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PubMed2005

Myocardial regeneration with bone-marrow-derived stem cells.

Despite significant therapeutic advances, heart failure remains the predominant cause of mortality in the Western world. Ischaemic cardiomyopathy and myocardial infarction are typified by the irreversible loss of cardiac muscle (cardiomyocytes) and vasculature composed of endothelial cells and smooth muscle cells, which are essential for maintaining cardiac integrity and function. The recent identification of adult and embryonic stem cells has triggered attempts to directly repopulate these tissues by stem cell transplantation as a novel therapeutic option. Reports describing provocative and hopeful examples of myocardial regeneration with adult bone-marrow-derived stem and progenitor cells have increased the enthusiasm for the use of these cells, yet many questions remain regarding their therapeutic potential and the mechanisms responsible for the observed therapeutic effects. In this review article we discuss the current preclinical and clinical advances in bone-marrow-derived stem or progenitor cell therapies for regeneration or repair of the ischaemic myocardium and their multiple related mechanisms involved in myocardial repair and regeneration.

Animals↗
PubMed2006

Pluripotency in adult stem cells: state of the art.

For many years, it has long been known that stem cells derived from adult tissues maintain the capacity for self-renewal and differentiation into multiple cell types that are characteristic of the tissue of origin. Recent studies have shown new evidence that several tissues may contain cells capable of generating differentiated cells beyond their own tissue boundaries, defining a process termed stem cell plasticity. The pluripotency of adult stem cells have evoked significant excitement over the possibility of novel functional uses of stem cells, with the final purpose to develop new and more effective treatment strategies. However, despite the number of promising studies describing the plasticity of adult stem cells, many questions remain to be answered. In this article, we critically review the current state of the art in the field of adult stem cells, focussing on the present understanding of the concepts of stem cell pluripotency and plasticity.

Adult Stem Cells↗
PubMed2005

High-potential human mesenchymal stem cells.

Bone marrow-derived stromal mesenchymal stem cells (MSCs) have been characterized in vitro by their growth characteristics, the expression of a panel of surface antigens, and their potential to differentiate into mesenchymal lineages. They can be separated by physical methods as well as by immunological or chemical separation or cultivation. Different protocols are used in different laboratories, making the comparison of various reported MSC populations difficult. Here we describe a population of bone marrow-derived adult stem cells that has been separated on a Percoll gradient with low density. It is characterized by an extraordinary high proliferative potential and a conserved phenotype characteristic of MSCs that retain their plutipotentiality in culture, as evidenced by their ability to differentiate into osteo-, chondro-, and adipogenic lineages. Separation of these cells provide an effective and convenient method for rapid expansion of pluripotential human MSCs for clinical use where large amounts of stem cells are needed.

Adipocytes↗
PubMed2005

Schwann cells induce neuronal differentiation of bone marrow stromal cells.

Bone marrow stromal cells are multipotent stem cells that have the potential to differentiate into bone, cartilage, fat and muscle. Recently, bone marrow stromal cells have been shown to have the capacity to differentiate into neurons under specific experimental conditions, using chemical factors. We now describe how bone marrow stromal cells can be induced to differentiate into neuron-like cells when they are co-cultured with Schwann cells. When compared with chemical differentiation, expression of neuronal differentiation markers begins later, but one week after beginning co-culture, most bone marrow stromal cells showed a typical neuronal morphology. Our present findings support the transdifferentiation of bone marrow stromal cells, and the potential utility of these cells for the treatment of degenerative and acquired disorders of the nervous system.

Animals↗
PubMed2003

In vitro differentiation of human processed lipoaspirate cells into early neural progenitors.

Human processed lipoaspirate (PLA) cells are multipotent stem cells, capable of differentiating into multiple mesenchymal lineages (bone, cartilage, fat, and muscle). To date, differentiation to nonmesodermal fates has not been reported. This study demonstrates that PLA cells can be induced to differentiate into early neural progenitors, which are of an ectodermal origin. Undifferentiated cultures of human PLA cells expressed markers characteristic of neural cells such as neuron-specific enolase (NSE), vimentin, and neuron-specific nuclear protein (NeuN). After 2 weeks of treatment of PLA cells with isobutylmethylxanthine, indomethacin, and insulin, about 20 to 25 percent of the cells differentiated into cells with typical neural morphologic characteristics, accompanied by increased expression of NSE, vimentin, and the nerve-growth factor receptor trk-A. However, induced PLA cells did not express the mature neuronal marker, MAP, or the mature astrocyte marker, GFAP. It was also found that neurally induced PLA cells displayed a delayed-rectifier type K+ current (an early developmental ion channel) concomitantly with morphologic changes and increased expression of neural-specific markers. The authors concluded that human PLA cells might have the potential to differentiate in vitro into cells that represent early progenitors of neurons and/or glia.

