Genetic modification of mesenchymal stem cells in spinal cord injury repair strategies.

Spinal cord injury (SCI) is a serious injury of the central nervous system and up until now there is no evident effective treatment for SCI. Axonal regeneration is the only way to restore functions after serious SCI that interrupt the long tracts mediating motor and sensory function. The hurdles for axonal regeneration in SCI include: glial scar tissue and molecular barriers, the inhibiting microenvironment, and the lack of sufficient neurotrophic support. Therefore, the key point of applying stem cells to treat SCI is to build a microenvironment conducive to the survival and differentiation of stem cells and regulate neurotrophic factor expression. Adult mesenchymal stem cells (MSCs) have been applied in experimental animal models and clinical trials of SCI. Genetic modification of MSCs can increase secretion of peptides or total length proteins with potential to repair SCI and promote survival of themselves and survival or regeneration of neurons. There are many proteins that have been applied to modified MSCs, such as neurotrophic factors (neurotrophin 3, brain-derived neurotrophic factor, glial cell line-derived neurotrophic factor, nerve growth factor, and MNTS1), receptor tyrosine kinases (tropomyosin-related kinase C), and hepatocyte growth factor. In the future, there will be more molecules acting as transgenes in MSCs for treatment of SCI.