Transplantation and perfusion of microvascular fragments in a rodent model of volumetric muscle loss injury.

Few clinical options are available for the treatment of volumetric muscle loss (VML). An important consideration that needs to be addressed for the development of treatments for these injuries is the establishment of a vascular supply sufficient to support skeletal muscle regeneration. The objective of the current study was to evaluate the potential for microvascular fragments (MVFs) harvested from adipose tissue to support tissue perfusion for VML. Tibialis anterior muscle defects in rats were replaced with constructs that were created on the day of surgery containing either (1) collagen only (COL), (2) freshly isolated microvascular fragments in collagen (MVF), or (3) adipose tissue derived stem cells (ASCs) in collagen. Muscles were harvested 7 and 14 days after surgery. Defects treated with MVFs had a vessel density higher than the other groups at both 7 and 14 days, and those treated with ASCs had a higher vessel density than COL by day 14 (p < 0.05). Perfused vessels were observed in both the ASC and MVF treated defects at day 14, as well as at day 7 in the MVF. This study supports the use of MVFs as a platform to improve tissue perfusion to treat large VML defects. The use of freshly isolated MVFs on the day of surgery supports their clinical use and application.