Support of human alveolar organoid growth by pulmonary endothelial cells: possible influence of cigarette smoke exposure

Abstract

Emphysema is a component of Chronic Obstructive Pulmonary Disease (COPD) and is characterized by destruction of alveolar walls, which includes alveolar epithelial, endothelial and mesenchymal cells. It is increasingly realized that microvascular endothelial cell (dys)function contributes to emphysema development. The aim is to study the mechanistic interactions of human pulmonary microvascular endothelial and alveolar cells CD31+ pulmonary endothelial cells were isolated from human resected lung tissue homogenate, and expanded in vitro. Endothelial cells at passage 2 (P2)(n=3) were allowed to form a monolayer in the bottom of a culture plate (no fibroblasts added), that contained an insert with freshly isolated HTII-280+ alveolar cells from human resected lung tissue, were seeded in basement membrane extract matrix Co-culture of alveolar type 2 cells with primary lung endothelial cells increased (2.3-fold) human alveolar organoid number after 10 days. This finding supports a role for pulmonary endothelial cells in alveolar cell progenitor functioning. Next, endothelial cells (n=4) at P2, were exposed to 1, 2.5 or 5 arbitrary units (AU)/ml of cigarette smoke extract (CSE) for 1, 4 and 24 hours. Exposure of pulmonary endothelial cells to CSE reduced expression of genes involved in alveolar support (TMEM100, ALK1, BMPR1, MMP14, TSP-1) at 24hrs in a concentration-dependent manner. Expression of stress response genes (HMOX1, NQO1, GADD34 and spliced XBP1) increased at 24 hours in all concentrations of CSE. We are currently analyzing the impact of COPD-associated triggers such as cigarette smoke on endothelial cell-driven alveolar organoid formation. Funded by Longfonds