Recent observations demonstrated that translation of mRNAs may occur in axonal processes at sites that are long distances away from the neuronal perikaria. While axonal protein synthesis has been documented in several studies, the mechanism of its regulation remains unclear. The aim of this study was to investigate whether RNA interference (RNAi) may be one of the pathways that control local protein synthesis in axons. Here we show that sciatic nerve contains Argonaute2 nuclease, fragile X mental retardation protein, p100 nuclease, and Gemin3 helicase-components of the RNA-induced silencing complex (RISC). Application of short-interfering RNAs against neuronal beta-tubulin to the sciatic nerve initiated RISC formation, causing a decrease in levels of neuronal beta-tubulin III mRNA and corresponding protein, as well as a significant reduction in retrograde labeling of lumbar motor neurons. Our observations indicate that RNAi is functional in peripheral mammalian axons and is independent from the neuronal cell body or Schwann cells. We introduce a concept of local regulation of axonal translation via RNAi.

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Study design: Experimental study. Objective: To evaluate the treatment of spinal cord injury with glial cell-derived neurotrophic factor (GDNF) delivered using an adenoviral vector (AdV-GDNF group) in comparison with treatment performed using human umbilical cord blood mononuclear cells (UCB-MCs)-transduced with an adenoviral vector carrying the GDNF gene (UCB-MCs+AdV-GDNF group) in rat. Setting: Kazan, Russian Federation. Methods: We examined the efficacy of AdV-GDNF and UCB-MCs+AdV-GDNF therapy by conducting behavioral tests on the animals and morphometric studies on the spinal cord, performing immunofluorescence analyses on glial cells, investigating the survival and migration potential of UCB-MCs, and evaluating the expression of the recombinant GDNF gene. Results: At the 30th postoperative day, equal positive locomotor recovery was observed after both direct and cell-based GDNF therapy. However, after UCB-MCs-mediated GDNF therapy, the area of preserved tissue and the number of spared myelinated fibers were higher than those measured after direct GDNF gene therapy. Moreover, we observed distinct changes in the populations of glial cells; expression patterns of the specific markers for astrocytes (GFAP, S100B and AQP4), oligodendrocytes (PDGFαR and Cx47) and Schwann cells (P0) differed in various areas of the spinal cord of rats treated with AdV-GDNF and UCB-MCs+AdV-GDNF. Conclusion: The differences detected in the AdV-GDNF and UCB-MCs+AdV-GDNF groups could be partially explained by the action of UCB-MCs. We discuss the insufficiency and the advantages of these two methods of GDNF gene delivery into the spinal cord after traumatic injury. INTRODUCTIONSpinal cord injury (SCI) leads to complex pathological changes that include the death of neurons and glial cells and the demyelination and degeneration of nerve fibers. The limited growth capacity of mature central nervous system (CNS) neurons and the non-permissive environment of the CNS for axon regrowth are the main factors responsible for the little or no regeneration toward targets displayed by injured axons and for the permanent functional deficit observed after SCI. One promising approach for preventing neurodegeneration involves locally treating the site of injury in order to increase the expression of neurotrophic factors. Exploiting the stimulatory effects of neurotrophic factors on neuroregeneration appears to also be useful for SCI treatment, and one neurotrophic factor that is particularly suitable for SCI treatment is glial cell-derived neurotrophic factor (GDNF). GDNF is a member of the TGF-β superfamily that binds to the receptor GFRα1 and upregulates several signaling pathways; these pathways include those involving intracellular RAS/extracellular signalregulated kinase, phosphatidylinositol 3-kinase/AKT, p38 mitogen-

Amyotrophic lateral sclerosis (ALS) is an incurable, chronic, fatal neuro-degenerative disease characterized by progressive loss of moto-neurons and paralysis of skeletal muscles. Reactivating dysfunctional areas is under earnest investigation utilizing various approaches. Here we present an innovative gene-cell construct aimed at reviving inert structure and function. Human umbilical cord blood cells (hUCBCs) transduced with adeno-viral vectors encoding human VEGF, GDNF and/or NCAM genes were transplanted into transgenic ALS mice models. Significant improvement in behavioral performance (open-field and grip-strength tests), as well as increased life-span was observed in rodents treated with NCAM-VEGF or NCAM-GDNF co-transfected cells. Active trans-gene expression was found in the spinal cord of ALS mice 10 weeks after delivering genetically modified hUCBCs, and cells were detectable even 5 months following transplantation. Our gene-cell therapy model yielded prominent symptomatic control and prolonged life-time in ALS. Incredible survivability of xeno-transpanted cells was also observed without any immune-suppression. These results suggest that engineered hUCBCs may offer effective gene-cell therapy in ALS.

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