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Cardiac stem cells: isolation, expansion and experimental use for myocardial regeneration.

Cellular cardiomyoplasty (myogenic cell grafting) is actively being explored as a novel method to regenerate damaged myocardium. The adult human heart contains small populations of indigenous committed cardiac stem cells or multipotent cardiac progenitor cells, identified by their cell-surface expression of c-kit (the receptor for stem cell factor), P-glycoprotein (a member of the multidrug resistance protein family), and Sca-1 (stem cell antigen 1, a mouse hematopoietic stem cell marker) or a Sca-1-like protein. Cardiac stem cells represent a logical source to exploit in cardiac regeneration therapy because, unlike other adult stem cells, they are likely to be intrinsically programmed to generate cardiac tissue in vitro and to increase cardiac tissue viability in vitro. Cardiac stem cell therapy could, therefore, change the fundamental approach to the treatment of heart disease.

Heart↗

Specific defect in N-acetylglucosamine incorporation in the biosynthesis of the glycosylphosphatidylinositol anchor in cloned cell lines from patients with paroxysmal nocturnal hemoglobinuria.

Paroxysmal nocturnal hemoglobinuria (PNH) is a clonal disorder arising in a multipotent hemopoietic stem cell. PNH manifests clinically with intravascular hemolysis resulting from an increased sensitivity of the red cells belonging to the PNH clone to complement-mediated lysis. Numerous studies have shown that surface proteins anchored to the membrane via a glycosylphosphatidylinositol (GPI) anchor (including proteins protecting the cell from complement) are deficient on the cells of the PNH clone, leading to the notion that GPI-anchor biosynthesis may be abnormal in these cells. To investigate the biochemical defect underlying PNH we have used lymphoblastoid cell lines (LCLs) with the PNH phenotype obtained by Epstein-Barr virus immortalization of lymphocytes from nine patients with PNH. By labeling cells with myo-[3H]inositol we have found that PNH LCLs produce phosphatidylinositol normally. By contrast, PNH LCLs fail to incorporate [3H]mannose into GPI anchor precursors. When cell-free extracts of PNH LCLs and normal LCLs obtained from the same patients (and expected therefore to be isogeneic except for the PNH mutation) were incubated with uridine diphospho-N-acetyl[3H]glucosamine (UDP-[3H]GlcNAc), we observed complete failure or marked reduction in the production of N-acetylglucosaminyl(alpha-1,6)phosphatidylinositol and glucosaminyl(alpha-1,6)phosphatidylinositol by the PNH LCLs in all cases. These findings pinpoint the block in PNH at an early stage in the biosynthesis of the GPI anchor, suggesting that the defective enzyme is UDP-GlcNAc:phosphatidylinositol-alpha-1,6-N- acetylglucosaminyltransferase. The existence of PNH type III cells and type II cells is probably explained by the transferase deficiency being total or partial, respectively.

Acetylglucosamine↗

Neurogenic potential of progenitors derived from human circulating CD14+ monocytes.

We previously reported a primitive cell fraction derived from human circulating CD14+ monocytes, named monocyte-derived multipotential cells (MOMC), that can differentiate along mesenchymal lineages, including bone, cartilage, fat, skeletal muscle and cardiac muscle. In this study, we investigated whether MOMC can differentiate into the neuronal lineage. MOMC were fluorescently labelled and cocultivated with a primary culture of rat neurons for up to 4 weeks. The protein and gene expressions of neuron-specific markers in the human MOMC were evaluated over time using immunohistochemistry, in situ hybridization and reverse transcription followed by PCR. Shortly after cocultivation with rat neurons, nearly all the MOMC expressed early neuroectodermal markers, Mash1, Neurogenin2 and NeuroD, together with nestin, an intermediate filament expressed in neurogenesis. After 14 days of coculture, a subpopulation of MOMC displayed a multipolar morphology with elongated neurites and expressed mature neuron-specific markers, including neurofilament, microtubule-associated protein type 2, beta3-tubulin, NeuN and Hu. Transdifferentiation of monocytes into the neuroectodermal lineage was shown by the simultaneous expression of proneural markers and CD45/CD14 early in the differentiation process. The cocultivated MOMC retained their proliferative capacity for at least 16 days. Finally, the neuronal differentiation of MOMC was observed when they were cultured with neurons without cell-to-cell contact. The capacity of MOMC to differentiate into both mesodermal and neuroectodermal lineages suggests that circulating CD14+ monocytes are more multipotential than previously thought.

