A Model of Ischemia-Induced Neuroblast Activation in the Adult Subventricular Zone

Abstract

We have developed a rat brain organotypic culture model, in which tissue slices contain cortex-subventricular zone-striatum regions, to model neuroblast activity in response to in vitro ischemia. Neuroblast activation has been described in terms of two main parameters, proliferation and migration from the subventricular zone into the injured cortex. We observed distinct phases of neuroblast activation as is known to occur after in vivo ischemia. Thus, immediately after oxygen/glucose deprivation (6–24 hours), neuroblasts reduce their proliferative and migratory activity, whereas, at longer time points after the insult (2 to 5 days), they start to proliferate and migrate into the damaged cortex. Antagonism of ionotropic receptors for extracellular ATP during and after the insult unmasks an early activation of neuroblasts in the subventricular zone, which responded with a rapid and intense migration of neuroblasts into the damaged cortex (within 24 hours). The process is further enhanced by elevating the production of the chemoattractant SDf-1α and may also be boosted by blocking the activation of microglia. This organotypic model which we have developed is an excellent in vitro system to study neurogenesis after ischemia and other neurodegenerative diseases. Its application has revealed a SOS response to oxygen/glucose deprivation, which is inhibited by unfavorable conditions due to the ischemic environment. Finally, experimental quantifications have allowed us to elaborate a mathematical model to describe neuroblast activation and to develop a computer simulation which should have promising applications for the screening of drug candidates for novel therapies of ischemia-related pathologies.

An organotypic culture model to study nigro-striatal degeneration

“…Cell division can be activated by a combination of injury and growth factor stimulation (Gleason et al, 2008). Alternatively, division may be inhibited by a negative environment, such as that associated with ischemia, (Vergni et al, 2009). On the basis of the results obtained with the novel organotypic model which we have described here, it seems reasonable to think that dopamine depletion predisposes neural stem cells of the subventricular zone to differentiate into dopaminergic cells (Fig.…”

Utility of Organotypic Slices in Parkinson's Disease Research

“…It is still not clear whether the increment of TH in SVZ cells means an increment in protein synthesis or generation of newborn TH + cells, but the functional meaning seems to be a response to the damage generated in the striatal area. PD can also be modeled in organotypic cultures from cortex-striatum and SVZ (Cavaliere et al, 2005;Vergni et al, 2009;Tønnesen et al, 2011;Fig.3) in which dopaminergic inputs from the substantia nigra to the striatum are severed by slicing. This model is extremely useful especially in studying neurogenesis induced after severe nigro-striatal degeneration.…”

“…In fact, the most important problem with the use of human fetal stem cells, besides the poor availability, is the lack of standardization, which results in a high variability in the degree of symptomatic relief. To overcome the secondary effects of using embryonic and fetal stem cells, several groups have used adult stem cells for transplantation located primarily in the SVZ of the forebrain and in the sub-granular layer of the dentate gyrus of the hippocampal formation (Vergni et al, 2009). However, newly generated cells with a neuronal phenotype can be generated also from adult tissues that are different from the brain.…”

“…with neurotrophic factors), or by the clearance of local negative environment (e.g. blocking excitotoxicity and apoptosis) (Vergni et al, 2009) Despite problems, the use of cell therapy for the replacement of dead neurons results an attractive strategy for the treatment of PD. Here we review different in vitro experimental models used to study the cellular mechanisms of PD and highlight the feasibility of such models for each of the use described above (pharmacological treatment, gene therapy or cell transplantation).…”

Culturing conditions remarkably affect viability and organization of mouse subventricular zone in ex vivo cultured forebrain slices

“…The interface method is ideally suited for questions requiring a threedimensional structure, whereas slices cultured in roller tubes remain the method of choice for experiments that require optimal optical conditions. Subsequently, both methods were adapted for the study of specific neural circuits (e.g., corticostriatal and mesencephalostriatal pathways (Plenz and Kitai, 1996)), and more recently, they have been employed to study processes of postnatal neurogenesis/neurodegeneration, including: the migration of neural precursors generated within the normal embryonic/postnatal SVZ (De Marchis et al, 2001;Tanvig et al, 2009), the capacity of neural stem/progenitor cells to divide and migrate after transplantation (Dayer et al, 2008;Soares and Sotelo, 2004), lesion experimental models such as stroke and induced ischemia (Cavaliere et al, 2005(Cavaliere et al, , 2006Cavaliere et al, 2010;Cho et al, 2004;Laskowski et al, 2005;Newell et al, 1995;Vergni et al, 2009), or neurodegeneration models (Bernaudin et al, 1998;Noraberg et al, 1999).…”