Relationship among LRP1 expression, Pyk2 phosphorylation and MMP-9 activation in left ventricular remodelling after myocardial infarction.

Left ventricular (LV) remodelling after myocardial infarction (MI) is a crucial determinant of the clinical course of heart failure. Matrix metalloproteinase (MMP) activation is strongly associated with LV remodelling after MI. Elucidation of plasma membrane receptors related to the activation of specific MMPs is fundamental for treating adverse cardiac remodelling after MI. The aim of current investigation was to explore the potential association between the low-density lipoprotein receptor-related protein 1 (LRP1) and MMP-9 and MMP-2 spatiotemporal expression after MI. Real-time PCR and Western blot analyses showed that LRP1 mRNA and protein expression levels, respectively, were significantly increased in peri-infarct and infarct zones at 10 and 21 days after MI. Confocal microscopy demonstrated high colocalization between LRP1 and the fibroblast marker vimentin, indicating that LRP1 is mostly expressed by cardiac fibroblasts in peri-infarct and infarct areas. LRP1 also colocalized with proline-rich tyrosine kinase 2 (pPyk2) and MMP-9 in cardiac fibroblasts in ischaemic areas at 10 and 21 days after MI. Cell culture experiments revealed that hypoxia increases LRP1, pPyk2 protein levels and MMP-9 activity in fibroblasts, without significant changes in MMP-2 activity. MMP-9 activation by hypoxia requires LRP1 and Pyk2 phosphorylation in fibroblasts. Collectively, our in vivo and in vitro data support a major role of cardiac fibroblast LRP1 levels on MMP-9 up-regulation associated with ventricular remodelling after MI.

Fast-proliferating adipose tissue mesenchymal-stromal-like cells for therapy.

Human mesenchymal stromal cells, whether from the bone marrow or adipose tissue (hASCs), are promising cell therapy agents. However, generation of abundant cells for therapy remains to be a challenge, due to the need of lengthy expansion and the risk of accumulating genomic defects during the process. We show that hASCs can be easily induced to a reversible fast-proliferating phenotype (FP-ASCs) that allows rapid generation of a clinically useful quantity of cells in <2 weeks of culture. Expanded FP-ASCs retain their finite expansion capacity and pluripotent properties. Despite the high proliferation rate, FP-ASCs show genomic stability by array-comparative genomic hybridization, and did not generate tumors when implanted for a long time in an SCID mouse model. Comparative analysis of gene expression patterns revealed a set of genes that can be used to characterize FP-ASCs and distinguish them from hASCs. As potential candidate therapeutic agents, FP-ASCs displayed high vasculogenic capacity in Matrigel assays. Moreover, application of hASCs and FP-ASCs in a fibrin scaffold over a myocardium infarct model in SCID mice showed that both cell types can differentiate to endothelial and myocardium lineages, although FP-ASCs were more potent angiogenesis inducers than hASCs, at promoting myocardium revascularization.