Expanding tubular microvessels on stiff substrates with endothelial cells and pericytes from the same adult tissue.

Endothelial cells (ECs) usually form a monolayer on two-dimensional (2D) stiff substrates and a tubular structure with soft hydrogels. The coculture models using ECs and pericytes derived from different adult tissues or pluripotent stem cells cannot mimic tissue-specific microvessels due to vascular heterogeneity. Our study established a method for expanding tubular microvessels on 2D stiff substrates with ECs and pericytes from the same adult tissue. We isolated microvessels from adult rat subcutaneous soft connective tissue and cultured them in the custom-made tubular microvascular growth medium on 2D stiff substrates (TGM2D). TGM2D promoted adult microvessel growth for at least 4 weeks and maintained a tubular morphology, contrary to the EC monolayer in the commercial medium EGM2MV. Transcriptomic analysis showed that TGM2D upregulated angiogenesis and vascular morphogenesis while suppressing oxidation and lipid metabolic pathways. Our method can be applied to other organs for expanding organ-specific microvessels for tissue engineering.