Biomimetic integration of functionally controlled modular tissue building blocks for engineering 3D vascularized adipose tissue

Adipose tissue is highly vascularized, which is crucial for homeostasis and energy storage. Current efforts to engineer 3D vascularized adipose tissue in vitro typically involve co-culturing adipocytes and endothelial cells, but adipogenic differentiation often suppresses endothelial function. In this study, we propose a novel approach to reconstruct vascularized adipose tissues in vitro by effectively coupling adipogenesis and vasculogenesis. First, we developed adipo-inductive nanofibers (ID/F@INS) that contain indomethacin and insulin. The in vitro adipogenesis of human adipose-derived stem cells (hADSCs) in general medium was significantly enhanced in adipogenic spheroids (AS) prepared with hADSCs and ID/F@INS, which were encapsulated in a gelatin methacryloyl (GelMA) hydrogel. To further replicate clustering during de novo adipogenesis, we generated AS of varying sizes and found that larger spheroids exhibited markedly greater adipogenesis than smaller ones. At the same time, we used hADSCs and human umbilical vein endothelial cells to generate vascular spheroids (VS). The biomimetic integration of AS and VS within GelMA hydrogels enabled us to investigate the interactions between de novo adipogenesis and vascularization. The integration of the two types of spheroids (VS:AS ratio of 2:1) significantly improved vascular network formation, indicating the concurrent stimulation of adipogenesis and vasculogenesis. This system was then applied to develop an in vitro obesity-like white adipose dysfunction model characterized by reduced vascularization and the elevated expression of pro-inflammatory cytokines. In addition, we found both vascularization and adipogenesis in vivo when we implanted the engineered tissue into mice, demonstrating the potential of our tissue for therapeutic applications in tissue reconstruction.