Dll4 inhibition promotes angiogenesis and graft volume retention in cell-assisted lipotransfer

Purpose: Autologous fat grafting is one of the most effective and safest treatment for soft tissue restoration and augmentation, and many efforts has been done to improve its efficiency including adipose tissue derived stem cell (ASC) supplementation. Here, we evaluated the role of Notch ligand Delta-like ligand 4 (Dll4) in angiogenesis in grafted fat and the effect on graft survival using the murine fat graft model, and its impact on the ASC supplementation. Methods: We performed RNA-seq analysis of 3 mouse fat graft groups: 1) control fat grafts, 2) ASC added fat graft, and 3) ASC added fat graft with Dll4 inhibition. The fat grafts were harvested 8 weeks after grafting (n=4), and generated mRNA profiles by deep sequencing using Illumina NovaSeq 6000. Results: We found that when we treated Dll4 blocking antibody to inhibit Dll4, which was highly expressed in endothelial cells (ECs) of grafted fat, angiogenesis in the grafted fat was significantly induced, promoting fat graft retention. In addition, this effect was shown to synergistically improve the fat graft retention when ASCs were concomitantly supplemented. Transcriptome analysis further identified that the expression of the junctional proteins was increased in the ECs and inflammatory processes were downregulated in the grafted fat with ASC supplementation and Dll4 inhibition. Conclusions: This study serves as a basis for developing new potential therapeutic approaches to improve graft retention after cell-assisted transfer by Dll4 inhibition. Overall design: Adipose mRNA profiles of 8 week fat graft: 1) control fat grafts, 2) ASC added fat graft, and 3) ASC added fat graft with Dll4 inhibition.