The derivation of neural progenitor cells from human embryonic stem (ES) cells is of value both in the study of early human neurogenesis and in the creation of an unlimited source of donor cells for neural transplantation therapy. Here we report the generation of enriched and expandable preparations of proliferating neural progenitors from human ES cells. The neural progenitors could differentiate in vitro into the three neural lineages--astrocytes, oligodendrocytes, and mature neurons. When human neural progenitors were transplanted into the ventricles of newborn mouse brains, they incorporated in large numbers into the host brain parenchyma, demonstrated widespread distribution, and differentiated into progeny of the three neural lineages. The transplanted cells migrated along established brain migratory tracks in the host brain and differentiated in a region-specific manner, indicating that they could respond to local cues and participate in the processes of host brain development. Our observations set the stage for future developments that may allow the use of human ES cells for the treatment of neurological disorders.

To evaluate the feasibility, safety, and immunological effects of intrathecal and intravenous administration of autologous mesenchymal stem cells (MSCs) (also called mesenchymal stromal cells) in patients with multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS). Design: A phase 1/2 open-safety clinical trial. Patients: Fifteen patients with MS (mean [SD] Expanded Disability Status Scale [EDSS] score, 6.7 [1.0]) and 19 with ALS (mean [SD] Amyotrophic Lateral Sclerosis Functional Rating Scale [ALSFRS] score, 20.8 [8.0]) were enrolled. Intervention: After culture, a mean (SD) of 63.2ϫ 10 6(2.5ϫ10 6 ) MSCs was injected intrathecally (n =34) and intravenously (n = 14). In 9 cases, MSCs were magnetically labeled with the superparamagnetic iron oxide ferumoxides (Feridex). Main Outcome Measures:The main outcome measure was the recording of side effects. Follow-up (Յ25 months) included adverse events evaluation, neurological disability assessment by means of the EDSS, magnetic resonance imaging to exclude unexpected pathologies and track the labeled stem cells, and immunological tests to assess the short-term immunomodulatory effects of MSC transplantation.Results: Twenty-one patients had injection-related adverse effects consisting of transient fever, and 15 reported headache. No major adverse effects were reported during follow-up. The mean ALSFRS score remained stable during the first 6 months of observation, whereas the mean (SD) EDSS score improved from 6.7 (1.0) to 5.9 (1.6). Magnetic resonance imaging visualized the MSCs in the occipital horns of the ventricles, indicating the possible migration of ferumoxides-labeled cells in the meninges, subarachnoid space, and spinal cord. Immunological analysis revealed an increase in the proportion of CD4 ϩ CD25 ϩ regulatory T cells, a decrease in the proliferative responses of lymphocytes, and the expression of CD40 ϩ , CD83 ϩ , CD86 ϩ , and HLA-DR on myeloid dendritic cells at 24 hours after MSC transplantation. Conclusion:Transplantation of MSCs in patients with MS and ALS is a clinically feasible and relatively safe procedure and induces immediate immunomodulatory effects.

Several lines of evidence implicate the pro-inflammatory cytokine interleukin-1 (IL-1) in the etiology and pathophysiology of major depression. To explore the role of IL-1 in chronic stress-induced depression and some of its underlying biological mechanisms, we used the chronic mild stress (CMS) model of depression. Mice subjected to CMS for 5 weeks exhibited depressive-like symptoms, including decreased sucrose preference, reduced social exploration and adrenocortical activation, concomitantly with increased IL-1b levels in the hippocampus. In contrast, mice with deletion of the IL-1 receptor type I (IL-1rKO) or mice with transgenic, brain-restricted overexpression of IL-1 receptor antagonist did not display CMS-induced behavioral or neuroendocrine changes. Similarly, whereas in wild-type (WT) mice CMS significantly reduced hippocampal neurogenesis, measured by incorporation of bromodeoxyuridine (BrdU) and by doublecortin immunohistochemistry, no such decrease was observed IL-1rKO mice. The blunting of the adrenocortical activation in IL-1rKO mice may play a causal role in their resistance to depression, because removal of endogenous glucocorticoids by adrenalectomy also abolished the depressive-like effects of CMS, whereas chronic administration of corticosterone for 4 weeks produced depressive symptoms and reduced neurogenesis in both WT and IL-1rKO mice. The effects of CMS on both behavioral depression and neurogenesis could be mimicked by exogenous subcutaneous administration of IL-1b via osmotic minipumps for 4 weeks. These findings indicate that elevation in brain IL-1 levels, which characterizes many medical conditions, is both necessary and sufficient for producing the high incidence of depression found in these conditions. Thus, procedures aimed at reducing brain IL-1 levels may have potent antidepressive actions.

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To investigate the therapeutic potential of mesenchymal stromal cells (MSCs) in the chronic model of experimental autoimmune encephalomyelitis (EAE). Design: Mesenchymal stromal cells were obtained from the bone marrow of naïve C57BL and green fluorescent protein-transgenic mice and cultured with Eagle minimum essential medium/alpha medium after removal of adhering cells. Following 2 to 3 passages, MSCs were injected intraventricularly or intravenously into mice in which chronic EAE had been induced with myelin oligodendrocyte glycoprotein 35-55 peptide. Results: In 8 separate experiments, the intravenously and intraventricularly injected green fluorescent proteinpositive MSCs were attracted to the areas of central nervous system inflammation and expressed galactocerebroside, O4, glial fibrillary acidic protein, and ␤-tubulin type III. The clinical course of chronic EAE was ameliorated in MSC-treated animals (0% mortality; mean [SE] maximal EAE score, 1.76 [1.01] and 1.8 [0.46] in the intraventricular and intravenous groups, respectively, vs 13% and 21% mortality and 2.80 [0.79] and 3.42 [0.54]

IV administration of neural precursors inhibits EAE by a peripheral immunosuppressive effect. Our findings suggest a profound bystander inhibitory effect of NPCs on T-cell activation and proliferation in the lymph nodes, leading to amelioration of EAE.

Human embryonic stem cells (hESCs) may potentially serve as a renewable source of cells for transplantation. In Parkinson's disease, hESC-derived dopaminergic (DA) neurons may replace the degenerated neurons in the brain. Here, we generated highly enriched cultures of neural progenitors from hESCs and grafted the progenitors into the striatum of Parkinsonian rats. The grafts survived for at least 12 weeks, the transplanted cells stopped proliferating, and teratomas were not observed. The grafted cells differentiated in vivo into DA neurons, though at a low prevalence similar to that observed following spontaneous differentiation in vitro. Transplanted rats exhibited a significant partial correction of D-amphetamine and apomorphine-induced rotational behavior, along with a significant improvement in stepping and placing nonpharmacological behavioral tests. While transplantation of uncommitted hESC-derived neural progenitors induced partial behavioral recovery, our data indicate that the host-lesioned striatum could not direct the transplanted neural progenitors to acquire a dopaminergic fate. Hence, induction of their differentiation toward a midbrain fate prior to transplantation is probably required for complete correction of behavioral deficit. Our observations encourage further developments for the potential use of hESCs in the treatment of Parkinson's disease.

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