Segregation of human neural stem cells in the developing primate forebrain.

Many central nervous system regions at all stages of life contain neural stem cells (NSCs). We explored how these disparate NSC pools might emerge. A traceable clone of human NSCs was implanted intraventricularly to allow its integration into cerebral germinal zones of Old World monkey fetuses. The NSCs distributed into two subpopulations: One contributed to corticogenesis by migrating along radial glia to temporally appropriate layers of the cortical plate and differentiating into lamina-appropriate neurons or glia; the other remained undifferentiated and contributed to a secondary germinal zone (the subventricular zone) with occasional members interspersed throughout brain parenchyma. An early neurogenetic program allocates the progeny of NSCs either immediately for organogenesis or to undifferentiated pools for later use in the "postdevelopmental" brain.

IGF-I and bFGF improve dopamine neuron survival and behavioral outcome in parkinsonian rats receiving cultured human fetal tissue strands.

To promote dopamine cell survival in human fetal tissue strands transplanted into immunosuppressed 6-OHDA-lesioned rats, we have preincubated tissue in insulin-like growth factor-I (IGF-I, 150 ng/ml) and basic fibroblast growth factor (bFGF, 15 ng/ml) in vitro for 2 weeks. Growth factor treatment did not affect the rate of homovanillic acid production in vitro but increased overall dopamine neuron survival in animals after transplant from 1240 +/- 250 to 2380 +/- 440 neurons (P < 0.05). Animals in the growth factor-treated group had a significantly greater reduction in methamphetamine-induced rotation (66%) compared to control transplants (30%, P < 0.05). We conclude that in vitro preincubation of human fetal tissue strands with IGF-I and bFGF improves dopamine cell survival and the behavioral outcome of transplants.

Inhibitors of p38 MAP kinase increase the survival of transplanted dopamine neurons.

Fetal cell transplantation therapies are being developed for the treatment of a number of neurodegenerative disorders including Parkinson's disease [10-12,21,22,24,36,43]. Massive apoptotic cell death is a major limiting factor for the success of neurotransplantation. We have explored a novel protein kinase pathway for its role in apoptosis of dopamine neurons. We have discovered that inhibitors of p38 MAP kinase (the pyridinyl imidazole compounds: PD169316, SB203580, and SB202190) improve survival of rat dopamine neurons in vitro and after transplantation into hemiparkinsonian rats. In embryonic rat ventral mesencephalic cultures, serum withdrawal led to 80% loss of dopamine neurons due to increased apoptosis. Incubation of the cultures with p38 MAP kinase inhibitors at the time of serum withdrawal prevented dopaminergic cell death by inhibiting apoptosis. In the hemiparkinsonian rat, preincubation of ventral mesencephalic tissue with PD169316 prior to transplantation accelerated behavioral recovery and doubled the survival of transplanted dopamine neurons. We conclude that inhibitors of stress-activated protein kinases improve the outcome of cell transplantation by preventing apoptosis of neurons after grafting.

IGF-1 and bFGF reduce glutaric acid and 3-hydroxyglutaric acid toxicity in striatal cultures.

Glutaric acid (GA) and 3-hydroxyglutaric acid (3GA) are thought to contribute to the degeneration of the caudate and putamen that is seen in some children with glutaric acidaemia type I, a metabolic disorder caused by a glutaryl-CoA dehydrogenase deficiency. This study assessed the neurotoxicity of GA and 3GA (0-50 mmol/L) compared to quinolinic acid (QUIN) in striatal and cortical cultures. All three acids were neurotoxic in a dose-dependent manner; however, GA and 3GA were both more toxic than QUIN. The neurotoxic effects of low concentrations of GA or 3GA were additive to QUIN toxicity. A series of hormones and growth factors were tested for protection against GA and 3GA toxicity. Insulin (5-500 microU /ml), basic fibroblast growth factor (bFGF; 10 ng/ml), insulin-like growth factor (IGF-1; 50 ng/ml), brain-derived neurotrophic factor (BDNF; 10 ng/ml), glial-derived neurotrophic factor (GDNF; 10 ng/ml), and two glutamate antagonists were evaluated in brain cultures to which 7 mmol/L GA or 3GA were added. GA and 3GA neurotoxicities were prevented by bFGF. Attenuation of 3GA-induced neurotoxicity was seen with insulin (5 microU/ml) and IGF-1. BDNF and GDNF had no effects on neuronal survival. Glutamate antagonists MK801 (10 micromol/L) and NBQX (10 micromol/L) failed to prevent GA or 3GA neurotoxicity. We conclude that GA and 3GA are neurotoxic in cultures of embryonic rat striatum and cortex. Striatal neurons were rescued from death by bFGF and IGF-1 but not by glutamate antagonist, suggesting that toxicity in this embryonic system is not necessarily mediated by glutamate receptors.