Animals↗

Engraftment of marrow-derived epithelial cells: the role of fusion.

Contribution of transplanted bone marrow has, in many models, led to the appearance of marrow-derived epithelial cells in a variety of organs, including the lung. Following the initial descriptions of these cells, many questions remain about the mechanisms by which bone marrow adopts an epithelial phenotype in the murine lung. Data from other epithelial lineages, such as those of the kidney and colon, suggest that one mechanism is fusion of transplanted marrow with host pneumocytes. This process appears to require severe damage and may not be the only mechanism by which mature lung epithelia can derive from marrow. This article discusses the processes leading to the appearance of marrow-derived pneumocytes and highlights the therapeutic potential of bone marrow to fuse with or differentiate into epithelial cells of the lung.

Animals↗

Interleukin-3-specific modification of cell membrane "fluidity" of haemopoietic cells.

The work reported here clearly demonstrates that a specific growth factor, interleukin-3 (IL-3), which acts on multipotent haemopoietic stem cells as well as on committed myeloid progenitor cells of different lineages (Schrader, 1988; Whetton and Dexter, 1986), specifically induces a modification of the physical state ("fluidity") of the cell membranes of two IL-3-responsive and apparently normal haemopoietic cell lines. Furthermore, in a derived IL-3 independent myeloid leukaemic cell line, no such physical response to IL-3 binding was observed. The rapidity of the "normal" response suggests further that it may be associated with, or even constitute per se a critical early effect elicited by IL-3 in sensitive cells, the necessity for which is abrogated in the malignant derivative.

Animals↗

[Stem cells of mammalian brain: biology of the stem cells in vivo and in vitro].

Stem cells are totipotent cells of the blastocyst (embryonal stem cells) and multipotent germinative cells of ento-, ecto-, and mesoderm that give rise to all tissues during embryogenesis. The stem cells have high proliferation activity and an unlimited capacity for self-production by symmetrical mitosis. Asymmetrical mitosis of the stem cells generates daughter cells ("progenitor cells") with unlimited proliferation potential. During differentiation, the progenitor cells give rise to definitive somatic cells. The stem and progenitor cells are preserved in most tissues of adult organism and provide for the constant replacement of the cells after their physiological death and damage. At the end of last century, stem cells were found in the brain of the adult mouse and rat and later in the brain of other mammals including humans. The subependymal zone of the lateral ventricles is considered the site of stem cells localization; however, there are indications of stem cells origination from ependyma while the subependymal zone serves as a collector of the progenitor cells where these cells divide. The problem of the localization of stem cells in a mature brain has not yet been resolved and is actively discussed. The stem and progenitor cells, as well as neuro- and gliogenesis, are most explored in the hippocampus and olfactory bulb. The progenitor cells migrate to the olfactory bulb from the subependymal zone of the lateral ventricles via a rostral migratory stream formed by the astrocytes, and then they differentiate to neural and glial cells. In the hippocampus, the neurons are formed in the subgranular zone of dentate gyrus. The discovery of stem and progenitor cells in the mature brain and their subsequent investigation point to an ongoing neuro- and gliogenesis in all periventricular sections of the brain and spinal cord during the whole animal or human lifespan. These processes proved to be related to the functional condition of CNS, and the de novo formed neural and glial cells proved to be involved in certain brain functions. Stress inhibits the proliferation of the stem cells, while certain brain pathologies (ischemia, injury, or epilepsy) can promote their division. Isolating and cultivating in vitro the stem progenitor cells yeilded their long-living clones, revealed the factors of their directed differentiation, and demonstrated the application of the native and genetically modified stem cells for the intrabrain transplantation of the cell and gene therapy of certain experimental brain pathologies, which offers a promising application of the stem cells for CNS maladies treatment. The aim of this review is to introduce the readers to the state of foreign studies on the brain stem cells by the beginning of 2001.

