Cases reporting traumatic injuries to the brain and spinal cord are extended range of disorders that affect a large percentage of the world's population. But, there are only few effective treatments available for central nervous system (CNS) injuries because the CNS is refractory to axonal regeneration and relatively inaccessible to many pharmacological treatments. The use of stem cell therapy in regenerative medicine has been extensively examined to replace lost cells during CNS injuries. But, given the complexity of CNS injuries oxidative stress, toxic byproducts, which prevails in the microenvironment during the diseased condition, may limit the survival of the transplanted stem cells affecting tissue regeneration and even longevity. Carbon nanotubes (CNT) are a new class of nanomaterials, which have been shown to be promising in different areas of nanomedicine for the prevention, diagnosis and therapy of certain diseases, including CNS diseases. In particular, the use of CNTs as substrates/scaffolds for supporting the stem cell differentiation has been an area of active research. Single-walled and multi-walled CNT's have been increasingly used as scaffolds for neuronal growth and more recently for neural stem cell growth and differentiation. This review summarizes recent research on the application of CNT-based materials to direct the differentiation of progenitor and stem cells toward specific neurons and to enhance axon regeneration and synaptogenesis for the effective treatment of CNS injuries. Nonetheless, accumulating data support the use of CNTs as a biocompatible and permissive substrate/scaffold for neural cells and such application holds great potential in neurological research.

BackgroundIn physiologic and pathologic conditions of the central nervous system (CNS), astrocytes are a double-edged sword. They not only support neuronal homeostasis but also contribute to increases in neuronal demise. A large body of experimental evidence has shown that impaired astrocytes play crucial roles in the pathologic process of cerebral ischemia; therefore, astrocytes may represent a breakthrough target for neuroprotective therapeutic strategies. Agmatine, an endogenous polyamine catalyzed from L-arginine by arginine decarboxylase (ADC), is a neuromodulator and it protects neurons/glia against various injuries.ResultsIn this investigation, agmatine-producing mouse cortical astrocytes were developed through transduction of the human ADC gene. Cells were exposed to oxygen-glucose deprivation (OGD) and restored to a normoxic glucose-supplied condition. Intracellular levels of agmatine were measured by high performance liquid chromatography. Cell viability was evaluated by Hoechest/propidium iodide nuclear staining and lactate dehydrogenase assay. Expression of inducible nitric oxide synthase (iNOS) and matrix metalloproteinase s (MMPs) were assessed by a reverse transcription polymerase chain reaction, Western immunoblots, and immunofluorescence. We confirmed that ADC gene-expressed astrocytes produce a great amount of agmatine. These cells were highly resistant to not only OGD but also restoration, which mimicked ischemia-reperfusion injury in vivo. The neuroprotective effects of ADC seemed to be related to its ability to attenuate expression of iNOS and MMPs.ConclusionOur findings imply that astrocytes can be reinforced against oxidative stress by endogenous agmatine production through ADC gene transduction. The results of this study provide new insights that may lead to novel therapeutic approaches to reduce cerebral ischemic injuries.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2202-15-99) contains supplementary material, which is available to authorized users.