Elsevier

Experimental Cell Research

Volume 338, Issue 2, 1 November 2015, Pages 239-244
Experimental Cell Research

Research Article
Multiple immunophenotypes of cardiac telocytes

https://doi.org/10.1016/j.yexcr.2015.08.012Get rights and content

Highlights

  • TCs’ movement and extension of their prolongations lasted for approximately 1.5 h.

  • The unique structural characteristics of TCs were observed by SEM for the first time.

  • Cardiac TCs cultured in vitro expressed vimentin, CD34, nanog, sca-1 and c-kit.

Abstract

Aims

Telocytes (TCs) form a 3-dimensional network in the myocardial interstitium, which most probably play important role(s) in heart development. However, the dynamics of their prolongations, continuous cell shape changes and adherence properties have not been well documented till recently. The aim of this study was to investigate dynamics of extension of prolongations (Telopods) and multiple phenotypes of cardiac TCs cultured in vitro.

Methods

Cardiac TCs were isolated from neonatal rats by a combined enzyme digestion process and identified by light microscopy, immunofluorescence analysis and scanning using electron microscopy (SEM). Their continuous changes in shape were analyzed by a Live Cell Imaging System and multiple phenotypes were identified by immunofluorescence analysis using various markers, like vimentin, c-kit, CD34, nanog and sca-1.

Results

Cardiac TCs displayed piriform/spindle/triangular shapes with long and slender telopodes showing extremely long prolongations. The morphology of cell body was continuously changing while their prolongations were extending gradually. After adhering to the surface, TCs’ movement and extension of their prolongations lasted for approximately 1.5 h. Cardiac TCs expressed mesenchymal cell marker vimentin, hematopoietic stem cell marker CD34, embryonic stem cell-associated gene of Nanog, and myocardial stem cell markers sca-1 and c-kit.

Conclusion

These findings indicate that cultured TCs in vitro have multiple phenotypes, which are most likely important for evaluating their functional roles in heart development.

Introduction

Telocytes (TCs) are described as interstitial cells with extremely long and thin prolongations, called telopodes (Tps) (www.telocytes.com). Tps have dilated portions (podoms) and very thin segments (podomeres), exhibiting moniliform appearance [1], [2]. These unique structural characteristics evoked substantial interest in terms of their functional significance [3], [4], [5], [6], [7], [8], [9]. However, dynamics of Tps extension, cell shape changes and adherence have not been well understood.

Cardiac TCs have been identified in epicardium [10], myocardium [11], endocardium [12], subendocardium [13], stem cell niches [14], myocardial sleeves [15] and heart valves [16]. They form an interstitial network that plays a very important role in heart development, renewal and repair [17], [18]. Intramyocardial transplantation of TCs has potential to reduce myocardial infarction and improve cardiac function in rats [19].

To date, specific molecular markers were not available to detect TCs, so morphology identification using transmission electron microscopy (TEM) remains as only firm diagnostic tool for detection of TCs [2], [20]. In this study, cardiac TCs were identified by light microscopy and scanning electron microscopy (SEM). The phenotype of TCs was characterized by CD34, c-kit, vimentin and caveolin-1 positivity [21]. TCs in different tissues display different phenotypes [22], [23]. Cardiac TCs express vimentin, CD34 and PDGFR-β [16]. The present study was to investigate dynamics of telopdes and features of their multiple immunophenotypes. The findings in this study may provide the direct evidence of the morphology of the cardiac TCs and a theoretical background to explain the role of TCs in heart development and myocardial repair following cardiac injury.

Section snippets

Animals

Neonatal Sprague-Dawley rats (1–3 day-old, 7.2±0.35 g, n=20) were utilized in this study. Animal treatment was performed according to the guidelines of The Ministry of Science and Technology of the People's Republic of China [(2006)398] and approved by the Xinxiang Medical University Animal Care Committee (No. 030032).

Isolation and culture of cardiac TCs

Cardiac TCs were isolated from neonatal rat hearts. Briefly, heart tissues were minced into small pieces of about 1 mm3 after washing with sterile phosphate-buffered saline (PBS).

Morphology of cardiac TCs

The isolated cells from rat hearts in suspension showed small and round shapes. Cardiac fibroblasts attached to the flasks after plating for 30–60 min, TCs attached after plating for 60–90 min, and cardiomyocytes attached after plating for 90 min by differential velocity adherence technique. Most of the attached cells were mainly cardiac fibroblasts and cardiomyocytes that presented spindle, oval and triangle shapes (Fig. 1). A few cells were TCs that exhibited small prominent body with 1–7 very

Discussion

TCs are novel type of interstitial cells that are dispersed in the connective tissues and form a three-dimensional network with endothelial cells, fibroblasts and other cells including cardiomyocytes [13]. It is known that cardiac TCs constitute approximately 1–1.5% of atrial myocardial volume [24]. The morphology of the cardiac TCs is different from cardiac fibroblasts and cadiomyocytes. TCs have a distinctive shape with a small pyriform, spindle or triangular body, as well as one or two oval

Conflicts of interest

The authors confirmed that there are no conflicts of interest.

Acknowledgments

We thank all members of our lab for sharing reagents and advice. This work was supported by a grant from the Brilliancy Talent Project of Henan Province (No. 084200510020), PR China.

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