Direct intracardiac injection of umbilical cord-derived stromal cells and umbilical cord blood-derived endothelial cells for the treatment of ischemic cardiomyopathy.

The development of new therapeutic strategies is necessary to reduce the worldwide social and economic impact of cardiovascular disease, which produces high rates of morbidity and mortality. A therapeutic option that has emerged in the last decade is cell therapy. The aim of this study was to compare the effect of transplanting human umbilical cord-derived stromal cells (UCSCs), human umbilical cord blood-derived endothelial cells (UCBECs) or a combination of these two cell types for the treatment of ischemic cardiomyopathy (IC) in a Wistar rat model. IC was induced by left coronary artery ligation, and baseline echocardiography was performed seven days later. Animals with a left ventricular ejection fraction (LVEF) of ≤40% were selected for the study. On the ninth day after IC was induced, the animals were randomized into the following experimental groups: UCSCs, UCBECs, UCSCs plus UCBECs, or vehicle (control). Thirty days after treatment, an echocardiographic analysis was performed, followed by euthanasia. The animals in all of the cell therapy groups, regardless of the cell type transplanted, had less collagen deposition in their heart tissue and demonstrated a significant improvement in myocardial function after IC. Furthermore, there was a trend of increasing numbers of blood vessels in the infarcted area. The median value of LVEF increased by 7.19% to 11.77%, whereas the control group decreased by 0.24%. These results suggest that UCSCs and UCBECs are promising cells for cellular cardiomyoplasty and can be an effective therapy for improving cardiac function following IC.

Polysome profiling shows the identity of human adipose-derived stromal/stem cells in detail and clearly distinguishes them from dermal fibroblasts.

Although fibroblasts and multipotent stromal/stem cells, including adipose-derived stromal cells (ADSCs), have been extensively studied, they cannot be clearly distinguished from each other. We, therefore, investigated the cellular and molecular characteristics of ADSCs and fibroblasts. ADSCs and fibroblasts share several morphological similarities and surface markers, but were clearly found to be different types of cells. Contrary to previous reports, fibroblasts were not able to differentiate into adipocytes, osteoblasts, or chondrocytes. Polysome-bound mRNA profiling revealed that ∼ 1,547 genes were differentially expressed (DE) in the two cell types; the genes were related to cell adhesion, the extracellular matrix, differentiation, and proliferation. These findings were confirmed by functional analyses showing that ADSCs had a greater adhesion capacity than fibroblasts; the proliferation rate of fibroblasts was also higher than that of ADSCs. Importantly, 185 DE genes were integral to the plasma membrane and, thus, candidate markers for ADSC isolation and manipulation. We also observed that an established marker of fibroblasts and ADSCs, CD105, was overexpressed in ADSCs at both mRNA and protein levels. CD105 expression seemed to be related to differentiation capacity, at least for adipogenesis. This study shows that ADSCs and fibroblasts are distinct cell types. These findings should be taken into account when using these two cell types in basic and therapeutic studies.

Polysome profiling shows extensive posttranscriptional regulation during human adipocyte stem cell differentiation into adipocytes.

Adipocyte stem cells (hASCs) can proliferate and self-renew and, due to their multipotent nature, they can differentiate into several tissue-specific lineages, making them ideal candidates for use in cell therapy. Most attempts to determine the mRNA profile of self-renewing or differentiating stem cells have made use of total RNA for gene expression analysis. Several lines of evidence suggest that self-renewal and differentiation are also dependent on the control of protein synthesis by posttranscriptional mechanisms. We used adipogenic differentiation as a model, to investigate the extent to which posttranscriptional regulation controlled gene expression in hASCs. We focused on the initial steps of differentiation and isolated both the total mRNA fraction and the subpopulation of mRNAs associated with translating ribosomes. We observed that adipogenesis is committed in the first days of induction and three days appears as the minimum time of induction necessary for efficient differentiation. RNA-seq analysis showed that a significant percentage of regulated mRNAs were posttranscriptionally controlled. Part of this regulation involves massive changes in transcript untranslated regions (UTR) length, with differential extension/reduction of the 3'UTR after induction. A slight correlation can be observed between the expression levels of differentially expressed genes and the 3'UTR length. When we considered association to polysomes, this correlation values increased. Changes in the half lives were related to the extension of the 3'UTR, with longer UTRs mainly stabilizing the transcripts. Thus, changes in the length of these extensions may be associated with changes in the ability to associate with polysomes or in half-life.

Human cardiac explant-conditioned medium: soluble factors and cardiomyogenic effect on mesenchymal stem cells.

The use of conditioned medium (CM) from human cardiac explants (HCEs) as a potential source of paracrine factors for adult stem cell signaling has never been evaluated. We hypothesized that HCEs might provide a source of soluble factors triggering the differentiation of mesenchymal stem cells (MSCs) into cardiomyocyte-like cells. By using two-dimensional electrophoresis (2-DE) gels/mass spectrometry and antibody macroarray assays, we found that HCEs release macromolecules, including cytokines, growth factors and myocardial and metabolism-related proteins into the culture medium. We identified a total of 20 proteins in the HCE-CM. However, as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 2-DE, these 20 proteins account for only a fraction of the total number of proteins present in the HCE-CM. We also found that CM increased the proliferation of bone marrow-derived-MSCs (BM-MSCs) in vitro. Unlike the other effects, this effect was most evident after 48 h of culture. Moreover, we examined the effect of HCE-CM on levels of mRNA and protein for specific cardiac markers. We showed that a surprisingly big fraction of BM-MSCs (3.4-5.0%) treated in vitro with HCE-CM became elongated and began to express cardiac markers, consistent with their possible differentiation into cardiomyocyte-like cells. Our in vitro model may be useful not only per se, but also for studies of the mechanisms of action of soluble factors involved in cell differentiation, paving the way for possible new protein-based treatments in the future.