Cell-based therapies for ischemic heart disease--"trick and treat"

Differential function and regulation of orphan nuclear receptor TR3 isoforms in endothelial cells

TR3 has been reported to be an excellent target for angiogenesis therapies. We reported three TR3 transcript variant messenger RNAs (mRNAs) are expressed in human umbilical vein endothelial cell (HUVEC) and are differentially regulated by vascular endothelial growth factor (VEGF). TR3 transcript variant 1 (TR3-TV1) and variant 2 (TR3-TV2) encoding the same TR3 isoform 1 protein (TR3-iso1) that was named TR3 has been extensively studied. However, the function of TR3 isoform 2 protein (TR3-iso2) encoded by TR3 transcript variant 3 (TR3-TV3) is still not known. Here, we clone and express the novel TR3-iso2 protein and find that expression of TR3-iso2, in contrast to TR3-iso1, inhibits endothelial cell proliferation induced by VEGF-A, histamine, and phorbol-12-myristate-13-acetate (PMA). The differential function of TR3-iso2 correlates with the down-regulation of cyclin D1. However, TR3-iso2 plays similar roles in endothelial cell migration and monolayer permeability as TR3-iso1. We further demonstrate that several intracellular signaling pathways are involved in histamine-induced TR3 transcript variants, including histamine receptor H1-mediated phospholipase C (PLC)/calcium /calcineurin/protein kinase C (PKC)/protein kinase D (PKD) pathway and ERK pathway, as well as histamine receptor H3-mediated PKC-ERK pathway. Further, expressions of TR3-TV1, TR3-TV2, and TR3-TV3 by VEGF and histamine are regulated by different promoters, but not by their mRNA stability.

Development and evaluation of a perfusion decellularization porcine heart model--generation of 3-dimensional myocardial neoscaffolds

BACKGROUND

Reports about the generation of 3-dimensional neoscaffolds for myocardial tissue engineering are limited. The architecture provided by perfusion decellularization of whole hearts would support the production of human-sized 3-dimensional living tissues from an acellular matrix. The aim of this study was to evaluate the potential of a perfusion decellularization model for whole heart tissue engineering.

METHODS AND RESULTS

Hearts were obtained from 12 German Landrace pigs from a selected abattoir. After preparation, the hearts were mounted and perfused on a modified Langendorff decellularization model specifically constructed for this reason. Decellularization was achieved by an ionic detergent-based perfusion protocol. The quality of the decellularization process was quantified by histology and fluorescence microscopy. Data regarding the presence of residual DNA within the decellularized hearts was measured with spectrophotometric quantification and compared to controls. After histological examination, all hearts lacked intracellular components but retained various types of collagen, proteoglycan and elastin. Quantitative DNA analysis demonstrated a significant reduction of DNA in decellularized hearts compared to controls (84.32±3.99 ng DNA/mg tissue vs. 470.13±18.77 ng DNA/mg tissue (P<0.05)).

CONCLUSIONS

The modified Langendorff perfusion decellularization model described here is applicable for whole porcine hearts by removing cellular content and DNA. The resulting 3-dimensional matrix provides an interesting tool for further studies in the field of whole heart tissue engineering.

Tongue muscle-derived stem cells express connexin 43 and improve cardiac remodeling and survival after myocardial infarction in mice

BACKGROUND

Cell transplantation therapy for heart failure is hindered by poor differentiation into cardiomyocytes and arrhythmias caused by the poor expression of connexin 43 (Cx43). A new stem cell source for cardiac regeneration is needed.

METHODS AND RESULTS

Tongue muscle-derived Sca-1(+) cells (TDSCs) were isolated from normal and green fluorescence protein (GFP)-transgenic mouse tongues using surface antigen Sca-1. Cardiomyogenic differentiation was confirmed by measuring the calcium transient and the expression of cardiac-specific genes. The formation of gap junctions was confirmed by the expression of Cx43 and the dye transfer method. The contraction of regenerated cells was demonstrated by the calcium transients. GFP mouse-derived TDSCs were transplanted into hearts in a model of acute myocardial infarction. Three months after transplantation, LV remodeling was attenuated and the survival rate was improved compared with the control group.

CONCLUSIONS

TDSCs form gap junctions and improve cardiac function and long-term survival after myocardial infarction.

Role of the SDF-1/CXCR4 system in myocardial infarction

Myocardial infarction (MI) is accompanied by an inflammatory response, leading to the recruitment of leukocytes and subsequent myocardial injury and healing. Chemokines are potent chemoattractant cytokines that regulate leukocyte trafficking in inflammatory processes. Recent evidence indicates that chemokines play a role not only in leukocyte trafficking but also in angiogenesis and cardioprotection. In particular, stromal cell-derived factor-1alpha (SDF-1alpha) has generated considerable interest for its role in the pathophysiology of MI. This review will focus on the role of SDF-1 and its receptor CXC chemokine receptor 4 (CXCR4; ie, the SDF-1/CXCR4 system) in the pathophysiology of MI and discuss their potential as therapeutic targets for MI.