Strands of embryonic mesencephalic tissue show greater dopamine neuron survival and better behavioral improvement than cell suspensions after transplantation in parkinsonian rats.

The success of embryonic neural transplants as a treatment for patients with Parkinson's disease has been limited by poor survival of transplanted dopamine neurons. To see if a new partially intact tissue preparation method improves survival, we have developed a technique for extruding embryonic tissue into strands. We expected this method to reduce cell damage and improve transplant survival as well as provide improved tissue delivery. We have compared transplants of tissue strands with mechanically dispersed suspensions of embryonic day 15 rat ventral mesencephalon. Tissue from ventral mesencephalon was transplanted into a single site in dopamine denervated striatum of unilateral 6-hydroxydopamine (6-OHDA) lesioned rats. To evaluate the effects of striatal cografts and growth factors on dopamine cell survival, dispersed mesencephalic cells were cotransplanted with dispersed striatal cells. Another group had dispersed mesencephalic cells cotransplanted with striatal cells incubated in the cold for 2 h with glial cell line-derived neurotrophic factor (GDNF, 100 ng/ml), insulin-like growth factor-I (IGF-I, 1500 ng/ml), and basic fibroblast growth factor (bFGF, 150 ng/ml). Behavioral improvement was assessed monthly by changes in methamphetamine-induced rotational behavior. Animals were sacrificed after 3 months, and dopamine neurons were identified by tyrosine hydroxylase (TH) immunohistochemistry. Transplants of tissue strands produced better dopamine neuron survival and led to more robust behavioral restoration than did cell suspensions even when suspensions were supported with cografts of striatal cells or pretreatment with growth factors.

Growth factors improve immediate survival of embryonic dopamine neurons after transplantation into rats.

Embryonic dopamine neurons survive poorly after transplant into models of Parkinson's disease, possibly due to programmed cell death (apoptosis). Apoptosis in cultured dopamine neurons can be reduced by growth factors such as glial cell line-derived neurotrophic factor (GDNF) or a combination of insulin-like growth factor-I (IGF-I) and basic fibroblast growth factor (bFGF). To improve the survival of dopamine neurons in grafts, strands of E15 rat ventral mesencephalon were pretreated with a combination of GDNF, IGF-I, and bFGF and then transplanted into 6-hydroxydopamine-lesioned rats. In control animals, only 32% of dopamine neuron profiles survived the first 24 h after transplant. Growth factor pretreatment increased survival to 49% on day 1. Growth factors reduced the apoptotic rate of transplanted cells, just as they had in the previous in vitro experiments. Apoptotic nuclear morphology was observed in the transplanted dopamine neurons. We conclude that the majority of transplanted dopamine neurons die in grafts within the first 24 h after transplant, most likely by an apoptotic mechanism. Prevention of apoptosis with anti-apoptotic agents may improve the viability of dopamine neurons grafted for Parkinson's disease.

Somatic cell cloned transgenic bovine neurons for transplantation in parkinsonian rats.

Parkinson's disease symptoms can be improved by transplanting fetal dopamine cells into the putamen of parkinsonian patients. Because the supply of human donor tissue is limited and variable, an alternative and genetically modifiable non-human source of tissue would be valuable. We have generated cloned transgenic bovine embryos, 42% of which developed beyond 40 days. Dopamine cells collected from the ventral mesencephalon of the cloned fetuses 42 to 50 days post-conception survived transplantation into immunosuppressed parkinsonian rats and cells from cloned and wild-type embryos improved motor performance. Somatic cell cloning can efficiently produce transgenic animal tissue for treating parkinsonism.

GDNF improves survival and reduces apoptosis in human embryonic dopaminergic neurons in vitro.

Dopamine cell death is the primary problem limiting the value of neurotransplantation in human patients with Parkinson's disease. To address this problem, we added glial cell line-derived neurotrophic factor (GDNF) to cultures of embryonic dopaminergic neurons obtained from human and from Bonnet monkey (Macaca radiata) in an effort to reduce apoptotic cell death and improve overall cell survival. Tissue from three human embryos, 7-8 weeks post-conception, and one 9-week post-conception monkey embryo were dissociated and cultured in F-12 media with 5% human placental serum. GDNF (10 ng/ml) in human cultures nearly doubled dopamine neuron survival and reduced the rate of apoptosis from 6% to 3%. In monkey cultures, GDNF also enhanced dopamine neuron survival and reduced the apoptotic rate. We conclude that GDNF improves the survival of primate embryonic dopamine neurons in culture by reducing apoptosis.

