Human cord blood-derived cells attain neuronal and glial features in vitro

Cord blood mesenchymal stem cells: Potential use in neurological disorders

Our previous studies demonstrate enhanced neural protective effects of cord blood (CB) cells in comparison to stem cells from adult marrow. To determine further whether mesenchymal stem cells (MSCs) derived from human umbilical cord blood (hUCB) possess optimal characteristics for neural therapy, we isolated populations of plastic-adherent CB MSCs. These cells generated CD34-, CD45-, CD11b-, CD3-, CD19- cells in culture and failed to produce CFU-M, CFU-GEMM, or CFU-GM hematopoietic colonies in methylcellulose. However, cultured CB MSCs possessed a remarkable ability to support proliferation as well as differentiation of hematopoietic cells in vitro. In addition, supernatants from cultured CB MSCs promoted survival of NT2 N neural cells and peripheral blood mononuclear cells (MNCs) cultured under conditions designed to induce cell stress and limit protein synthesis. After incubation in neural differentiation medium, CB MSCs expressed the neural cell-surface antigen A2B5, the neurofilament polypeptide NF200, the oligodendrocyte precursor marker 04, intermediate filament proteins characteristic of neural differentiation (nestin and vimentin), as well as the astrocyte marker glial fibrillary acidic protein (GFAP) and the neural progenitor marker TUJ-1. We examined the immunomodulatory effects of the CB MSCs after co-culture with murine splenocytes. Whereas spleen cells from normal C57Bl/6 mice exhibited a prominent immunoglobulin M (IgM) response after immunization with the T cell-dependent antigen sheep red blood cells, this response was significantly decreased after incubation with CB MSCs. These data indicate that CB MSCs possess multiple utilities that may contribute to their therapeutic potency in the treatment of neurological disorders.

The use of hemopoietic stem cells derived from human umbilical cord blood to promote restoration of spinal cord tissue and recovery of hindlimb function in adult rats

OBJECT

The use of human umbilical cord blood (HUCB) cells has been reported to improve functional recovery in cases of central nervous system injuries such as stroke, traumatic brain injury, and spinal cord injury (SCI). The authors investigated the effects of hemopoietic stem cells that were derived from HUCB and transplanted into the injured spinal cords of rats.

METHODS

One week after injury, an HUCB fraction enriched in CD34-positive cells was transplanted into the experimental group. In control animals, vehicle (Matrigel) was transplanted. Recovery of motor functions was assessed using the Basso-Beattie-Bresnahan Locomotor Scale, and immunohistochemical examinations were performed. Cells from HUCB that were CD34 positive improved functional recovery, reduced the area of the cystic cavity at the site of injury, increased the volume of residual white matter, and promoted the regeneration or sparing of axons in the injured spinal cord. Immunohistochemical examination revealed that transplanted CD34-positive cells survived in the host spinal cord for at least 3 weeks after transplantation but had disappeared by 5 weeks. The transplanted cells were not positive for neural markers, but they were positive for hemopoietic markers. There was no evidence of an immune reaction at the site of injury in either group.

CONCLUSIONS

These results suggest that transplantation of a CD34-positive fraction from HUCB may have therapeutic effects for SCI. The results of this study provide important preclinical data regarding HUCB stem cell-based therapy for SCI.

Neuronal differentiation of human umbilical cord blood neural stem-like cell line

The expanding population of neural stem/progenitor cells can be selected from human cord blood nonhematopoietic (CD34-negative) mononuclear fraction. Due to repeated expansion and selection of these cells we have established the first clonogenic, nonimmortalized human umbilical cord blood neural stem-like cell (HUCB-NSC) line. This line can be maintained at different stages of neural progenitor development by the presence of trophic factors, mitogens and neuromorphogens in culture media. Neurogenic potential of HUCB-NSC was established for serum-free and low-serum cultured cells. Commitment of HUCB-NSC by serum was shown to be important for the optimal response to the signals provided by surrounding environment in vitro. Enhanced neuronal differentiation induced by dBcAMP treatment was accompanied by expression of several functional proteins including glutamatergic, GABAergic, dopamine, serotonin and acetylcholine receptors, which was shown by microarray, immunocytochemistry and electrophysiology. Electrophysiological studies, whole-cell patch-clamp recordings, revealed in differentiated HUCB-NSC two types of voltage-sensitive and several ligand-gated currents typical for neuronal cells. The above HUCB-NSC characteristic conceivably implicates that cord blood-derived progenitors could be effectively differentiated into functional neuron-like cells in vitro.

Chondrogenic differentiation of human embryonic stem cells: the effect of the micro-environment

We have previously induced differentiation of embryonic stem cells (ESC) to specific phenotypes by manipulating the culture conditions, including the use of indirect co-culture. In this study, we hypothesized that co-culture with primary chondrocytes can induce human embryonic stem cells (hESC) to differentiate towards the chondrocyte lineage. Co-cultures of hESC and chondrocytes were established using well inserts, with control comprising hESC grown alone or with fibroblasts. After 28 days, after removal of the chondrocyte inserts, hESC differentiation was assessed, by morphology, immunocytochemistry, and reverse transcription polymerase chain reaction. hESC, co-cultured or grown alone, were also implanted into SCID mice on a poly-D, L-lactide scaffold, harvested 35 days later and assessed in the same way. hESC co-cultured with chondrocytes formed colonies and secreted extracellular matrix containing glycosaminoglycans (GAG). Quantitative assay showed increased synthesis of sulfated GAG in co-culture as compared with control hESC grown alone for the same period (p < 0.0001). In addition, co-cultured hESC expressed Sox 9 and collagen type II, unlike control hESC. Co-culture with fibroblasts did not induce chondrogenic differentiation. The implanted constructs with co-cultured hESC contained significantly more type II collagen (p < 0.01), type I collagen (p < 0.05), total collagen (p < 0.01), and GAG (p < 0.01) than those with hESC grown alone. Thus, we show for the first time differentiation of hESC to chondrocytes. Our results confirm the potential of the culture micro-environment to influence ESC differentiation and could provide the basis for future generation of chondrogenic cells for use in tissue repair and increase our understanding of the mechanisms that direct differentiation.

Early appearance of stem/progenitor cells with neural-like characteristics in human cord blood mononuclear fraction cultured in vitro

OBJECTIVE

The exposure of human umbilical cord blood mononuclear cells devoid of hematopoietic stem cells (HUCB-MNCsCD34-) to defined culture condition promotes their conversion into neural lineage. We have asked the question if observed fate change of HUCB-MNCsCD34- results from direct conversion of hematopoietic precursors into neural-like phenotypes due to expression of overlapping genetic program or, alternatively, these neural phenotypes arise from sequential differentiation of more primitive progenitors (embryonic-like cells) preexisting in HUCB-MNCsCD34- fraction.

MATERIALS AND METHODS

HUCB-MNCs negatively selected for CD34 antigens were cultured in vitro up to 14 days. Changes in stem/neural cell genes and proteins were successively evaluated during this period and after evoked neuronal differentiation of cells in the presence of RA or BDNF or cocultured with neonatal rat brain astrocytes.

RESULTS

Freshly isolated HUCB-MNCsCD34- expressed pluripotent cell markers: Oct3/4, Sox2, and Rex1 genes. During 24 hours of culture the frequency of Oct3/4 immunopositive cells increased markedly with parallel enlargement of "side population" and CD133+ cell appearance. Concomitantly, cultured cells start to form aggregates and express pro-neural genes, i.e., enhanced Sox2, OTX1, Nestin, GFAP, and NF-200. During the next days of culture immunoreactions for beta-tubulin III, MAP2, GFAP, S100beta, Doublecortin, and GalC were induced with reciprocal lowering of stem cell gene and protein markers. At this stage cells successively adhered to the bottom, dispersed, and decreased proliferation rate (Ki67 expression). Additional treatments with neuromorphogenes or coculturing with rat brain primary culture induced further differentiation of these neural precursors toward more advanced neuronal phenotypes.

CONCLUSIONS

HUCB-MNCs(CD34-) fraction contains embryonic-like stem/progenitor cells which increase rapidly but transiently in culture, then differentiate spontaneously after cell aggregate adhesion toward neural lineage. Neurally promoted cells from 10-14 DIV culture acquire three main neural-like phenotypes, i.e., neurons, astrocytes, and oligodendrocytes. In this respect they are promising candidates for experimental treatment of neuronal injury; however, the final proof for conversion of HUCB cells to neural cells can be obtained through transplantation experiments.

