Effects of age and heart failure on human cardiac stem cell function.

Currently, it is unknown whether defects in stem cell growth and differentiation contribute to myocardial aging and chronic heart failure (CHF), and whether a compartment of functional human cardiac stem cells (hCSCs) persists in the decompensated heart. To determine whether aging and CHF are critical determinants of the loss in growth reserve of the heart, the properties of hCSCs were evaluated in 18 control and 23 explanted hearts. Age and CHF showed a progressive decrease in functionally competent hCSCs. Chronological age was a major predictor of five biomarkers of hCSC senescence: telomeric shortening, attenuated telomerase activity, telomere dysfunction-induced foci, and p21(Cip1) and p16(INK4a) expression. CHF had similar consequences for hCSCs, suggesting that defects in the balance between cardiomyocyte mass and the pool of nonsenescent hCSCs may condition the evolution of the decompensated myopathy. A correlation was found previously between telomere length in circulating bone marrow cells and cardiovascular diseases, but that analysis was restricted to average telomere length in a cell population, neglecting the fact that telomere attrition does not occur uniformly in all cells. The present study provides the first demonstration that dysfunctional telomeres in hCSCs are biomarkers of aging and heart failure. The biomarkers of cellular senescence identified here can be used to define the birth date of hCSCs and to sort young cells with potential therapeutic efficacy.

The role of Galectin-1 in the interaction between chondrocytes and a lactose-modified chitosan.

Evidences for the involvement of the Galectin-1 in the interaction of pig chondrocytes with a lactose-modified chitosan, namely Chitlac, are reported. The Chitlac glycopolymer has been shown to promote pig chondrocyte aggregation and to induce extracellular matrix production. Highly pure Galectin-1 was obtained from pig spleen by affinity chromatography and its identity was determined by ion spray mass spectrometry analysis of tryptic peptide fragments obtained after in-gel digestion. The complete sequence of pig Galectin-1 CDS was obtained by screening a pig EST database using human Galectin-1 sequence as template. The Galectin-1 cDNA was cloned into a pGEX-4T-1 expression vector and the recombinant protein was purified, characterized and used to produce a rabbit anti-serum. Recombinant Galectin-1 interacts in a dose-dependent manner with Chitlac as determined with ELISA assay. Expression level of galectin-1 gene, quantified by real-time PCR, was significantly higher in chondrocytes cultivated on Chitlac. In the same way, the presence of Chitlac stimulates secretion of Galectin-1 in culture medium that, by immunohistochemical analysis, revealed to be clustered on the surface of Chitlac-induced aggregates. These data indicate the role of Galectin-1 as a bridging agent between Chitlac and chondrocyte aggregates.

Cardiac stem cell senescence.

Cellular senescence processes affecting tissue resident stem cells are considered, at present, an hallmark of both aging and age-related pathologies. Therefore it is mandatory to address this problem with adequate techniques that could highlight the molecular alterations associated with this complex cellular response to stressors. Here we describe methods to characterize cardiac stem cell (CSC) senescence from a molecular and functional standpoint.

Multipotent cells can be generated in vitro from several adult human organs (heart, liver, and bone marrow).

The aims of our study were to verify whether it was possible to generate in vitro, from different adult human tissues, a population of cells that behaved, in culture, as multipotent stem cells and if these latter shared common properties. To this purpose, we grew and cloned finite cell lines obtained from adult human liver, heart, and bone marrow and named them human multipotent adult stem cells (hMASCs). Cloned hMASCs, obtained from the 3 different tissues, expressed the pluripotent state-specific transcription factors Oct-4, NANOG, and REX1, displayed telomerase activity, and exhibited a wide range of differentiation potential, as shown both at a morphologic and functional level. hMASCs maintained a human diploid DNA content, and shared a common gene expression signature, compared with several somatic cell lines and irrespectively of the tissue of isolation. In particular, the pathways regulating stem cell self-renewal/maintenance, such as Wnt, Hedgehog, and Notch, were transcriptionally active. Our findings demonstrate that we have optimized an in vitro protocol to generate and expand cells from multiple organs that could be induced to acquire morphologic and functional features of mature cells even embryologically not related to the tissue of origin.