Antiapoptotic Effect of Highly Secreted GMCSF From Neuronal Cell-specific GMCSF Overexpressing Neural Stem Cells in Spinal Cord Injury Model

Considerations about Hypoxic Changes in Neuraxis Tissue Injuries and Recovery

Hypoxia represents the temporary or longer-term decrease or deprivation of oxygen in organs, tissues, and cells after oxygen supply drops or its excessive consumption. Hypoxia can be (para)-physiological-adaptive-or pathological. Thereby, the mechanisms of hypoxia have many implications, such as in adaptive processes of normal cells, but to the survival of neoplastic ones, too. Ischemia differs from hypoxia as it means a transient or permanent interruption or reduction of the blood supply in a given region or tissue and consequently a poor provision with oxygen and energetic substratum-inflammation and oxidative stress damages generating factors. Considering the implications of hypoxia on nerve tissue cells that go through different ischemic processes, in this paper, we will detail the molecular mechanisms by which such structures feel and adapt to hypoxia. We will present the hypoxic mechanisms and changes in the CNS. Also, we aimed to evaluate acute, subacute, and chronic central nervous hypoxic-ischemic changes, hoping to understand better and systematize some neuro-muscular recovery methods necessary to regain individual independence. To establish the link between CNS hypoxia, ischemic-lesional mechanisms, and neuro-motor and related recovery, we performed a systematic literature review following the" Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA") filtering method by interrogating five international medical renown databases, using, contextually, specific keywords combinations/"syntaxes", with supplementation of the afferent documentation through an amount of freely discovered, also contributive, bibliographic resources. As a result, 45 papers were eligible according to the PRISMA-inspired selection approach, thus covering information on both: intimate/molecular path-physiological specific mechanisms and, respectively, consequent clinical conditions. Such a systematic process is meant to help us construct an article structure skeleton giving a primary objective input about the assembly of the literature background to be approached, summarised, and synthesized. The afferent contextual search (by keywords combination/syntaxes) we have fulfilled considerably reduced the number of obtained articles. We consider this systematic literature review is warranted as hypoxia's mechanisms have opened new perspectives for understanding ischemic changes in the CNS neuraxis tissue/cells, starting at the intracellular level and continuing with experimental research to recover the consequent clinical-functional deficits better.

Progress in Stem Cell Therapy for Spinal Cord Injury

Background

Spinal cord injury (SCI) is one of the serious neurological diseases that occur in young people with high morbidity and disability. However, there is still a lack of effective treatments for it. Stem cell (SC) treatment of SCI has gradually become a new research hotspot over the past decades. This article is aimed at reviewing the research progress of SC therapy for SCI.

Methods

Review the literature and summarize the effects, strategies, related mechanisms, safety, and clinical application of different SC types and new approaches in combination with SC in SCI treatment.

Results

A large number of studies have focused on SC therapy for SCI, most of which showed good effects. The common SC types for SCI treatment include mesenchymal stem cells (MSCs), hematopoietic stem cells (HSCs), neural stem cells (NSCs), induced pluripotent stem cells (iPSCs), and embryonic stem cells (ESCs). The modes of treatment include in vivo and in vitro induction. The pathways of transplantation consist of intravenous, transarterial, nasal, intraperitoneal, intrathecal, and intramedullary injections. Most of the SC treatments for SCI use a number of cells ranging from tens of thousands to millions. Early or late SC administration, application of immunosuppressant or not are still controversies. Potential mechanisms of SC therapy include tissue repair and replacement, neurotrophy, and regeneration and promotion of angiogenesis, antiapoptosis, and anti-inflammatory. Common safety issues include thrombosis and embolism, tumorigenicity and instability, infection, high fever, and even death. Recently, some new approaches, such as the pharmacological activation of endogenous SCs, biomaterials, 3D print, and optogenetics, have been also developed, which greatly improved the application of SC therapy for SCI.

Conclusion

Most studies support the effects of SC therapy on SCI, while a few studies do not. The cell types, mechanisms, and strategies of SC therapy for SCI are very different among studies. In addition, the safety cannot be ignored, and more clinical trials are required. The application of new technology will promote SC therapy of SCI.

