Effects of miR126 Expressing Adipose-Derived Stem Cells on Fat Graft Survival and Angiogenesis

Fat transplantation supported by supplementation with ASCs has become a reliable procedure for treating soft tissue defects. However, the unpredictable survival rates for grafted fat remains a challenge with post-transplantation ischemia causing tissue loss. MiR126, which regulates VEGF signaling, is an endothelial cell-specific miRNA known to play an essential role in angiogenesis. We hypothesized that increased miR126 expression in grafted ASCs may promote fat survival within an autologous fat transfer model.

Rat adipose-derived stem cells were isolated, expanded ex vivo for three passages and then transduced with miR126. We used PCR to verify lentiviral transduction and ELISA to confirm VEGF expression. We then mixed autologous fat tissues from our rat model with transduced ASCs, augmented with a nonsense control or miR126 expression vector. These mixtures were used in the fat grafting procedure, completed via subcutaneous injection at three paravertebral points in each rat. Fat grafts were then harvested on days 4, 7, 14, and 28 post-transplant and evaluated for survival, neovascularization, and protein expression via western blot.

VEGF expression levels in ASCs, Con-ASCs, and miR126-ASCs were not significantly different. However, miR126-ASCs experienced significantly improved survival on days 7, 14, and 28 when compared with the other groups. These ASCs also presented with the greatest capillary density on days 7, 14, and 28 post-transplantation as well as increased p-ERK and p-AKT expression when compared to the other groups.

This data suggests that miR126 augmentation of ASCs may help to enhance the survival and angiogenic capacity of transplanted fat tissues, and that this augmentation was not dependent on VEGF but rather the activation of the ERK/AKT pathway.

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