Cerebrolysin is a peptide preparation mimicking the action of neurotrophic factors and has beneficial effects on neurodegenerative diseases and stroke. The present study investigated the effect of Cerebrolysin on neurogenesis in a rat model of embolic middle cerebral artery occlusion (MCAo). Treatment with Cerebrolysin at doses of 2.5 and 5 ml/kg significantly increased the number of bromodeoxyuridine positive (BrdU + ) subventricular zone (SVZ) neural progenitor cells and doublecortin (DCX) immunoreactivity (migrating neuroblasts) in the ipsilateral SVZ and striatal ischemic boundary 28 days after stroke when the treatment was initiated 24h after stroke. The treatment also reduced TUNEL + cells by ~50% in the ischemic boundary. However, treatment with Cerebrolysin at a dose of 2.5 ml/kg initiated at 24 and 48h did not significantly reduce infarct volume, but substantially improved neurological outcomes measured by an array of behavioral tests 21 and 28 days after stroke. Incubation of SVZ neural progenitor cells from ischemic rats with Cerebrolysin dose dependently augmented BrdU + cells and increased the number of Tuj1 + cells (a marker of immature neurons). Blockage of the PI3K/Akt pathway abolished Cerebrolysinincreased BrdU + cells. Moreover, Cerebrolysin treatment promoted neural progenitor cell migration. Collectively, these data indicate that Cerebrolysin treatment when initiated 24 and 48h after stroke enhances neurogenesis in the ischemic brain and improves functional outcome and that Cerebrolysin-augmented proliferation, differentiation, and migration of adult SVZ neural progenitor cells contribute to Cerebrolysin-induced neurogenesis, which may be related to improvement of neurological outcome. The PI3K/Akt pathway mediates Cerebrolysin-induced progenitor cell proliferation.

Aims/hypothesis Diabetic peripheral neuropathy (DPN) is one of the major complications of diabetes, which contributes greatly to morbidity and mortality. There is currently no effective treatment for this disease. Exosomes are cell-derived nanovesicles and play an important role in intercellular communications. The present study investigated whether mesenchymal stromal cell (MSC)-derived exosomes improve neurological outcomes of DPN. Methods Exosomes were isolated from the medium of cultured mouse MSCs by ultracentrifugation. Diabetic mice (BKS.Cg-m+/+Lepr db /J, db/db) at the age of 20 weeks were used as DPN models. Heterozygous mice (db/m) of the same age were used as the control. MSC-exosomes were administered weekly via the tail vein for 8 weeks. Neurological function was evaluated by testing motor and sensory nerve conduction velocities, and thermal and mechanical sensitivity. Morphometric analysis was performed by myelin sheath staining and immunohistochemistry. Macrophage markers and circulating cytokines were measured by western blot and ELISA. MicroRNA (miRNA) array and bioinformatics analyses were performed to examine the exosomal miRNA profile and miRNA putative target genes involved in DPN. Results Treatment of DPN with MSC-exosomes markedly decreased the threshold for thermal and mechanical stimuli and increased nerve conduction velocity in diabetic mice. Histopathological analysis showed that MSC-exosomes markedly augmented the density of FITC-dextran perfused blood vessels and increased the number of intraepidermal nerve fibres (IENFs), myelin thickness and axonal diameters of sciatic nerves. Western blot analysis revealed that MSC-exosome treatment decreased and increased M1 and M2 macrophage phenotype markers, respectively. Moreover, MSC-exosomes substantially suppressed proinflammatory cytokines. Bioinformatics analysis revealed that MSC-exosomes contained abundant miRNAs that target the Toll-like receptor (TLR)4/NF-κB signalling pathway. Conclusions/interpretation MSC-derived exosomes alleviate neurovascular dysfunction and improve functional recovery in mice with DPN by suppression of proinflammatory genes.

Peripheral neuropathy is a common and major complication of diabetes, the underlying mechanisms of which are not fully understood. Using a mouse model of type II diabetes, the present study investigated the role of phosphodiesterase-5 (PDE5) in peripheral neuropathy. BKS.Cg-m+/+Leprdb/J (db/db) mice were treated with sildenafil, a specific inhibitor of PDE5, at doses of 2 and 10 mg/kg or saline. Levels of PDE5 and morphometric parameters in sciatic nerve tissue as well as the motor and sensory function were measured in these mice. In diabetic mice, PDE5 expression in sciatic nerve tissue was significantly upregulated, while the myelin sheath thickness, myelin basic protein (MBP), and subcutaneous nerve fibers were significantly reduced. Treatment with sildenafil, significantly improved neurological function, assayed by motor and sensory conducting velocities and thermal and mechanical noxious stimuli, concomitantly with increases in myelin sheath thickness, MBP levels, and subcutaneous nerve fibers. In vitro, hyperglycemia upregulated PDE5 in Schwann cells, and reduced Schwann cell proliferation, migration and expression of brain-derived neurotrophic factor (BDNF). Blockage of PDE5 with sildenafil, increased cGMP, and completely abolished the effect of hyperglycemia on Schwann cells. Sildenafil upregulated cGMP-dependent protein kinase G1 (PKG1), whereas inhibition of PKG1 with a PKG inhibitor, KT5823, suppressed the inhibitory effect of sildenafil on Schwann cells. These data indicate that hyperglycemia substantially upregulates PDE5 expression and that the cGMP/PKG signaling pathway activated by sildenafil mediates the beneficial effects of sildenafil on diabetic peripheral neuropathy.

