A review of regenerative therapy for spinal cord injury using human iPS cells

Upregulation of Intracellular Zinc Ion Level after Differentiation of the Neural Stem/Progenitor Cells In Vitro with the Changes in Gene Expression of Zinc Transporters

We measured the intracellular zinc ion concentration of murine fetal neural stem/progenitor cells (NSPCs) and that in the differentiated cells. The NSPCs cultured with 1.5 μM Zn2+ proliferated slightly faster than that in the zinc-deficient medium and the intracellular zinc concentration of the NSPCs and that of their differentiated cells (DCs) cultured with 1.5 μM Zn2+ was 1.34-fold and 2.00-fold higher than those in the zinc-deficient medium, respectively. The zinc transporter genes upregulated over the 3.5-fold change were Zip1, Zip4, Zip12, Zip13, ZnT1, ZnT8, and ZnT10 whereas the only downregulated one was Zip8 during the differentiation of NSPCs to DCs. The cell morphologies of both NSPCs and DCs in the low oxygen culture condition consisting of 2%O2 and 5%CO2, the high carbon dioxide condition consisting of 21%O2 and 10%CO2, and the normal condition consisting of 21%O2 and 5%CO2 were essentially the same each other. The expression of Zip4, Zip8, Zip12, and Zip14 was not drastically changed depending on the O2 and CO2 concentrations.

Bioorthogonal non-canonical amino acid tagging to track transplanted human induced pluripotent stem cell-specific proteome

BACKGROUND

Human induced pluripotent stem cells (hiPSCs) and their differentiated cell types have a great potential for tissue repair and regeneration. While the primary focus of using hiPSCs has historically been to regenerate damaged tissue, emerging studies have shown a more potent effect of hiPSC-derived paracrine factors on tissue regeneration. However, the precise contents of the transplanted hiPSC-derived cell secretome are ambiguous. This is mainly due to the lack of tools to distinguish cell-specific secretome from host-derived proteins in a complex tissue microenvironment in vivo.

METHODS

In this study, we present the generation and characterization of a novel hiPSC line, L274G-hiPSC, expressing the murine mutant methionyl-tRNA synthetase, L274GMmMetRS, which can be used for tracking the cell specific proteome via biorthogonal non-canonical amino acid tagging (BONCAT). We assessed the trilineage differentiation potential of the L274G-hiPSCs in vitro and in vivo. Furthermore, we assessed the cell-specific proteome labelling in the L274G-hiPSC derived cardiomyocytes (L274G-hiPSC-CMs) in vitro following co-culture with wild type human umbilical vein derived endothelial cells and in vivo post transplantation in murine hearts.

RESULTS

We demonstrated that the L274G-hiPSCs exhibit typical hiPSC characteristics and that we can efficiently track the cell-specific proteome in their differentiated progenies belonging to the three germ lineages, including L274G-hiPSC-CMs. Finally, we demonstrated cell-specific BONCAT in transplanted L274G-hiPSC-CMs.

CONCLUSION

The novel L274G-hiPSC line can be used to study the cell-specific proteome of hiPSCs in vitro and in vivo, to delineate mechanisms underlying hiPSC-based cell therapies for a variety of regenerative medicine applications.

Epigenetic regulation and factors that influence the effect of iPSCs-derived neural stem/progenitor cells (NS/PCs) in the treatment of spinal cord injury

Spinal cord injury (SCI) is a severe neurological disorder that causes neurological impairment and disability. Neural stem/progenitor cells (NS/PCs) derived from induced pluripotent stem cells (iPSCs) represent a promising cell therapy strategy for spinal cord regeneration and repair. However, iPSC-derived NS/PCs face many challenges and issues in SCI therapy; one of the most significant challenges is epigenetic regulation and that factors that influence this mechanism. Epigenetics refers to the regulation of gene expression and function by DNA methylation, histone modification, and chromatin structure without changing the DNA sequence. Previous research has shown that epigenetics plays a crucial role in the generation, differentiation, and transplantation of iPSCs, and can influence the quality, safety, and outcome of transplanted cells. In this study, we review the effects of epigenetic regulation and various influencing factors on the role of iPSC-derived NS/PCs in SCI therapy at multiple levels, including epigenetic reprogramming, regulation, and the adaptation of iPSCs during generation, differentiation, and transplantation, as well as the impact of other therapeutic tools (e.g., drugs, electrical stimulation, and scaffolds) on the epigenetic status of transplanted cells. We summarize our main findings and insights in this field and identify future challenges and directions that need to be addressed and explored.

bFGF-like Activity Supported Tissue Regeneration, Modulated Neuroinflammation, and Rebalanced Ca2+ Homeostasis following Spinal Cord Injury

A spinal cord injury (SCI) is a well-defined debilitating traumatic event to the spinal cord that usually triggers permanent changes in motor, sensory, and autonomic functions. Injured tissue becomes susceptible to secondary mechanisms caused by SCIs, which include pro-inflammatory cytokine release, the activation of astrocytes and microglia, and increased neuronal sensibility. As a consequence, the production of factors such as GFAP, IBA-1, TNF-α, IL-1β, IFN-γ, and S100-β slow down or inhibit central nervous system (CNS) regeneration. In this regard, a thorough understanding of the mechanisms regulating the CNS, and specifically SCI, is essential for the development of new therapeutic strategies. It has been demonstrated that basic fibroblast growth factor (bFGF) was successful in the modulation of neurotrophic activity, also promoting neurite survival and tissue repair, thus resulting in the valuable care of CNS disorders. However, bFGF therapeutic use is limited due to the undesirable effects developed following its administration. Therefore, the synthetic compound mimetic of bFGF, SUN11602 (with chemical name 4-[[4-[[2-[(4-Amino-2,3,5,6-tetramethylphenyl)amino]acetyl]methylamino]-1-piperidinyl]methyl]benzamide), has been reported to show neuroprotective activities similar to those of bFGF, also demonstrating a good pharmacokinetic profile. Here, we aimed to investigate the neuroprotective activity of this bFGF-like compound in modulating tissue regeneration, neuroinflammation, and Ca2+ overload by using a subacute mouse model of SCI. SUN11602 (1, 2.5, and 5 mg/kg) was administered orally to mice for 72 h daily following the in vivo model of SCI, which was generated by the extradural compression of the spinal cord. The data obtained demonstrated that SUN11602 treatment considerably decreased motor alteration and diminished the neuroinflammatory state through the regulation of glial activation, the NF-κB pathway, and kinases. Additionally, by controlling Ca2+-binding proteins and restoring neurotrophin expression, we showed that SUN11602 therapy restored the equilibrium of the neuronal circuit. Because of these findings, bFGF-like compounds may be an effective tool for reducing inflammation in SCI patients while enhancing their quality of life.