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Transplantation of expanded bone marrow-derived very small embryonic-like stem cells (VSEL-SCs) improves left ventricular function and remodelling after myocardial infarction.

ABSTRACT: Adult bone marrow-derived very small embryonic-like stem cells (VSEL-SCs) exhibit a Sca-1(+)/Lin(-)/CD45(-) phenotype and can differentiate into various cell types, including cardiomyocytes and endothelial cells. We have previously reported that transplantation of a small number (1 × 10(6)) of freshly isolated, non-expanded VSEL-SCs into infarcted mouse hearts resulted in improved left ventricular (LV) function and anatomy. Clinical translation, however, will require large numbers of cells. Because the frequency of VSEL-SCs in the marrow is very low, we examined whether VSEL-SCs can be expanded in culture without loss of therapeutic efficacy. Mice underwent a 30 min. coronary occlusion followed by reperfusion and, 48 hrs later, received an intramyocardial injection of vehicle (group I, n = 11), 1 × 10(5) enhanced green fluorescent protein (EGFP)-labelled expanded untreated VSEL-SCs (group II, n = 7), or 1 × 10(5) EGFP-labelled expanded VSEL-SCs pre-incubated in a cardiogenic medium (group III, n = 8). At 35 days after myocardial infarction (MI), mice treated with pre-incubated VSEL-SCs exhibited better global and regional LV systolic function and less LV hypertrophy compared with vehicle-treated controls. In contrast, transplantation of expanded but untreated VSEL-SCs did not produce appreciable reparative benefits. Scattered EGFP(+) cells expressing α-sarcomeric actin, platelet endothelial cell adhesion molecule (PECAM)-1, or von Willebrand factor were present in VSEL-SC-treated mice, but their numbers were very small. No tumour formation was observed. We conclude that VSEL-SCs expanded in culture retain the ability to alleviate LV dysfunction and remodelling after a reperfused MI provided that they are exposed to a combination of cardiomyogenic growth factors and cytokines prior to transplantation. Counter intuitively, the mechanism whereby such pre-incubation confers therapeutic efficacy does not involve differentiation into new cardiac cells. These results support the potential therapeutic utility of VSEL-SCs for cardiac repair.

SUBMITTER: Zuba-Surma EK

PROVIDER: S-EPMC3064954 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:We report a genome-wide survey of early responses of the mouse heart transcriptome to acute myocardial infarction (AMI). For three regions of the left ventricle (LV), namely ischemic/infarcted tissue (IF), the surviving LV free wall (FW) and the interventricular septum (IVS), 36,899 transcripts were assayed at six time points from 15 min to 48 h post-AMI in both AMI and sham surgery mice. For each transcript, temporal expression patterns were systematically compared between AMI and sham groups, which identified 515 AMI-responsive genes in IF tissue, 35 in the FW, 7 in the IVS, with three genes induced in all three regions. Using the literature, we assigned functional annotations to all 519 nonredundant AMI-induced genes and present two testable models for central signaling pathways induced early post-AMI. First, the early induction of 15 genes involved in assembly and activation of the activator protein-1 (AP-1) family of transcription factors implicates AP-1 as a dominant regulator of earliest post-ischemic molecular events. Second, dramatic increases in transcripts for arginase 1 (ARG1), the enzymes of polyamine biosynthesis and protein inhibitor of nitric oxide synthase (NOS) activity indicates that NO production may be regulated, in part, by inhibition of NOS and coordinate depletion of the NOS substrate, L-arginine. ARG1 was the single most highly induced transcript in the database (121-fold in IF region) and its induction in heart has not been previously reported. Keywords: heart attack, mouse, time course, regional responses We report temporal and regional changes in steady state mRNA levels in the mouse LV following a surgically-induced AMI. Three regions of the infarcted LV were surveyed: IF, FW and IVS. For each region, mRNA levels were assayed at t=0 and six time points after occlusion of the left anterior descending coronary artery (t = 15 min, 1 h, 4 h, 12 h, 24 h, 48 h). As control, an identical time course was carried out in the mouse LV after sham surgery in which the suture was passed under the artery, but not ligated. For sham surgical mice and naïve mice (t=0), the IVS and the LV free wall were harvested and assayed. The AMI and sham time courses were repeated for a total of two independent repetitions of the experiment. For each repetition, 96 GeneChips were hybridized. Thus, for two repetitions, 192 GeneChips (2 x 96) were hybridized. In addition, the naïve time point was assayed a second time during Repetition 1 for six additional GeneChips (two tissues x three chips). The overall total number of samples is 198 GeneChips (192 + 6). Total RNA was isolated from each individual tissue sample. Equal weights of total RNA from 4-10 mice were combined for each LV region, time point and treatment. Copy RNA mixtures were synthesized from each total RNA pool and hybridized to the Affymetrix GeneChip set MG U74 v2 (A, B, and C) that carries 36,899 probe sets. The global normalization of fluorescence emissions for the 198 GeneChips used in this study and their conversion to relative transcript concentrations measured in relative fluorescence units (RFU) was conducted using Robust Multi-array Averaging (RMA; www.bioconductor.org). Each of the 198 Accessions is titled as follows: time point / treatment / tissue, repetition, GeneChip. The additional assays of naïve mice in Repetition 1 are labeled “Naive2”.

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Transplantation of expanded bone marrow-derived very small embryonic-like stem cells (VSEL-SCs) improves left ventricular function and remodelling after myocardial infarction.

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