| 1. |
- Deierborg, Tomas, et al.
(författare)
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Absence of striatal newborn neurons with mature phenotype following defined striatal and cortical excitotoxic brain injuries.
- 2009
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Ingår i: Experimental Neurology. - : Elsevier BV. - 0014-4886. ; 219, s. 363-367
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Tidskriftsartikel (refereegranskat)abstract
- Experimental stroke and excitotoxic brain lesion to the striatum or cortex increase the proliferation of cells residing within the ventricular wall and cause subsequent migration of newborn neuroblasts into the lesioned brain parenchyma. In this study, we clarify the different events of neurogenesis following striatal or cortical excitotoxic brain lesions in adult rats. Newborn cells were labeled by intraperitoneal injection of bromo-deoxy-uridine (BrdU), or by green fluorescent protein (GFP)-expressing lentiviral vectors injected into the subventricular zone (SVZ). We show that only neural progenitors born the first 5 days in the SVZ reside and expand within this neurogenic niche over time, and that these early labeled cells are more prone to migrate towards the striatum as neuroblasts. However, these neuroblasts could not mature into NeuN(+) neurons in the striatum. Furthermore, we found that cortical lesions, close or distant from the SVZ, could not upregulate SVZ cell proliferation nor promote neurogenesis. Our study demonstrates that both the time window for labeling proliferating cells and the site of lesion are crucial when assessing neurogenesis following brain injury.
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| 2. |
- Englund Johansson, Ulrica, et al.
(författare)
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Transplantation of human neural progenitor cells into the neonatal rat brain: extensive migration and differentiation with long-distance axonal projections.
- 2002
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Ingår i: Experimental Neurology. - : Elsevier BV. - 0014-4886 .- 1090-2430. ; 173:1, s. 1-21
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Tidskriftsartikel (refereegranskat)abstract
- Here we examined the ability of human neural progenitors from the embryonic forebrain, expanded for up to a year in culture in the presence of growth factors, to respond to environmental signals provided by the developing rat brain. After survival times of up to more than a year after transplantation into the striatum, the hippocampus, and the subventricular zone, the cells were analyzed using human-specific antisera and the reporter gene green fluorescent protein (GFP). From grafts implanted in the striatum, the cells migrated extensively, especially within white matter structures. Neuronal differentiation was most pronounced at the striatal graft core, with axonal projections extending caudally along the internal capsule into mesencephalon. In the hippocampus, cells migrated throughout the entire hippocampal formation and into adjacent white matter tracts, with differentiation into neurons both in the dentate gyrus and in the CA1-3 regions. Directed migration along the rostral migratory stream to the olfactory bulb and differentiation into granule cells were observed after implantation into the subventricular zone. Glial differentiation occurred at all three graft sites, predominantly at the injection sites, but also among the migrating cells. A lentiviral vector was used to transduce the cells with the GFP gene prior to grafting. The reporter gene was expressed for at least 15 weeks and the distribution of the gene product throughout the entire cytoplasmic compartment of the expressing cells allowed for a detailed morphological analysis of a portion of the grafted cells. The extensive integration and differentiation of in vitro-expanded human neural progenitor cells indicate that multipotent progenitors are capable of responding in a regionally specific manner to cues present in the developing rat brain.
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| 3. |
- Ericson, Cecilia, et al.
(författare)
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Ex vivo and in vitro studies of transgene expression in rat astrocytes transduced with lentiviral vectors.
- 2002
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Ingår i: Experimental Neurology. - : Elsevier BV. - 0014-4886. ; 173:1, s. 22-30
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Tidskriftsartikel (refereegranskat)abstract
- Implantation of cells genetically modified to express therapeutic genes into the brain has been proposed as a potential treatment for neurodegenerative diseases. In the current study embryonic rat-derived astrocytes were cultured and transduced with a lentiviral vector expressing the reporter gene green fluorescent protein (GFP) and subsequently grafted into the adult rat brain. The proportion of GFP expressing cells was stable, albeit small (1%), at all survival times, up to 6 weeks, the longest time point studied. In parallel in vitro studies, the astrocytes were lentivirally transduced to express either one of the two isoforms of glutamate decarboxylase (GAD(65) or GAD(67)) or glial cell line-derived neurotrophic factor (GDNF). When transducing 293T cells with the two GAD vectors, released GABA could be measured using high-performance liquid chromatography. Further studies of rat astrocytes transduced with the same vectors resulted in a level of GAD activity about 10 times higher than the activity of an intact rat striatum. One hundred thousand astrocytes transduced with LV-GDNF released approximately 27 ng of GDNF per hour. Thus, taken together, our observations provide support for the use of rat astrocytes in ex vivo gene transfer of these proteins in animal models of CNS disorders, e.g., Parkinson's disease or epilepsy.
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| 4. |
- Lundberg, Cecilia, et al.
(författare)
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Differentiation of the RN33B Cell Line into Forebrain Projection Neurons after Transplantation into the Neonatal Rat Brain.
