Pericardial Grafting of Cardiac Progenitor Cells in Self-Assembling Peptide Scaffold Improves Cardiac Function After Myocardial Infarction.

Many studies have explored cardiac progenitor cell (CPC) therapy for heart disease. However, optimal scaffolds are needed to ensure the engraftment of transplanted cells. We produced a three-dimensional hydrogel scaffold (CPC-PRGmx) in which high-viability CPCs were cultured for up to 8 weeks. CPC-PRGmx contained an RGD peptide-conjugated self-assembling peptide with insulin-like growth factor-1 (IGF-1). Immediately after creating myocardial infarction (MI), we transplanted CPC-PRGmx into the pericardial space on to the surface of the MI area. Four weeks after transplantation, red fluorescent protein-expressing CPCs and in situ hybridization analysis in sex-mismatched transplantations revealed the engraftment of CPCs in the transplanted scaffold (which was cellularized with host cells). The average scar area of the CPC-PRGmx-treated group was significantly smaller than that of the non-treated group (CPC-PRGmx-treated group = 46 ± 5.1%, non-treated MI group = 59 ± 4.5%; p < 0.05). Echocardiography showed that the transplantation of CPC-PRGmx improved cardiac function and attenuated cardiac remodeling after MI. The transplantation of CPCs-PRGmx promoted angiogenesis and inhibited apoptosis, compared to the untreated MI group. CPCs-PRGmx secreted more vascular endothelial growth factor than CPCs cultured on two-dimensional dishes. Genetic fate mapping revealed that CPC-PRGmx-treated mice had more regenerated cardiomyocytes than non-treated mice in the MI area (CPC-PRGmx-treated group = 0.98 ± 0.25%, non-treated MI group = 0.25 ± 0.04%; p < 0.05). Our findings reveal the therapeutic potential of epicardial-transplanted CPC-PRGmx. Its beneficial effects may be mediated by sustainable cell viability, paracrine function, and the enhancement of de novo cardiomyogenesis.

Regeneration of the Cardiac Conduction System by Adipose Tissue-Derived Stem Cells.

BACKGROUND: Adipose tissue is one of the sources of mesenchymal stem cells, which have the potential to differentiate into various types of cells, including myocytes. Whether brown adipose tissue (BAT)-derived cells might differentiate into the cardiac pacemaking-conducting cells, and have the potential to regenerate the cardiac conduction system (CCS), is investigated in this study. METHODS AND RESULTS: BAT was isolated from the interscapular area of mice and enzymatically digested before culture. Round or fusiform cells showed spontaneous beating at 4-7 days after culturing of BAT-derived cells. Reverse transcriptase-polymerase chain reaction analysis and immunocytochemical analysis revealed that BAT-derived cells expressed several cardiomyocytes, the CCS and pacemaker (PM) cell marker genes and proteins. Patch-clamp techniques revealed that spontaneous electrical activity and the shape of the action potential showed properties of cardiac PM cells. Next, a complete atrioventricular (AV) block was created in mice and green fluorescent protein-positive (GFP (+)) BAT-derived cells were injected intramyocardially around the AV node. At 1 week after transplantation, 50% of BAT-derived cells injected mice showed a sinus rhythm or a 2:1 AV block. Immunohistochemical analysis revealed that injected GFP (+) cells were engrafted and some GFP (+) cells co-expressed several cardiac PM cell marker proteins. CONCLUSIONS: BAT-derived cells differentiate into the CCS and PM-like cells in vitro and in vivo, and may become a useful cell source for arrhythmia therapy.

Anti-inflammatory peptides from cardiac progenitors ameliorate dysfunction after myocardial infarction.

BACKGROUND: Cardiac cell therapy has been proposed as one of the new strategies against myocardial infarction. Although several reports showed improvement of the function of ischemic heart, the effects of cell therapy vary among the studies and the mechanisms of the beneficial effects are still unknown. Previously, we reported that clonal stem cell antigen-1-positive cardiac progenitor cells exerted a therapeutic effect when transplanted into the ischemic heart. Our aims were to identify the cardiac progenitor-specific paracrine factor and to elucidate the mechanism of its beneficial effect. METHODS AND RESULTS: By using an antibody array, we found that soluble junctional adhesion molecule-A (JAM-A) was abundantly secreted from cardiac progenitor cells. Pretreatment of neutrophils with conditioned medium from cultured cardiac progenitor cells or soluble JAM-A inhibited transendothelial migration and reduced motility of neutrophils. These inhibitory effects were attenuated by anti-JAM-A neutralizing antibody. Injection of cardiac progenitor cells into infarct heart attenuated neutrophil infiltration and expression of inflammatory cytokines. Injection of soluble JAM-A-expressing, but not of JAM-A siRNA-expressing, cardiac progenitor cells into the infarct heart prevented cardiac remodeling and reduced fibrosis area. CONCLUSIONS: Soluble JAM-A secreted from cardiac progenitor cells reduces infiltration of neutrophils after myocardial infarction and ameliorates tissue damage through prevention of excess inflammation. Our finding may lead to a new therapy for cardiovascular disease by using the anti-inflammatory effect of JAM-A.

Implantation of cardiac progenitor cells using self-assembling peptide improves cardiac function after myocardial infarction.

Implantation of various types of cells into the heart has been reported to be effective for heart failure, however, it is unknown what kinds of cells are most suitable for myocardial repair. To examine which types of cells are most effective, we injected cell-Puramatrix™ (PM) complex into the border area and overlaid the cell-PM patch on the myocardial infarction (MI) area. We compared cardiac morphology and function at 2 weeks after transplantation. Among clonal stem cell antigen-1 positive cardiac progenitors with PM (cSca-1/PM), bone marrow mononuclear cells with PM (BM/PM), skeletal myoblasts with PM (SM/PM), adipose tissue-derived mesenchymal cells with PM (AMC/PM), PM alone (PM), and non-treated MI group (MI), the infarct area of cSca-1/PM was smaller than that of BM/PM, SM/PM, PM and MI. cSca-1/PM and AMC/PM attenuated ventricular enlargement and restored cardiac function in comparison with MI. Capillary density in the infarct area of cSca-1/PM was higher than that of other five groups. The percentage of TUNEL positive cardiomyocytes in the infarct area of cSca-1/PM was lower than that of MI and PM. cSca-1 secreted VEGF and some of them differentiated into cardiomyocytes and vascular smooth muscle cells. These results suggest that transplantation of cSca-1/PM most effectively prevents cardiac remodeling and dysfunction through angiogenesis, inhibition of apoptosis and myocardial regeneration.