Bioactive glass activates VEGF paracrine signaling of cardiomyocytes to promote cardiac angiogenesis

The heart contains a wide range of cell types, which are not isolated but interact with one another via multifarious paracrine, autocrine and endocrine factors. In terms of cardiac angiogenesis, previous studies have proved that regulating the communication between cardiomyocytes and endothelial cells is efficacious to promote capillary formation. Firstly, this study investigated the effect and underlying mechanism of bioactive glass (BG) acted on vascular endothelial growth factor (VEGF) paracrine signaling in cardiomyocytes. We found that bioactive ions released from BG significantly promoted the VEGF production and secretion of cardiomyocytes. Subsequently, we proved that cardiomyocyte-derived VEGF played an important role in mediating the behavior of endothelial cells. Further research showed that the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/hypoxia-inducible factor 1α (HIF-1α) signaling pathway was upregulated by BG, which was involved in VEGF expression of cardiomyocytes. This study revealed that by means of modulating cellular crosstalk via paracrine signaling of host cells in heart is a new direction for the application of BGs in cardiac angiogenesis.

Danggui Buxue decoction promotes angiogenesis by up-regulation of VEGFR1/2 expressions and down-regulation of sVEGFR1/2 expression in myocardial infarction rat

BACKGROUND

The traditional herbal compound Danggui Buxue decoction (DBD), has long been used for the prevention and treatment of cardiovascular diseases, however, the underlying molecular mechanism for its effect remains still unknown. So this study would to investigate the effect of DBD on cardiac damage induced by myocardial infarction (MI) challenge.

METHODS

SD Rats with ligation of left anterior descending (LAD) coronary artery were randomly divided into MI, MI plus Betaloc Zok, MI plus DBD high dose, and MI plus DBD low dose group, together with sham-operated group. After corresponding treatment for consecutive 4 weeks, cardiac function was evaluated by hemodynamics with the method of pressure-volume conduit system. Cardiac histological morphology, microvascular density and the expressions of VEGF and VEGFR_1/2 mRNA and their relative protein including VEGF, membranous VEGFR₁ (VEGFR₁), soluble VEGFR₁ (sVEGFR₁), VEGFR₂, and sVEGFR₂ were examined by hematoxylin & eosin staining, immunohistochemical staining and quantitative polymerase chain reaction and western blot assay, respectively.

RESULTS

It showed that a significant impaired cardiac function and a remarkably inducible increase in fibrotic scar formation, microvascular density and VEGF mRNA expressions in MI rats. While DBD treatment could markedly boost cardiac angiogenesis further, hinder fibrotic scar formation, and improve declined cardiac function. Apart from the up-regulation of VEGF mRNA and VEGF and the down-regulation of sVEGFR_1/2, high dose of DBD dedicated to increasing VEGFR₁ mRNA and VEGFR₁ expression, while low dose to elevating VEGFR₂ mRNA and VEGFR₂ expression.

CONCLUSION

The present study demonstrated that DBD could accelerate cardiac angiogenesis, restrain fibrous scar formation and thus ameliorate cardiac function in post-MI, via the active regulation of VEGF/VEGFRs signaling pathway.

Subsets of telocytes: Myocardial telocytes

Telocytes (TCs) are morphologically defined as small-sized cells with long, thin, moniliform processes called telopodes (Tps). Numerous papers imply that TCs are a distinctive cell type, and that transmission electron microscopy (TEM) is the gold standard tool for their identification. We aimed to reproduce previous studies on myocardial TCs to check their validity. For this purpose we performed an immunohistochemical study on human cardiac samples from six autopsied donor cadavers, using antibodies against CD10, CD31, CD34, CD146, Ki67, alpha-smooth muscle actin (α-SMA), Platelet-Derived Growth Factor Receptor-alpha (PDGFRα) and laminin. Additionally we performed a TEM study on cardiac samples from three human autopsied donor cadavers and five adult Sprague-Dawley rats. We found endothelial cells (ECs), cords, and filopodia-projecting endothelial tip cells (ETCs) that expressed CD10, CD31, CD34, CD146, and PDGFR-α. Often, endothelial cells closely neighbored the sarcolemmal basal laminae. Endothelial progenitor cells, as well as nascent capillaries, were CD31+/CD34+. Proliferative endothelial cells expressed Ki67. In larger vessels we found pericytes that expressed CD146 and α-SMA; scarce α-SMA-expressing spindle-shaped cells lining cardiomyocytes were suggestive of a pericytic role in angiogenic sprout guidance. The TEM study showed that endothelial tubes are almost exclusively found in the narrow myocardial interstitia. ECs that built them up appeared identical to the cells that previous TEM studies have suggested to be myocardial telocytes. A subset of stromal cells with TC-like phenotype and telopodes-like processes actually seem to configure blood vessels, and therefore belong to the endothelial lineage. This study shows that data presented in previous studies on myocardial telocytes is not enough to allow the reproducibility of the results. At least a subset of cells considered to be TCs might belong to the endothelial lineage.