Polarized Anti-Inflammatory Mesenchymal Stem Cells Increase Hippocampal Neurogenesis and Improve Cognitive Function in Aged Mice.

Age-related decline in cognitive functions is associated with reduced hippocampal neurogenesis caused by changes in the systemic inflammatory milieu. Mesenchymal stem cells (MSC) are known for their immunomodulatory properties. Accordingly, MSC are a leading candidate for cell therapy and can be applied to alleviate inflammatory diseases as well as aging frailty via systemic delivery. Akin to immune cells, MSC can also polarize into pro-inflammatory MSC (MSC1) and anti-inflammatory MSC (MSC2) following activation of Toll-like receptor 4 (TLR4) and TLR3, respectively. In the present study, we apply pituitary adenylate cyclase-activating peptide (PACAP) to polarize bone-marrow-derived MSC towards an MSC2 phenotype. Indeed, we found that polarized anti-inflammatory MSC were able to reduce the plasma levels of aging related chemokines in aged mice (18-months old) and increased hippocampal neurogenesis following systemic administration. Similarly, aged mice treated with polarized MSC displayed improved cognitive function in the Morris water maze and Y-maze assays compared with vehicle- and naïve-MSC-treated mice. Changes in neurogenesis and Y-maze performance were negatively and significantly correlated with sICAM, CCL2 and CCL12 serum levels. We conclude that polarized PACAP-treated MSC present anti-inflammatory properties that can mitigate age-related changes in the systemic inflammatory milieu and, as a result, ameliorate age related cognitive decline.

Transplantation of mesenchymal stem cells causes long-term alleviation of schizophrenia-like behaviour coupled with increased neurogenesis.

Schizophrenia is a neurodevelopmental disease with a mixed genetic and environmental aetiology. Impaired adult hippocampal neurogenesis was suggested both as a pathophysiological mechanism and as a target for therapy. In the present study, we utilized intracerebroventricular transplantation of bone marrow-derived mesenchymal stem cells (MSC) as a means to enhance hippocampal neurogenesis in the ketamine-induced neurodevelopmental murine model for schizophrenia. Syngeneic MSC have successfully engrafted and survived for up to 3 months following transplantation. Improvement in social novelty preference and prepulse inhibition was noted after transplantation. In parallel to behavioural improvement, increased hippocampal neurogenesis as reflected in the numbers of doublecortin expressing neurons in the dentate gyrus and gene expression was noted both 2 weeks following transplantation as well as 3 months later compared with nontreated animals. An independent aging effect was observed for both behaviour and neurogenesis, which was attenuated by MSC treatment. As opposed to MSC treatment, short-term treatment with clozapine was efficient only during treatment and diminished 3 months later. Interestingly, while shortly after transplantation (2 weeks) behavioural improvement was correlated mainly to FGF2 gene expression, 3 months later it was mainly correlated to the expression of the notch ligand DLL1. This suggests that long-term effect during ageing may depend on neural stem cell self-renewal. We conclude that a single intracerebroventricular injection of bone marrow-derived MSC can suffice for long-term reversal of changes in adult hippocampal neurogenesis and improve schizophrenia-like behavioural phenotype inflicted by developmental exposure to ketamine in mice.

Implementation of a six-around-one optical probe based on diffuse light spectroscopy for study of cerebral properties in a murine mouse model of autism spectrum disorder.

Light reflectance spectroscopy (LRS) is a multispectral technique, sensitive to the absorption and scattering properties of biological molecules in tissues. It is used as a noninvasive tool to extract quantitative physiological information from human tissues and organs. A near-infrared LRS based on a single optical probe was used to monitor changes in optical and hemodynamic parameters in a mouse model of autism. A murine model of autism induced by developmental exposure to valproic acid (VPA) was used. Since autism could be attributed to neuroanatomical changes, we hypothesize that these changes can be detected using the LRS because spectral properties depend on both molecular composition and structural changes. The fiber-optic probe in the setup consisted of seven small optical fibers: six fibers for illumination placed in a circular manner around a central single collection fiber. Overall, measurements demonstrate changes in diffused reflectance spectra, cerebral optical tissue properties (absorption and scattering), and chromophore levels. Furthermore, we were able to identify differences between male and female groups. Finally, the effectiveness of S-Adenosylmethionine as a drug therapy was studied and found to improve the hemodynamic outcome. For the first time, to the best of our knowledge, the LRS is utilized to study variations in brain parameters in the VPA autism model mice through an intact scalp.

Interleukine-17 Administration Modulates Adult Hippocampal Neurogenesis and Improves Spatial Learning in Mice.

