A novel small animal model of irradiated, implant based breast reconstruction

PURPOSE: There is currently a need for a clinically relevant small animal model for irradiated, implant based breast reconstruction. Present models are inadequate in terms of suboptimal location of expander placement and mode of radiation delivery, correlating poorly with the human clinical scenario. We hypothesized that by delivering fractionated radiation and placing an expander under the scalp of the animal, we would achieve histologically analogous soft tissue changes seen in human irradiated, implant based breast reconstruction. METHODS: This study consisted of eleven immunocompetent, hairless rats divided into three groups: an untreated control (n=3), tissue expanded scalps (n=4) and fractionated radiation plus tissue expansion of the scalp (n=4). At the completion of the experiment for each group, skin tissue samples were analyzed histologically for vascularity, epidermal and dermal thickness, and collagen fiber alignment or scar formation. RESULTS: Expanded rat epidermis was significantly thicker and dermis was more vascular than non-expanded skin. We observed a greater degree of collagen fiber alignment in the expanded group compared with non-expanded skin. The combination of radiation and expansion resulted in significant dermal thinning, vascular depletion and increased scar formation compared with expanded skin alone. CONCLUSIONS: We describe a novel small animal model for irradiated, implant based breast reconstruction where histologic analysis shows structural changes in the skin consistent with known effects of radiation and expansion in human skin. This model represents a significant improvement from previous ones and as such, holds the potential to be used to test new therapeutic agents to improve clinical outcomes. Financial Disclosure Statement: The authors have no disclosures. Internal funding from the University of Virginia School of Medicine Research and Development Grant was used for this research. This article has been approved by the Institutional Animal Care and Use Committee at the University of Virginia Acknowledgements: We would like to thank Quan Chen, PhD and Brian Neal, PhD for their participation in this work. Corresponding Author/Reprints: Kant Y. Lin, MD, FACS, Department of Plastic and Reconstructive Surgery, University of Virginia Health System, P.O Box 800376, Charlottesville VA, 22908, Kyl5s@hscmail.mcc.virginia.edu, Phone: 434-924-2528, Fax: 434-924-1333 ©2018American Society of Plastic Surgeons