Cardiac Repair and Regeneration: The Value of Cell Therapies.

Ischaemic heart disease is the predominant contributor to cardiovascular morbidity and mortality; one million myocardial Infarctions occur per year in the USA, while more than five million patients suffer from chronic heart failure. Recently, heart failure has been singled out as an epidemic and is a staggering clinical and public health problem associated with significant mortality, morbidity and healthcare expenditures, particularly among those aged ≥65 years. Death rates have improved dramatically over the last four decades, but new approaches are nevertheless urgently needed for those patients who go on to develop ventricular dysfunction and chronic heart failure. Over the past decade, stem cell transplantation has emerged as a promising therapeutic strategy for acute or chronic ischaemic cardiomyopathy. Multiple candidate cell types have been used in preclinical animal models and in humans to repair or regenerate the injured heart, either directly or indirectly (through paracrine effects), including: embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs), neonatal cardiomyocytes, skeletal myoblasts (SKMs), endothelial progenitor cells, bone marrow mononuclear cells (BMMNCs), mesenchymal stem cells (MSCs) and, most recently, cardiac stem cells (CSCs). Although no consensus has emerged yet, the ideal cell type for the treatment of heart disease should: (a) improve heart function; (b) create healthy and functional cardiac muscle and vasculature, integrated into the host tissue; (c) be amenable to delivery by minimally invasive clinical methods; (d) be available 'off the shelf' as a standardised reagent; (e) be tolerated by the immune system; (f) be safe oncologically, i.e. not create tumours; and (g) circumvent societal ethical concerns. At present, it is not clear whether such a 'perfect' stem cell exists; what is apparent, however, is that some cell types are more promising than others. In this brief review, we provide ongoing data on agreement and controversy arising from clinical trials and touch upon the future directions of cell therapy for heart disease.

Denosumab could be a Potential Inhibitor of Valvular Interstitial Cells Calcification in vitro.

OBJECTIVE: Denosumab is a fully human monoclonal antibody and novel antiresorptive agent that works by binding receptor activator of nuclear factor kappa-ß ligand (RANKL) and inhibiting the signaling cascade that causes osteoclast maturation, activity, and survival. We aimed to elucidate the effect of Denosumab in the process of spontaneous and induced calcification in an in vitro porcine valvular interstitial cells (VICs) model. MATERIALS AND METHODS: VICs were extracted from fresh porcine hearts by serial collagenase digestion. Spontaneous calcification of VICs was increased in vitro by adding Na3PO4 (3 mM, pH 7.4) and different concentrations (0.1, 1 and 10 ng/ml) of transforming growth factor beta (TGFß). The degree of calcification before and after treatment with Denosumab was estimated by Alizarin Red staining for calcium deposition, and Sirius Red staining for collagen. Colorimetric techniques were used to determine calcium and collagen deposition quantitatively. For statistical analysis we used SPSS and Microsoft Office Excel 2013. RESULTS: Porcine aortic VICs in vitro were induced to calcify by the addition of either 3 mM Na3PO4, showing a 5.2 fold increase by 14 days (P<0.001), or 3 mM Na3PO4 + 10 ng/ml of TGFß, showing a 7 fold increase by Day 14 (P<0.001). Denosumab inhibited induced calcification by 3 mM Na3PO4 and 3 mM Na3PO4 with the addition of TGFß at either 0.1, 1 or 10 ng/ml to basal levels only at a concentration of 50 µg/ml (P<0.001). CONCLUSION: This study has proved that Denosumab could be a potential inhibitor of the calcification of VICs in vitro. A fuller understanding of the actions of Denosumab may identify a novel therapeutic strategy for clinical intervention against aortic valve calcification and aortic stenosis.

Using Na3PO4 to Enhance In vitro Animal Models of Aortic Valve Calcification.

