Telocytes in human heart valves

Abstract

Valve interstitial cells (VICs) are responsible for maintaining the structural integrity and dynamic behaviour of the valve. Telocytes (TCs), a peculiar type of interstitial cells, have been recently identified by Popescu*s group in epicardium, myocardium and endocardium (visit http://www.telocytes.com). The presence of TCs has been identified in atria, ventricles and many other tissues and organ, but not yet in heart valves. We used transmission electron microscopy and immunofluorescence methods (double labelling for CD34 and c-kit, or vimentin, or PDGF Receptor-β) to provide evidence for the existence of TCs in human heart valves, including mitral valve, tricuspid valve and aortic valve. TCs are found in both apex and base of heart valves, with a similar density of 27–28 cells/mm2 in mitral valve, tricuspid valve and aortic valve. Since TCs are known for the participation in regeneration or repair biological processes, it remains to be determined how TCs contributes to the valve attempts to re-establish normal structure and function following injury, especially a complex junction was found between TCs and a putative stem (progenitor) cell.

Morphological Evidence of Telocytes in Canine Inferior Vena Cava

“…TCs, as a novel population of inferior vena cava, might play an important role during the process of the remodeling. Also, inferior vena cava TCs, presumed accessory cells for stem cells [20], might play a key part in maintaining the homeostasis including angiogenesis, regeneration and reparation during vascular injury. The possible mechanism of inferior vena cava TCs during the progress needs further to be investigated.…”

“…TEM was performed on small tissue fragments, processed according to routine Epon-embedding procedure. And the processed specimen were observed under FEI TECAI SPIRITTEM (Eindhoven, The Netherlands), as previously described by Gherghiceanu [20]. Digital TEM images were processed using Adobe Photoshop CS5 in order to highlight TCs.…”

A comprehensive guide to telocytes and their great potential in cardiovascular system

“…Subepicardium and epicardium, in the part close to the coronary artery branching, are the locations of cardiac stem cell niches -the place where CSCs coexist with TCs and many other supporting cells (10,14,34). As for the valves, it is proven that TCs exist in human mitral, tricuspid and aortic valve (35).…”

“…Based on the example of heart valves, TCs' network helps in balanced force distribution in tissue and enables to maintain proper valve fl exibility (35). TCs are also supposed to be a source of cardiac mesenchymal cells, because they express mesenchymal marker CD29 and have the ability to lose expression of CD34 (19).…”

“…TCs form heterocellular contacts with a great variety of cells, such as: cardiomyocytes, cardiomyocyte progenitors, cardiac stem cells, endothelial cells, pericytes, Schwann cells, macrophages, mast cells, lymphocytes, fi broblasts/myofi broblasts and valve interstitial cells (11,18,33,35). One of the most distinctive types of TCs-related junctions in heart is a stromal synapse, which links TCs with CSCs and immune cells (11,26).…”