- 2002
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Ingår i: Experimental Neurology. - : Elsevier BV. - 0014-4886 .- 1090-2430. ; 175:2, s. 370-387
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Tidskriftsartikel (refereegranskat)abstract
- The rat neural cell line RN33B has a remarkable ability to undergo region-specific neuronal differentiation after transplantation into the CNS. To further study its neurogenic properties in vivo, we used a recombinant lentiviral vector to genetically label the cells with the Green Fluorescent Protein (GFP) gene before implantation into the striatum/cortex, hippocampus, or mesencephalon of newborn rats. Three weeks after implantation, about 1-2% of the GFP-expressing cells had developed morphologies typical of neurons, astrocytes, or oligodendrocytes, the rest remained as either immature or undifferentiated nestin-positive cells. At 15-17 weeks postgrafting, the immature cells had disappeared in most graft recipients and only cells with neuronal or glial morphologies remained in similar numbers as at 3 weeks. The GFP distributed throughout the expressing cells, revealing fine morphological details, including dendrites with spines and extensive axonal projections. In all forebrain regions, the grafted cells differentiated into neurons with morphologies characteristic for each site, including large numbers of pyramidal-like cells in the cortex and the hippocampus, giving rise to dense projections to normal cortical target regions and to the contralateral hippocampus, respectively. In lower numbers, it was also possible to identify GFP-positive granulelike cells in the hippocampus, as well as densely spiny neurons in the striatum. In the mesencephalon by contrast, cells with astrocytic features predominated. The ability of the grafted RN33B cells to undergo region-specific differentiation into highly specialized types of forebrain projection neurons and establish connections with appropriate targets suggests that cues present in the microenvironment of the neonatal rat brain can effectively guide the development of immature progenitors, also in the absence of ongoing neurogenesis. (c) 2002 Elsevier Science (USA).
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| 5. |
- Rogelius, Nina, et al.
(författare)
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Retrovirally delivered Islet-1 increases recruitment of Ng2 expressing cells from the postnatal SVZ into the striatum.
- 2006
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Ingår i: Experimental Neurology. - : Elsevier BV. - 0014-4886. ; 201:Jun 23, s. 388-398
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Tidskriftsartikel (refereegranskat)abstract
- Neural stem and progenitor cells hold the promise to be used in cell-based therapies to treat both acute and degenerative neurological diseases. To date, most research has been focused on the use of in vitro propagated stem cells used as a source of cells in cell replacement therapies. However, mobilization of endogenous neural stem cells to generate a specific differentiated cell type offers an attractive alternative. In this study, we investigate the possibility to direct the formation of specific cells from the endogenous stem and progenitor cells residing in the subventricular region of the postnatal brain. With the aim to induce postnatal generation of striatal neurons, we ectopically expressed Islet-1, a LIM homeodomain transcription factor expressed by striatal progenitors during development, in cells of the subventricular zone (SVZ) of neonatal and adult rats. Ectopic expression of Islet-1 in the neonatal, but not adult, SVZ resulted in the appearance of a population of cells in the striatum. These cells were primarily located in the ventrolateral area of the striatum where they differentiate into Ng2 expressing cells. However, no neurogenesis was observed in the striatum, nor was ectopic striatal differentiation observed in any other area of the brain after retroviral expression of Islet-1 in the SVZ. Thus, although ectopic expression of Islet-1 is sufficient to direct the migration of cells into the striatum in neonatal animals, it does not specify a striatal projection neuron phenotype in cells generated from the SVZ after birth. (c) 2006 Elsevier Inc. All rights reserved.
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| 6. |
- Toft Sörensen, Andreas, et al.
(författare)
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Activity-dependent long-term plasticity of afferent synapses on grafted stem/progenitor cell-derived neurons.
- 2011
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Ingår i: Experimental Neurology. - : Elsevier BV. - 0014-4886. ; 229, s. 274-281
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Tidskriftsartikel (refereegranskat)abstract
- Stem cell-based cell replacement therapies aiming at restoring injured or diseased brain function ultimately rely on the capability of transplanted cells to promote functional recovery. The mechanisms by which stem cell-based therapies for neurological conditions can lead to functional recovery are uncertain, but structural and functional repair appears to depend on integration of transplanted cell-derived neurons into neuronal circuitries. The nature by which stem/progenitor cell-derived neurons synaptically integrate into neuronal circuitries is largely unexplored. Here we show that transplanted GFP-labeled neuronal progenitor cells into the rat hippocampus exhibit mature neuronal morphology following 4-10 weeks. GFP-positive cells were preferentially integrated into the principal cell layers of hippocampus, particularly CA3. Patch-clamp recordings from GFP-expressing cells revealed that they generated fast action potentials, and their intrinsic membrane properties were overall similar to endogenous host neurons recorded in same areas. As judged by occurrence of spontaneous excitatory postsynaptic currents (EPSCs), transplanted GFP-positive cells were synaptically integrated into the host circuitry. Comparable to host neurons, both paired-pulse depression and facilitation of afferent fiber stimulation-evoked EPSCs were observed in GFP-positive cells. Upon high-frequency stimulation, GFP-positive cells displayed post-tetanic potentiation of EPSCs, in some cases followed by long-term potentiation (LTP) lasting for more than 30 min. Our data show for the first time that transplanted neuronal progenitor cells can become functional neurons and their afferent synapses are capable of expressing activity-dependent short and long-term plasticity. These synaptic properties may facilitate host-to-graft interactions and regulate activity of the grafted cells promoting functional recovery of the diseased brain.
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