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On the basis of the previous studies which described in the myocardium the presence of primitive cells that in vitro differentiate in the myocardial lineages, we identified by immunofluorescence in the adult hearts of healthy donors (n=10) and diseased hearts (ischemic and dilated cardiomyopathy, n=7) the population of c-kit (+) cells whose localization and phenotype differed between the groups. In the normal hearts c-kit(+) cells were observed mainly in the epicardial layer of ventricles. These cells were expressing transcription factors GATA-4 and MEF2C and were negative for alpha-sarcomeric actin. Confocal microscopy revealed the co-localization of alpha laminin and alpha4 integrin chain on these cells, but the western blot analysis showed the differences in the laminin expression between normal and pathological hearts: in the latter the level of expression was significantly higher and interestingly isoform 1 of laminin (characteristic for fetal, developing heart) was present. In the pathological hearts the c-kit(+) cells were not longer found in the epicardial region, but their presence was evidenced in the main myocardium. These cells also expressed MEF2C and GATA-4, but, in contrast with those found in the epicardial region of normal hearts, were alphasarcomeric actin positive.

Periosteum contains mesenchymal stem cells (Pe-MSCs) that contribute to normal bone growth, healing, and turnover; understanding Pe-MSC capabilities may shed light over the treatment of bone defects using tissue engineering. Bone tissue regeneration needs in vitro bone precursors or stem cell coculture onto specific scaffolds but, despite extensive research in the field, very little is known about the matrix structure of the tissue-engineered tissues and the scaffold's effects on cell differentiation. To this purpose we have selected a clonal population (murine Pe-MSCs) that was seeded and differentiated onto an acellular bone scaffold. Cell differentiation was assessed after 3 months and 1 year by molecular, histological, biochemical, and biophysical analyses and results were compared with the same osteoinduced clonal cells cultured as cellular aggregates. Our data show that Pe-MSCs cultured onto acellular bone scaffold develop a complex three-dimensional matrix and an osteoblastic phenotype but do not produce hydroxyapatite (HA); moreover, they seem able to reabsorb the colonized bone scaffold. On the contrary, cells cultured as three-dimensional aggregates differentiate and produce osteoblastic markers and HA nanocrystals.

Exosomes are one of the most important mediators of the cross talk occurring between glioma stem cells (GSCs) and the surrounding microenvironment. We have previously shown that exosomes released by patient-derived glioma-associated stem cells (GASC) are able to increase, in vitro, the aggressiveness of both GSC and glioblastoma cell lines. To understand which molecules are responsible for this tumour-supporting function, we performed a descriptive proteomic analysis of GASC-exosomes and identified, among the others, Semaphorin7A (SEMA7A). SEMA7A was described as a promigratory cue in physiological and pathological conditions, and we hypothesised that it could modulate GSC migratory properties. Here, we described that SEMA7A is exposed on GASC-exosomes&rsquo, surface and signals to GSC through Integrin &beta, 1. This interaction activates focal adhesion kinase into GSC and increases their motility, in our patient-based in vitro model. Our findings suggest SEMA7A-&beta, 1-integrin as a new target to disrupt the communication between GSCs and the supporting microenvironment.

Aging is by far the dominant risk factor for the development of cardiovascular diseases, whose prevalence dramatically increases with increasing age reaching epidemic proportions. In the elderly, pathologic cellular and molecular changes in cardiac tissue homeostasis and response to injury result in progressive deteriorations in the structure and function of the heart. Although the phenotypes of cardiac aging have been the subject of intense study, the recent discovery that cardiac homeostasis during mammalian lifespan is maintained and regulated by regenerative events associated with endogenous cardiac stem cell (CSC) activation has produced a crucial reconsideration of the biology of the adult and aged mammalian myocardium. The classical notion of the adult heart as a static organ, in terms of cell turnover and renewal, has now been replaced by a dynamic model in which cardiac cells continuously die and are then replaced by CSC progeny differentiation. However, CSCs are not immortal. They undergo cellular senescence characterized by increased ROS production and oxidative stress and loss of telomere/telomerase integrity in response to a variety of physiological and pathological demands with aging. Nevertheless, the old myocardium preserves an endogenous functionally competent CSC cohort which appears to be resistant to the senescent phenotype occurring with aging. The latter envisions the phenomenon of CSC ageing as a result of a stochastic and therefore reversible cell autonomous process. However, CSC aging could be a programmed cell cycle-dependent process, which affects all or most of the endogenous CSC population. The latter would infer that the loss of CSC regenerative capacity with aging is an inevitable phenomenon that cannot be rescued by stimulating their growth, which would only speed their progressive exhaustion. The resolution of these two biological views will be crucial to design and develop effective CSC-based interventions to counteract cardiac aging not only improving health span of the elderly but also extending lifespan by delaying cardiovascular disease-related deaths.

Hemoglobin (Hb) is the major protein in erythrocytes and carries oxygen (O2) throughout the body. Recently, Hb has been found synthesized in atypical sites, including the brain. Hb is highly expressed in A9 dopaminergic (DA) neurons of the substantia nigra (SN), whose selective degeneration leads to Parkinson’s disease (PD). Here we show that Hb confers DA cells’ susceptibility to 1-methyl-4-phenylpyridinium (MPP+) and rotenone, neurochemical cellular models of PD. The toxic property of Hb does not depend on O2 binding and is associated with insoluble aggregate formation in the nucleolus. Neurochemical stress induces epigenetic modifications, nucleolar alterations and autophagy inhibition that depend on Hb expression. When adeno-associated viruses carrying α- and β-chains of Hb are stereotaxically injected into mouse SN, Hb forms aggregates and causes motor learning impairment. These results position Hb as a potential player in DA cells’ homeostasis and dysfunction in PD.

