Unbiased stereological method to assess proliferation throughout the subependymal zone

The subependymal zone (SEZ), frequently named as adult subventricular zone (SVZ), is a niche of adult neural stem and progenitor cells that lines a large extension of the lateral ventricles of the brain. The majority of the studies do not analyze the SEZ throughout its entire extension. Instead, studies of cell populations within the SEZ typically focus their analysis on a narrow space between specific bregma coordinates that provides a perspective of only a small portion of the SEZ. We have previously proposed a standard division for the SEZ at the anterior-posterior and dorsal-ventral axes based on external brain anatomical hallmarks (Falcao et al., PLoS One 7:e38647, 2012). Herein, we describe in detail the procedure and a stereological approach that can be used to obtain an unbiased estimation of the SEZ cell proliferation under physiological and pathological conditions. This approach takes into consideration clear SEZ anatomical divisions, both on the anterior-posterior and dorsal-ventral axes, which will standardize future studies on the SEZ

Adult Hippocampal Neurogenesis Modulation by the Membrane-Associated Progesterone Receptor Family Member Neudesin

Neudesin (Neuron-derived neurotrophic factor, NENF), a membrane-associated progesterone receptor family (MAPR) member, is a neuron secreted protein with neurotrophic properties during embryonic stages. However, its role in the adult brain is still poorly addressed. In this study we have used neudesin-null (Nenf-/-) mice and performed a characterization of the proliferation state of the adult neurogenic niches, the adult subventricular zone (SVZ) and the hippocampus subgranular zone (SGZ). Nenf-/- males did not presented any deficits in proliferation in the SVZ neither in vivo nor in vitro. On the other hand a decrease in cell proliferation in the SGZ was observed, as well as a decrease in the number of newborn neurons in the dentate gyrus (DG) that was accompanied by impaired context discrimination in a contextual fear conditioning (CFC) task. Since NENF neurotrophic action is suggested to occur via the formation of a progesterone stability complex for the activation of non-genomic cascade, we further evaluated progesterone metabolism in the absence of NENF. Interestingly, expression of progesterone catabolic rate-determining enzyme, 5-α-reductase was upregulated in the DG of Nenf-/-, together with a significant increase in the expression of the δGABAA receptor gene, involved in DG tonic inhibition. Taken together, these findings add in vivo evidence on the neurotrophic properties of NENF in the adult brain. Furthermore, the mechanism of action of NENF in this process might implicate neurosteroids modulation, at least in the DG.This work was funded by the Bial Foundation through Grant 217/12 (to JS), by the European Regional Development Fund (FEDER), through the Competitiveness Factors Operational Programme (COMPETE), and by National funds, through the Foundation for Science and Technology (FCT), under the scope of the project POCI-01-0145-FEDER-007038, and by the project NORTE-01-0124-FEDER-000023, supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through FEDERinfo:eu-repo/semantics/publishedVersio

Altered human oligodendrocyte heterogeneity in multiple sclerosis

Oligodendrocyte pathology is increasingly implicated in neurodegenerative diseases as oligodendrocytes both myelinate and provide metabolic support to axons. In multiple sclerosis (MS), demyelination in the central nervous system thus leads to neurodegeneration, but the severity of MS between patients is very variable. Disability does not correlate well with the extent of demyelination1, which suggests that other factors contribute to this variability. One such factor may be oligodendrocyte heterogeneity. Not all oligodendrocytes are the same—those from the mouse spinal cord inherently produce longer myelin sheaths than those from the cortex2, and single-cell analysis of the mouse central nervous system identified further differences3,4. However, the extent of human oligodendrocyte heterogeneity and its possible contribution to MS pathology remain unknown. Here we performed single-nucleus RNA sequencing from white matter areas of post-mortem human brain from patients with MS and from unaffected controls. We identified subclusters of oligodendroglia in control human white matter, some with similarities to mouse, and defined new markers for these cell states. Notably, some subclusters were underrepresented in MS tissue, whereas others were more prevalent. These differences in mature oligodendrocyte subclusters may indicate different functional states of oligodendrocytes in MS lesions. We found similar changes in normal-appearing white matter, showing that MS is a more diffuse disease than its focal demyelination suggests. Our findings of an altered oligodendroglial heterogeneity in MS may be important for understanding disease progression and developing therapeutic approaches

