Hyunjin Cho

Human umbilical-cord-derived mesenchymal stem cells (hUC-MSC) are a type of mesenchymal stem cells and are more primitive than other MSCs. In this study, we identify novel genes and signal-activating proteins involved in the neural differentiation of hUC-MSCs induced by Low-Intensity Sub-Sonic Vibration (LISSV). RNA sequencing was used to find genes involved in the differentiation process by LISSV. The changes in hUC-MSCs caused by LISSV were confirmed by PLXNA4 overexpression and gene knockdown through small interfering RNA experiments. The six genes were increased among genes related to neurons and the nervous system. One of them, the PLXNA4 gene, is known to play a role as a guide for axons in the development of the nervous system. When the PLXNA4 recombinant protein was added, neuron-related genes were increased. In the PLXNA4 gene knockdown experiment, the expression of neuron-related genes was not changed by LISSV exposure. The PLXNA4 gene is activated by sema family ligands. The expression of SEMA3A was increased by LISSV, and its downstream signaling molecule, FYN, was also activated. We suggest that the PLXNA4 gene plays an important role in hUC-MSC neuronal differentiation through exposure to LISSV. The differentiation process depends on SEMA3A-PLXNA4-dependent FYN activation in hUC-MSCs.

Background Rosacea is one of the most common dermatoses of adults. Although the detailed pathophysiology remains unknown, it is thought that rosacea is caused by a consistently aberrant, innate immune response, and that LL‐37 plays an important role. However, involvement of the inflammatory cytokine IL‐33 has not yet been studied. Objectives We explored the role played by IL‐33 in the pathophysiology of rosacea. Methods First, we immunohistochemically evaluated the expression of IL‐33 and its receptor (ST2) in rosacea skin. Second, we exposed HaCaT cells to ultraviolet B (UVB) irradiation in the presence or absence of LL‐37, and measured the expression of proinflammatory cytokines including IL‐33. We also analyzed VEGF (vascular endothelial growth factor) mRNA expression and protein release after co‐stimulation of HaCaT cells by LL‐37 and IL‐33. Results Immunohistochemically, IL‐33 expression was enhanced in the skin of rosacea patients, especially with erythematotelangiectatic subtype. In vitro, UVB and LL‐37 synergistically increased mRNAs expression of proinflammatory cytokines, especially IL‐33 and IL‐1β. IL‐33 protein release was also synergistically increased by LL‐37 and UVB treatment. LL‐37 and IL‐33 stimulated VEGF mRNA expression and VEGF release from HaCaT cells. Conclusions Our findings suggest that rosacea skin with abundant LL‐37 may robustly produce and release IL‐33 when exposed to UV radiation. IL‐33 may participate in the angiogenesis and vasodilation of rosacea skin by enhancing VEGF release.

Human bone marrow-derived mesenchymal stem cells (hBM-MSCs) have been investigated as a new cell-therapeutic solution due to their capacity that could differentiate into neural-like cells. Extremely low-frequency electromagnetic fields (ELF-EMFs) therapy has emerged as a novel technique, using mechanical stimulus to differentiate hBM-MSCs and significantly enhance neuronal differentiation to affect cellular and molecular reactions. Magnetic iron oxide (Fe₃O₄) nanoparticles (MNPs) have recently achieved widespread use for biomedical applications and polyethylene glycol (PEG)-labeled nanoparticles are used to increase their circulation time, aqueous solubility, biocompatibility, and nonspecific cellular uptake as well as to decrease immunogenicity. Many studies have used MNP-labeled cells for differentiation, but there have been no reports of MNP-labeled neural differentiation combined with EMFs. In this study, synthesized PEG-phospholipid encapsulated magnetite (Fe₃O₄) nanoparticles are used on hBM-MSCs to improve their intracellular uptake. The PEGylated nanoparticles were exposed to the cells under 50 Hz of EMFs to improve neural differentiation. First, we measured cell viability and intracellular iron content in hBM-MSCs after treatment with MNPs. Analysis was conducted by RT-PCR, and immunohistological analysis using neural cell type-specific genes and antibodies after exposure to 50 Hz electromagnetic fields. These results suggest that electromagnetic fields enhance neural differentiation in hBM-MSCs incorporated with MNPs and would be an effective method for differentiating neural cells.