Combined Method of Neuronal Cell-Inducible Vector and Valproic Acid for Enhanced Gene Expression under Hypoxic Conditions

BACKGROUND

Gene therapy shows the ability to restore neuronal dysfunction via therapeutic gene expression. The efficiency of gene expression and delivery to hypoxic injury sites is important for successful gene therapy. Therefore, we established a gene/stem cell therapy system using neuron-specific enolase promoter and induced neural stem cells in combination with valproic acid to increase therapeutic gene expression in hypoxic spinal cord injury.

METHODS

To examine the effect of combined method on enhancing gene expression, we compared neuronal cell-inducible luciferase levels under normoxia or hypoxia conditions in induced neural stem cells with valproic acid. Therapeutic gene, vascular endothelial growth factor, expression with combined method was investigated in hypoxic spinal cord injury model. We verified gene expression levels and the effect of different methods of valproic acid administration in vivo.

RESULTS

The results showed that neuron-specific enolase promoter enhanced gene expression levels in induced neural stem cells compared to Simian Virus 40 promoter under hypoxic conditions. Valproic acid treatment showed higher gene expression of neuron-specific enolase promoter than without treatment. In addition, gene expression levels and cell viability were different depending on the various concentration of valproic acid. The gene expression levels were increased significantly when valproic acid was directly injected with induced neural stem cells in vivo.

CONCLUSION

In this study, we demonstrated that the combination of neuron-specific enolase promoter and valproic acid induced gene overexpression in induced neural stem cells under hypoxic conditions and also in spinal cord injury depending on valproic acid administration in vivo. Combination of valproic acid and neuron-specific enolase promoter in induced neural stem cells could be an effective gene therapy system for hypoxic spinal cord injury.

Regulation of Inflammatory Cytokines for Spinal Cord Injury Repair Through Local Delivery of Therapeutic Agents

The balance of inflammation is critical to the repair of spinal cord injury (SCI), which is one of the most devastating traumas in human beings. Inflammatory cytokines, the direct mediators of local inflammation, have differential influences on the repair of the injured spinal cord. Some inflammatory cytokines are demonstrated beneficial to spinal cord repair in SCI models, while some detrimental. Various animal researches have revealed that local delivery of therapeutic agents efficiently regulates inflammatory cytokines and promotes repair from SCI. Quite a few clinical studies have also shown the promotion of repair from SCI through regulation of inflammatory cytokines. However, local delivery of a single agent affects only a part of the inflammatory cytokines that need to be regulated. Meanwhile, different individuals have differential profiles of inflammatory cytokines. Therefore, future studies may aim to develop personalized strategies of locally delivered therapeutic agent cocktails for effective and precise regulation of inflammation, and substantial functional recovery from SCI.

miR-381 Regulates Neural Stem Cell Proliferation and Differentiation via Regulating Hes1 Expression

Neural stem cells are self-renewing, multipotent and undifferentiated precursors that retain the capacity for differentiation into both glial (astrocytes and oligodendrocytes) and neuronal lineages. Neural stem cells offer cell-based therapies for neurological disorders such as Alzheimer's disease, Parkinson's disease, Huntington's disease and spinal cord injuries. However, their cellular behavior is poorly understood. MicroRNAs (miRNAs) are a class of small noncoding RNAs involved in cell development, proliferation and differentiation through regulating gene expression at post-transcriptional level. The role of miR–381 in the development of neural stem cells remains unknown. In this study, we showed that overexpression of miR–381 promoted neural stem cells proliferation. It induced the neural stem cells differentiation to neurons and inhibited their differentiation to astrocytes. Furthermore, we identified HES1 as a direct target of miR–381 in neural stem cells. Moreover, re-expression of HES1 impaired miR-381-induced promotion of neural stem cells proliferation and induce neural stem cells differentiation to neurons. In conclusion, miR–381 played important role in neural stem cells proliferation and differentiation.