Neural stem-like cell line derived from a nonhematopoietic population of human umbilical cord blood

The ability of stem and progenitor cells to proliferate and differentiate into other lineages is widely viewed as a characteristic of stem cells. Previously, we have reported that cells from a CD34(-) (nonhematopoietic) adherent subpopulation of human cord blood can acquire a feature of multipotential neural progenitors in vitro. In the present study, using these cord blood-derived stem cells, we have established a clonal cell line termed HUCB-NSCs (human umbilical cord blood-neural stem cells) that expresses several neural antigens and has been grown in culture for more than 60 passages. During this time, HUCB-NSCs retained their growth rate, the ability to differentiate into neuronal-, astrocyte-, and oligodendrocyte-like cells and displayed a stable karyotype. DNA microarray analysis of HUCB-NSCs revealed enhanced expression of selected genes encoding putative stem and progenitor cell markers when compared to other mononuclear cells. dBcAMP-induced HUCBNSCs were further differentiated into more advanced neuronal cells. This is the first report of the establishment and characterization of a nontransformed HUCB-NSC line that can be grown continuously in a monolayer culture and induced to terminal differentiation. These cells should further our understanding of the regulatory mechanisms involved in NSC self-renewal and differentiation.

Differentiation of human umbilical cord blood stem cells into hepatocytes in vivo and in vitro

AIM: To study the condition and potentiality of human umbilical cord blood stem cells (HUCBSC) to differentiate into hepatocytes in vivo or in vitro.

METHODS: In a cell culture study of human umbilical cord blood stem cell (HUCBSC) differentiation, human umbilical cord blood mononuclear cells (HUCBMNC) were separated by density gradient centrifugation. Fibroblast growth factor (FGF) and hepatocyte growth factor (HGF) and the supernatant of fetal liver were added in the inducing groups. Only FGF was added in the control group. The expansion and differentiation of HUCBMNC in each group were observed. Human alpha fetoprotein (AFP) and albumin (ALB) were detected by immunohistochemistry. In the animal experiments, the survival SD rats with acute hepatic injury after carbon tetrachloride (CCL₄) injection 48 h were randomly divided into three groups. The rats in group A were treated with human umbilical cord blood serum. The rats in group B were treated with HUCBMNC transplantation. The rats in group C were treated with HUCBMNC transplantation followed by intraperitoneal cyclophosphamide for 7 d. The rats were killed at different time points after the treatment and the liver tissue was histopathologically studied and human AFP and ALB detected by immunohistochemistry. The human X inactive-specific transcript gene fragment in the liver tissue was amplified by PCR to find human DNA.

RESULTS: The results of cell culture showed that adherent cells were stained negative for AFP or ALB in control group. However, the adherent cells in the inducing groups stained positive for AFP or ALB. The result of animal experiment showed that no human AFP or ALB positive cells present in the liver tissue of group A (control group). However, many human AFP or ALB positive cells were scattered around sinus hepaticus and the central veins of hepatic lobules and in the portal area in group B and group C after one month. The fragment of human X chromagene could be detected in the liver tissue of groups B and C, but not in group A.

CONCLUSION: Under certain conditions HUCBSC can differentiate into liver cells in vivo and in vitro.

Umbilical cord blood-derived stem cells and brain repair

Human umbilical cord blood (HUCB) is now considered a valuable source for stem cell-based therapies. HUCB cells are enriched for stem cells that have the potential to initiate and maintain tissue repair. This potential is especially attractive in neural diseases for which no current cure is available. Furthermore, HUCB cells are easily available and less immunogenic compared to other sources for stem cell therapy such as bone marrow. Accordingly, the number of cord blood transplants has doubled in the last year alone, especially in the pediatric population. The therapeutic potential of HUCB cells may be attributed to inherent ability of stem cell populations to replace damaged tissues. Alternatively, various cell types within the graft may promote neural repair by delivering neural protection and secretion of neurotrophic factors. In this review, we evaluate the preclinical studies in which HUCB was applied for treatment of neurodegenerative diseases and for traumatic and ischemic brain damage. We discuss how transplantation of HUCB cells affects these disorders and we present recent clinical studies with promising outcome.

Signals from embryonic fibroblasts induce adult intestinal epithelial cells to form nestin-positive cells with proliferation and multilineage differentiation capacity in vitro

The intestinal epithelium has one of the greatest regenerative capacities in the body; however, neither stem nor progenitor cells have been successfully cultivated from the intestine. In this study, we applied an "artificial niche" of mouse embryonic fibroblasts to derive multipotent cells from the intestinal epithelium. Cocultivation of adult mouse and human intestinal epithelium with fibroblast feeder cells led to the generation of a novel type of nestin-positive cells (intestinal epithelium-derived nestin-positive cells [INPs]). Transcriptome analyses demonstrated that mouse embryonic fibroblasts expressed relatively high levels of Wnt/bone morphogenetic protein (BMP) transcripts, and the formation of INPs was specifically associated with an increase in Lef1, Wnt4, Wnt5a, and Wnt/BMP-responsive factors, but a decrease of BMP4 transcript abundance. In vitro, INPs showed a high but finite proliferative capacity and readily differentiated into cells expressing neural, pancreatic, and hepatic transcripts and proteins; however, these derivatives did not show functional properties. In vivo, INPs failed to form chimeras following injection into mouse blastocysts but integrated into hippocampal brain slice cultures in situ. We conclude that the use of embryonic fibroblasts seems to reprogram adult intestinal epithelial cells by modulation of Wnt/BMP signaling to a cell type with a more primitive embryonic-like stage of development that has a high degree of flexibility and plasticity.

Neurogenic potential of human umbilical cord blood: neural-like stem cells depend on previous long-term culture conditions

In vitro studies conducted by our research group documented that neural progenitor cells can be selected from human umbilical cord blood (HUCB-NPs). Due to further expansion of these cells we have established the first human umbilical cord blood-derived neural-like stem cell line (HUCB-NSC) growing in serum-free (SF) or low-serum (LS) medium for over 3 years. The purpose of the study was to evaluate the neurogenic potential of HUCB-NSCs cultured in SF and LS condition in different in vitro settings before transplantation. We have shown that the number of cells attaining neuronal features was significantly higher for cultures expanded in LS than in SF condition. Moreover, the presence of neuromorphogens, cultured rat astrocytes or hippocampal slices promoted further differentiation of HUCB-NSCs into neural lineage much more effectively when the cells had derived from LS cultures. The highest response was observed in the case of co-cultures with rat primary astrocytes as well as hippocampal organotypic slices. However, the LS cells co-cultured with hippocampal slices expressed exclusively a set of early and late neuronal markers whereas no detection of cells with glial-specific markers was possible. In conclusion, certain level of stem/progenitor cell commitment is important for optimal response of HUCB-NSC on the neurogenic signals provided by surrounding environment in vitro.

Failure of transdifferentiation of adult hematopoietic stem cells into neurons

Previous studies of bone marrow-derived stem cell transdifferentiation into neurons have not involved purified cell populations and determined their exact phenotype prior to differentiation. The present study investigates whether highly purified mouse adult hematopoietic stem cells (HSCs), characterized by lineage marker depletion and expression of the cell surface markers Sca1 and c-Kit (Lin(-) Sca1(+) c-Kit(+) [LSK]), can be stimulated to adopt a neuronal fate. When the HSC(LSK) cells were cultured in vitro in neuronal differentiation medium supplemented with retinoic acid, 50% of the cells expressed the neural progenitor marker nestin and no cells had become postmitotic. Electrophysiological recordings on neuron-like cells showed that these cells were incapable of generating action potentials. When the HSC(LSK) cells either were grown in vitro together with neural precursor cells or were transplanted into the striatum or cerebellum of wild-type mouse, they either differentiated into Iba1-immunopositive macrophage/microglia or died. In conclusion, we demonstrate that adult HSC(LSK) cells do not have the capacity to leave the hematopoietic lineage and differentiate into neurons.

