TRPV1 Receptor Identification in Bovine and Canine Mitral Valvular Interstitial Cells.

Cristina Vercelli,Rossella V Barberis,Massimiliano Tursi,Graziana Gambino,Izabela Janus,Eugenio Martignani,Michela Amadori,Giovanni Re

doi:10.3390/vetsci8090183

Abstract

Myxomatous mitral valve degeneration (MMVD) is the most common acquired cardiac disease in canine species, and valvular interstitial cells (VICs) are considered the main responsible for the development of this pathology. The scientific interest is focused on isolating and characterizing these cells. The aims of the present study were to verify a novel VICs mechanical isolation method and to characterize isolated cells using immunocytochemistry and immunofluorescence, with parallel histological and immunohistochemistry assays on bovine and canine healthy and MMVD mitral valves. Antibodies against vimentin (VIM), smooth muscle actin (SMA), von Willebrand (vW) factor, Transforming Growth Factor (TGF) β1, and Transient Receptor Potential Vanilloid 1 (TRPV1) were used. The isolation method was considered reliable and able to isolate only VICs. The different assays demonstrated a different expression of SMA in healthy and MMVD mitral valves, and TRPV1 was isolated for the first time from bovine and canine VICs and the correspondent mitral valve leaflets. The novelties of the present study are the new isolation method, that may allow correlations between laboratory and clinical conditions, and the identification of TRPV1, which will lead to further investigations to understand its function and possible role in the etiology of MMVD and to the design of new therapeutic strategies.

Highlights

Myxomatous mitral valve degeneration (MMVD) is the most common acquired cardiac disease in elderly dogs and causes high mortality due to cardiac insufficiency [1]
A preliminary study aimed to verify if this simplified technique was able to isolate mitral valvular interstitial cells from bovine hearts
Cells had a fibroblast-like morphology, and the immunocytochemistry evaluation confirmed that only valvular interstitial cells (VICs) were isolated and cultured, as shown by a strong and diffuse cytoplasmatic

Summary

Introduction

Myxomatous mitral valve degeneration (MMVD) is the most common acquired cardiac disease in elderly dogs and causes high mortality due to cardiac insufficiency [1]. It has been demonstrated that valvular interstitial cells (VICs) are the main cell population in mitral valve leaflets in humans and respond to mechanical, chemical, and molecular changes that can damage leaflet integrity [7,8]. These cells are mainly involved in valvular homeostasis, preserving modifications of the extracellular matrix (ECM), composed of collagen, elastin, and proteoglycans [9]. VICs phenotype can be heterogenous, presenting differences in cell morphology and function that can vary along the lifetime and can lead to a pathological process [10]. The transition from quiescent or normal to activated VIC is reflected by a morphology change from a fibroblasts-like to a myofibroblast phenotype, with double immunoreactivity for vimentin (VIM) and smooth muscle actin (SMA) [7,11]

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