Adult↗
PubMed1991

Multipotent and committed CD34+ cells in bone marrow transplantation.

In order to study the role of CD34+ cells in hematological recovery following bone marrow transplantation (BMT), bone marrow cells stained with HPCA-1 (CD34) and MY-9 (CD33) monoclonal antibodies were analyzed by using a fluorescence-activated cell sorter on or about days 14 and 28, as well as at later times, following BMT in 6 recipients. Single cell cultures of CD34+ cells were also performed to evaluate their in vitro hematopoietic function. CD34+ cells were detectable in bone marrow cells on day 14. More than 80% of CD34+ cells co-expressed the CD33 antigen, and macrophage (Mac) colony-forming cells predominated among total colony-forming cells of CD34+ cells. In normal bone marrow cells, CD34+, CD33+ cells amounted to about 40% of CD34+ cells, and the incidences of erythroid bursts, granulocyte/macrophage (GM) colonies, and Mac colonies were similar to each other. After more than 10 weeks, CD34+, CD33- cells gradually recovered, as erythroid burst colony-forming cells increased following GM colony-forming cells. This phenomenon was well-correlated with the time course of peripheral blood cell recovery. CD34+, CD33+ cells as committed progenitors and CD34+, CD33- cells as multipotent stem cells have distinctive biological behaviors in BMT.

Antibodies, Monoclonal↗
PubMed1990

Effect of head activator on proliferation, head-specific determination and differentiation of epithelial cells in hydra.

In hydra the differentiation of head-specific ectodermal epithelial cells from multipotent stem cells is a multistep process in which cell cycle progression is regulated at three restriction points. Head activator acts as a positive signal at these restriction points. At the G2/mitosis boundary of epithelial stem cells head activator functions as a mitogen, being necessary for cell division. Subsequently, in or before S phase, head activator acts as determinant to ensure commitment of epithelial cells to head-specific determination. This effect of head activator requires hundredfold-higher concentrations, and may also require longer incubation times, than for cell proliferation. Epithelial cells thus committed to head-specific differentiation become arrested in G2 as a third and last restriction point in the cell cycle. They require disinhibition by decapitation and probably the presence of head activator for final differentiation, which then occurs in G2.

Animals↗
PubMed2006

Bone marrow-derived mesenchymal stem cells for regenerative medicine in craniofacial region.

The craniofacial region contains many specified tissues including bone, cartilage, muscle, blood vessels and neurons. Defect or dysfunction of the craniofacial tissue after post-cancer ablative surgery, trauma, congenital malformations and progressive deforming skeletal diseases has a huge influence on the patient's life. Therefore, functional reconstruction of damaged tissues is highly expected. Bone marrow-derived mesenchymal stem cells (BMMSCs) are one of the most well characterized postnatal stem cell populations, and considered to be utilized for cell-based clinical therapies. Here, the current understanding and the potential applications in craniofacial tissue regeneration of BMMSCs are reviewed, and the current limitations and drawbacks are also discussed.

Animals↗
PubMed2005

NF-kappaB activation in human dental pulp stem cells by TNF and LPS.

Post-natal human dental pulp stem cells (DPSCs) represent a unique precursor population in the dental pulp, which has multipotential and can regenerate a dentin/pulp-like structure. Because the dental pulp is frequently infected by oral bacteria due to dental decay, in this study, we examined whether lipopolysaccharide (LPS) and tumor necrosis factor (TNF) activated the immunologic transcription factor nuclear factor kappa B (NF-kappaB) in DPSCs. We found that both TNF and LPS activated the I-kappa B kinase complex (IKK) in DPSCs to induce the phosphorylation and degradation of IkappaBalpha, resulting in the nuclear translocation of NF-kappaB. Consistently, both TNF and LPS rapidly induced the expression of the NF-kappaB-dependent gene interleukin-8 (IL-8). However, unlike in monocytes, we found that LPS could not induce the phosphorylation of the NF-kappaB active subunit p65 in DPSCs. In summary, our studies suggest that DPSCs may be involved in immune responses during pulpal infection through activating NF-kappaB.

Blotting, Northern↗
PubMed2006

Spastic paresis after perinatal brain damage in rats is reduced by human cord blood mononuclear cells.

