Hyun Joo Son

Iridium Oxide as a Stimulating Neural Electrode Formed by Reactive Magnetron Sputtering

Implantable neural prostheses form hybrid interfaces with biological constructs, and the application of electrical fields can restore functions of patients with neurological damages. The various stoichiometric compositions of iridium oxide were synthesized using reactive magnetron sputtering. The charge injection behavior of iridium oxide deposited with an O2/Ar ratio of 0.5 was similar to pure Ir. The charge density of iridium oxide increased with increasing O2/Ar ratio, and increasing thickness of iridium oxide.

Protection of Human Fibroblasts from Reactive Oxygen Species by Green Tea Polyphenolic Compounds

The potential protective roles played by green tea compounds (GTPCs) against reactive oxygen species-induced oxidative stress in cultured fetal human dermal fibroblasts (fHDFs) were investigated according to cell viability measurement methods, such as fluorescence double staining followed by flow cytometry (FCM), MTT assay and crystal violet uptake. Oxidative stress was induced in the fHDFs, either by adding 50 mM H2O2 or by the action of 40 U/L xanthine oxidase (XO) in the presence of xanthine (250 µM). FCM analysis was the most suitable to show that both treatments produced a significant (p < 0.05) reduction in the fHDF viability, attributed to its high sensitivity. On the microscopic observations, the cell death with necrotic morphology was appreciably induced by both treatments. These oxidative stress-induced damages were significantly (p < 0.05) prevented by pre-incubating the fHDFs with 200 µg/ml GTPC for 1 h. These results suggest that GTPC can act as a biological antioxidant in a cell culture experimental model and prevent oxidative stress-induced cytotoxicity in cells.

Effects Of (1→3), (1→6)-β-D-Glucan Behavior in Human Dermal Fibroblast Cells under Serum Starvation

Glucans have been reported to stimulate immunity and to promote wound healing. Adult human dermal fibroblast (aHDF) cultured in serum free (serum-starvation). Proliferation of aHDF was measured at various concentrations of β-glucan by MTT assay, and migration was observed for 36h on microscope. The result of fibroblast bioassay, β-glucan had positive influence. In this study, the direct effects of β-glucan on proliferation and migration of human dermal fibroblasts were examined in vitro. That means β-D-glucan has the effect to enhance proliferation and aHDF migration speed, and has the potential as a wound healing agent.

Attachment and Proliferation of Human Dermal Fibroblasts onto ECM-Immobilized PLGA Films

In this study, human dermal fibroblast behaviors onto non-porous PLGA (75:25) films immobilized with 1, 10 and 100 µg/ml collagen (CN) or fibronectin (FN) were investigated according to different cell-seeding densities (1,000, 10,000 and 100,000 cells/ml). Cell attachment and proliferation were assessed using water soluble tetrazolium salt. The results indicated that 1 µg/ml of FN-immobilized PLGA film demonstrated significantly (p < 0.05) superior cellular attachment to the intact PLGA film after 4 hr of incubation. Moreover, the number of attached cells was shown to be directly proportional to that of initially seeded cells. After 48 hr, the cells showed significantly (p < 0.05) higher proliferation onto 1 or 10 µg/ml of FN-immobilized PLGA films than onto other PLGA films, regardless of the initial cell-seeding density. In terms of CN-immobilization, cell proliferation was appreciably increased but it was relatively lower than FN-immobilization. These results suggested that ECM-immobilization can enhance the cell affinity of hydrophobic scaffolds and be used to potential applications for tissue engineering by supporting cell growth.

Computer-Assisted Image Processing Techniques for Quantitative Analysis of Cell Migrations on Collagen-Coated Glass

In this study, a computer-assisted cell tracking system including an automatic image processing program for rapid and precise analysis of cell migration in various conditions was self-designed and L-929 cell migration on the glass coated with type I collagen was examined using this cell tracking system. Furthermore, computer-based image processing software, with the capture program to choose the capture interval and period, and analysis techniques were developed for quantitative analysis of the cell migration on extracellular matrices. The results showed that the migration speed of L-929 cells on the collagen-coated glass was significantly (p < 0.05) increased compared to the non-coated control. On the morphological observations, it was showed that the cells on the collagen-coated glass looked much healthier than those on the control. These results suggested that this cell tracking system would provide tools for the analysis of cell migration in various in vitro conditions and might be effective enough to evaluate various biological events including embryonic development as well as physiological and pathological tissue reorganization.