Naloxone differentially alters fevers induced by cytokines.

Interferon-alpha (IFN-alpha), a cytokine acting as an endogenous pyrogen and a putative activator of the opioid system, binds to opiate receptors in vitro. The mu opioid receptor antagonist, naloxone hydrochloride (NLX), attenuates IFN-alpha-induced increases in the firing rate of cold-sensitive neurons within thermosensitive areas of the brain. The influence of NLX on fevers induced by central endogenous pyrogens was investigated in rats. Subcutaneous (SQ) injection of NLX (1 mg/kg) was made 30 min prior to intracerebroventricular (ICV) injection of IFN-alpha 2b (7900IU). Alternatively, NLX (10 or 80 micrograms) was microinjected ICV 30 min prior to administration of IFN-alpha 2b. Administered SQ, NLX attenuated the febrile response to IFN-alpha 2b. In contrast, central (ICV) NLX did not attenuate fevers induced by IFN-alpha 2b. Animals previously exposed to both IFN-alpha 2b and NLX (SQ or ICV) subsequently lost their sensitivity to this cytokine, and also showed diminished reactivity to human recombinant interleukin-1 beta (hrIL-1 beta; 10 ng) and prostaglandin E2 (PGE2; 250 ng). These results suggest that systemic and central elements of the opioid system may play differential roles in temperature regulation. Previous administration of NLX and IFN-alpha 2b may alter the sensitivity of the CNS to subsequent injections of different pyrogens.

Conditioned medium from aged monkey fibroblasts stably expressing GDNF and BDNF improves survival of embryonic dopamine neurons in vitro.

Fibroblasts derived from the cerebral cortex of an aged Bonnet monkey (Macaca radiata) were utilized to express recombinant cDNAs encoding rat glial-cell-line-derived neurotrophic factor (GDNF) and human prepro brain-derived neurotrophic factor (BDNF) by lipofection. The cells showed stable expression and secretion of biologically active proteins. Conditioned medium from fibroblasts expressing BDNF or GDNF increased the number of surviving mesencephalic tyrosine-hydroxylase-immunoreactive neurons after 7 days in culture. The trophic effects of BDNF and GDNF were examined at two different plating densities of embryonic mesencephalic cells. At 50 000 cells/cm2 plating density, treatment of the mesencephalic cultures with BDNF-conditioned medium increased the number of tyrosine-hydroxylase-immunoreactive neurons by about 40% compared with vector-transfected control. At the same plating density, GDNF-conditioned medium increased the number of surviving tyrosine-hydroxylase-immunoreactive neurons above the vector-transfected control by 30%. When the tissue was plated at a higher density, viz., 75 000 cells/cm2, the number of tyrosine-hydroxylase-immunoreactive neurons increased by 41% with BDNF-conditioned medium, and by 56% with GDNF-conditioned medium above vector-transfected controls. Conditioned medium from cells secreting GDNF was also found to reduce the number of apoptotic tyrosine-hydroxylase-immunoreactive cells by 50%.

Insulin-like growth factor binding proteins in fetal rat mesencephalic cultures: regulation by fibroblast growth factor and insulin-like growth factor I.

In rat ventral mesencephalic cultures, IGF-I and bovine fibroblast growth factor (bFGF) act cooperatively to support the survival of dopaminergic neurons. To determine the potential role of IGFBPs in modulating the actions of IGF-I in the ventral mesencephalon, we identified the IGFBPs present in ventral mesencephalic cultures and examined their regulation by IGF-I and bFGF. In the absence of added growth factors, the major binding protein secreted from these cultures was IGFBP-2. Small amounts of IGFFBP-3 and IGFBP-4 were also detected. Addition of bFGF to the cultures increased the amounts of IGFBP-3 and IGFBP-4 released from the cells by 4.4 +/- 2.6 -fold (P < 0.1) and 11.5 +/- 3.5 -fold (P < 0.05), respectively. IGF-I, itself, had little effect on the production of IGFBPs, but when added together with bFGF increased the levels of IGFBP-3 and IGFBP-4 by 12.4 +/- 5.1 -fold (P < 0.05) and 27.4 +/- 5.3 -fold (P < 0.02), respectively. The stimulatory effect of bFGF and IGF-I on IGFBP production was apparent after a 2- to 3-day exposure of the mesencephalic cultures to the peptides. IGFBP-4, the most abundant IGFBP present in the cultures after 7 days of growth factor treatment, was immunocyto-chemically localized primarily to neurons, of which a subset were dopaminergic neurons. The addition of purified rat IGFBP-4 to the cultures in the absence of added growth factors had no effect on the survival of dopaminergic neurons, but when added with IGF-I potentiated the effect of IGF-I on neuronal survival. We propose that the up-regulation of IGFBP-4 by IGF-I and bFGF may serve to localize IGF-I to sites of action in the nervous system and thereby potentiate the neurotrophic actions of IGF-I.

