3D printed chip as platform to vascularize hiPSCs-derived kidney organoids.

Human induced pluripotent stem cells (hiPSCs)-derived kidney organoids can resemble early stages of human kidney development, morphology and architecture. However, one of the main limitations of the organoids is the reduced vascularization, which limits differentiation and maturation. To increase the oxygen and nutrient supply, multiple vascularization strategies were proposed in literature, including organ-on-chip, hydrogels with angiogenetic cues, and co-culture with endothelial cells. In this work, we developed a three-dimensional (3D) printed chip by extruding sacrificial pluronic, in a fully automated and cost-effective way. By dissolving the pluronic, two circular cross-sectional channels, together with three separated central gel compartments, were created. Human umbilical vein endothelial cells (HUVECs) were seeded in the coated 3D printed chip, and after seven days kidney organoids were added in the central gel compartments, embedded in a partially digested decellularized extracellular matrix (ddECM) hydrogel, and co-cultured for five days under perfusion. At the end of the co-culture, capillary-like structures were formed towards the organoids both in the outer and central parts, colocalizing with LTL and PODXL positive stained areas. We were able to develop primitive capillary-like structures throughout the organoids, using an ad-hoc designed 3D printed chip. Our strategy provides new possibilities to investigate further organoid maturation, drug testing and disease modeling.