Adult hippocampal neurogenesis plays an important role in health and disease. Regulating neurogenesis may be a key mechanism in the pathophysiology and treatment of several neurobehavioral disorders such as schizophrenia, depression, autism spectrum disorders and Alzheimer's disease. Cytokines are known to affect adult neurogenesis, but conflicting studies have been reported with regard to their actual role. Interleukine-17 (IL-17), a potent pro-inflammatory cytokine, has been shown to inhibit proliferation of neuroprogenitors and thus reduce hippocampal neurogenesis, while other studies suggested it can promote neurite outgrowth. In the present study we sought to explore the possible effect of a single dose administration of IL-17 on neurogenesis related behavior, i.e. spatial learning. Surprisingly, ICR mice injected with IL-17 (8 µg) had a significant slight improvement in spatial learning in the Morris water maze paradigm, without any changes in general locomotion compared with control mice. Indeed, the expression of neurogenesis related genes was down regulated following IL-17 treatment. However, we detected an upregulation in the expression of FGF-13, a gene promoting microtubule polymerization and neurite outgrowth, thus supporting neuronal maturation. We thus suggest that IL-17 has a complex role in regulating adult neurogenesis: inhibiting neuroprogenitors proliferation on one hand, while promoting maturation of already formed neuroblasts on the other hand. Our findings suggest that these roles can potentially affect neurogenesis related behavior. Its actual role in health and disease is yet to be determined.

S-adenosyl methionine prevents ASD like behaviors triggered by early postnatal valproic acid exposure in very young mice.

INTRODUCTION: A common animal model of ASD is the one induced by valproic acid (VPA), inducing epigenetic changes and oxidative stress. We studied the possible preventive effect of the methyl donor for epigenetic enzymatic reactions, S-adenosine methionine (SAM), on ASD like behavioral changes and on redox potential in the brain and liver in this model. METHODS: ICR albino mice were injected on postnatal day 4 with one dose of 300 mg/kg of VPA, with normal saline (controls) or with VPA and SAM that was given orally for 3 days at the dose of 30 mg/kg body weight. From day 50, we carried out neurobehavioral tests and assessment of the antioxidant status of the prefrontal cerebral cortex, liver assessing SOD and CAT activity, lipid peroxidation and the expression of antioxidant genes. RESULTS: Mice injected with VPA exhibited neurobehavioral deficits typical of ASD that were more prominent in males. Changes in the activity of SOD and CAT increased lipid peroxidation and changes in the expression of antioxidant genes were observed in the prefrontal cortex of VPA treated mice, more prominent in females, while ASD like behavior was more prominent in males. There were no changes in the redox potential of the liver. The co-administration of VPA and SAM alleviated most ASD like neurobehavioral symptoms and normalized the redox potential in the prefrontal cortex. CONCLUSIONS: Early postnatal VPA administration induces ASD like behavior that is more severe in males, while the redox status changes are more severe in females; SAM corrects both. VPA-induced ASD seems to result from epigenetic changes, while the redox status changes may be secondary.

Optically derived metabolic and hemodynamic parameters predict hippocampal neurogenesis in the BTBR mouse model of autism.

In this study, we made use of dual-wavelength laser speckle imaging (DW-LSI) to assess cerebral blood flow (CBF) in the BTBR-genetic mouse model of autism spectrum disorder, as well as control (C57Bl/6J) mice. Since the deficits in social behavior demonstrated by BTBR mice are attributed to changes in neural tissue structure and function, we postulated that these changes can be detected optically using DW-LSI. BTBR mice demonstrated reductions in both CBF and cerebral oxygen metabolism (CMRO2 ), as suggested by studies using conventional neuroimaging technologies to reflect impaired neuronal activation and cognitive function. To validate the monitoring of CBF by DW-LSI, measurements with laser Doppler flowmetry (LDF) were also performed which confirmed the lowered CBF in the autistic-like group. Furthermore, we found in vivo cortical CBF measurements to predict the rate of hippocampal neurogenesis, measured ex vivo by the number of neurons expressing doublecortin or the cellular proliferation marker Ki-67 in the dentate gyrus, with a strong positive correlation between CBF and neurogenesis markers (Pearson, r = 0.78; 0.9, respectively). These novel findings identifying cortical CBF as a predictive parameter of hippocampal neurogenesis highlight the power and flexibility of the DW-LSI and LDF setups for studying neurogenesis trends under normal and pathological conditions.

Transplantation of mesenchymal stem cells reverses behavioural deficits and impaired neurogenesis caused by prenatal exposure to valproic acid.