Brain damage around birth may cause lifelong neurodevelopmental deficits. We examined the therapeutic potential of human umbilical cord blood-derived mononuclear cells containing multipotent stem cells to facilitate motor recovery after cerebral hypoxic-ischemic damage in neonatal rats. Left carotid artery ligation followed by 8% O(2) inhalation for 80 min was performed on postnatal d 7, succeeded by intraperitoneal transplantation of human umbilical cord blood-derived mononuclear cells on postnatal d 8 in a sham-controlled design. Histologic and immunohistochemical analysis on postnatal d 21 revealed that neonates developed severe cerebral damage after the hypoxic-ischemic insult. These animals also suffered from contralateral spastic paresis, as evidenced by their locomotor behavior. After transplantation of human umbilical cord blood-derived mononuclear cells, spastic paresis was largely alleviated, resulting in a normal walking behavior. This "therapeutic" effect was accompanied by the fact that mononuclear cells had entered the brain and were incorporated around the lesion without obvious signs of transdifferentiation. This study demonstrates that intraperitoneal transplantation of human umbilical cord blood-derived mononuclear cells in a rat model of perinatal brain damage leads to both incorporation of these cells in the lesioned brain area and to an alleviation of the neurologic effects of cerebral palsy as assessed by footprint and walking pattern analysis.

Animals↗
PubMed1978

Regulation of interstitial cell differentiation in Hydra attenuata. IV. Nerve cell commitment in head regeneration is position-dependent.

In hydra, nerve cells are a differentiation product of the interstitial cell, a multipotent stem cell. Nerve cell commitment was examined during head regeneration in Hydra attenuata. Within 3 h of head removal there is a 10- to 20-fold increase in nerve cell commitment in the tissue which subsequently forms the new head. Nerve cell commitment is unaltered in the remainder of the gastric region. This local increase in nerve cell commitment is responsible for about one half the new nerve cells formed during head regeneration, while one half differentiate from interstitial cells that migrate into the regenerating tip.

Animals↗
PubMed2005

Autoregulatory mechanism of Runx2 through the expression of transcription factors and bone matrix proteins in multipotential mesenchymal cell line, ROB-C26.

Runx2 is essential for osteoblast differentiation and gene expression of bone matrix proteins, however, little is known about the mechanism regulating its activity. In this study, the role of Runx2 on gene expression of transcription factors, AJ18, Msx2, and Dlx5, was examined in vitro. It is known that AJ18 and Msx2 act as repressors to inhibit activity of Runx2, whereas Dlx5 promotes its activity. An expression vector inserted Runx2 cDNA was transiently overexpressed in a rat multipotential mesenchymal cell line, ROB-C26 (C26). Real time reverse transcription-PCR analysis showed that, in exogenous Runx2-overexpressing C26 cells (C26-Rx), AJ18 expression increased 1.8-fold, Msx2 expression increased 3.0-fold, and Dlx5 expression increased 2.7-fold compared to the cells transfected with vector alone (C26-Co). Luciferase assay also showed that, in C26-Rx, AJ18 promoter activity increased 2.1-fold compared to C26-Co. Furthermore, gene expression of alkaline phosphatase (ALP) and bone matrix proteins including type I collagen (Col1), osteocalcin (OC), osteopontin (OPN), and matrix Gla protein (MGP) was examined. In C26-Rx, MGP expression increased 1.8-fold, and OPN expression increased 1.4-fold compared to C26-Co. However, no significant difference in Col1, ALP, and OC expressions was detected between C26-Rx and C26-Co. These results suggest that the existence of autoregulatory feed back loops, which inhibit Runx2 activity through the interaction of AJ18, Dlx5, and Msx2 cooperating with that of MGP and OPN, interferes with the differentiation of C26 cells toward mature osteoblasts.

Alkaline Phosphatase↗
PubMed2004

Heterogeneous populations of bone marrow stem cells--are we spotting on the same cells from the different angles?

Accumulated evidence suggests that in addition to hematopoietic stem cells (HSC), bone marrow (BM) also harbors endothelial stem cells (ESC), mesenchymal stem cells (MSC), multipotential adult progenitor cells (MAPC), pluripotent stem cells (PCS) as well as tissue committed stem cells (TCSC) recently identified by us. In this review we discuss the similarities and differences between these cell populations. Furthermore, we will present the hypothesis that all of these versatile BM derived stem cells are in fact different subpopulations of TCSC. These cells accumulate in bone marrow during ontogenesis and being a mobile population of cells are released from BM into peripheral blood after tissue injury to regenerate damaged organs. Furthermore, since BM is a "hideout" for TCSC, their presence in preparations of bone marrow derived mononuclear cells should be considered before experimental evidence is interpreted simply as trans-differentiation or plasticity of HSC. Finally, our observation that the number of TCSC accumulate in the bone marrow of young animals and their numbers decrease during senescence provides a new insight into aging and may explain why the regeneration processes becomes less effective in older individuals.

