CBE Seminar: Reciprocal Communication Between Human Neural Stem Cells and Human Endothelial Cells in a 3D Biomaterial Niche

Abstract: Neural stem and progenitor cell (NSPC) and vessel-forming endothelial cell communication throughout development and adulthood is vital for normal brain function. Despite this, much remains unclear regarding coordinated regulation of these cells, particularly in humans. NSPCs regulate vascularization of the developing central nervous system and we found human NSPCs (hNSPCs) promote human endothelial cell (hEC) vessel formation in a three-dimensional human neurovascular model. The biomaterial component of our neurovascular model used a combination of salmon fibrin, hyaluronic acid and laminin to generate compliant hydrogels matching the physical properties of brain tissue. We co-cultured hNSPCs and hECs in this in vitro niche to investigate the mechanisms driving the pro-vasculogenic effect of hNSPCs. Comparison of human and mouse NPSC bulk RNA-sequencing data revealed several vessel-promoting factors were more highly expressed by human cells, highlighting the importance of studying human NSPC-EC communication. Analysis by single cell RNA sequencing (scRNAseq) showed that hNPSCs co-cultured with hECs up-regulated vessel forming genes. Many factors identified by RNAseq were secreted proteins, and hNSPC conditioned media was sufficient to induce hEC vasculogenesis. ScRNAseq data for hNSPCs co-cultured with hECs identified up-regulation of genes associated with extracellular vesicles (EVs), including exosomes. EVs isolated from hNSPCs promoted hEC vasculogenesis, and blocking hNSPC exosomes abrogated the effect of hNSPC conditioned media on vessel formation. As further evidence of the reciprocal communication between hNSPCs and hECs, scRNAseq and immunostaining showed hEC contact increased hNSPC type B cells, which are GFAP-expressing adult NSPCs in the brain subventricular zone. Induction of the type B phenotype was driven by Notch signaling, and both blocking hNSPC Notch signaling and reducing hEC expression of the Notch ligand DLL4 abrogated the effect of hECs on type B hNSPCs. Thus, hNSPCs increase hEC vessel formation via secreted material, including EVs/exosomes and hEC contact promotes human type B cells via Notch signaling. These data reveal critical reciprocal communication governing function of these important cell types.

Bio: Lisa Flanagan is professor and vice chair for Academic Affairs in the Department of Neurology at UC Irvine with joint appointments in Biomedical Engineering and Anatomy and Neurobiology. Flanagan’s research combines cell biology and bioengineering to decipher neural stem cell function and to optimize cell transplantation to treat neurological conditions. Her overall goal is to better understand stem cell activity during brain development since this knowledge can be used to maximize repair of the central nervous system after debilitating conditions such as stroke. Before joining UC Irvine, Dr. Flanagan completed her Ph.D. at UC San Diego and post-doctoral training at Harvard Medical School in Boston, Massachusetts. She received the National Science Foundation CAREER Award, serves on the Editorial Board for Scientific Reports, is a fellow of the Center for the Neurobiology of Learning and Memory and has organized multiple international scientific conferences.

Host: Tayloria Adams