Glial grafting for demyelinating disease

Remyelination of demyelinated central nervous system (CNS) axons is considered as a potential treatment for multiple sclerosis, and it has been achieved in experimental models of demyelination by transplantation of pro-myelinating cells. However, the experiments undertaken have not addressed the need for tissue-type matching in order to achieve graft-mediated remyelination since they were performed in conditions in which the chance for graft rejection was minimized. This article focuses on the factors determining survival of allogeneic oligodendrocyte lineage cells and their contribution to the remyelination of demyelinating CNS lesions. The immune status of the CNS as well as the suitability of different models of demyelination for graft rejection studies are discussed, and ways of enhancing allogeneic oligodendrocyte-mediated remyelination are presented. Finally, the effects of glial graft rejection on host remyelination are described, highlighting the potential benefits of the acute CNS inflammatory response for myelin repair.

The value of alternative testing for neurotoxicity in the context of regulatory needs

Detection and characterisation of chemical-induced toxic effects in the central and peripheral nervous system represent a major challenge for employing newly developed technologies in the field of neurotoxicology. Precise cellular predictive test batteries for chemical-induced neurotoxicity are increasingly important for regulatory decision making, but also the most efficient way to keep costs and time of testing within a reasonable margin. Current in vivo test methods are based on behavioural and sensory perturbations coupled with routine histopathological investigations. In spite of the empirical usefulness of these tests, they are not always sensitive enough and often, they do not provide information that facilitates a detailed understanding of potential mechanisms of toxicity, thus enabling predictions. In general, such in vivo tests are unsuitable for screening large number of agents. One way to meet the need for more powerful and comprehensive tests via an extended scientific basis is to study neurotoxicity in specific cell types of the brain and to derive generalised mechanisms of action of the toxicants from such series of experiments. Additionally, toxicokinetic models are to be developed in order to give a rough account for the whole absorption, distribution, metabolism, excretion (ADME) process including the blood-brain barrier (BBB). Therefore, an intensive search for the development of alternative methods using animal and human-based in vitro and in silico models for neurotoxic hazard assessment is appropriate. In particular, neurotoxicology represents one of the major challenges to the development of in vitro systems, as it has to account also for heterogeneous cell interactions of the brain which require new biochemical, biotechnological and electrophysiological profiling methods for reliable alternative ways with a high throughput.

HIV-1 Tat and opiate-induced changes in astrocytes promote chemotaxis of microglia through the expression of MCP-1 and alternative chemokines

Opiates exacerbate human immunodeficiency virus type 1 (HIV-1) Tat(1-72)-induced release of key proinflammatory cytokines by astrocytes, which may accelerate HIV neuropathogenesis in opiate abusers. The release of monocyte chemoattractant protein-1 (MCP-1, also known as CCL2), in particular, is potentiated by opiate-HIV Tat interactions in vitro. Although MCP-1 draws monocytes/macrophages to sites of CNS infection, and activated monocytes/microglia release factors that can damage bystander neurons, the role of MCP-1 in neuro-acquired immunodeficiency syndrome (neuroAIDS) progression in opiate abusers, or nonabusers, is uncertain. Using a chemotaxis assay, N9 microglial cell migration was found to be significantly greater in conditioned medium from mouse striatal astrocytes exposed to morphine and/or Tat(1-72) than in vehicle-, mu-opioid receptor (MOR) antagonist-, or inactive, mutant Tat(delta31-61)-treated controls. Conditioned medium from astrocytes treated with morphine and Tat caused the greatest increase in motility. The response was attenuated using conditioned medium immunoneutralized with MCP-1 antibodies, or medium from MCP-1(-/-) astrocytes. In the presence of morphine (time-release, subcutaneous implant), intrastriatal Tat increased the proportion of neural cells that were astroglia and F4/80+ macrophages at 7 days post-injection. This was not seen after treatment with Tat alone, or with morphine plus inactive Tat(delta31-61) or naltrexone. Glia displayed increased MOR and MCP-1 immunoreactivity after morphine and/or Tat exposure. The findings indicate that MCP-1 underlies most of the response of microglia, suggesting that one way in which opiates exacerbate neuroAIDS is by increasing astroglial-derived proinflammatory chemokines at focal sites of CNS infection and promoting macrophage entry and local microglial activation. Importantly, increased glial expression of MOR can trigger an opiate-driven amplification/positive feedback of MCP-1 production and inflammation.

Novel cell therapy approaches for brain repair

Numerous reports elucidate that tissue-specific stem cells are phenotypically plastic and their differentiation pathways are not strictly delineated. Although the identity of all the epigenetic factors which may trigger stem cells to make a lineage selection are still unknown, the plasticity of adult stem cells opens new approaches for their application in the treatment of various disorders. There is increasing researcher interest in hematopoietic stem cells for treatment of not only blood-related diseases but also various unrelated disorders including neurodegenerative diseases. Human umbilical cord blood (hUCB) cells, due to their primitive nature and ability to develop into nonhematopoietic cells of various tissue lineages, including neural cells, may be useful as an alternative cell source for cell-based therapies requiring either the replacement of individual cell types and/or substitution of missing substances. Here we focus on recent findings showing the robustness of adult stem cells derived from hUCB and their potential as a source of transplant cells for the treatment of diseased or injured brains and spinal cords. Depending upon the pathological microenvironment in which the hUCB cells are introduced, neuroprotective and/or trophic effects of these cells, from release of various growth or anti-inflammatory factors to moderation of immune-inflammatory effectors, may be more likely than neural replacement. These protective effects may prove essential to maintaining restored tissue integrity over the course of various diseases or injuries.

Human umbilical cord blood-derived cells differentiate into hepatocyte-like cells in the Fas-mediated liver injury model

Human umbilical cord blood (HUCB) contains stem/progenitor cells, which can differentiate into a variety of cell types. In this study, we investigated whether HUCB cells differentiate into hepatocytes in vitro and in vivo. We also examined whether CD34 could be the selection marker of stem cells for hepatocytes. HUCB cells were obtained from normal full-term deliveries, and CD34(+/-) cells were further separated. For in vitro study, HUCB cells were cultured for 4 wk, and expressions of liver-specific genes were examined. For the in vivo study, nonobese diabetic/severe combined immunodeficient mice were subjected to liver injury by a Fas ligand-carried adenoviral vector or only radiated. Mice were treated simultaneously with or without cell transplantation of HUCB, CD34(+), or CD34(-) cells. After 4 wk, human-specific gene/protein expression was examined. In the in vitro study, human liver-specific genes were positive after 7 days of culture. The immunofluorescent study showed positive staining of alpha-fetoprotein, cytokeratin 19, and albumin in round-shaped cells. In the in vivo study, immunohistochemical analysis showed human albumin-positive, hepatocyte-specific antigen-positive cells in mouse livers of the Fas ligand/transplantation group. Fluorescence in situ hybridization analysis using the human Y chromosome also showed positive signals. However, no difference between transplanted cell types was detected. In contrast, immunopositive cells were not detected in the irradiated/transplantation group. The RT-PCR result also showed human hepatocyte-specific gene expressions only in the Fas ligand/transplantation group. HUCB cells differentiated into hepatocyte-like cells in the mouse liver, and liver injury was essential during this process. The differences between CD34(+) and CD34(-) cells were not observed in human hepatocyte-specific expression.

Human cord blood-derived neural stem cell line—Possible implementation in studying neurotoxicity

Neural stem cell line developed from human umbilical cord blood (HUCB-NSC) [Buzańska et al., 2003. Journal of Neurochemistry 85, 33] is an ethically uncontroversial source of stem cells, able to differentiate into neuronal, astrocytic and oligodendroglial lineages. Developmental fate decisions of HUCB-NSC can be experimentally manipulated in vitro by the presence of trophic factors, mitogenes and neuromorphogenes, but can also be influenced by neurotoxins. In this report two-dimensional (2-D) and three-dimensional (3-D) HUCB-NSC cultures are introduced as useful models for testing developmental neurotoxicity. For 2-D culture models we established a standardized method for the assessment of the growth rate and cell differentiation in 96-well plates. The proliferative capacity of the HUCB-NSC was monitored by the MTT test while their ability to differentiate into neural-like cells by immunocytochemistry of beta-tubulin III and MAP-2 for neurons, GFAP and S-100beta for astrocytes and GalC for oligodendrocytes. The 3-D culture of HUCB-NSC is represented by neurospheres. Proliferation and migration of the intermediate precursors from attached neurospheres are shown to be controlled and altered by various growth factors and further modulated by the extracellular matrix component-fibronectin. Thus, neurospheres derived from the HUCB-NSC line can represent a suitable model of the activation of dormant stem cells residing in their niche, and can be used for neurotoxic studies.