Topographical analysis of the subependymal zone neurogenic niche

The emerging model for the adult subependymal zone (SEZ) cell population indicates that neuronal diversity is not generated from a uniform pool of stem cells but rather from diverse and spatially confined stem cell populations. Hence, when analysing SEZ proliferation, the topography along the anterior-posterior and dorsal-ventral axes must be taken into account. However, to date, no studies have assessed SEZ proliferation according to topographical specificities and, additionally, SEZ studies in animal models of neurological/psychiatric disorders often fail to clearly specify the SEZ coordinates. This may render difficult the comparison between studies and yield contradictory results. More so, by focusing in a single spatial dimension of the SEZ, relevant findings might pass unnoticed. In this study we characterized the neural stem cell/progenitor population and its proliferation rates throughout the rat SEZ anterior-posterior and dorsal-ventral axes. We found that SEZ proliferation decreases along the anterior-posterior axis and that proliferative rates vary considerably according to the position in the dorsal-ventral axis. These were associated with relevant gradients in the neuroblasts and in the neural stem cell populations throughout the dorsal-ventral axis. In addition, we observed spatially dependent differences in BrdU/Ki67 ratios that suggest a high variability in the proliferation rate and cell cycle length throughout the SEZ; in accordance, estimation of the cell cycle length of the neuroblasts revealed shorter cell cycles at the dorsolateral SEZ. These findings highlight the need to establish standardized procedures of SEZ analysis. Herein we propose an anatomical division of the SEZ that should be considered in future studies addressing proliferation in this neural stem cell niche.Fundação para a Ciência e a Tecnologia (FCT

Acute treatment with valproic acid and L-thyroxine ameliorates clinical signs of experimental autoimmune encephalomyelitis and prevents brain pathology in DA rats

This work was supported by grants from the Swedish Research Council (MJ (K2008-66X-20776-01-4 and K2012-99X-20776-05-3)), OH (2011-3457) and GCB (K2011-80P-21816-01-4 and K2011-80X- 21817-01-4)), Harald and Greta Jeanssons Foundation (MJ), Swedish Association for Persons with Neurological Disabilities (MJ), ÅkeWibergs Foundation (MJ), Åke Löwnertz Foundation (MJ), Swedish Brain Foundation (MJ and GCB), David and Astrid Hagélen Foundation (GCB), Swedish Society for Medical Research (GCB), Swedish Society of Medicine (GCB), Socialstyrelsen (MJ), Karolinska Institutet funds (MJ and GCB), Marie Curie Integration Grant, Seventh Framework Programme, European Union (GCB, PCIG12-GA-2012-333713)), Neuropromise LSHM-CT-2005-018637 (MZA, HL) and Theme Center for Regenerative Medicine at Karolinska Institutet (OH)

Disease-specific oligodendrocyte lineage cells arise in multiple sclerosis

Multiple sclerosis (MS) is characterized by an immune system attack targeting myelin, which is produced by oligodendrocytes (OLs). We performed single-cell transcriptomic analysis of OL lineage cells from the spinal cord of mice induced with experimental autoimmune encephalomyelitis (EAE), which mimics several aspects of MS. We found unique OLs and OL precursor cells (OPCs) in EAE and uncovered several genes specifically alternatively spliced in these cells. Surprisingly, EAE-specific OL lineage populations expressed genes involved in antigen processing and presentation via major histocompatibility complex class I and II (MHC-I and -II), and in immunoprotection, suggesting alternative functions of these cells in a disease context. Importantly, we found that disease-specific oligodendroglia are also present in human MS brains and that a substantial number of genes known to be susceptibility genes for MS, so far mainly associated with immune cells, are expressed in the OL lineage cells. Finally, we demonstrate that OPCs can phagocytose and that MHC-II-expressing OPCs can activate memory and effector CD4-positive T cells. Our results suggest that OLs and OPCs are not passive targets but instead active immunomodulators in MS. The disease-specific OL lineage cells, for which we identify several biomarkers, may represent novel direct targets for immunomodulatory therapeutic approaches in MS

Neural stem and progenitor cells decrease along the subependymal zone dorsal-ventral axis.

<p>A DCX wholemount staining for the lateral wall is represented in <b>(A)</b> (Scale bar = 1 mm). DCX positive cell rates were estimated through the lateral wall for anterior, intermediate and posterior SEZ <b>(B)</b>, dorsolateral and ventral SEZ <b>(C)</b>. BrdU retaining cells were double stained with GFAP and assessed in the dorsolateral and ventral SEZ <b>(D)</b>. The same analysis was performed for proliferating neuroblasts (double BrdU/DCX positive cells) <b>(E)</b>. The images for the BrdU, DCX and BrdU/DCX staining are represented in <b>(F)</b> (Scale bar = 20 µm). LV, lateral ventricle; Str, striatum. All results are expressed as number of positive cells per area (in mm²). The threshold value for statistical significance was set at 0.05 (* p<0.05).</p

Anterior-posterior axis landmarks of the SEZ divisions.

<p>Bregma coordinates are according to Paxinos & Watson (2004) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038647#pone.0038647-Paxinos1" target="_blank">[42]</a>.</p

The BrdU/Ki67 ratio differs throughout the subpendymal zone.

<p>The SEZ total BrdU/Ki67 ratio is represented for the anterior-posterior <b>(A)</b> and dorsal-ventral axes <b>(B)</b>. For the different dorsal-ventral regions the BrdU/Ki67 ratios were assessed at the anterior, intermediate and posterior levels <b>(C)</b>. The threshold value for statistical significance was set at 0.05 (* p<0.05).</p