Glial cells: modulators of neuronal environment

Protein-Induced Pluripotent Stem Cells Ameliorate Cognitive Dysfunction and Reduce Aβ Deposition in a Mouse Model of Alzheimer's Disease

Transplantation of stem cells into the brain attenuates functional deficits in the central nervous system via cell replacement, the release of specific neurotransmitters, and the production of neurotrophic factors. To identify patient‐specific and safe stem cells for treating Alzheimer's disease (AD), we generated induced pluripotent stem cells (iPSCs) derived from mouse skin fibroblasts by treating protein extracts of embryonic stem cells. These reprogrammed cells were pluripotent but nontumorigenic. Here, we report that protein‐iPSCs differentiated into glial cells and decreased plaque depositions in the 5XFAD transgenic AD mouse model. We also found that transplanted protein‐iPSCs mitigated the cognitive dysfunction observed in these mice. Proteomic analysis revealed that oligodendrocyte‐related genes were upregulated in brains injected with protein‐iPSCs, providing new insights into the potential function of protein‐iPSCs. Taken together, our data indicate that protein‐iPSCs might be a promising therapeutic approach for AD. Stem Cells Translational Medicine2017;6:293–305

Neuronal-specific endoplasmic reticulum Mg2+/Ca2+ ATPase Ca2+ sequestration in mixed primary hippocampal culture homogenates

Endoplasmic reticulum Mg(2+)/Ca(2+) ATPase Ca(2+) sequestration is crucial for maintenance of neuronal Ca(2+) homeostasis. The use of cell culture in conjunction with modern Ca(2+) imaging techniques has been invaluable in elucidating these mechanisms. While imaging protocols evaluate endoplasmic reticulum Ca(2+) loads, measurement of Mg(2+)/Ca(2+) ATPase activity is indirect, comparing cytosolic Ca(2+) levels in the presence or absence of the Mg(2+)/Ca(2+) ATPase inhibitor thapsigargin. Direct measurement of Mg(2+)/Ca(2+) ATPase by isolation of microsomes is impossible due to the minuscule amounts of protein yielded from cultures used for imaging. In the current study, endoplasmic reticulum Mg(2+)/Ca(2+) ATPase Ca(2+) sequestration was measured in mixed homogenates of neurons and glia from primary hippocampal cultures. It was demonstrated that Ca(2+) uptake was mediated by the endoplasmic reticulum Mg(2+)/Ca(2+) ATPase due to its dependence on ATP and Mg(2+), enhancement by oxalate, and inhibition by thapsigargin. It was also shown that neuronal Ca(2+) uptake, mediated by the type 2 sarco(endo)plasmic reticulum Ca(2+) ATPase isoform, could be distinguished from glial Ca(2+) uptake in homogenates composed of neurons and glia. Finally, it was revealed that Ca(2+) uptake was sensitive to incubation on ice, extremely labile in the absence of protease inhibitors, and significantly more stable under storage conditions at -80 degrees C.

Glial cell line-derived neurotrophic factor (GDNF) as a defensive molecule for neurodegenerative disease: a tribute to the studies of antonia vernadakis on neuronal-glial interactions

Research stemming from interests in neuronal-glial interactions has led to the identification of a number of novel trophic factors, such as the dopaminergic neurotrophic factor glial cell line-derived neurotrophic factor (GDNF). Delivery of the GDNF gene to rat models of Parkinson's disease suggests a potential clinical use of GDNF gene therapy for humans with this disease. This review article briefly summarizes the history of GDNF and the effects of GDNF gene delivery prior to or after a lesion of the rat nigrostriatal system.

Effects of neuron-conditioned medium and fetal calf serum content on glial growth in dissociated cultures

The influence of the microenvironment as assessed by medium conditioned by 6-day-old chick embryo neurons in culture and of the nutrients derived from fetal bovine serum was evaluated in cultures of primary chick embryo glial cells. Glia-enriched cultures from 15-day-old chick embryo were incubated from culture days 3-9 with various concentrations of neuron-conditioned medium, with or without 10% fetal bovine serum in the final culture medium. Also, glial growth was studied in cultures with 5%, 10% or 20% fetal bovine serum in the medium. Glutamine synthetase and 2',3',-cyclic nucleotide 3'-phosphohydrolase were used as astrocytic and oligodendrocytic markers, respectively. Cultures were harvested at day 9. The presence of neuron-conditioned medium in the cultures was associated with persistence of immature glioblast-like cells. This persistence of glial immature cells was also reflected by the lower glutamine synthetase activity in the cultures with neuron-conditioned medium as compared to cultures with neuron-conditioned medium and fetal calf serum. In cultures with 5% neuron-conditioned medium without fetal bovine serum, cyclic nucleotide phosphohydrolase activity was increased. We are assuming that the input of neurons to the microenvironment is partially mediated through the neuron-conditioned medium. Thus, the present findings show that neurons influence the growth and differentiation of glial cells in culture.

Glial cell growth in culture: influence of living cell substrata

The role of the microenvironment in the growth of glial cells in culture has been the topic of ongoing research in this laboratory. Recently, we reported a study on the contribution of fibroblast cell substratum and extracellular matrix in glial cell growth. In the present study we report data concerning a) the influence of a neuronal-enriched living substratum from chick embryo on the growth of glial cells derived from chick embryonic brain and plated onto the substratum; b) the influence of dissociated cells derived from chick embryonic brain on the growth of established glial cells in culture, and c) the influence of dissociated cells derived from adult rat spinal cord on the growth of established glial cells from newborn rat in culture. The activities of glutamine synthetase (GS) and 2', 3'-cyclic nucleotide 3'-phosphohydrolase (CNP) were the biochemical probes determined for astrocytes and oligodendrocytes, respectively. We found that glial growth as assessed by both enzyme activities, was enhanced when a nervous tissue derived cell population was plated onto a glial-enriched substratum, whereas glial growth was inhibited when the neuronal-enriched population was the cell substratum.

Ultrastructure of 6-aminonicotinamide (6-AN)-induced lesions in the central nervous system of rats. III. Alterations of the spinal gray matter lesion with aging

Following a single i.p. injection of 6-AN (10 mg/kg), the anterior horn cells of 20- and 25-month-old rats increased more in size and recovered slower from chromatolytic changes than those of 3-month-old rats. Neurofilamentous hyperplasia of the perikarya was more prominent in aged rats; proliferated neurofilaments were arranged in thick parallel bundles. In the acute stage, reactive and degenerative changes of glial and mesenchymal elements were more conspicuous in 3-month-old rats; however, they disappeared by day 14 with prominent proliferation of hypertrophic astrocytes. The older rats showed less intensity and slower progression of these changes; sponginess and swelling of the astrocytic cytoplasm were still observed at day 14. Our results suggest that these age-dependent changes in the response to neurotoxins are not only induced on the neuron without mitotic phenomena after birth, but also on neuroglial cells. Furthermore, an alteration or reduction in the support of the neuron augments its intensified and delayed susceptibility to neurotoxins.