Primary Human Lung Pericytes Support and Stabilize In Vitro Perfusable Microvessels

Abstract

The formation of blood vessels is a complex tissue-specific process that plays a pivotal role during developmental processes, in wound healing, cancer progression, fibrosis, and other pathologies. To study vasculogenesis and vascular remodeling in the context of the lung, we developed an in vitro microvascular model that closely mimics the human lung microvasculature in terms of three-dimensional architecture, accessibility, functionality, and cell types. Human pericytes from the distal airway were isolated and characterized using flow cytometry. To assess their role in the generation of normal microvessels, lung pericytes were mixed in fibrin gel and seeded into well-defined microcompartments together with primary endothelial cells (human umbilical cord vein endothelial cells). Patent microvessels covering an area of 3.1 mm(2) formed within 3-5 days and were stable for up to 14 days. Soluble signals from the lung pericytes were necessary to establish perfusability, and pericytes migrated toward endothelial microvessels. Cell-cell communication in the form of adherens and tight junctions, as well as secretion of basement membrane were confirmed using transmission electron microscopy and immunocytochemistry on chip. Direct coculture of pericytes with endothelial cells decreased the microvascular permeability by one order of magnitude from 17.8×10(-6) to 2.0×10(-6) cm/s and led to vessels with significantly smaller and less variable diameter. Upon phenylephrine administration, vasoconstriction was observed in microvessels lined with pericytes, but not in endothelial microvessels only. Perfusable microvessels were also generated with human lung microvascular endothelial cells and lung pericytes. Human lung pericytes were thus shown to have a prominent influence on microvascular morphology, permeability, vasoconstriction, and long-term stability in an in vitro microvascular system. This biomimetic platform opens new possibilities to test functions and interactions of patient-derived cells in a physiologically relevant microvascular setting.

Human pericytes adopt myofibroblast properties in the microenvironment of the IPF lung

“…org/10.1172/jci.insight.96352DS1), with the increased ECM density of IPF lungs resulting in an 11.6-fold increase in mechanical stiffness compared with control lungs at a physiological 20% strain (Supplemental Figure 1, B and C). Because human lung PC isolates are difficult to obtain in sufficient numbers for experimentation and, when isolated, are collected from tissue resection of lung cancer patients (22)(23)(24), we made use of an alternate and inexhaustible source of PC: namely, the human placenta (25). We began by culturing NG2/CD90/PDGFR-β/CD146-expressing human placental microvascular PC (Supplemental Figure 2) that were then seeded onto decellularized IPF or control lungs and cultured for 7 days.…”

Lung Pericytes and Resident Fibroblasts

“…54,55 Moreover, in sophisticated in vitro microfluidics experiments, primary human lung pericytes also caused vasoconstriction. 56 It is therefore likely that pericytes directly constrict or relax a subset of blood vessels as well as more broadly coregulating the lung vascular system.…”

Tissue culture on a chip: Developmental biology applications of self‐organized capillary networks in microfluidic devices

“…These cells tend to surround the self‐organized capillary network and show mural cell‐like behavior (Bichsel et al . ). However, whether these cells function as vascular smooth muscle remains to be elucidated.…”

“…Therefore, more realistic synthetic vascular networks can be produced by including other cells such as pericytes (Bichsel et al . ; Kim et al . ) or mesenchymal stem cells (Jeon et al .…”