There is great clinical interest in cell-based therapies for ischemic tissue repair in cardiovascular disease. However, the regenerative potential of these therapies is limited due to poor cell viability and minimal retention following application. We report here the development of bioactive peptide amphiphile nanofibers displaying the fibronectin-derived RGDS cell adhesion epitope as a scaffold for therapeutic delivery of bone marrow derived stem and progenitor cells. When grown on flat substrates, a binary peptide amphiphile system consisting of 10% by weight RGDS-containing molecules and 90% negatively charged diluent molecules was found to promote optimal cell adhesion. This binary system enhanced adhesion 1.4 fold relative to substrates composed of only the non-bioactive diluent. Additionally, no enhancement was found upon scrambling the epitope and adhesion was no longer enhanced upon adding soluble RGDS to the cell media, indicating RGDSspecific adhesion. When encapsulated within self-assembled scaffolds of the binary RGDS nanofibers in vitro, cells were found to be viable and proliferative, increasing in number by 5.5 times after only 5 days, an effect again lost upon adding soluble RGDS. Cells encapsulated within a nonCorrespondence to: Samuel I. Stupp. 1 Contributed equally to this work Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access Author ManuscriptActa Biomater. Author manuscript; available in PMC 2011 January 1. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript bioactive scaffold and those within a binary scaffold with scrambled epitope showed minimal viability and no proliferation. Cells encapsulated within this RGDS nanofiber gel also increase in endothelial character, evident by a decrease in the expression of CD34 paired with an increase in the expression of endothelial-specific markers VE-Cadherin, VEGFR2, and eNOS after 5 days. In an in vivo study, nanofibers and luciferase-expressing cells were co-injected subcutaneously in a mouse model. The binary RGDS material supported these cells in vivo, evident by a 3.2 fold increase in bioluminescent signal attributable to viable cells; this suggests the material has an anti-apoptotic and/ or proliferative effect on the transplanted bone marrow cells. We conclude that the binary RGDSpresenting nanofibers developed here demonstrate enhanced viability, proliferation, and adhesion of associated bone marrow derived stem and progenitor cells. This study suggests potential for this material as a scaffold to overcome current limitations of stem cell therapies for isc...

Rationale The ACCRUE (Meta-Analysis of Cell-based CaRdiac stUdiEs) is the first prospectively declared collaborative multinational database including individual data of patients (IPD) with ischemic heart disease treated with cell therapy. Objective We analyzed the safety and efficacy of intracoronary cell therapy after acute myocardial infarction (AMI) including IPDs from 12 randomized trials (ASTAMI, Aalst, BOOST, BONAMI, CADUCEUS, FINCELL, REGENT, REPAIR-AMI, SCAMI, SWISS-AMI, TIME, LATE-TIME; n=1252). Methods and Results The primary endpoint was freedom from combined major adverse cardiac and cerebrovascular events (MACCE; including all-cause death, re-AMI, stroke, and target vessel revascularization). The secondary endpoint was freedom from hard clinical endpoints (death, re-AMI, or stroke), assessed with random-effects meta-analyses and Cox regressions for interactions. Secondary efficacy endpoints included changes in end-diastolic volume (ΔEDV), end-systolic volume (ΔESV), and ejection fraction (ΔEF), analyzed with random-effects meta-analyses and analysis of covariance. We reported weighted mean differences between cell therapy and control groups. No effect of cell therapy on MACCE (14.0% vs. 16.3%, hazard ratio 0.86, 95%CI: 0.63;1.18) or death (1.4% vs 2.1%) or death/re-AMI/stroke (2.9% vs 4.7%) was identified in comparison to controls. No change in ΔEF (mean difference: 0.96%, 95%CI: −0.2;2.1), ΔEDV, or ΔESV was observed compared to controls. These results were not influenced by anterior AMI location, reduced baseline EF, or the use of MRI for assessing left ventricular parameters. Conclusions This meta-analysis of IPD from randomized trials in patients with recent AMI revealed that intracoronary cell therapy provided no benefit, in terms of clinical events or changes in left ventricular function.

Recent studies showed that mesenchymal stem cells (MSCs) transplantation significantly decreased cardiac fibrosis; however, the mechanisms involved in these effects are still poorly understood. In this work, we investigated whether the antifibrotic properties of MSCs involve the regulation of matrix metalloproteinases (MMPs) and matrix metalloproteinase endogenous inhibitor (TIMP) production by cardiac fibroblasts. In vitro experiments showed that conditioned medium from MSCs decreased viability, a-smooth muscle actin expression, and collagen secretion of cardiac fibroblasts. These effects were concomitant with the stimulation of MMP-2/MMP-9 activities and membrane type 1 MMP expression. Experiments performed with fibroblasts from MMP2-knockout mice demonstrated that MMP-2 plays a preponderant role in preventing collagen accumulation upon incubation with conditioned medium from MSCs. We found that MSC-conditioned medium also decreased the expression of TIMP2 in cardiac fibroblasts. In vivo studies showed that intracardiac injection of MSCs in a rat model of postischemic heart failure induced a significant decrease in ventricular fibrosis. This effect was associated with the improvement of morphological and functional cardiac parameters. In conclusion, we showed that MSCs modulate the phenotype of cardiac fibroblasts and their ability to degrade extracellular matrix. These properties of MSCs open new perspectives for understanding the mechanisms of action of MSCs and anticipate their potential therapeutic or side effects. STEM

The 5-year follow-up is consistent with the 30-day outcomes of the trial, showing similar mortality for primary percutaneous coronary intervention and a policy of pre-hospital lysis followed by transfer to an interventional center. In addition, for patients treated within 2 h of symptom onset, 5-year mortality was lower with pre-hospital lysis.