Bone marrow-derived mesenchymal stem cell and simvastatin treatment leads to improved functional recovery and modified c-Fos expression levels in the brain following ischemic stroke

Objective(s): The beneficial outcomes of bone marrow-derived mesenchymal stem cell (BMSC) treatment on functional recovery following stroke has been well established. Furthermore, 5-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors have also been shown to increase neuronal survival and promote the movement of BMSCs towards the sites of inflammation. However, the precise mechanisms mediating the improved neurological functional recovery in stoke models following a combination treatment of Simvastatin and BMSCs still remained poorly understood. Materials and Methods: Here, an embolic stroke model was used to experimentally induce a focal ischemic brain injury by inserting a preformed clot into the middle cerebral artery (MCA). Following stroke, animals were treated either with an intraperitoneal injection of Simvastatin, an intravenous injection of 3 ×106 BMSCs, or a combination of these two treatments.Results: Seven days after ischemia, the combination of Simvastatin and BMSCs led to a significant increase in BMSC relocation, endogenous neurogenesis, arteriogenesis and astrocyte activation while also reducing neuronal damage when compared to BMSC treatment alone (PConclusion: These results further demonstrate the synergistic benefits of a combination treatment and help to improve our understanding of the underlying mechanisms mediating this beneficial effect

Targeting Neogenin as a Novel Therapeutic Approach for the Treatment of Retinal Degeneration

Retinitis Pigmentosa (RP) is a genetically inherited condition characterized by progressive loss of photoreceptor cells and represents one of the most prevalent causes of blindness among working age populations. The mechanisms leading to photoreceptor death remain largely unknown and there are no available treatments. We have previously shown that the protein Neogenin is involved in regulating cell survival in the CNS. Here we show that Neogenin expression is induced in degenerating photoreceptors in two mouse RP models (Rd1 and Rd10). Degenerating photoreceptors have abnormally high levels of cGMP and cAMP, and here we demonstrate that 8-Bromo-cAMP administration was sufficient to induce Neogenin expression in-vivo in wild type mouse photoreceptors and in-vitro in human photoreceptor surrogate cells. Using targeted in-vivo electroporation, we then demonstrate that i) overexpressing Neogenin in mouse photoreceptors induces cell death and ii) that silencing Neogenin in degenerating Rd1 photoreceptors promotes survival. This suggests Neogenin acts as a previously unidentified pro-death signal in RP. To develop a potential therapeutic approach for targeting Neogenin in RP, we utilized a Neogenin function blocking peptide (4Ig) we developed that is capable of blocking Neogenin’s pro-apoptotic activity. Intravitreal injections of 4Ig were administered at the onset of photoreceptor degeneration in Rd1 and Rd10 mice. When assessed at advanced stages of disease progression, 4Ig treatment significantly improved rod photoreceptor survival and cone photoreceptor survival. Photoreceptor function was also significantly improved following 4Ig treatment as demonstrated by i) improved light-evoked ganglion cell recordings, ii) improved scotopic/photopic electroretinogram recordings and iii) improved visual acuity (OptoMotry; CerebralMechanics). Targeting Neogenin therefore represents an exciting new approach for the treatment of RP.Ph.D.2020-07-10 00:00:0

The Expression Profile of KIAA0319-like in Chick Embryos and its Involvement in Cell Migration in the Developing Optic Tectum

Several genes thought to confer susceptibility to dyslexia have been identified, and the purpose of this study is to 1) determine the expression pattern of one of these gene products and 2) characterize the function of the product of one of these genes, namely KIAA0319-Like (KIAA0319L), using the developing chick visual system as a model. Whole mount in situ hybridization was performed for KIAA0319L on embryonic day (E)3 – E5 and in situ hybridization on sections was performed at later stages. Engineered microRNA (miRNA) constructs targeting KIAA0319L were prepared and their specificity and efficiency for knocking down KIAA0319L were tested. miRNAs were electroporated in E5 optic tecta (OT). Embryos were sacrificed at E12. OT were removed, sectioned and analyzed. Results demonstrate that KIAA0319L is expressed in the developing chick visual system. Knockdown of KIAA0319L in the OT results in abnormal migration indicating that KIAA0319L is necessary for this process.MAS

Exosomes Mediate Mobilization of Autocrine Wnt10b to Promote Axonal Regeneration in the Injured CNS

Developing strategies that promote axonal regeneration within the injured CNS is a major therapeutic challenge, as axonal outgrowth is potently inhibited by myelin and the glial scar. Although regeneration can be achieved using the genetic deletion of PTEN, a negative regulator of the mTOR pathway, this requires inactivation prior to nerve injury, thus precluding therapeutic application. Here, we show that, remarkably, fibroblast-derived exosomes (FD exosomes) enable neurite growth on CNS inhibitory proteins. Moreover, we demonstrate that, upon treatment with FD exosomes, Wnt10b is recruited toward lipid rafts and activates mTOR via GSK3β and TSC2. Application of FD exosomes shortly after optic nerve injury promoted robust axonal regeneration, which was strongly reduced in Wnt10b-deleted animals. This work uncovers an intercellular signaling pathway whereby FD exosomes mobilize an autocrine Wnt10b-mTOR pathway, thereby awakening the intrinsic capacity of neurons for regeneration, an important step toward healing the injured CNS

The liver and muscle secreted HFE2-protein maintains central nervous system blood vessel integrity

Abstract Liver failure causes breakdown of the Blood CNS Barrier (BCB) leading to damages of the Central-Nervous-System (CNS), however the mechanisms whereby the liver influences BCB-integrity remain elusive. One possibility is that the liver secretes an as-yet to be identified molecule(s) that circulate in the serum to directly promote BCB-integrity. To study BCB-integrity, we developed light-sheet imaging for three-dimensional analysis. We show that liver- or muscle-specific knockout of Hfe2/Rgmc induces BCB-breakdown, leading to accumulation of toxic-blood-derived fibrinogen in the brain, lower cortical neuron numbers, and behavioral deficits in mice. Soluble HFE2 competes with its homologue RGMa for binding to Neogenin, thereby blocking RGMa-induced downregulation of PDGF-B and Claudin-5 in endothelial cells, triggering BCB-disruption. HFE2 administration in female mice with experimental autoimmune encephalomyelitis, a model for multiple sclerosis, prevented paralysis and immune cell infiltration by inhibiting RGMa-mediated BCB alteration. This study has implications for the pathogenesis and potential treatment of diseases associated with BCB-dysfunction