Figure 1.
Generating blood vessels in an islet-specialized vascularized micro-organ (islet-VMO). (A) A microfluidic design for generating vascularized islet tissues comprises a central, enlarged cell chamber (inset) flanked by two channels, C1 (acting as an arteriole) and C2 (venule). Reservoirs at the end of each channel (VA–VD) are filled with varying heights of medium such that medium is driven by hydrostatic pressure in a net direction from VA, through the tissue chamber, and to VD. (B) To generate vascularized tissues, islets, EC, and stromal cells are loaded together in a fibrin hydrogel through the loading tunnel (labeled in A). Fluid flow is driven across the cell chamber to activate vessel formation in the central chamber with development of intact vessel networks by 5–7 d post-loading. (C) Upon maturation, blood vessels (fluorophore-transduced ECs, red) carry 70 kDa FITC-dextran (green) with minimal leak. (D), (E), (G) Mature vessels are wrapped by stromal (pericyte) cells (magenta arrows; transduced stromal cells, white). (D), (F), (G) These stromal cells help remodel the hydrogel to generate basement membrane (laminin, green) around the CD31+ endothelium (red). Scale bar, 200 μm, inset, 100 μm.