Close relation of arterial ICC‐like cells to the contractile phenotype of vascular smooth muscle cell

Vladimír Pucovský,Ray F Moss,Oleksandr V Povstyan,Thomas B Bolton,Maksym I Harhun,Dmitri V Gordienko

doi:10.1111/j.1582-4934.2007.00066.x

Abstract

This work aimed to establish the lineage of cells similar to the interstitial cells of Cajal (ICC), the arterial ICC-like (AIL) cells, which have recently been described in resistance arteries, and to study their location in the artery wall. Segments of guinea-pig mesenteric arteries and single AIL cells freshly isolated from them were used. Confocal imaging of immunostained cells or segments and electron microscopy of artery segments were used to test for the presence and cellular localization of selected markers, and to localize AIL cells in intact artery segments. AIL cells were negative for PGP9.5, a neural marker, and for von Willebrand factor (vWF), an endothelial cell marker. They were positive for smooth muscle α-actin and smooth muscle myosin heavy chain (SM-MHC), but expressed only a small amount of smoothelin, a marker of contractile smooth muscle cells (SMC), and of myosin light chain kinase (MLCK), a critical enzyme in the regulation of smooth muscle contraction. Cell isolation in the presence of latrunculin B, an actin polymerization inhibitor, did not cause the disappearance of AIL cells from cell suspension. The fluorescence of basal lamina protein collagen IV was comparable between the AIL cells and the vascular SMCs and the fluorescence of laminin was higher in AIL cells compared to vascular SMCs. Moreover, cells with thin processes were found in the tunica media of small resistance arteries using transmis-sion electron microscopy. The results suggest that AIL cells are immature or phenotypically modulated vascular SMCs constitutively present in resistance arteries.

Highlights

The vascular smooth muscle cell (VSMC) is regarded as a multifunctional mesenchymal cell [1]
To test whether the arterial ICC-like (AIL) cells are of neural or endothelial origin, single cells adhering to coverslips were immunostained for PGP9.5 (C-terminal ubiquitin hydroxylase), a neural marker [23] or for von Willebrand factor (vWF), a marker of endothelial cells, respectively
The intensity of myosin light chain kinase (MLCK) fluorescent signal was significantly lower in AIL cells than in VSMCs (Fig. 3F), which is in accordance with their inability to contract and corroborates the view that they are of immature VSMC phenotype

Summary

Introduction

The vascular smooth muscle cell (VSMC) is regarded as a multifunctional mesenchymal cell [1]. All the experiments involving SMC markers were carried out by imaging pairs of closely adjacent AIL cells and VSMCs in the same microscope field, to allow for direct comparison between their fluorescent signals. In this work we compared the SM-MHC signal intensity between AIL cells and VSMCs, which were imaged as pairs of cells (Fig. 2D).

Objectives

Results

Conclusion