Spinal cord neuroepithelial progenitor cells display developmental plasticity when co-cultured with embryonic spinal cord slices at different stages of development

All neurons and glial cells of the vertebrate CNS are derived from embryonic neuroepithelial progenitor cells (NEP). Distinct modes of radial neuronal migration, locomotion, and somal translocation have been described in the cerebral cortex, but less is known about the migratory behavior of neuroepithelial cells and their neuronal and glial descendants in the developing spinal cord. Here a novel spinal cord slice co-culture was developed to investigate the migration and differentiation potential of NEPs in the developing spinal cord. E12 NEPs from eGFP transgenic mouse cells were co-cultured with E12, E14, E16, and E18 organotypic spinal cord slices. Time-lapse confocal microscopy and quantitative 3D image analysis revealed that the co-cultured E12 eGFP NEP cells differentiated at a faster rate with increasing age of embryonic spinal cord slice but migrated further in younger slices. Furthermore, it revealed fast tangentially migrating cells and slower radially migrating cells undergoing locomotion and somal translocation. The ability of NEP cells to alter their migration and differentiation within embryonic microenvironments of different ages highlights their developmental plasticity and ability to respond to temporally expressed extrinsic signals

A method to investigate radial glia cell behavior using two-photon time-lapse microscopy in an ex vivo model of spinal cord development

The mammalian central nervous system (CNS) develops from multipotent progenitor cells, which proliferate and differentiate into the various cell types of the brain and spinal cord. Despite the wealth of knowledge from progenitor cell culture studies, there is a significant lack of understanding regarding dynamic progenitor cell behavior over the course of development. This is in part due to shortcomings in the techniques available to study these processes in living tissues as they are occurring. In order to investigate cell behavior under physiologically relevant conditions we established an ex vivo model of the developing rat spinal cord. This method allows us to directly observe specific populations of cells ex vivo in real time and over extended developmental periods as they undergo proliferation, migration, and differentiation in the CNS. Previous investigations of progenitor cell behavior have been limited in either spatial or temporal resolution (or both) due to the necessity of preserving tissue viability and avoiding phototoxic effects of fluorescent imaging. The method described here overcomes these obstacles. Using two-photon and confocal microscopy and transfected organotypic spinal cord slice cultures we have undertaken detailed imaging of a unique population of neural progenitors, radial glial cells. This method uniquely enables analysis of large populations as well as individual cells; ultimately resulting in a 4D dataset of progenitor cell behavior for up to 7 days during embryonic development. This approach can be adapted to study a variety of cell populations at different stages of development using appropriate promoter driven fluorescent protein expression. The ability to control the tissue micro-environment makes this ex vivo method a powerful tool to elucidate the underlying molecular mechanisms regulating cell behavior during embryonic development

Characterisation of the consequences of maternal immune activation on distinct cell populations in the developing rat spinal cord

Maternal immune activation (MIA) during gestation has been implicated in the development of neurological disorders such as schizophrenia and autism. Epidemiological studies have suggested that the effect of MIA may depend on the gestational timing of the immune challenge and the region of the central nervous system (CNS) in ques?tion. This study investigated the effects of MIA with 100 μg/kg lipopolysaccharide at  either Embryonic days (E)12 or E16 on the oligodendrocytes, microglia and astrocytes  of the offspring spinal cord. At E16, MIA decreased the number of olig2+ and Iba-1+cells in multiple grey and white matter regions of the developing spinal cord 5 h after  injection. These decreases were not observed at postnatal day 14. In contrast, MIA at  E12 did not alter Olig2+ or Iba-1+ cell number in the developing spinal cord 5 h after  injection, however, Olig2+ cell number was decreased in the ventral grey matter of  the P14 spinal cord. No changes were observed in glial fibrillary acidic protein (GFAP)  expression at P14 following MIA at either E12 or E16. These data suggest that E16  may be a window of immediate vulnerability to MIA during spinal cord development,  however, the findings also suggest that the developmental process may be capable of  compensation over time. Potential changes in P14 animals following the challenge at  E12 are indicative of the complexity of the effects of MIA during the developmental  process</p

