Hypoxia induced the differentiation of Tbx18-positive epicardial cells to CoSMCs

Abstract

Understanding the origin and differentiation mechanism of coronary vascular smooth muscle cells (CoSMCs) is very important to cardiovascular biology. The early cardiovascular system is formed in a hypoxic microenvironment, and Tbx18-positive epicardial cells are a source of CoSMCs. However, the effects of hypoxia on the differentiation of Tbx18-positive epicardial cells to CoSMCs and the primary regulatory mechanism are insufficiently understood. Using Tbx18:Cre/R26REYFP/LacZ fate-tracing mice, we cultured highly purified Tbx18-positive epicardial cells. We further showed that hypoxia induced Tbx18-positive epicardial cells to differentiate into CoSMCs and promoted the epithelial-mesenchymal transition (EMT) process of the cells in vitro. The induction of differentiation was primarily achieved via the hypoxia inducible factor-1α (HIF-1α)-mediated effects exerted on Snail. Using a cell migration assay, we showed that hypoxia enhanced the motility of Tbx18-positive epicardial cells. By constructing a hypoxic model of the embryonic epicardium in vivo, we showed that hypoxia led to premature in situ differentiation of Tbx18-positive epicardial cells to CoSMCs. Furthermore, hypoxia was sufficient to induce Snail expression in Tbx18-positive epicardial cells in vivo. Our study suggests that hypoxia intervention was sufficient to induce the differentiation of Tbx18-positive epicardial cells to CoSMCs. Furthermore, this differentiation was achieved primarily via HIF-1α-mediated regulation of Snail.

Hypoxia Supports Epicardial Cell Differentiation in Vascular Smooth Muscle Cells through the Activation of the TGFβ Pathway

“…The epicardium has been identified as a hypoxic microenvironment expressing Hif-1α and harboring progenitor cells during embryogenesis and in adults [ 39 , 49 , 50 , 51 ]. Supporting the present observations, Jing et al [ 40 ] recently showed that hypoxia induced the differentiation of TBX18 + epicardial cells to undergo EMT and differentiate into VSMCs through HIF-mediated activation of Snail (a major regulator of EMT) that is also known to be induced by TGFβ [ 52 , 53 , 54 ]. However, in vivo loss of epicardial Snail1 did not lead to any aberrant morphogenetic processes [ 55 ].…”

“…Because VSMCs are critical for the growth, remodeling and homeostasis of vessels and also involved in cardiovascular pathogenesis (reviewed in [ 15 ]), it is important to reveal the functional mediators of epicardial mobilization and the steps involved in their differentiation in the context of the developing epicardium. It was recently reported that hypoxia induces the developmental differentiation of Tbx18+ epicardial cells to VSMCs through Snail [ 40 ]. As molecular hypoxic signals are key regulators in differentiation of various stem cell types, we postulated that hypoxia influences the development of the coronary vasculature in part by controlling the plasticity of epicardial cells.…”

Bone morphogenetic protein 4 promotes the differentiation of Tbx18‑positive epicardial progenitor cells to pacemaker‑like cells

“…After the ventricles were removed, EPCs were cultured in Dulbecco's modified Eagle's medium containing 10% fetal bovine serum (both Gibco; Thermo Fisher Scientific, Inc., Waltham, MA, USA). The procedure used to obtain the EPCs was in accordance with previous studies ( 9 , 17 ). Tbx18 + EPCs were separated into the following four treatment groups: Control, Bmp4 (60 ng/ml; cat.…”

“…Cells migrate from the pro-epicardial organ to cover the surface of the embryonic heart and form the epicardium. Studies have confirmed that most of the epicardial cells express the Tbx18 transcription factor ( 9 ). Tbx18-positive (Tbx18 + ) pro-epicardium develops into the SAN as a process of epicardium formation ( 1 , 3 , 10 , 11 ).…”

Bioengineering strategies to control epithelial-to-mesenchymal transition for studies of cardiac development and disease

“…EMT was promoted in mouse Tbx18-positive epicardial cells which differentiated into coronary vascular smooth muscle cells as a result of hypoxia, through hypoxia inducible factor-1alpha (HIF-1alpha)-mediated effects on Snail. 143 The authors also showed that hypoxia led to premature differentiation of epicardial cells to coronary vascular smooth muscle cells and induced Snail expression in vivo. Likewise, other work with mouse cells demonstrated that hypoxia stimulated EMT and differentiation of epicardial cells into vascular smooth muscle cells in a manner involving the TGF-β pathway.…”