Fabrication of Neurovascular Organoids in Microdevices

Our body maintains homeostasis through three network systems: blood vessels, lymph vessels, and nerves. Among them, blood vessels and nerves interact with each other, especially when morphogenesis occurs during development. In this study, we fabricated a microdevice to test neuro-vascular interactions with neurovascular organoids consisting of neuronal stem cells and vascular endothelial cells. We used fatal rat cerebral-derived neural stem cells and human umbilical cord-derived vascular endothelial cells to generate neurovascular organoids. Reciprocal interactions of each cell types on angiogenic and neuronal gene expression were evaluated by RT-PCR and fluorescent immunostaining. Interestingly, in the co-culture of neural stem cells and vascular endothelial cells, the neurogenesis and angiogenesis potential increased with the increase in the ratio of vascular endothelial cells. Furthermore, considering the length of axons in the central nervous system is several mm, we fabricated microdevices with a few mm-long microfluidic channel using photolithography. When two organoids were placed at both ends of the microchannel, axons and vascular sprougin spontaneously grew from each of them, and finally the two organoids were connected by axon bundle tissues including vascular endothelial cell networks. These results show that when the direction of axon and vascular extension from the organoids is spatially controlled, formation of neuro-vascular interconnections in neural axon bundles can be partially replicated <i>in vitro</i>. This neurovascular organoid will be a useful tool for understanding neural-vascular interactions during neurogenesis and testing drugs.