Engineered adipose-derived stem cells with self-amplifying RNA enhance vascular network formation in porous GelMA...

Dependence on exogenous growth factor (GF) supplementation of culture media and the limited diffusion of these GFs in densely populated hydrogel structures remain major obstacles to achieving extensive vascularization in engineered tissues. Here, we introduce a biofabrication strategy that embeds cellulose-purified self-amplifying RNA (saRNA)-engineered adipose-derived stem cells (ASCs) within hydrogels constructs, enhancing endogenous GF production and paracrine signaling. Compared with a no-transfection control, which exhibited only 10 ± 7 mm mm^-3 of vasculogenic network formation and 0.2 ± 0.25 mm of sprouting per spheroid within porous gelatin methacryloyl scaffolds, dual VEGF/FGF2 expression induced by saRNA produced markedly stronger outcomes, yielding 25.3 ± 11.3 mm mm^-3 of network formation and 1.85 ± 0.8 mm of sprouting after 7 days of culture. This system is also compatible with 3D bioprinting, enabling engineered ASCs to be precisely bioprinted at defined locations within the hydrogel structure. Moreover, within bioprinted constructs, this system allows microvascular networks formed by engineered spheroids to extend toward surrounding macrovascular channel structures. Collectively, these results demonstrate a versatile platform where cell-mediated GF delivery promotes vascularization of tissue-engineered constructs while substantially minimizing the need for exogenous GF supplementation.