Adult multipotent stromal cells (MSCs), also known as mesenchymal stem cells, represent an important source of cells for the repair of a number of damaged tissues. Both bone marrow (BM)-derived and amniotic MSCs expressed detectable surface levels of two (tumor necrosis factor-related apoptosis-inducing ligand receptor 2 [TRAIL-R2] and TRAIL-R4) of four transmembrane TRAIL receptors. Although the best-characterized activity of TRAIL-R2 is the transduction of apoptotic signals, neither recombinant TRAIL (rTRAIL) nor infection with an adenovirus-expressing TRAIL induced cytotoxic effects on MSCs. Moreover, whereas rTRAIL did not affect proliferation or differentiation of MSCs along the osteogenic and adipogenic lineages, it significantly promoted the migration of human MSCs in range of concentrations comparable to that of soluble TRAIL in human plasma (100 pg/ml). Since rTRAIL induced the rapid phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) in MSC cultures and pretreatment with pharmacological inhibitors of the ERK1/2 pathway efficiently counteracted the rTRAIL-induced human MSC migration, these data indicate that ERK1/2 is involved in mediating the ability of rTRAIL to stimulate MSC migration. Taking into consideration that the soluble factors able to induce MSC migration have not been extensively characterized, our current data indicate that the TRAIL/TRAIL-R system might play an important role in the biology of MSCs. Disclosure of potential conflicts of interest is found at the end of this article.

Background: Translational medicine aims at transferring advances in basic science research into new approaches for diagnosis and treatment of diseases. Low-grade gliomas (LGG) have a heterogeneous clinical behavior that can be only partially predicted employing current state-of-the-art markers, hindering the decision-making process. To deepen our comprehension on tumor heterogeneity, we dissected the mechanism of interaction between tumor cells and relevant components of the neoplastic environment, isolating, from LGG and high-grade gliomas (HGG), proliferating stem cell lines from both the glioma stroma and, where possible, the neoplasm. Methods and Findings: We isolated glioma-associated stem cells (GASC) from LGG (n=40) and HGG (n=73). GASC showed stem cell features, anchorage-independent growth, and supported the malignant properties of both A172 cells and human glioma-stem cells, mainly through the release of exosomes. Finally, starting from GASC obtained from HGG (n=13) and LGG (n=12) we defined a score, based on the expression of 9 GASC surface markers, whose prognostic value was assayed on 40 subsequent LGG-patients. At the multivariate Cox analysis, the GASC-based score was the only independent predictor of overall survival and malignant progression free-survival. Conclusions: The microenvironment of both LGG and HGG hosts non-tumorigenic multipotent stem cells that can increase in vitro the biological aggressiveness of glioma-initiating cells through the release of exosomes. The clinical importance of this finding is supported by the strong prognostic value associated with the characteristics of GASC. This patient-based approach can provide a groundbreaking method to predict prognosis and to exploit novel strategies that target the tumor stroma. Stem Cells 2014;32:1239–1253

Background Cases in which a male patient receives a heart from a female donor provide an unusual opportunity to test whether primitive cells translocate from the recipient to the graft and whether cells with the phenotypic characteristics of those of the recipient ultimately reside in the donor heart. The Y chromosome can be used to detect migrated undifferentiated cells expressing stem-cell antigens and to discriminate between primitive cells derived from the recipient and those derived from the donor. Methods We examined samples from the atria of the recipient and the atria and ventricles of the graft by fluorescence in situ hybridization to determine whether Y chromosomes were present in eight hearts from female donors implanted into male patients. Primitive cells bearing Y chromosomes that expressed c-kit, MDR1, and Sca-1 were also investigated. Results Myocytes, coronary arterioles, and capillaries that had a Y chromosome made up 7 to 10 percent of those in the donor hearts and were highly proliferat...

The scarring of the heart that results from myocardial infarction has been interpreted as evidence that the heart is composed of myocytes that are unable to divide. However, recent observations have provided evidence of proliferation of myocytes in the adult heart. Therefore, we studied the extent of mitosis among myocytes after myocardial infarction in humans.Samples from the border of the infarct and from areas of the myocardium distant from the infarct were obtained from 13 patients who had died 4 to 12 days after infarction. Ten normal hearts were used as controls. Myocytes that had entered the cell cycle in preparation for cell division were measured by labeling of the nuclear antigen Ki-67, which is associated with cell division. The fraction of myocyte nuclei that were undergoing mitosis was determined, and the mitotic index (the ratio of the number of nuclei undergoing mitosis to the number not undergoing mitosis) was calculated. The presence of mitotic spindles, contractile rings, karyokinesis, and cytokinesis was also recorded.In the infarcted hearts, Ki-67 expression was detected in 4 percent of myocyte nuclei in the regions adjacent to the infarcts and in 1 percent of those in regions distant from the infarcts. The reentry of myocytes into the cell cycle resulted in mitotic indexes of 0.08 percent and 0.03 percent, respectively, in the zones adjacent to and distant from the infarcts. Events characteristic of cell division--the formation of the mitotic spindles, the formation of contractile rings, karyokinesis, and cytokinesis--were identified; these features demonstrated that there was myocyte proliferation after myocardial infarction.Our results challenge the dogma that the adult heart is a postmitotic organ and indicate that the regeneration of myocytes may be a critical component of the increase in muscle mass of the myocardium.