Growth factors rescue embryonic dopamine neurons from programmed cell death.

Poor survival of embryonic dopamine neurons is a primary problem limiting the value of neurotransplantation for Parkinson's disease. Several neurotrophic factors have been shown to promote dopamine neuron survival when used individually in culture. We have found that two peptides, insulin-like growth factor-I (IGF-I) and basic fibroblast growth factor (bFGF), have additive effects on cell survival when used in combination. These growth factors reduced the number of dopamine cells undergoing apoptotic cell death. The neurotrophic factors induced proliferation of astrocytes but not dopamine neurons. When cell proliferation was blocked by cytosine arabinoside, the beneficial effects of IGF-I and bFGF were abolished, suggesting that effects of the growth factors were mediated, at least in part, by factors associated with glia. These results indicate that growth factors in combination may prove useful for enhancing dopamine neuron survival for neurotransplantation.

GDNF reduces apoptosis in dopaminergic neurons in vitro.

To explore the mechanism by which glial cell line-derived neurotrophic factor (GDNF) improves cell survival, we measured the apoptotic rate of dopamine neurons incubated with GDNF. Cultures were prepared from embryonic day 15 rat mesencephalon in medium with 5% human placental serum. GDNF reduced the rate of apoptosis in dopamine neurons from 5% to 2%. By contrast, GDNF had no effect on apoptoisis in astrocytes from embryonic mesencephalon or from neonatal cortex. Co-cultures with embryonic striatum as well as with combinations of growth factors were also tested for effects on dopamine neuron survival. Neuronal survival was maximal during co-culture with striatal cells with or without added growth factors. We conclude that GDNF inhibits apoptotic cell death in dopamine neurons.

Chemokine-induced fever: intracerebroventricular actions of MIP-1 and MIP-1 alpha in rats.

The central pyrogenic actions in the rat of doublet macrophage inflammatory protein-1 (MIP-1) and MIP-1 alpha were determined by their intracerebroventricular infusion. Doses of 560 pg and 11.2 ng of MIP-1 or 10.0 ng MIP-1 alpha infused into the third cerebral ventricle induced a long lasting fever. However, MIP-1 alpha was much less potent than MIP-1 in terms of intensity and longer latency. Overall, these cytokines are pyrogenic when acting on the walls of the third ventricle; however, a dose 10 times greater than that injected directly into the anterior hypothalamus is required to evoke fever, as based on earlier experiments. Finally, circulating MIP-1 could act centrally by its entry through the choroid plexus into the ventricular system of the brain.

Fever evoked by macrophage inflammatory protein-1 (MIP-1) injected into preoptic or ventral septal area of rats depends on intermediary protein synthesis.

Macrophage inflammatory protein-1 (MIP-1), a novel cytokine composed of alpha/beta subunits, is released from macrophages during infection. MIP-1 injected intravenously in the rabbit or into the anterior hypothalamic, preoptic area (AH/POA) of the rat causes an intense fever, which is not blocked by prostaglandin synthesis inhibitors, ibuprofin or indomethacin, respectively. The purpose of this study was to determine the role of de novo protein synthesis on the fever evoked by MIP-1 applied to thermosensitive cells of the AH/POA. Guide cannulae were implanted bilaterally above the AH/POA or ventral septal area (VSA) and medially above the third cerebral ventricle in each of 11 male Sprague-Dawley rats. Following postoperative recovery, body temperature (Tb) was monitored by a colonic thermistor probe. The bilateral microinjection of MIP-1 in a dose of 14 pg per 0.5 microliters into the AH/POA caused a biphasic elevation in Tb to 0.9 +/- 0.2 degrees C within 1.0 h, which reached 1.5 +/- 0.2 degrees C within 3.0 h, and persisted for over 6.0 h. An identical injection of MIP-1 into the VSA increased Tb biphasically to 0.1 +/- 0.1 degrees C within 1.0 h and to 0.8 +/- 0.3 degrees C within 3.0 h. The infusion into the third ventricle of 80 micrograms/10 microliters of the inhibitor of protein synthesis, anisomycin, either 10 or 30 min before the microinjection of MIP-1 into the AH/POA, attenuated significantly the rise in Tb for 1.0 to 3.0 h or 2.5 to 3.0 h, respectively. These results coincide with the earlier finding that anisomycin inhibits both endotoxin- and IL-1 beta-induced fevers.(ABSTRACT TRUNCATED AT 250 WORDS)