Engineering of vascularized 3D cell constructs to model cellular interactions through a vascular network.

Current in vitro 3D culture models lack a vascular system to transport oxygen and nutrients, as well as cells, which is essential to maintain cellular viability and functions. Here, we describe a microfluidic method to generate a perfusable vascular network that can form inside 3D multicellular spheroids and functionally connect to microchannels. Multicellular spheroids containing endothelial cells and lung fibroblasts were embedded within a hydrogel inside a microchannel, and then, endothelial cells were seeded into both sides of the hydrogel so that angiogenic sprouts from the cell spheroids and the microchannels were anastomosed to form a 3D vascular network. Solution containing cells and reagents can be perfused inside the cell spheroids through the vascular network by injecting it into a microchannel. This method can be used to study cancer cell migration towards 3D co-culture spheroids through a vascular network. We recapitulated a bone-like microenvironment by culturing multicellular spheroids containing osteo-differentiated mesenchymal stem cells (MSCs), as well as endothelial cells, and fibroblasts in the device. After the formation of vascularized spheroids, breast cancer cells were injected into a microchannel connected to a vascular network and cultured for 7 days on-chip to monitor cellular migration. We demonstrated that migration rates of the breast cancer cells towards multicellular spheroids via blood vessels were significantly higher in the bone-like microenvironment compared with the microenvironment formed by undifferentiated MSCs. These findings demonstrate the potential value of the 3D vascularized spheroids-on-a-chip for modeling in vivo-like cellular microenvironments, drug delivery through blood vessels, and cellular interactions through a vascular network.