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RESEARCH PRODUCT

External Volume Expansion Increases Subcutaneous Thickness, Cell Proliferation, and Vascular Remodeling in a Murine Model

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Background Fat grafting is a powerful tool for soft-tissue reconstruction; however, the science behind recipient bed preparation has not been thoroughly explored. External volume expansion using suction before fat grafting has been used clinically to improve reliability and consistency of graft survival. The authors developed a murine model to investigate the underlying mechanism of external volume expansion. Methods The authors created an external volume expansion device using a soft-silicone dome connected to a vacuum source (25 mmHg) to treat the dorsum of mice, and the response was compared with treatment with an occlusive dressing. Treated areas were monitored with magnetic resonance imaging. Remodeling of microvasculature was studied with corrosion casting on day 7. Effects on tissue thickness, number of adipocytes, cell proliferation, and blood vessel density were analyzed at 28 days. Results Macroscopic analysis showed tissue swelling at sites treated with the external volume expansion device by 21 days, without skin damage. On day 28, external volume expansion increased the thickness of the subcutaneous fat layer twofold, consistent with magnetic resonance imaging observations. The proliferation rate in the subcutaneous layer of expansion-treated areas increased twofold, with a net 2.2-fold increase in number of adipocytes in columns; remodeling of the vessels network occurred, with reorientation and increase of vessel diameters shown by corrosion casting and 1.9-fold augmentation of vessels density. Conclusions External volume expansion applied to mouse integument induces highly proliferative and vascularized subcutaneous tissue. Recipient-site preparation using external volume expansion devices may be a promising tool to enhance cell and tissue engraftment.