Microfluidic device (white) with a connector and orange microspheres being perfuse through the red plastic channels. The PLGA layer (transparent) usually closes the channels and an endothelial cells layer is cultured on top of it prior to the collagen sponge placing. Once the vascularized collagen sponge is place on top of the cells layer, the whole device is inside a bioreactor and cultured for 52 days together. After degradation of the PLGA membrane (inset), the connection between the plastic channel and the endothelial cells capillary network within the tissue engineered construct is possible, thus allowing in vitro perfusion of the tissue.