Animals↗

C/EBPalpha determines hematopoietic cell fate in multipotential progenitor cells by inhibiting erythroid differentiation and inducing myeloid differentiation.

C/EBPalpha is an essential transcription factor required for myeloid differentiation. While C/EBPalpha can act as a cell fate switch to promote granulocyte differentiation in bipotential granulocyte-macrophage progenitors (GMPs), its role in regulating cell fate decisions in more primitive progenitors is not known. We found increased numbers of erythroid progenitors and erythroid cells in C/EBPalpha(-/-) fetal liver (FL). Also, enforced expression of C/EBPalpha in hematopoietic stem cells resulted in a loss of erythroid progenitors and an increase in myeloid cells by inhibition of erythroid development and inducing myeloid differentiation. Conditional expression of C/EBPalpha in murine erythroleukemia (MEL) cells induced myeloid-specific genes, while inhibiting erythroid-specific gene expression including erythropoietin receptor (EpoR), which suggests a novel mechanism to determine hematopoietic cell fate. Thus, C/EBPalpha functions in hematopoietic cell fate decisions by the dual actions of inhibiting erythroid and inducing myeloid gene expression in multipotential progenitors.

Animals↗

Transient Notch activation initiates an irreversible switch from neurogenesis to gliogenesis by neural crest stem cells.

The genesis of vertebrate peripheral ganglia poses the problem of how multipotent neural crest stem cells (NCSCs) can sequentially generate neurons and then glia in a local environment containing strong instructive neurogenic factors, such as BMP2. Here we show that Notch ligands, which are normally expressed on differentiating neuroblasts, can inhibit neurogenesis in NCSCs in a manner that is completely dominant to BMP2. Contrary to expectation, Notch activation did not maintain these stem cells in an uncommitted state or promote their self-renewal. Rather, even a transient activation of Notch was sufficient to cause a rapid and irreversible loss of neurogenic capacity accompanied by accelerated glial differentiation. These data suggest that Notch ligands expressed by neuroblasts may act positively to instruct a cell-heritable switch to gliogenesis in neighboring stem cells.

Animals↗

Hirschsprung disease is linked to defects in neural crest stem cell function.

Genes associated with Hirschsprung disease, a failure to form enteric ganglia in the hindgut, were highly up-regulated in gut neural crest stem cells relative to whole-fetus RNA. One of these genes, the glial cell line-derived neurotrophic factor (GDNF) receptor Ret, was necessary for neural crest stem cell migration in the gut. GDNF promoted the migration of neural crest stem cells in culture but did not affect their survival or proliferation. Gene expression profiling, combined with reverse genetics and analyses of stem cell function, suggests that Hirschsprung disease is caused by defects in neural crest stem cell function.

Animals↗

Role of melanoma chondroitin sulphate proteoglycan in patterning stem cells in human interfollicular epidermis.

Human interfollicular epidermis is renewed by stem cells that are clustered in the basal layer in a patterned, non-random distribution. Stem cells can be distinguished from other keratinocytes by high expression of beta1 integrins and lack of expression of terminal differentiation markers; they divide infrequently in vivo but form actively growing colonies in culture. In a search for additional stem cell markers, we observed heterogeneous epidermal expression of melanoma chondroitin sulphate proteoglycan (MCSP). MCSP was expressed by those keratinocytes with the highest beta1 integrin levels. In interfollicular epidermis, expression was confined to non-cycling cells and, in culture, to self-renewing clones. However, fluorescence-activated cell sorting on the basis of MCSP and beta1 integrin expression gave no more enrichment for clonogenic keratinocytes than sorting for beta1 integrins alone. To interfere with endogenous MCSP, we retrovirally infected keratinocytes with a chimera of the CD8 extracellular domain and the MCSP cytoplasmic domain. CD8/MCSP did not affect keratinocyte proliferation or differentiation but the cohesiveness of keratinocytes in isolated clones or reconstituted epidermal sheets was greatly reduced. CD8/MCSP caused stem cell progeny to scatter without differentiating. CD8/MCSP did not alter keratinocyte motility but disturbed cadherin-mediated cell-cell adhesion and the cortical actin cytoskeleton, effects that could be mimicked by inhibiting Rho. We conclude that MCSP is a novel marker for epidermal stem cells that contributes to their patterned distribution by promoting stem cell clustering.

