The role of neuroendothelial cells in organ blood flow regulation
Authors: Deepak Sachin , Shroff Urvi , Izuhara Audrey , Peti-Peterdi Janos , Gyarmati Georgina 
Published: May 2023

Vascular endothelial cells (ECs) play important roles in the physiological maintenance of organ blood flow. Recent transcriptomic studies found many EC subtypes in multiple organs including the brain and the kidneys; however, their functions are incompletely understood. Our studies identified for the first time a new endothelial cell type expressing both endothelial and neuron-like functional and gene transcriptomic signatures, with highest density in the brain>kidney>heart. Based on their neuronal and endothelial molecular and functional characteristics, we named them neuroendothelial cells (NECs). The present study aimed to explore the physiological functional significance of this newly discovered minority subtype of scattered ECs and their role in organ blood flow regulation. We hypothesized that the activation of a single NEC has the potential to cause vasodilation of the entire resistance arteriole, in contrast their inactivation results in vasoconstriction. A comprehensive research toolbox was applied in this study including transgenic mouse models (Nos1-GFP, GCaMP6, Ai27 and 39), intravital multiphoton imaging of calcium dynamics of Nos1+ endothelial cells in the brain and the kidney, genetic cell fate tracking, novel optogenetic stimulation or inhibition of NEC function, whole mount organ imaging for 3D vascular density measurements, and single-cell transcriptomic analysis. NECs exhibit a well-defined arteriovenous zonal localization exclusively to small resistance arterioles. In vivo multiphoton microscopy (MPM) of intact brain arterioles revealed that NEC specific functional stimulation via blue light in the newly developed Nos1-Ai27 mice resulted in significant increases of the diameter (D) and blood flow (F) of the corresponding resistance arterioles compared to control (Dmax/0: 1.23+/-0.03, 1.01+/-0.02, Fmax/0: 1.52+/-0.07, 1.02+/-0.05; p<0.0001, respectively). In contrast, yellow/red light stimulation of NECs in the inhibitory Nos1-Ai39 mice resulted in significant vasoconstriction and a reduction in blood flow in the corresponding resistance arterioles compared to control animals (Dmax/0: 0.85+/-0.03, 1.01+/-0.02, Fmax/0: 0.75+/-0.05, 1.02+/-0.05; p<0.0001, respectively). Control light stimulation did not change the diameter or blood flow of resistance arterioles. In addition, MPM of intact brain and kidney arterioles in vivo revealed regular, autonomous NEC calcium transients with blood pressure-dependent frequency alterations in Nos1-GCaMP6 animals. Single-cell RNA sequencing and transcriptomic analyses showed that, in contrast to other ECs, NECs highly express several traditional (e.g., Nos1, Klotho) and novel (e.g., Aard) tissue trophic factors that are known to play important roles in angiogenesis, aging, vascular (dys)function, and chronic vascular diseases.These new vascular anatomy and hemodynamic findings strongly suggest sensory, baroreceptor, and blood flow regulatory functions of NECs in multiple organs. USC Keck School of Medicine Dean's Pilot Funding Program and NIH R01 DK123564 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.