Are bone marrow stem cells plastic or heterogenous--that is the question

The concept that bone marrow (BM) may contain heterogeneous populations of stem cells was surprisingly not taken carefully enough into consideration in several recently reported experiments demonstrating so-called plasticity or trans-dedifferentiation of hematopoietic stem cells (HSC). These studies, without including proper controls to exclude this possibility, often lead to wrong interpretations. Accumulated evidence suggests that in addition to hematopoietic stem cells (HSC), bone marrow (BM) also harbors versatile subpopulations of tissue-committed stem cells (TCSC) and perhaps even more primitive pluripotent stem cells (PSC), and that these rare 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. Thus, the presence of TCSC/PSC in BM tissue should be considered before experimental evidence is interpreted simply as trans-dedifferentiation/plasticity of HSC. In this review, we will discuss this alternative explanation of plasticity of HSC, providing data from others and our laboratory that supports the concept that BM-derived stem cells are heterogeneous.

Functional recovery after human umbilical cord blood cells transplantation with brain-derived neutrophic factor into the spinal cord injured rat

There have been many efforts to recover neuronal function from spinal cord injuries, but there are some limitations in the treatment of spinal cord injuries. The neural stem cell has been noted for its pluripotency to differentiate into various neural cell types. The human umbilical cord blood cells (HUCBs) are more pluripotent and genetically flexible than bone marrow neural stem cells. The HUCBs could be more frequently used for spinal cord injury treatment in the future. Moderate degree spinal cord injured rats were classified into 3 subgroups, group A: media was injected into the cord injury site, group B: HUCBs were transplanted into the cord injury site, and group C: HUCBs with BDNF (Brain-derived neutrophic factor) were transplanted into the cord injury site. We checked the BBB scores to evaluate the functional recovery in each group at 8 weeks after transplantation. We then, finally checked the neural cell differentiation with double immunofluorescence staining, and we also analyzed the axonal regeneration with retrograde labelling of brain stem neurons by using fluorogold. The HUCBs transplanted group improved, more than the control group at every week after transplantation, and also, the BDNF enabled an improvement of the BBB locomotion scores since the 1 week after its application (P<0.05). 8 weeks after transplantation, the HUCBs with BDNF transplanted group had more greatly improved BBB scores, than the other groups (P<0.001). The transplanted HUCBs were differentiated into various neural cells, which were confirmed by double immunofluorescence staining of BrdU and GFAP & MAP-2 staining. The HUCBs and BDNF each have individual positive effects on axonal regeneration. The HUCBs can differentiate into neural cells and induce motor function improvement in the cord injured rat models. Especially, the BDNF has effectiveness for neurological function improvement due to axonal regeneration in the early cord injury stage. Thus the HUCBs and BDNF have recovery effects of a moderate degree for cord injured rats.

Transplantation of Human Umbilical Cord Blood-Derived Adherent Progenitors Into the Developing Rodent Brain

The results of several recent studies suggest that human umbilical cord blood (HUCB)-derived cells have the potential to undergo neural differentiation both in vitro and in vivo. Transplantation into the embryonic ventricular zone provides a unique opportunity to study the migration and differentiation of nonneural somatic progenitor cells in response to instructive cues within the developing neuroepithelium. We isolated an adherently growing population of HUCB-derived cells expressing CD13, CD29, CD49e, CD71, CD73, CD166, Flk-1, and vimentin but lacking CD34 and CD45. On transplantation into the ventricles of embryonic day 16.5 rat embryos, these cells formed subventricular clusters that extended into a variety of host brain regions, including striatum, cortex, hippocampus, thalamus, hypothalamus, tectum, pons, and cerebellum. Donor cells identified with an antibody to human nuclei or human-specific DNA in situ hybridization maintained expression of their original marker antigens and showed no expression of the neural markers MAP2 and NeuN (neurons), GFAP (astrocytes), and CNP (oligodendrocytes). In contrast to grafted primary neural cells, they remained largely confined to subventricular clusters with little evidence for intraparenchymal integration. Thus, the neurogenic environment of the embryonic ventricular zone does not promote the elaboration of a neural phenotype in HUCB-derived cells.

Voltage-Sensitive and Ligand-Gated Channels in Differentiating Neural Stem-Like Cells Derived from the Nonhematopoietic Fraction of Human Umbilical Cord Blood

Fetal cells with the characteristics of neural stem cells (NSCs) can be derived from the nonhematopoietic fraction of human umbilical cord blood (HUCB), expanded as a nonimmortalized cell line (HUCB-NSC), and further differentiated into neuron-like cells (HUCB-NSCD); however, the functional and neuronal properties of these cells are poorly understood. To address this issue, we used whole-cell patch-clamp recordings, gene microarrays, and immunocytochemistry to identify voltage-gated channels and ligand-gated receptors on HUCB-NSCs and HUCB-NSCDs. Gene microarray analysis identified genes for voltage-dependent potassium and sodium channels and the neurotransmitter receptors acetylcholine (ACh), gamma-aminobutyric acid (GABA), glutamate, glycine, 5-hydroxytryptamine (5-HT), and dopamine (DA). Several of these genes (GABA-A, glycine and glutamate receptors, voltage-gated potassium channels, and voltage-gated sodium type XII alpha channels) were not expressed in the HUCB mono-nuclear fraction (HUCB-MC), which served as a starting cell population for HUCB-NSC. HUCB-NSCD acquired neuronal phenotypes and displayed an inward rectifying potassium current (Kir) and an outward rectifying potassium current (I(K+)). Kir was present on most HUCB-NSCs and HUCB-NSCDs, whereas I(K+) was present only on HUCB-NSCDs. Many HUCB-NSCDs were immunopositive for glutamate, glycine, nicotinic ACh, DA, 5-HT, and GABA receptors. Kainic acid (KA), a non-N-methyl-D-asparate (NMDA) glutamate-receptor agonist, induced an inward current in some HUCB-NSCDs. KA, glycine, DA, ACh, GABA, and 5-HT partially blocked Kir through their respective receptors. These results suggest that HUCB-NSCs differentiate toward neuron-like cells, with functional voltage- and ligand-gated channels identified in other neuronal systems.

Control of CREB-binding Protein Signaling by Nuclear Fibroblast Growth Factor Receptor-1

In integrative nuclear fibroblast growth factor receptor-1 (FGFR1) signaling a newly synthesized FGFR1 translocates to the nucleus to stimulate cell differentiation and associated gene activities. The present study shows that FGFR1 accumulates and interacts with the transcriptional co-activator CREB-binding protein (CBP) in nuclear speckle domains in the developing brain and in neural progenitor-like cells in vitro, which accompanies differentiation and postmitotic growth. Cell differentiation and gene activation by nuclear FGFR1 do not require tyrosine kinase activity. Instead, FGFR1 stimulates transcription in cooperation with CBP by increasing recruitment of RNA polymerase II and histone acetylation at the active gene promoter. FGFR1 is a multifactorial protein whose N terminus interacts with CBP and C terminus with ribosomal S6 kinase 1 (RSK1). Nuclear FGFR1 augments CBP-mediated transcription by 1) releasing the CBP C-terminal domain from RSK1 inhibition and 2) activating the CBP N-terminal domain. The interaction of FGFR1 with CBP and RSK1 allows activation of gene transcription and may play a role in cell differentiation.

Resuscitation from experimental heatstroke by transplantation of human umbilical cord blood cells

OBJECTIVE

Human umbilical cord blood cells (HUCBCs) are effective in the treatment of conventional stroke in experimental models. In the study described herein, we administered HUCBCs into the femoral vein or directly into the cerebral ventricular system and assessed their effects on circulatory shock, cerebral ischemia, and damage during heatstroke.

DESIGN

Controlled, prospective study.

SETTING

Hospital medical research laboratory.

SUBJECTS

Sprague-Dawley rats (287 +/- 16 g body weight, males).

