Experimental acute myocardial infarction: telocytes involvement in neo-angiogenesis

Abstract

We used rat experimental myocardial infarction to study the ultrastructural recovery, especially neo-angiogenesis in the infarction border zone. We were interested in the possible role(s) of telocytes (TCs), a novel type of interstitial cell very recently discovered in myocardim (see ). Electron microscopy, immunocytochemistry and analysis of several proangiogenic microRNAs provided evidence for TC involvement in neo-angiogenesis after myocardial infarction. Electron microscopy showed the close spatial association of TCs with neoangiogenetic elements. Higher resolution images provided the following information: (a) the intercellular space between the abluminal face of endothelium and its surrounding TCs is frequently less than 50 nm; (b) TCs establish multiple direct nanocontacts with endothelial cells, where the extracellular space seems obliterated; such nanocontacts have a length of 0.4–1.5 μm; (c) the absence of basal membrane on the abluminal face of endothelial cell. Besides the physical contacts (either nanoscopic or microscopic) TCs presumably contribute to neo-angiognesis via paracrine secretion (as shown by immunocytochemistry for VEGF or NOS2). Last but not least, TCs contain measurable quantities of angiogenic microRNAs (e.g. let-7e, 10a, 21, 27b, 100, 126-3p, 130a, 143, 155, 503). Taken together, the direct (physical) contact of TCs with endothelial tubes, as well as the indirect (chemical) positive influence within the ‘angiogenic zones’, suggests an important participation of TCs in neo-angiogenesis during the late stage of myocardial infarction.

Exosomes and Cardiac Repair After Myocardial Infarction

“…Reports have suggested that the myocardial tissue secretes exosomes, and exosomes and microvesicles could be an important mechanism involved in heterocellular communication in the adult heart, 78,79 especially exosomes emerging from telocytes in the border zone of MI. 79 Barile et al 78 provided ultrastructural evidence for the first time that exosomes and microvesicles are secreted by the progenitor cells in a normal adult mouse heart. They have also demonstrated a possible uptake of exosomes by cardiomyocytes in the adult mouse heart.…”

miRNome in myocardial infarction: Future directions and perspective

“…Rat experimental MI was investigated using electron microscopy, immunocytochemistry and analysis of several pro-angiogenic miRNAs that provided evidence for TC involvement in neo-angiogenesis after MI. TCs contain measurable quantities of angiogenic miRNAs (let- 7e, miR-10a, miR-21, miR-27b, miR-100, miR-126-3p, miR130a, miR-143, miR-155 and miR-503) [101] .…”

Ultrastructural identification of telocytes in the muscularis of chicken ileum

“…TCs may be nurse cells, integrating local, short-distance signals (direct contacts, exosomes and shedding vesicles) and long-distance signals through the long TPs, due to their 3D network. Recent studies have demonstrated a particular immunophenotype (34,35), distinct microRNA expression (36), specific gene-expression profiles (37) and peculiar electrophysiological properties of TCs in various organs (38). Close contact between TCs and fibroblasts was indicated in the present study.…”