real-time, noninvasive assessment of hemoglobin content and oxygen saturation in living tissues, generating high-resolution, three-dimensional maps of the nascent microvasculature within acellular dermal matrices. Confirmatory histologic and immunohistochemical assessments were performed at the terminal time point. Results: Fenestrated acellular dermal matrices demonstrated increased fibroblast and macrophage lineage host cell infiltration, greater mean percentage surface area vascular penetration (21 percent versus 11 percent; p = 0.08), and greater mean oxygen saturation (13.5 percent versus 6.9 percent; p < 0.05) than nonfenestrated matrices by 2 weeks after implantation. By 21 days, host cells had progressed nearly 1 mm within the acellular dermal matrix fenestrations, resulting in significantly more vascularity across the top of the fenestrated matrix (3.8 vessels per high-power field versus 0.07 vessels per high-power field; p < 0.05). Conclusions: Inclusion of fenestrations in acellular dermal matrices improves the recellularization and revascularization that are crucial to biointegration of these materials. Future studies will investigate the optimal distance between fenestrations.