INTERVENTIONS

Anesthetized rats, immediately after the onset of heatstroke, were divided into four major groups and given the following: a) normal saline or AIM-V medium intravenously (0.3 mL) or intracerebroventricularly (10 microL); b) peripheral blood mononuclear cells (5 x 10 in 0.3 mL AIM-V medium, intravenously, or 5 x 10 in 10 microL AIM-V medium, intracerebroventricularly); or c) HUCBCs (5 x 10 in 0.3 mL AIM-V medium, intravenously, or 5 x 10 in 10 microL AIM-V medium, intracerebroventricularly). Another group of rats, under urethane anesthesia, were exposed to room temperature (26 degrees C) and used as normothermic controls. Urethane-anesthetized animals were exposed to an ambient temperature of 43 degrees C to induce heatstroke. Their physiologic and biochemical parameters were continuously monitored.

MEASUREMENTS AND MAIN RESULTS

When the vehicle-treated rats underwent heat exposure, their survival time values were found to be 21-23 mins. Resuscitation with intravenous or intracerebroventricular doses of HUCBCs, but not peripheral blood mononuclear cells, immediately at the onset of heatstroke significantly improved survival during heatstroke (61-148 mins). As compared with values for normothermic controls, the vehicle-treated heatstroke rats had lower mean arterial pressure, cerebral blood flow, and brain PO2 values but higher intracranial pressure and cerebral ischemia values and more injury markers. The circulatory shock, intracranial hypertension, cerebral hypoperfusion and hypoxia, increment of cerebral ischemia, and damage markers during heatstroke were all significantly attenuated by intravenous or intracerebroventricular delivery of HUCBCs but not peripheral blood mononuclear cells.

CONCLUSIONS

We successfully demonstrate that HUCBC therapy may resuscitate heatstroke victims by reducing circulatory shock and cerebral ischemic injury; central delivery of HUCBCs seems superior to systemic delivery of HUCBCs in resuscitating patients with heatstroke.

Transplantation of GABAergic neurons into adult mouse neocortex

GABAergic neurons in the neocortex contribute to various brain functions by regulating cortical pyramidal neurons. A deficiency of GABAergic neurons in the neocortex leads to the dysregulation of cortical neuronal circuits, but this can be overcome by cell transplantation, which provides a practical approach to repair damaged neuronal circuits. Here, we focused on the transplantation of committed neuronal progenitor cells. Because neuronal differentiation is considerably suppressed in the adult neocortex, we transfected proneural bHLH transcription factors into neural precursor cells to commit them to a neuronal lineage prior to the cell transplantation. We show that ventral neural stem cells transfected with Ngn1 are integrated as GABAergic neurons within a few days of transplantation into the adult mouse neocortex. These results demonstrate that the transplantation of committed neuronal progenitor cells is an effective method for brain repair.

Coculture of Embryonic Stem Cells with Pulmonary Mesenchyme: A Microenvironment That Promotes Differentiation of Pulmonary Epithelium

Coculture of stem/progenitor cells with mature cells or tissues can drive their differentiation toward required lineages. Thus, we hypothesized that coculture of murine embryonic stem (ES) cells with embryonic mesenchyme from distal lung promotes the differentiation of pneumocytes. Murine ES cells were differentiated to embryoid bodies (EBs) and cultured for 5 or 12 days with pulmonary mesenchyme from embryonic day 11.5 or 13.5 murine embryos, in direct contact or separated by a membrane. Controls included EBs cultured alone or with embryonic gut mesenchyme. Histology revealed epithelium-lined channels in directly cocultured EBs, whereas EBs grown alone showed little structural organization. The lining cells expressed cytokeratin and thyroid transcription factor 1, an early developmental marker in pulmonary epithelium. Differentiation of type II pneumocytes specifically was demonstrated by the presence of surfactant protein C (SP-C) in some of the epithelial cells. None of these markers was seen in EBs cultured alone or with embryonic gut mesenchyme. Indirect coculture of EBs with lung mesenchyme resulted in a 14-fold increase in SP-C gene expression. Thus, provision of an appropriate microenvironment, in the form of pulmonary mesenchyme, appears to promote the differentiation of ES cells toward lung epithelium. Our findings may have applications in regenerative medicine strategies and the engineering of lung tissue.

Bone marrow as a home of heterogenous populations of nonhematopoietic stem cells

Evidence is presented that bone marrow (BM) in addition to CD45(positive) hematopoietic stem cells contains a rare population of heterogenous CD45(negative) nonhematopoietic tissue committed stem cells (TCSC). These nonhematopoietic TCSC (i) are enriched in population of CXCR4(+) CD34(+) AC133(+) lin(-) CD45(-) and CXCR4(+) Sca-1(+) lin(-) CD45(-) in humans and mice, respectively, (ii) display several markers of pluripotent stem cells (PSC) and (iii) as we envision are deposited in BM early in development. Thus, since BM contains versatile nonhematopoietic stem cells, previous studies on plasticity trans-dedifferentiation of BM-derived hematopoietic stem cells (HSC) that did not include proper controls to exclude this possibility could lead to wrong interpretations. Therefore, in this spotlight review we present this alternative explanation of 'plasticity' of BM-derived stem cells based on the assumption that BM stem cells are heterogenous. We also discuss a potential relationship of TCSC/PSC identified by us with other BM-derived CD45(negative) nonhematopoietic stem cells that were recently identified by other investigators (eg MSC, MAPC, USSC and MIAMI cells). Finally, we discuss perspectives and pitfalls in potential application of these cells in regenerative medicine.

Bone marrow as a source of circulating CXCR4+ tissue-committed stem cells

Several studies have suggested that adult haematopoietic stem cells (HSCs) may be capable of transdifferentiating across tissue-lineage boundaries, giving rise to the concept that these stem cells are plastic in their differentiative capacity. This topic created much excitement in the scientific community, with the prospect of employing HSCs in tissue/organ regeneration (e.g. heart infarct, stroke, liver damage) as an alternative to multipotent embryonic stem cells. However, recent observations, and several alternative explanations of previously published data (e.g. cell fusion, epigenetic changes), do not support the concept of HSC plasticity. Our recent studies, in which we employed chemotactic isolation to a stromal-cell-derived-factor-1 (SDF-1) gradient combined with real-time reverse transcriptase (RT)-PCR/immuno-histochemical analyses, revealed that bone marrow (BM) contains a highly mobile population of CXCR4+ cells that express mRNA/proteins for various markers of early tissue-committed stem cells (TCSCs). Based on this we postulate that the BM is not only a home for HSCs, but also a 'hideout' for non-haematopoietic CXCR4+ TCSCs, and we suggest that their presence in BM tissue should be considered before experimental evidence is interpreted simply as transdifferentiation/plasticity of HSCs. Furthermore, our observation that the number of TCSCs is the highest in BM of young animals and decreases with age provides a novel insight into aging, and may explain why the regeneration process becomes less effective in older individuals.

Toxicity testing: creating a revolution based on new technologies

Biotechnology is evolving at a tremendous rate. Although drug discovery is now heavily focused on high throughput and miniaturized screening, the application of these advances to the toxicological assessment of chemicals and chemical products has been slow. Nevertheless, the impending surge in demands for the regulatory toxicity testing of chemicals provides the impetus for the incorporation of novel methodologies into hazard identification and risk assessment. Here, we review the current and likely future value of these new technologies in relation to toxicological evaluation and the protection of human health.

Bone marrow-derived mesenchymal stem cells already express specific neural proteins before any differentiation

Bone marrow mesenchymal stem cells (MSC) are multipotent cells. To explain their plasticity, we postulated that undifferentiated MSC may express proteins from other tissues such as neuronal tissues. MSC are obtained by two different approaches: plastic adhesion or negative depletion (RosetteSep and magnetic beads CD45/glycophorin A). MSC are evaluated through FACS analysis using a panel of antibodies (SH2, SH3, CD14, CD33, CD34, CD45, etc.). To confirm the multipotentiality in vitro, we have differentiated MSC into adipocytes, chondrocytes, osteocytes, and neuronal/glial cells using specific induction media. We have evaluated neuronal and glial proteins (Nestin, Tuj-I, betaIII Tubulin, tyrosine hydroxylase [TH], MAP-2, and GFAP) by using flow cytometry, Western blots, and RT-PCR. We found that MSC constituently express native immature neuronal proteins such as Nestin and Tuj-1. After only five passages, MSC can already express more mature neuronal or glial proteins, such as TH, MAP-2, and GFAP, without any specific induction. We noticed an increase in the expression of more mature neuronal/glial proteins (TH, MAP-2, and GFAP) after exposure to neural induction medium, thus confirming the differentiation of MSC into neurons and astrocytes. The constitutive expression of Nestin or Tuj-1 by MSC suggests that these cells are "multidifferentiated" cells and thus can retain the ability for neuronal differentiation, enhancing their potentiality to be employed in the treatment of neurological diseases.