BACKGROUND/OBJECTIVES: The pathogenesis of calcific aortic valvular disease (CAVD) involves an active inflammatory process of valvular interstitial cells (VICs) characterized by the activation of specific osteogenic signaling pathways and apoptosis. This process can be studied by analyzing certain molecular markers and gene expression pathways of spontaneous calcification. The purpose of our study is to investigate the role of sodium phosphate (Na3PO4) as a calcification promoter, with the aim of improving in vitro animal models for testing potential calcification inhibitors. MATERIALS AND METHODS: VICs were extracted from 6 healthy 6-month-old fresh porcine hearts by serial collagenase digestion. Quantitative polymerase chain reaction (qPCR) was used to quantify trans-differentiation of genes of interest during spontaneous calcification of VICs. Spontaneous calcification of VICs was increased by adding Na3PO4 (3 mM, pH 7.4). The degree of calcification was estimated by Alizarin Red staining for calcium deposition, and Sirius Red staining for collagen. Colorimetric techniques were used to determine calcium and collagen deposition quantitatively. Additionally, the enzymatic activity of alkaline phosphatase (ALP) was measured by a kinetic assay. For statistical analysis we used SPSS and Microsoft Office Excel 2013. RESULTS: Porcine VICs calcify spontaneously with demonstrable calcium and collagen deposition. In this study we observed an increase of calcium and collagen deposition from day 0 to day 14 (calcium: 376%; P<0.001, collagen: 3553%; P<0.001). qPCR analysis of mRNA by day 14 showed the following results: α-actin, a marker of myoblast phenotype, was increased to 1.6-fold; P<0.001. Runx2, an osteoblast marker, rose to 1.3 fold; P<0.05, TGF-ß, a promoter of osteogenesis, increased to 3.2-fold; P<0.001, and RhoA, a regulator of nodular formation in myoblasts, increased to 4.5-fold; P<0.001, compared to their levels at day 0. RANKL mRNA and calponin did not change significantly. Treatment of porcine VICs with Na3PO4 (3 mM, pH 7.4) led to a marked increase in calcium deposition by day 14 (522%; P<0.001), and a significant increase in ALP activity by day 7 (228%; P<0.05). There were no significant changes in ALP activity between the groups by day 14. CONCLUSION: This study has demonstrated the upregulation of some specific molecules during spontaneous calcification of aortic VICs with an active increase of calcium, collagen and ALP activity. In this in vitro model it was possible to increase spontaneous VICs calcification with Na3PO4 (3 mM, pH 7.4) to a level in which inhibitors of calcification could be tested to identify a novel potential therapeutic strategy against calcific aortic stenosis.

Early Results of a Novel Mitral Valve Repair Procedure: The Interpapillary Polytetrafluoroethylene Bridge Formation.

BACKGROUND: Surgical repair of ischemic mitral regurgitation (IMR) associated with chordal rupture in patients with ischemic cardiomyopathy is challenging as it aims to correct several structural pathologies at once. There are ongoing studies evaluating multiple approaches, however long term results are still scarce. METHODS AND RESULTS: 19 patients with IMR underwent mitral valve repair with interpapillary polytetrafluoroethylene (PTFE) bridge and neochordae formation at the Zala County Teaching Hospital. Concomitant coronary artery bypass grafting was performed in all patients. Post-procedural Transesophageal Echocardiogram (TEE) showed no mitral regurgitation (MR) in eighteen (94.7%) patients, with a leaflet coaptation mean height of 8 ± 3 mm. No operative mortality was observed. At the follow up (mean 17.7 ± 4.6 months; range 9 to 24 months), 17 (89%) patients showed no leakage and 2 had regurgitation grade ≤1, with documented NYHA functional class I or II in all patients. CONCLUSION: This retrospective study presents the first results of a novel surgical approach to treating ischemic mitral regurgitation. The interpapillary PTFE bridge formation is a safe and feasible surgical procedure that is reproducible, time sparing and effectively eliminates mitral valve regurgitation with promising long-term results.

Calcific Aortic Valve Disease: Molecular Mechanisms and Therapeutic Approaches.

Calcification occurs in atherosclerotic vascular lesions and In the aortic valve. Calcific aortic valve disease (CAVD) is a slow, progressive disorder that ranges from mild valve thickening without obstruction of blood flow, termed aortic sclerosis, to severe calcification with impaired leaflet motion, termed aortic stenosis. In the past, this process was thought to be 'degenerative' because of time-dependent wear and tear of the leaflets, with passive calcium deposition. The presence of osteoblasts in atherosclerotic vascular lesions and in CAVD implies that calcification is an active, regulated process akin to atherosclerosis, with lipoprotein deposition and chronic inflammation. If calcification is active, via pro-osteogenic pathways, one might expect that development and progression of calcification could be inhibited. The overlap in the clinical factors associated with calcific valve disease and atherosclerosis provides further support for a shared disease mechanism. In our recent research we used an in vitro porcine valve interstitial cell model to study spontaneous calcification and potential promoters and inhibitors. Using this model, we found that denosumab, a human monoclonal antibody targeting the receptor activator of nuclear factor-κB ligand may, at a working concentration of 50 µg/mL, inhibit induced calcium deposition to basal levels.