Neural precursor-derived astrocytes of wobbler mice induce apoptotic death of motor neurons through reduced glutamate uptake.

In the present study, we investigated whether cultured astrocytes derived from adult neural precursor cells (NPCs) obtained from the subventricular zone (SVZ) of wobbler mice display metabolic traits of the wobbler astrocytes in situ and in primary culture. We also utilized NPC-derived astrocytes as a tool to investigate the involvement of astrocytes in the molecular mechanism of MND focusing on the possible alteration of glutamate reuptake since excitotoxicity glutamate-mediated may be a contributory pathway. NPC-derived wobbler astrocytes are characterized by high immunoreactivity for GFAP, significant decrease of glutamate uptake and reduced immunoreactivity for glutamate transporters GLT1 and GLAST. Spinal cord motor neurons obtained from healthy mouse embryos, when co-cultured with wobbler NPC-derived astrocytes, show reduced viability and morphologic alterations. These suffering motor neurons are caspase-7 positive, and treatment with anti-apoptotic drug V5 increases cell survival. Physical contact with wobbler astrocytes is not essential because purified motor neurons display reduced survival also when treated with the medium conditioned by wobbler NPC-derived astrocytes. Toxic levels of glutamate were revealed by HPLC assay in the extracellular medium of wobbler NPC-derived astrocytes, whereas the level of intracellular glutamate is reduced if compared with controls. Moreover, glutamate receptor antagonists are able to enhance motor neuron survival. Therefore, our results demonstrate that astrocytes derived from wobbler neural precursor cells display impaired glutamate homeostasis that may play a crucial role in motor neuron degeneration. Finally, the cultured astrocytes derived from NPCs of adult mice may offer a useful alternative in vitro model to study the molecular mechanisms involved in neurodegeneration.

Glioblastoma-derived tumorospheres identify a population of tumor stem-like cells with angiogenic potential and enhanced multidrug resistance phenotype.

We investigated in vitro the properties of selected populations of cancer stem-like cells defined as tumorospheres that were obtained from human glioblastoma. We also assessed their potential and capability of differentiating into mature cells of the central nervous system. In vivo, their tumorigenicity was confirmed after transplantation into the brain of non-obese diabetic/severe combined immunodeficient (NOD-SCID) mice. The angiogenic potential of tumorospheres and glioblastoma-derived cells grown as adherent cells was revealed by evaluating the release of angiogenic factors such as vascular endothelial growth factor and CXCL12 by ELISA, as well as by rat aortic ring assay. The proliferative response of tumorospheres in the presence of CXCL12 was observed for the first time. Multidrug resistance-associated proteins 1 and 3 as well as other molecules conferring multidrug resistance were higher when compared with primary adherent cells derived from the same tumor. Finally, we obtained cells from the tumor developing after grafting that clearly expressed the putative neural stem cell marker CD133 as shown by FACS analysis and also nestin and CXCR4. The cells' positivity for glial fibrillary acidic protein was very low. Moreover these cells preserved their angiogenic potential. We conclude that human glioblastoma could contain tumor cell subsets with angiogenic and chemoresistance properties and that this chemoresistance potential is highly preserved by immature cells whereas the angiogenic potential is, to a higher extent, a property of mature cells. A better understanding of the features of these cell subsets may favor the development of more specifically targeted therapies.