Transplantation of human umbilical cord blood cells in the repair of CNS diseases

Cell transplantation therapies have been used to treat certain neurodegenerative diseases such as Parkinson's and Huntington's disease. However, ethical concerns over the use of fetal tissues, and the inherent complexities of standardising the procurement, processing and transplantation methods of this tissue, have prompted the search for a source of cells that have less ethical stigmatisations, are readily available and can be easily standardised. Several sources of human cells that meet these principles have been under investigation. Cells from human umbilical cord blood (HUCB) are one source that is consistent with these principles; therefore, they have become of great interest in the field of cellular repair/replacement for the treatment of CNS diseases and injury. This review will focus on the advantages of HUCB cells as a source for cellular transplantation therapies, recent studies that have examined the potential of these cells in vitro to be directed towards neural phenotypes, and in vivo studies that have investigated the functional recovery of animals in a number of models of CNS injury and disease following administration of HUCB cells.

Human umbilical cord blood cells express neurotrophic factors

Freshly isolated or culture-expanded human umbilical cord blood mononuclear cells (CBMNCs) have been known to express neural phenotypes in vitro and to differentiate into neural cells and improve neurological function recovery after being administrated into rodent models of neurological diseases. However, the mechanism of action remains unclear. The present study observed that CBMNCs expressed higher level mRNAs of several neurotrophic factors than adult peripheral blood mononuclear cells (PBMCs). In addition, a significantly increase in the levels of brain-derived neurotrophic factor (BDNF) and neurotrophin-4/5 (NT4/5) was found in culture supernatants of CBMNCs compared to that of PBMNCs. These findings indicate that CBMNCs express several neurotrophic factors and suggest that the neurotrophic factors secreted by CBMNCs may be responsible for amelioration of central nervous system deficits in animal models after CBMNC administration.

Intraspinal transplantation of CD34+ human umbilical cord blood cells after spinal cord hemisection injury improves functional recovery in adult rats

The present study was designed to compare the functional outcome of the intraspinal transplantation of CD34+ human umbilical cord blood (CB) cells with that of human bone marrow stromal (BMS) cells in adult rats with spinal cord injury. Sixty adult Wistar rats were subjected to left spinal cord hemisection, and then divided into three groups randomly. The control group received an injection of PBS without cells, while the two other groups of rats received a transplantation of 5 x 10(5) CD34+ CB or BMS cells, respectively. Functional outcome was measured using the modified Tarlov score at days 1, 7, 14, 21, and 28 after transplantation. A statistically significant improvement in functional outcome and survival rate in the experimental groups of rats was observed compared with the control group. Rats that received CD34+ CB cells achieved a better improvement in functional score than those that received BMS cells at days 7 and 14 after transplantation. Histological evaluation revealed that bromodeoxyuridine (BrdU)-labeled CD34+ CB and BMS cells survived and migrated into the injured area. Some of these cells expressed glial fibriliary acidic protein (GFAP) or neuronal nuclear antigen (NeuN). Our data demonstrate for the first time that intraspinal transplantation of human CD34+ CB cells provides benefit in function recovery after spinal cord hemisection in rats and suggest that CD34+ CB cells may be an excellent choice of cells as routine starting material of allogenic and autologous transplantations for the treatment of spinal cord injury.

Pancreas developing markers expressed on human mononucleated umbilical cord blood cells

Haematopoietic system represents the main source of haematopoietic stem cells and probably of multipotential adult progenitor cells and mesenchimal stem cells at first described as colony forming unit-fibroblast. Whereas there are many studies on the gene expression profile of the different precursors along their haematopoietic differentiation, few data (sometimes conflicting) have been reported about the phenotype of the cells (present in bone marrow and possibly in cord blood) able to differentiate into non-haematopoietic cells. As both postnatal bone marrow and umbilical cord blood contain nestin positive cells able to proliferate and differentiate into the main neural phenotype (neuron, astroglia and oligodendroglia) many authors considered nestin a neuroepithelial precursor marker that seems to be essential also in multipotential progenitor cells of pancreas present both in rat and in human pancreatic islets (called nestin positive islet derived progenitors). Although the importance of nestin in these cells appears to be evident, it remains yet to clarify the number and the sequential expression of the genes coding all the transcription factors essential for beta cells differentiation and therefore the conditions able to induce the expression of many important transcription factors genes such as isl-1, pax-4, pdx-1 and ngn-3. Among them pdx-1 is a gene essential for pancreas development which is able to control ngn-3 in activating the expression of other differentiation factors for endocrine cells. Here, we describe for the first time in human umbilical cord blood cells (UCB) the pattern of expression of a panel of markers (nestin, CK-8, CK-18) and transcription factors (Isl-1, Pdx-1, Pax-4, Ngn-3) considered important for beta cells differentiation. Our data demonstrate that UCB contains a cell population having a phenotype very similar to endocrine cell precursors in transition to beta cells.

Neuronal differentiation of murine bone marrow Thy-1- and Sca-1-positive cells

Recent evidence suggests that cells from bone marrow can acquire neuroectodermal phenotypes in cell culture or after transplantation in animal models and in the human brain. However, isolation of the bone marrow cell subpopulation with neuronal differentiation potential remains a challenge. To isolate and expand neural progenitors from whole murine bone marrow, bone marrow was obtained from hind limb bone of C57BL6 mice and plated in culture with neuronal medium with basic fibroblast growth factor and epidermal growth factor. After 5-7 days in culture, cellular spheres similar to brain neurospheres appeared either floating or attached to culture dishes. These spheres were collected, dissociated, and expanded. The bone marrow-derived spheres were positive for nestin as assessed by immunocytochemistry and by reverse transcriptase polymerase chain reaction. Thy-1- and Sca-1-positive bone marrow cells selected by magnetic cell sorting resulted in a higher yield of nestin-positive spheres. After exposure to neuronal differentiative medium retinoic acid with and without Sonic hedgehog, cells positive for neuronal markers tubulin III (TuJ-1) and neurofilament (NF) were detected. The mRNA profile of these cells included the expression of TuJ-1, neuronal-specific enolase (NSE), and NF-light chain. To evaluate the in vivo behavior of these cells, spheres derived from bone marrow-derived cells of transgenic green fluorescent protein (GFP) mice were transplanted into newborn mouse brain. Two months later, the mouse neural cortex contained a minor proportion of GFP(+) cells co-expressing neuronal markers (TuJ-1, NF, MAP-2, NeuN). Although cell fusion phenomena with the host cells could not be ruled out, bone marrow-derived neurosphere transplantation could be a strategy for cellular mediated gene therapy.

Stem cell therapy for Parkinson?s disease: where do we stand?

A major neuropathological feature of Parkinson's disease (PD) is the loss of nigrostriatal dopaminergic neuron. Patients exhibit motor symptoms, including bradykinesia, rigidity, and tremor. Neural grafting has been reported to restore striatial dopaminergic neurotransmission and induce symptomatic relief. The major limitation of cell replacement therapy for PD is the shortage of suitable donor tissue. The present review describes the possible sources of cells, including embryonic stem cells and somatic adult stem cells, both of which potentially could be used in cell therapy for PD, and discusses the advantages and disadvantages of each cell type.

Efficient generation of neural stem cell-like cells from adult human bone marrow stromal cells

Clonogenic neural stem cells (NSCs) are self-renewing cells that maintain the capacity to differentiate into brain-specific cell types, and may also replace or repair diseased brain tissue. NSCs can be directly isolated from fetal or adult nervous tissue, or derived from embryonic stem cells. Here, we describe the efficient conversion of human adult bone marrow stromal cells (hMSC) into a neural stem cell-like population (hmNSC, for human marrow-derived NSC-like cells). These cells grow in neurosphere-like structures, express high levels of early neuroectodermal markers, such as the proneural genes NeuroD1, Neurog2, MSl1 as well as otx1 and nestin, but lose the characteristics of mesodermal stromal cells. In the presence of selected growth factors, hmNSCs can be differentiated into the three main neural phenotypes: astroglia, oligodendroglia and neurons. Clonal analysis demonstrates that individual hmNSCs are multipotent and retain the capacity to generate both glia and neurons. Our cell culture system provides a powerful tool for investigating the molecular mechanisms of neural differentiation in adult human NSCs. hmNSCs may therefore ultimately help to treat acute and chronic neurodegenerative diseases.

