Balance macrophage polarization via cell synthesis of apoptotic bodies in hydrogel microspheres

Maintaining the homeostasis of immune ecological niches such as macrophages is essential for skin regeneration. In this study, apoptotic bodies (ABs) with intact bioactive substances of ADSC were constructed by biosynthesis. Further, injectable apoptotic bodies-GelMA microspheres (ABs@GMS) were constructed by microfluidics to maintain the homeostasis of the immune ecological niche in trauma, and inhibit the secretion of argininosuccinate synthetase 1 (ASS1) by ABs-induced downregulated JAK/STAT1 signaling pathway. Consequently, the macrophages' polarization and inflammatory response were balanced in the wound with promoted angiogenesis. This ABs-functionalized microsphere slowly released biosynthetic apoptotic vesicles that expressed C1q, C3b and other surface "eat me" signals. These vesicles can be directly recognized, phagocytosed and degraded by macrophages, and allow scavenger cells to give meaning to cell death. In vitro, ABs@GMS balanced the JAK/STAT signaling pathway in a form of positive communication from dead to living cells via apoptotic vesicles. In vivo, ABs@GMS balanced the polarization of macrophages and increased the expression of a-smooth muscle actin. In conclusion, ABs synthesized by ADSC can balance traumatic immune disorders and restore homeostasis of the wound immune microenvironment, which would be a highly promising material for macrophage-mediated wound repair. Overall design: RNA-seq of THP-1 cells stimulated with PMA and treated with LPS or ABS.