Neurodevelopmental impairment can affect lifelong brain functions such as cognitive and social behaviour, and may contribute to aging-related changes of these functions. In the present study, we hypothesized that bone marrow-derived mesenchymal stem cells (MSC) administration may repair neurodevelopmental behavioural deficits by modulating adult hippocampal neurogenesis. Indeed, postnatal intracerebral transplantation of MSC has restored cognitive and social behaviour in mice prenatally exposed to valproic acid (VPA). MSC transplantation also restored post-developmental hippocampal neurogenesis, which was impaired in VPA-exposed mice displaying delayed differentiation and maturation of newly formed neurons in the granular cell layer of the dentate gyrus. Importantly, a statistically significant correlation was found between neuronal differentiation scores and behavioural scores, suggesting a mechanistic relation between the two. We thus conclude that post-developmental MSC administration can overcome prenatal neurodevelopmental deficits and restore cognitive and social behaviours via modulation of hippocampal adult neurogenesis.

Mesenchymal stem cells can prevent alterations in behavior and neurogenesis induced by Aß25-35 administration.

Mesenchymal stem cells (MSCs) are known to enhance neurogenesis in the dentate gyrus, as well as to modulate immune cell activity and inflammation. Easily obtained and expanded from the bone marrow and other tissues, MSCs have been proposed as candidates for stem cell therapy in various neurodegenerartive diseases. In the present study, we sought to explore these therapeutic properties of MSC on Aß25-35-induced pathology when coadministered together. Apparently, coadministration of MSC prevented mild cognitive deficits observed following Aß administration alone, by promoting microglial activation and rapid clearance of injected Aß aggregates. Surprisingly, increased hippocampal neurogenesis was observed in the Aß-injected animals and was normal in MSC-coadministered animals just as in control animals. The observed increase in neurogenesis can be explained as a compensating mechanism responsible for the mild and temporary cognitive deficits observed in the Morris water maze assay in Aß-injected animals. Interestingly, MSC engrafted not only to the hippocampus but were also detected in the choroid plexus. We thus conclude that MSC may act in multiple pathways to protect the CNS from Aß pathology, while neurogenesis is a possible compensating mechanism; it is not always activated by MSC, which in turn may interact with local immune cells to regulate Aß accumulation.

Reversal of chlorpyrifos neurobehavioral teratogenicity in mice by allographic transplantation of adult subventricular zone-derived neural stem cells.

Neurobehavioral teratogenicity can be reversed with transplantation of neural stem cells. However, the usefulness of this therapy would be greatly enhanced by employing adult stem cells. In pursuit of this this goal, we developed a model that uses subventricular zone (SVZ) cells. HS/Ibg mice were exposed prenatally to chlorpyrifos on gestational days 9-18 (3 mg/kg/day, SC) in order to induce deficits in their performance in the Morris water maze test. Both the control and the exposed offspring were transplanted with SVZ cells (or vehicle) on postnatal day 35; this actually represents an allogenic transplantation, because the HS/Ibg strain is a heterogeneous stock. The transplanted cells were later observed in the host brain by DiI tracing, and their initial differentiation to cholinergic neurons and astrocytes was ascertained. On postnatal day 80, animals that had been exposed prenatally to chlorpyrifos displayed impaired Morris water maze performance, requiring more time to reach the platform. Transplantation of adult SVZ-derived neural stem cells (NSC) reversed the deficits. Applying autologous transplantation provides an important demonstration that the methodological obstacles of immunological rejection and the ethical concerns related to using embryonic stem cells may be successfully bypassed in developing stem cell therapies for neurodevelopmental disorders.

Truncated beta epithelial sodium channel (ENaC) subunits responsible for multi-system pseudohypoaldosteronism support partial activity of ENaC.

Aldosterone regulated epithelial sodium channels (ENaC) are constructed of three homologous subunits. Mutations in the alpha-, beta- and gamma-ENaC subunit genes (SCNN1A, SCNN1B and SCNN1G) are associated with multi-system pseudohypoaldosteronism (PHA), and mutations in the PY motif of carboxy-terminal region of beta and gamma subunits are associated with Liddle syndrome of hereditary hypertension. In this study we identified two frameshift mutations in the SCNN1B alleles of a female infant diagnosed with multi-system PHA inherited from her parents. This is the first case of PHA in an Ashkenazi family in Israel. The p.Glu217fs (c.648dupA in exon 4) and p.Tyr306fs (c.915delC in exon 6) mutations produce shortened beta-ENaC subunits with 253 and 317 residues respectively instead of the 640 residues present in beta-ENaC subunit. Expression of cRNAs carrying these mutations in Xenopus oocytes showed that the mutations drastically reduce but do not eliminate ENaC activity. The findings reveal that truncated beta-ENaC subunits are capable of partially supporting intracellular transport of the other two subunits to the membrane and the final assembly of a weakly active channel together with normal alpha- and gamma-ENaC subunits. Moreover, these results enhance our understanding of the long-term consequences of these types of mutations in PHA patients.