Transcriptomic comparison of human and mouse brain microvessels

Hannah W Song,John S Kuo,Benjamin D Gastfriend,Sean P Palecek,Eric V Shusta,Koji L Foreman

doi:10.1038/s41598-020-69096-7

Abstract

The brain vasculature maintains brain homeostasis by tightly regulating ionic, molecular, and cellular transport between the blood and the brain parenchyma. These blood–brain barrier (BBB) properties are impediments to brain drug delivery, and brain vascular dysfunction accompanies many neurological disorders. The molecular constituents of brain microvascular endothelial cells (BMECs) and pericytes, which share a basement membrane and comprise the microvessel structure, remain incompletely characterized, particularly in humans. To improve the molecular database of these cell types, we performed RNA sequencing on brain microvessel preparations isolated from snap-frozen human and mouse tissues by laser capture microdissection (LCM). The resulting transcriptome datasets from LCM microvessels were enriched in known brain endothelial and pericyte markers, and global comparison identified previously unknown microvessel-enriched genes. We used these datasets to identify mouse-human species differences in microvessel-associated gene expression that may have relevance to BBB regulation and drug delivery. Further, by comparison of human LCM microvessel data with existing human BMEC transcriptomic datasets, we identified novel putative markers of human brain pericytes. Together, these data improve the molecular definition of BMECs and brain pericytes, and are a resource for rational development of new brain-penetrant therapeutics and for advancing understanding of brain vascular function and dysfunction.

Highlights

The brain vasculature maintains brain homeostasis by tightly regulating ionic, molecular, and cellular transport between the blood and the brain parenchyma
While the mouse data have been instrumental in advancing our understanding of brain microvascular endothelial cells (BMECs) and pericytes, there are numerous species-specific differences that have been identified between mouse and human brain including in solute carrier and efflux transporter e xpression[14,15,16]
Brain microvessels isolated by centrifugation from two patient samples were subjected to RNA sequencing (RNA-seq) to analyze expression of ATP binding cassette (ABC) transporters and solute carriers (SLCs)[20], and brain endothelial cells isolated via immunopanning from two patient samples were transcriptomically profiled[21]

Summary

Introduction

The brain vasculature maintains brain homeostasis by tightly regulating ionic, molecular, and cellular transport between the blood and the brain parenchyma. The resulting transcriptome datasets from LCM microvessels were enriched in known brain endothelial and pericyte markers, and global comparison identified previously unknown microvessel-enriched genes We used these datasets to identify mouse-human species differences in microvessel-associated gene expression that may have relevance to BBB regulation and drug delivery. Single cell RNA-seq of human adult and embryonic cortex samples has been used to identify regional, developmental, and species differences in neuronal and glial gene expression; the approaches employed yielded extremely small populations of endothelial cells and pericytes, impeding analysis of human brain microvessel transcriptomes[17,18,19]. Data analysis allowed the identification of genes with microvessel-enriched expression despite patient-to-patient variability, identified species differences between mouse and human samples, and suggested putative novel human brain pericyte markers

Methods

Results

Conclusion