A Vascularized Multilayer Chip Reveals Shear Stress-Induced Angiogenesis in Diverse Fluid Conditions.

Tissues larger than 400 μm in size lacking microvascular networks cannot survive for long periods of time in vitro. The development of microfluidic technology provides an efficient research tool for constructing microvascular models in vitro. However, traditional single-layer microfluidic chips faced the limitation of spatial layout and could not provide diverse fluidic environments within a single chip. In this paper, we present a novel microfluidic chip design with a 3-layer configuration that utilizes a polycarbonate (PC) porous membrane to separate the culture fluid channels from the tissue chambers, featuring flexibly designable multitissue chambers. PC porous membranes act as the capillary in the vertical direction, enabling precise hydrogel patterning and successfully constructing a microfluidic environment suitable for microvascular tissue growth. The chip demonstrates the ability to build microvascular networks of different shapes such as triangle, rectangle, and inverted triangle on a single chip for more than 10 days. The microvascular networks cultured for 12 days were successfully perfused with 70-kDa fluorescein isothiocyanate, which indicated that the generated networks had good barrier properties. A correlation between tissue chamber shape and shear stress was demonstrated using COMSOL, and a preliminary validation of the flow direction of interstitial flow and the important effect of shear stress on microvascular growth was demonstrated by vascularization experiments. This flexible and scalable design is ideal for culturing multiple vascularized organ tissues on a single microfluidic chip, as well as for studying the effects of different fluidic factors on microvascular growth.