Rapid neural differentiation of human cord blood-derived mesenchymal stem cells

Human umbilical cord blood (UCB) contains hematopoietic stem cells (HSCs) and mesenchymal stem cells (MSCs), both of which are regarded as valuable sources for cell transplantation and cell therapy. Adherent cells expressing MSCs-related antigens such as SH2, CD13, CD29, and ASMA, have been isolated from a mononuclear cell fraction of human UCB. Under proneurogenic conditions, these UCB-derived adherent cells rapidly assumed the morphology of multipolar neurons. Both immunofluorescence and RT-PCR analyses indicated that the expression of a number of neural markers including Tuj1, TrkA, GFAP and CNPases, was markedly elevated during this acute differentiation. The neurogenic potential of UCB-derived may facilitate stem cell therapeutic approaches to neurodegenerative diseases.

Do hematopoietic cells exposed to a neurogenic environment mimic properties of endogenous neural precursors?

Hematopoietic progenitors are cells, which under challenging experimental conditions can develop unusual phenotypic properties, rather distant from their original mesodermal origin. As previously reported, cells derived from human umbilical cord blood (HUCB) or human bone marrow (BM) under certain in vivo or in vitro conditions can manifest neural features that resemble features of neural-derived cells, immunocytochemically and in some instances also morphologically. The present study explored how hematopoietic-derived cells would respond to neurogenic signals from the subventricular zone (SVZ) of adult and aged (6 and 16 months old) rats. The mononuclear fraction of HUCB cells was transplanted into the SVZ of immunosuppressed (single cyclosporin or three-drug treatment) animals. The triple-suppression paradigm allowed us to protect transplanted human cells within the brain and to explore further their phenotypic and migratory properties. One week after implantation, many surviving HUCB cells were located within the SVZ and the vertical limb of the rostral migratory stream (RMS). The migration of HUCB cells was restricted exclusively to the pathway leading to the olfactory bulb. In younger animals, grafted cells navigated almost halfway through the vertical limb, whereas, in the older animals, the migration was less pronounced. The overall cell survival was greater in younger animals than in older ones. Immunocytochemistry for surface CD antigen expression showed that many HUCB cells, either cultured or within the brain parenchyma, retained their hematopoietic identity. A few cells, identified by using human-specific antibodies (anti-human nuclei, or mitochondria) expressed nestin and doublecortin, markers of endogenous neural progenitors. Therefore, it is believed that the environment of the neurogenic SVZ, even in aged animals, was able to support survival, "neuralization," and migratory features of HUCB-derived cells.

Taking stock and planning for the next decade: realistic prospects for stem cell therapies for the nervous system

In thinking about the practical application of stem cell biology to clinical situations--particularly for the central nervous system (CNS)-it is instructive to remember that the neural stem cell (NSC) field--as a prototype for somatic stem cells in general-emerged as the unanticipated byproduct of investigations by developmental neurobiologists into fundamental aspects of neural determination, commitment, and plasticity. Stem cell behavior is ultimately an expression of developmental principles, an alluring vestige from the more plastic and generative stages of organogenesis. In attempting to apply stem cell biology therapeutically, it is instructive always to bear in mind what role the stem cell plays in development and to what cues it was "designed" to respond in trying to understand the "logic" behind its behavior (both what investigators want to see and what investigators do not want to see). Furthermore, in transplantation paradigms, the interaction between engrafted NSCs and recipient host is a dynamic, complex, ongoing reciprocal interaction where both entities are constantly in flux. In this review, we propose a "roadmap" to the clinic, with a particular emphasis on flagging the "potholes" and "speed bumps" through which we must navigate. Despite the admonitions to be circumspect, we also suggest disease processes that may be within the grasp of proven stem cell properties and might be approachable in the relatively near future.

Umbilical cord blood stem cells can expand hematopoietic and neuroglial progenitors in vitro

The ability of hematopoietic tissue-derived adult stem cells to transdifferentiate into neural progenitor cells offers an interesting alternative to central nervous system (CNS)- or embryonic-derived stem cells as a viable source for cellular therapies applied to brain regeneration. Umbilical cord blood (CB) due to its primitive nature and it unproblematic collection appears as a promising candidate for multipotent stem cell harvest. We developed a negative immunomagnetic selection method that depletes CB from hematopoietic lineage marker-expressing cells, hence isolating a discrete lineage negative (LinNeg) stem cell population (0.1% of CB mononucleated cell [MCN] population). In liquid culture supplemented with thrombopoietin, flt-3 ligand, and c-kit ligand (TPOFLK), CB LinNeg stem cells could expand primitive nonadherent hematopoietic progenitors (up to 47-fold) and simultaneously produce slow-dividing adherent cells with neuroglial progenitor cell morphology over 8 weeks. Laser scanning confocal microscopy analysis identified these adherent cells to express glial fibrillary acidic protein (GFAP). Gene expression analysis showed upregulation of primitive neuroglial progenitor cell markers including, GFAP, nestin, musashi-1, and necdin. ELISA quantification of liquid culture supernatant revealed the in vitro release of transforming growth factor beta-1 (TGFbeta1), glial cell line-derived neurotrophic factor (GDNF) suggesting their contribution to CB LinNeg stem cell transdifferentiation into neuroglial progenitors. Our study supports that a single CB specimen can be pre-expanded in TPOFLK to produce both primitive hematopoietic and neuropoietic progenitors, hence widening CB clinical potential for cellular therapies.

90-kDa ribosomal S6 kinase is a direct target for the nuclear fibroblast growth factor receptor 1 (FGFR1): role in FGFR1 signaling

Fibroblast growth factor receptor 1 (FGFR1) is a transmembrane protein capable of transducing stimulation by secreted FGFs. In addition, newly synthesized FGFR1 enters the nucleus in response to cellular stimulation and during development. Nuclear FGFR1 can transactivate CRE (cAMP responsive element), activate CRE-binding protein (CREB)-binding protein (CBP) and gene activities causing cellular growth and differentiation. Here, a yeast two-hybrid assay was performed to identify FGFR1-binding proteins and the mechanism of nuclear FGFR1 action. Ten FGFR1-binding proteins were identified. Among the proteins detected with the intracellular FGFR1 domain was a 90-kDa ribosomal S6 kinase (RSK1), a regulator of CREB, CBP, and histone phosphorylation. FGFR1 bound to the N-terminal region of RSK1. The FGFR1-RSK1 interaction was confirmed by co-immunoprecipitation and colocalization in the nucleus and cytoplasm of mammalian cells. Predominantly nuclear FGFR1-RSK1 interaction was observed in the rat brain during neurogenesis and in cAMP-stimulated cultured neural cells. In TE671 cells, transfected FGFR1 colocalized and coimmunoprecipitated, almost exclusively, with nuclear RSK1. Nuclear RSK1 kinase activity and RSK1 activation of CREB were enhanced by transfected FGFR1. In contrast, kinase-deleted FGFR1 (TK-), which did not bind to RSK1 failed to stimulate nuclear RSK1 activity or RSK1 activation of CREB. Kinase inactive FGFR1 (K514A) bound effectively to nuclear RSK1, but it failed to stimulate RSK1. Thus, active FGFR1 kinase regulates the functions of nuclear RSK1. The interaction of nuclear FGFR1 with pluripotent RSK1 offers a new mechanism through which FGFR1 may control fundamental cellular processes.

Mid-trimester fetal blood-derived adherent cells share characteristics similar to mesenchymal stem cells but full-term umbilical cord blood does not

Stem cell transplantation is a promising treatment for many conditions. Although stem cells can be isolated from many tissues, blood is the ideal source of these cells due to the ease of collection. Mesenchymal stem cells (MSCs) have been paid increased attention because of their powerful proliferation and pluripotent differentiating ability. But whether MSCs reside in blood (newborn umbilical cord blood and fetal or adult peripheral blood) is also debatable. The present study showed that MSC-like cells could be isolated and expanded from 16-26 weeks fetal blood but were not acquired efficiently from full-term infants' umbilical cord blood (UCB). Adherent cells separated from postnatal UCB were heterogeneous in cell morphology. Their proliferation capacity was limited and they were mainly CD45+, which indicated their haematopoietic derivation. On the contrary, MSC-like cells shared a similar phenotype to bone marrow MSCs. They were CD34- CD45- CD44+ CD71+ CD90+ CD105+. They could be induced to differentiate into osteogenic, adipogenic and neural lineage cells. Single cell clones also showed similar phenotype and differentiation ability. Our results suggest that early fetal blood is rich in MSCs but term UCB is not.