Amino Acid Sequence↗

Generation of functional radial glial cells by embryonic and adult forebrain neural stem cells.

Radial glial cells (RGCs), a transient cell population present only in the developing CNS, function both as precursor cells and as scaffolds to support neuron migration. Their cellular origin, however, is not understood. In the present study, we tested the hypothesis that functional RGCs can be generated by multipotent neural stem cells. Embryonic forebrain neural stem cells were studied in vitro to identify putative signals that promote the generation and differentiation of functional RGCs, determined by their ability to support neuronal migration. Epidermal growth factor receptor signaling was sufficient to regulate both the generation and differentiation of morphologically, antigenically, and functionally defined RGCs. In contrast, fibroblast growth factor-2 promoted the generation of RGCs but was unable to support their differentiation. Although RGCs are not normally present in the adult brain, epidermal growth factor stimulated adult forebrain neural stem cells to generate RGCs in vitro and functional RGCs within the adult forebrain subependyma in vivo. Surprisingly, epidermal growth factor receptor signaling also promoted adult forebrain ependymal cells to dedifferentiate and adopt a radial morphology in vivo. These results suggest that neural stem cells can give rise to RGCs and that RGC-guided neuronal migration can be recapitulated in the adult CNS.

Animals↗

Clonal development, stem-cell differentiation, and clinical remissions in acute nonlymphocytic leukemia.

To determine whether acute nonlymphocytic leukemia develops clonally, to study the pattern of differentiation of the involved stem cells, and to determine whether clinical remissions are true remissions, we studied 27 patients with acute nonlymphocytic leukemia who were heterozygous for the X-chromosome-linked glucose-6-phosphate dehydrogenase. In each case, leukemic blast cells manifested only one type of glucose-6-phosphate dehydrogenase, indicating that the malignant process had developed from a single cell. In six elderly patients, circulating erythrocytes, platelets, or both expressed only the glucose-6-phosphate dehydrogenase found in blast cells, indicating that these leukemias had arisen from stem cells with multipotent differentiative expression. In 16 younger adults and children, erythroid cells and platelets were predominantly derived from normal stem cells. In three other cases, the stem cell that gave rise to leukemic blasts apparently also gave rise to erythroid progenitors but not to mature erythrocytes. Heterogeneity was also found during remissions. In 8 of 13 patients, restoration of nonclonal hemopoiesis and repopulation of the marrow by normal stem cells was observed during remission. In the other five patients, marrow stem cells remained partially or completely clonal, even during remission. These data indicate that acute nonlymphocytic leukemia is a heterogeneous disease with respect to differentiation of the stem cells involved by leukemia and the nature of remissions.

Acute Disease↗

Dysplastic definitive hematopoiesis in AML1/EVI1 knock-in embryos.