Adult↗
PubMed2006

Human fetal heart-derived adherent cells with characteristics similar to mesenchymal progenitor cells.

This study was aimed to investigate if human heart harbored a population of primitive undifferentiated cells with the characteristics of MPC. Cells were isolated from human fetal heart and were cultured under conditions appropriate for bone marrow-derived MPCs. Their morphology, phenotypes and functions were tested by methods developed for MPC from other sources. The results showed that morphologically, cells were spindle shaped and resembled fibroblasts. In their undifferentiated state, cells were CD73, CD105, CD29, CD44, HLA-ABC, CD166 positive and CD45, CD34, CD86, HLA-DR negative. When cultured in adipogenic, osteogenic or chondrogenic media, cells differentiated into adipocytes, osteocytes and chondrocytes respectively. They could be extensively expanded in vitro and exhibited very low immunogenicity as evaluated by T cell proliferation assays. It is concluded that cells isolated from fetal heart possess similarity to their adult and fetal bone marrow counterparts in morphologic, immunophenotypic, and functional characteristics.

Bone Marrow Cells↗
PubMed1989

Effects of long-term in vivo treatment of mice with purified murine recombinant GM-CSF.

Normal adult BDF1 mice were injected s.c. with 1 or 10 micrograms/kg/day of recombinant murine granulocyte-macrophage colony-stimulating factor (rmGM-CSF; specific activity 3.9 x 10(7) U/mg) for periods up to 11 weeks. After 1, 3, 7, 9, or 11 weeks, groups of three mice were killed and various hematological parameters were evaluated. Such treatment induced a sustained increase in the number and phagocytic activity of peritoneal macrophages, increased weight and cellularity of the spleen, and increased numbers of lineage-restricted precursor cells and multipotent stem cells in the spleen. No significant differences in blood cell numbers or differential counts were observed during the experiment. Femoral granulocyte-macrophage colony-forming cells (GM-CFCs), mixed-lineage colony-forming cells (Mix-CFCs), and 7- and 12-day spleen colony-forming units (CFU-S) were increased in the first week of treatment, but returned to normal (or subnormal levels) later. Examination of histological preparations of liver, lung, skin, ileum, thymus, Peyer's patches, kidney, skin, and brain revealed no differences from control preparations. Mast cell numbers were not increased in any of these tissues. Despite continuing treatment, most hematological parameters normalized upon prolonged rmGM-CSF treatment. The reasons for this are unclear but are not apparently due to the presence of inhibitory factors in the blood of treated mice. The results indicate little evidence of side effects during prolonged therapy with doses of rGM-CSF commonly used in clinical situations.

Animals↗
PubMed2004

Transplantation of dermal multipotent cells promotes survival and wound healing in rats with combined radiation and wound injury.

Combined radiation and wound injury occurs after severe nuclear accidents that accompany explosions or nuclear attacks. High doses of ionizing radiation can cause bone marrow aplasia and delay wound healing. Combined radiation and wound injury is very complex and is more difficult to deal with than single injuries. Multipotent stem cells that have self-renewal potential and multilineage differentiation capacity are the relevant cells in regenerative medicine. To determine whether multipotent stem cells can have multiple therapeutic effects in vivo, systemic transplantation of cultured dermal multipotent cells was performed in rats with combined radiation and wound injury. The results showed that dermal multipotent cell transplantation promoted survival and accelerated both hematopoietic recovery and wound healing in rats with combined radiation and wound injury. FISH analysis using a Y-chromosome-specific probe indicated that donor dermal multipotent cells could engraft into recipient skin and bone marrow after transplantation. FACS analysis of the proportions of CD2- and CD25-positive peripheral lymphocytes indicated that dermal multipotent cell transplantation did not induce an obvious activation of allogeneic lymphocytes in vivo in 3 weeks. These data indicate that dermal multipotent cell transplantation may provide a new tool for the treatment of combined radiation and wound injuries.

Animals↗
PubMed2003

A niche for adult neural stem cells.

The adult mammalian brain harbors multipotent stem cells, which reside and participate in specialized niches that support self-renewal and differentiation. The first cellular and molecular elements of the stem cell niche in the adult brain have been identified and include cell-cell interactions and somatic cell signaling, the vasculature, the extracellular matrix and basal lamina. Furthermore, regulation at the epigenetic level via chromatin modification and remodeling is an integral aspect of stem cell biology. Understanding the in vivo stem cell niche will provide a framework for the elucidation of stem cell function in the adult brain.

Animals↗