We consider emergent collective behavior of a multicellular biological system. Specifically, we investigate the role of hypoxia (lack of oxygen) in migration of brain tumor cells. We performed two series of cell migration experiments. In the first set of experiments, cell migration away from a tumor spheroid was investigated. The second set of experiments was performed in a typical wound-healing geometry: Cells were placed on a substrate, a scratch was made, and cell migration into the gap was investigated. Experiments show a surprising result: Cells under normal and hypoxic conditions have migrated the same distance in the "spheroid" experiment, while in the "scratch" experiment cells under normal conditions migrated much faster than under hypoxic conditions. To explain this paradox, we formulate a discrete stochastic model for cell dynamics. The theoretical model explains our experimental observations and suggests that hypoxia decreases both the motility of cells and the strength of cell-cell adhesion. The theoretical predictions were further verified in independent experiments.

Human miR-146b-5p is located on chromosome 10q24.3. Loss of the 10q24-26 region is frequently observed in gliomas. Here, we report that miR-146b-5p suppresses expression of epidermal growth factor receptor (EGFR) in human glioblastoma cell lines. Introduction of miR-146b-5p decreases cell invasion, migration and phosphorylation of protein kinase B (AKT). MiR-146b-5p suppresses translation of EGFR, and binds to the EGFR 3′-UTR. Furthermore, analysis of U87-MG laser-capture micro-dissected cells in tumor-bearing mice indicated that expression of miR-146b-5p was inversely correlated with distance from the tumor core. These findings suggest that reconstitution of miR-146b-5p may be useful for treatment of this invasive tumor.

MicroRNA-146a (miR-146a) regulates multiple immune diseases. However, the role of miR-146a in diabetic peripheral neuropathy (DPN) has not been investigated. We found that mice (db/db) with type 2 diabetes exhibited substantial downregulation of miR-146a in sciatic nerve tissue. Systemic administration of miR-146a mimics to diabetic mice elevated miR-146a levels in plasma and sciatic nerve tissue and substantially increased motor and sensory nerve conduction velocities by 29 and 11%, respectively, and regional blood flow by 50% in sciatic nerve tissue. Treatment with miR-146a mimics also considerably decreased the response in db/db mice to thermal stimuli thresholds. Histopathological analysis showed that miR-146a mimics markedly augmented the density of fluorescein isothiocyanate–dextran-perfused blood vessels and increased the number of intraepidermal nerve fibers, myelin thickness, and axonal diameters of sciatic nerves. In addition, miR-146a treatment reduced and increased classically and alternatively activated macrophage phenotype markers, respectively. Analysis of miRNA target array revealed that miR-146a mimics greatly suppressed expression of many proinflammatory genes and downstream related cytokines. Collectively, our data indicate that treatment of diabetic mice with miR-146a mimics robustly reduces DPN and that suppression of hyperglycemia-induced proinflammatory genes by miR-146a mimics may underlie its therapeutic effect.

Background and Purpose-Cerebrolysin, a mixture of neurotrophic peptides, enhances neurogenesis and improves neurological outcome in experimental neurodegenerative diseases and stroke. The Sonic hedgehog (Shh) signaling pathway stimulates neurogenesis after stroke. The present study tests whether the Shh pathway mediates cerebrolysininduced neurogenesis and improves neurological outcome after stroke. Methods-Rats subjected to embolic stroke were treated with cerebrolysin with or without cyclopamine. Results-Using neural progenitor cells derived from the subventricular zone of the lateral ventricle of adult rats, we found that cerebrolysin significantly increased neural progenitor cells proliferation and their differentiation into neurons and myelinating oligodendrocytes, which were associated with upregulation of Shh and its receptors patched and smoothened. Blockage of the Shh signaling pathway with a pharmacological smoothened inhibitor, cyclopamine, abolished cerebrolysin-induced in vitro neurogenesis and oligodendrogenesis. In the ischemic rats, treatment with cerebrolysin starting 24 hours after stroke significantly increased neural progenitor cell proliferation in the subventricular zone and enhanced neurogenesis, oligodendrogenesis, and axonal remodeling in the peri-infarct area. Moreover, profound neurological function improvements were observed in rats treated with cerebrolysin from week 3 to week 5 after stroke onset compared with vehicle-treated rats. However, in vivo inhibition of the Shh pathway with cyclopamine completely reversed the effects of cerebrolysin on neurorestoration and functional recovery. Conclusions-These results demonstrate that the Shh pathway mediates cerebrolysin-enhanced neurogenesis and white matter remodeling and improves functional recovery in rats after stroke.

Schwann cell-derived exosomes communicate with dorsal root ganglia (DRG) neurons. The current study investigated the therapeutic effect of exosomes derived from healthy Schwann cells (SC-Exos) on diabetic peripheral neuropathy (DPN). We found that intravenous administration of SC-Exos to type 2 diabetic db/db mice with peripheral neuropathy remarkably ameliorated DPN by improving sciatic nerve conduction velocity and increasing thermal and mechanical sensitivity. These functional improvements were associated with the augmentation of epidermal nerve fibers and remyelination of sciatic nerves. Quantitative RT-PCR and Western blot analysis of sciatic nerve tissues showed that SC-Exo treatment reversed diabetes-reduced mature form of miRNA (miR)-21, -27a, and -146a and diabetes-increased semaphorin 6A (SEMA6A); Ras homolog gene family, member A (RhoA); phosphatase and tensin homolog (PTEN); and nuclear factor-kB (NF-kB). In vitro data showed that SC-Exos promoted neurite outgrowth of diabetic DRG neurons and migration of Schwann cells challenged by high glucose. Collectively, these novel data provide evidence that SC-Exos have a therapeutic effect on DPN in mice and suggest that SC-Exo modulation of miRs contributes to this therapy.