Retinoic acid-mediated induction of neurons and glial cells from human umbilical cord-derived hematopoietic stem cells

Recent studies reporting trans-differentiation of mononucleated cells derived from human umbilical cord blood into neuronal cells aroused interest among investigators for their clinical implication and significance in regenerative medicine. In the present study, purified populations of hematopoietic stem cells were isolated via magnetic bead sorting and fluorescence-activated cell sorter (FACS) using a specific CD133 antibody, a cell type-specific marker for hematopoietic stem cells, and grown in culture in the presence of retinoic acid (RA). CD133+ hematopoietic stem cells expressed neuronal and glial phenotypes after RA treatment. RT-PCR analysis indicated that the RA treated CD133+ cells expressed mRNA transcripts for ATP-binding cassettes transporter ABCG2 (a universal stem cell marker), nestin (a specific cell type marker for neural stem cells), Musashi1 (a specific marker for neural stem cells) and RA receptors (RAR) including RAR-alpha, RAR-beta, and retinoid X receptor (RXR)-gamma. RA-treated CD133+ cells expressed mRNA transcripts for neuron-specific markers neurofilament proteins (NF-L, -M, -H) and synaptophysin as determined by RT-PCR, structural proteins characteristic of neurons including tubulin beta III and neuron specific enolase (NSE) by Western blot, and neuron-specific markers NeuN and microtubule-associated protein-2 (MAP2) by immunocytochemistry. RA-treated CD133+ cells also expressed the astrocyte-specific marker glial fibrillary acidic protein (GFAP), as demonstrated by RT-PCR, Western blot, and immunocytochemistry. In addition, RA-treated CD133+ cells expressed cell type-specific markers for oligodendrocytes including myelin basic protein (MBP) as shown by RT-PCR, proteolipid protein (PLP) by Western blot analysis, and cyclic nucleotide phosphodiesterase (CNPase) by immunostaining. Upregulated expression of several basic helix-loop-helix (bHLH) transcription factors important for early neurogenesis, including Otx2, Pax6, Wnt1, Olig2, Hash1 and NeuroD1, was also demonstrated in CD133+ cells after RA treatment. These results indicate that human cord blood-derived CD133+ hematopoietic stem cells could trans-differentiate into neural cell types of neuron-like cells, astrocytes, and oligodendrocytes by RA treatment.

Clinical and experimental study on therapeutic effect of umbilical cord blood transplantation on severe viral hepatitis

AIM: To investigate the therapeutic effect of umbilical cord blood transplantation (UCBT) on patients with severe viral hepatitis and on liver lesions in rats.

METHODS: One hundred and fifty three patients with severe viral hepatitis were included in the study between April 1990 and July 2002. The patients were treated with adult plasma transfusion (control), UCBT, plasma exchange (PE) and UCBT combined with PE (UCBT+PE) respectively. The therapeutic effectiveness was evaluated by serial determinations of liver function, lipids and immune function in all patients before and after the treatment. The model of experimental hepatic failure was constructed in SD rats by injecting carbon tetrachloride. Then, the rats were given normal saline, adult plasma or neonate cord blood intraperitoneally. After detection of liver function, the rats were killed and morphological changes of the liver were microscopically observed.

RESULTS: UCBT group and UCBT+PE group had much better improvement in liver and immune functions than control group and PE group. The patients in UCBT+PE group had the best clinical efficacy. UCBT was safe and had no side effects. The animal experiment showed significant improvements in liver function and survival rate in neonate cord blood group as compared with adult plasma group. The histopathology of rat’s liver indicated that neonate cord blood application could decrease the liver injury and increase hepatocellular regeneration.

CONCLUSION: UCBT demonstrated a good therapeutic effect on severe viral hepatitis and no obvious side effects. Umbilical cord blood can attenuate the liver lesions and reproduce hepatocyte. The treatment of UCBT combined with PE was much better than that of single plasma exchange, thus UCBT can enhance the therapeutic effect of plasma exchange on severe viral hepatitis.

Intravenous versus intrastriatal cord blood administration in a rodent model of stroke

Human umbilical cord blood (hUCB) is a rich source of hematopoietic stem cells that have been used to reconstitute immune cells and blood lineages. Cells from another hematopoietic source, bone marrow, have been found to differentiate into neural cells and are effective in the treatment of stroke. In this study, we administered hUCB cells intravenously into the femoral vein or directly into the striatum and assessed which route of cell administration produced the greatest behavioral recovery in rats with permanent middle cerebral artery occlusion (MCAO). All animals were immunosuppressed with cyclosporine (CSA). When spontaneous activity was measured using the Digiscan automated system, it was found to be significantly less when hUCB was transplanted 24 hr after stroke compared with nontransplanted, stroked animals (P < 0.01). Furthermore, behavioral recovery was similar with both striatal and femoral hUCB delivery. This is in contrast to the step test, in which significant improvements were found only after femoral delivery of the hUCB cells. In the passive avoidance test, transplanted animals learned the task faster than nontransplanted animals (P < 0.05). Together, these results suggest that hUCB transplantation may be an effective treatment for brain injuries, such as stroke, or neurodegenerative disorders. In addition, intravenous delivery may be more effective than striatal delivery in producing long-term functional benefits to the stroked animal.

Human umbilical cord blood stem cells infusion in spinal cord injury: engraftment and beneficial influence on behavior

The use of human umbilical cord blood (hUCB)--a rich source of nonembryonic or adult stem cells--has recently been reported to ameliorate behavioral consequences of stroke. In this study, we tested whether human cord blood leukocytes also ameliorate behavioral impairments of spinal cord injury. Rats were divided into five groups: (1) laminectomy (without spinal cord injury) only; (2) laminectomy + cord blood infusion; (3) spinal cord injury + cord blood infused 1 day post injury; (4) spinal cord injury + cord blood infused 5 days post injury; and (5) spinal cord injury only. Spinal cord injury was induced by compressing the spinal cord for 1 min with an aneurysm clip calibrated to a closing pressure of 55 g. Open-field behavior was assessed 1, 2, and 3 weeks after intravenous injection of prelabeled human cord blood cells. Open-field test scores of spinal cord injured rats treated with human cord blood at 5 days were significantly improved as compared to scores of rats similarly injured but treated at day 1 as well as the otherwise untreated injured group. The results suggest that cord blood stem cells are beneficial in reversing the behavioral effects of spinal cord injury, even when infused 5 days after injury. Human cord blood-derived cells were observed in injured areas, but not in noninjured areas, of rat spinal cords, and were never seen in corresponding areas of spinal cord of noninjured animals. The results are consistent with the hypothesis that cord blood-derived stem cells migrate to and participate in the healing of neurological defects caused by traumatic assault.

Realistic prospects for stem cell therapeutics

Studies of the regenerating hematopoietic system have led to the definition of many of the fundamental principles of stem cell biology. Therapies based on a range of tissue stem cells have been widely touted as a new treatment modality, presaging an emerging new specialty called regenerative medicine that promises to harness stem cells from embryonic and somatic sources to provide replacement cell therapies for genetic, malignant, and degenerative conditions. Insights borne from stem cell biology also portend development of protein and small molecule therapeutics that act on endogenous stem cells to promote repair and regeneration. Much of the newfound enthusiasm for regenerative medicine stems from the hope that advances in the laboratory will be followed soon thereafter by breakthrough treatments in the clinic. But how does one sort through the hype to judge the true promise? Are stem cell biologists and the media building expectations that cannot be met? Which diseases can be treated, and when can we expect success? In this review, we outline the realms of investigation that are capturing the most attention, and consider the current state of scientific understanding and controversy regarding the properties of embryonic and somatic (adult) stem cells. Our objective is to provide a framework for appreciating the promise while at the same time understanding the challenges behind translating fundamental stem cell biology into novel clinical therapies.