The AML1/EVI1 chimeric gene is created by the t(3;21)(q26;q22) chromosomal translocation seen in patients with leukemic transformation of myelodysplastic syndrome or blastic crisis of chronic myelogenous leukemia. We knocked-in the AML1/EVI1 chimeric gene into mouse Aml1 genomic locus to explore its effect in developmental hematopoiesis in vivo. AML1/EVI1/+ embryo showed defective hematopoiesis in the fetal liver and died around embryonic day 13.5 (E13.5) as a result of hemorrhage in the central nervous system. The peripheral blood had yolk-sac-derived nucleated erythroblasts but lacked erythrocytes of the definitive origin. Although E12.5 fetal liver contained progenitors for macrophage only, E13.5 fetal liver contained multilineage progenitors capable of differentiating into dysplastic myelocyte and megakaryocyte. No erythroid progenitor was detected in E12.5 or E13.5 fetal liver. Hematopoietic progenitors from E13.5 AML1/EVI1/+ fetal liver were highly capable of self-renewal compared with those from wild-type liver. Maintained expression of PU.1 gene and decreased expression of LMO2 and SCL genes may explain the aberrant hematopoiesis in AML1/EVI1/+ fetal liver.

Adaptor Proteins, Signal Transducing↗

Neural stem cells suppress the hearing threshold shift caused by cochlear ischemia.

Neural stem cells are multipotent progenitor cells that show self-renewal activity. In this study, we assessed the use of neural stem cells for ameliorating ischemia-reperfusion injury of the gerbil cochlea. Neural stem cells were injected into one inner ear through the round window 1 day after ischemic insult. Immunostaining for nestin showed that the distribution of neural stem cells was concentrated within the organ of Corti. Seven days after ischemia, the injury-induced auditory brainstem response threshold shift and progressive inner hair cell damage were markedly less on the neural stem cell-transplanted side. These results suggest that the transplantation of neural stem cells is therapeutically useful for preventing damage to hair cells that occurs after transient ischemia of the cochlea.

Animals↗

Hydra, a niche for cell and developmental plasticity.

The silencing of genes whose expression is restricted to specific cell types and/or specific regeneration stages opens avenues to decipher the molecular control of the cellular plasticity underlying head regeneration in hydra. In this review, we highlight recent studies that identified genes involved in the immediate cytoprotective function played by gland cells after amputation; the early dedifferentiation of digestive cells into blastema-like cells during head regeneration, and the early late proliferation of neuronal progenitors required for head patterning. Hence, developmental plasticity in hydra relies on spatially restricted and timely orchestrated cellular modifications, where the functions played by stem cells remain to be characterized.

Animals↗

Clonal identification of multipotent precursors from adult mouse pancreas that generate neural and pancreatic lineages.

The clonal isolation of putative adult pancreatic precursors has been an elusive goal of researchers seeking to develop cell replacement strategies for diabetes. We report the clonal identification of multipotent precursor cells from the adult mouse pancreas. The application of a serum-free, colony-forming assay to pancreatic cells enabled the identification of precursors from pancreatic islet and ductal populations. These cells proliferate in vitro to form clonal colonies that coexpress neural and pancreatic precursor markers. Upon differentiation, individual clonal colonies produce distinct populations of neurons and glial cells, pancreatic endocrine beta-, alpha- and delta-cells, and pancreatic exocrine and stellate cells. Moreover, the newly generated beta-like cells demonstrate glucose-dependent Ca(2+) responsiveness and insulin release. Pancreas colonies do not express markers of embryonic stem cells, nor genes suggestive of mesodermal or neural crest origins. These cells represent a previously unidentified adult intrinsic pancreatic precursor population and are a promising candidate for cell-based therapeutic strategies.

Adult↗

Expression of low density lipoprotein receptor-related protein 4 (Lrp4) gene in the mouse germ cells.

The low density lipoprotein receptor-related protein 4 gene (Lrp4) was identified by subtractive screening of cDNAs of the migratory primordial germ cells (PGCs) of E8.5-9.5 embryo and E3.5 blastocysts. Lrp4 is expressed in PGCs in the hindgut and the dorsal mesentery of E9.5 embryos, and in germ cells in the genital ridges of male and female E10.5-13.5 embryos. Lrp4 is also expressed in spermatogonia of the neonatal and adult testes and in the immature oocytes and follicular cells of the adult ovary. The absence of Lrp4 expression in the blastocyst, embryonic stem cells and embryonic germ cells suggests the Lrp4 is a molecular marker that distinguishes the germ cells from embryo-derived pluripotent stem cells.

Amino Acid Sequence↗