An ex vivo model to quantitatively analyze cell migration in tissue

Background: Within the developing central nervous system, the ability of cells to migrate throughout the tissue parenchyma to reach their target destination and undergo terminal differentiation is vital to normal central nervous system (CNS) development. To develop novel therapies to treat the injured CNS, it is essential that the migratory behavior of cell populations is understood. Many studies have examined the ability of individual neurons to migrate through the developing CNS, describing specific modes of migration including locomotion and somal translocation. Few studies have investigated the mass migration of large populations of neural progenitors, particularly in the developing the spinal cord. Here, we describe a method to robustly analyze large numbers of migrating cells using a co-culture assay. Results: The ex vivo tissue model promotes the survival and differentiation of co-cultured progenitor cells. Using this assay, we demonstrate that migrating neuroepithelial progenitor cells display region specific migration patterns within the dorsal and ventral spinal cord at defined developmental time points. Conclusions: The technique described here is a viable ex vivo model to quantitatively analyze cell migration and differentiation. We demonstrate the ability to detect changes in cell migration within distinct tissue region across tissue samples using the technique described here

Migration and the labour market The case of Germany

SIGLEAvailable from British Library Document Supply Centre-DSC:D192411 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Reelin: Diverse roles in central nervous system development, health and disease

Over the past 20 years the structure and function of Reelin, an extracellular glycoprotein with a role in cell migration and positioning during development has been elucidated. Originally discovered in mice exhibiting a peculiar gait and hypoplastic cerebellar tissue, Reelin is secreted from Cajal-Retzius neurons during embryonic life and has been shown to act as a stop signal, guiding migrating radial neurons in a gradient-dependent manner. Reelin carries out its function by binding to the receptors, very low-density lipoprotein receptor (VLDLR) and apolipoprotein E receptor 2 (ApoER2) resulting in the phosphorylation of the intracellular protein Disabled-1 (Dab-1) which is essential for effective Reelin signaling. Abnormalities in the RELN gene can result in multiple unusual structural outcomes including disruption of cortical layers, heterotopia, polymicrogyria and lissencephaly. Recent research has suggested a potential role for Reelin in the pathogenesis of neurological diseases such as schizophrenia, autism and Alzheimer’s disease. This short review will address the current understanding of the structure and function of this protein and its emerging role in the development of neurological disorders

Rod and cone photoreceptor cells produce ROS in response to stress in a live retinal explant system

Purpose: The production of reactive oxygen species (ROS) can lead to oxidative stress, which is a strong contributory factor to many ocular diseases. In this study, the removal of trophic factors is used as a model system to investigate the effects of stress in the retina. The aims were to determine if both rod and cone photoreceptor cells produce ROS when they are deprived of trophic factor support and to demonstrate if the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox) enzymes are responsible for this ROS production. Methods: Retinas were explanted from mice aged between postnatal days 8–10 and cultured overnight. The following morning, confocal microscopy combined with various fluorescent probes was used to detect the production of ROS. Each time peanut agglutinin (PNA), a cone photoreceptor marker, was used to facilitate orientation of the retina. Dihydroethidium and dihydrorhodamine 123 (DHR123) were used to determine which cells produce ROS. Subsequently, western blots of retinal serial sections were used to detect the presence of Noxs in the different retinal layers. The Nox inhibitor apocynin was then tested to determine if it altered the production of ROS within these cells. Results: Live retinal explants, viewed at high magnifications using confocal microscopy, displayed an increase in the fluorescent products of dihydroethidium and DHR123 upon serum removal when compared to controls. DHR123 fluorescence, once oxidized, localized to mitochondria and was found in the same focal plane as the PNA staining. This showed that cones and rods produced ROS when stressed. Retinal serial sectioning established that the photoreceptor layer expressed Nox4, dual oxidase (Duox) 1, and Duox2 at varying levels. Finally, the Nox inhibitor apocynin decreased the burst stimulated by the stress of serum removal. Conclusions: Confocal microscopy and PNA staining allowed differentiation of cell types within the outermost layers of the retina, demonstrating that both rods and cones generated ROS in response to the stress of serum deprivation. Nox4 was the most abundantly expressed Nox in the photoreceptor layer, but Duox1 and Duox2 were also present at detectable levels, and as apocynin reduced the levels of ROS produced, this implied that these proteins may play some role in this production