Hye-Lee Kim

Asiaticoside enhances normal human skin cell migration, attachment and growth in vitro wound healing model.

Wound healing proceeds through a complex collaborative process involving many types of cells. Keratinocytes and fibroblasts of epidermal and dermal layers of the skin play prominent roles in this process. Asiaticoside, an active component of Centella asiatica, is known for beneficial effects on keloid and hypertrophic scar. However, the effects of this compound on normal human skin cells are not well known. Using in vitro systems, we observed the effects of asiaticoside on normal human skin cell behaviors related to healing. In a wound closure seeding model, asiaticoside increased migration rates of skin cells. By observing the numbers of cells attached and the area occupied by the cells, we concluded that asiaticoside also enhanced the initial skin cell adhesion. In cell proliferation assays, asiaticoside induced an increase in the number of normal human dermal fibroblasts. In conclusion, asiaticoside promotes skin cell behaviors involved in wound healing; and as a bioactive component of an artificial skin, may have therapeutic value.

Biological Advantages of Porous Hydroxyapatite Scaffold Made by Solid Freeform Fabrication for Bone Tissue Regeneration

Presently, commercially available porous bone substitutes are manufactured by the sacrificial template method, direct foaming method, and polymer replication method (PRM). However, current manufacturing methods provide only the simplest form of the bone scaffold and cannot easily control pore size. Recent developments in medical imaging technology, computer-aided design, and solid freeform fabrication (SFF), have made it possible to accurately produce porous synthetic bone scaffolds to fit the defected bone shape. Porous scaffolds were fabricated by SFF and PRM for a comparison of physical and mechanical properties of scaffold. The suggested three-dimensional model has interconnected cubic pores of 500 μm and its calculated porosity is 25%. Whereas hydroxyapatite scaffolds fabricated by SFF had connective macropores, those by PRM formed a closed pore external surface with internally interconnected pores. SFF was supposed to be a proper method for fabricating an interconnected macroporous network. Biocompatibility was confirmed by testing the cytotoxicity, hemolysis, irritation, sensitization, and implantation. In summary, the aim was to verify the safety and efficacy of the scaffolds by biomechanical and biological tests with the hope that this research could promote the feasibility of using the scaffolds as a bone substitute.

The biological activities of (1,3)-(1,6)-β-d-glucan and porous electrospun PLGA membranes containing β-glucan in human dermal fibroblasts and adipose tissue-derived stem cells

In this study, we investigated the possible roles of (1,3)-(1,6)-beta-d-glucan (beta-glucan) and porous electrospun poly-lactide-co-glycolide (PLGA) membranes containing beta-glucan for skin wound healing, especially their effect on adult human dermal fibroblast (aHDF) and adipose tissue-derived stem cell (ADSC) activation, proliferation, migration, collagen gel contraction and biological safety tests of the prepared membrane. This study demonstrated that beta-glucan and porous PLGA membranes containing beta-glucan have enhanced the cellular responses, proliferation and migration, of aHDFs and ADSCs and the result of a collagen gel contraction assay also revealed that collagen gels contract strongly after 4 h post-gelation incubation with beta-glucan. Furthermore, we confirmed that porous PLGA membranes containing beta-glucan are biologically safe for wound healing study. These results indicate that the porous PLGA membranes containing beta-glucan interacted favorably with the membrane and the topical administration of beta-glucan was useful in promoting wound healing. Therefore, our study suggests that beta-glucan and porous PLGA membranes containing beta-glucan may be useful as a material for enhancing wound healing.

Promotion of Full‐Thickness Wound Healing Using Epigallocatechin‐3‐O‐Gallate/Poly (Lactic‐Co‐Glycolic Acid) Membrane as Temporary Wound Dressing

Epigallocatechin-3-O-gallate (EGCG) is a major polyphenolic compound in green tea. It has been known that EGCG regulates the secretion of cytokines and the activation of skin cells during wound healing. In this study, various concentrations of EGCG were added to the electrospun membranes composed of poly (lactic-co-glycolic acid) (PLGA), and its healing effects on full-thickness wounds created in nude mice were investigated. The electrospun membranes containing 5 wt% EGCG (5EGCG/PLGA membrane) exhibited cytotoxicity in human dermal fibroblasts (HDFs) as HDF morphologies were transformed on them. In the animal study, cell infiltration of mice treated with electrospun membranes containing 1 wt% EGCG (1EGCG/PLGA membrane) significantly increased after 2 weeks. The immunoreactivity of Ki-67 (re-epithelialization at the wound site) and CD 31 (formation of blood vessels) also increased in the mice treated with 1EGCG/PLGA membranes in comparison with the mice treated with PLGA membranes. These results suggest that 1EGCG/PLGA can enhance wound healing in full thickness by accelerating cell infiltration, re-epithelialization, and angiogenesis.

Selective inhibitory effect of epigallocatechin-3-gallate on migration of vascular smooth muscle cells.

In order to prevent restenosis after angioplasty or stenting, one of the most popular targets is suppression of the abnormal growth and excess migration of vascular smooth muscle cells (VSMCs) with drugs. However, the drugs also adversely affect vascular endothelial cells (VECs), leading to the induction of late thrombosis. We have investigated the effect of epigallocatechin-3-gallate (EGCG) on the proliferation and migration of VECs and VSMCs. Both cells showed dose-dependent decrease of viability in response to EGCG while they have different IC50 values of EGCG (VECs, 150 μM and VSMCs, 1050 μM). Incubating both cells with EGCG resulted in significant reduction in cell proliferation irrespective of cell type. The proliferation of VECs were greater affected than that of VSMCs at the same concentrations of EGCG. EGCG exerted differential migration-inhibitory activity in VECs vs. VSMCs. The migration of VECs was not attenuated by 200 μM EGCG, but that of VSMCs was significantly inhibited at the same concentration of EGCG. It is suggested that that EGCG can be effectively used as an efficient drug for vascular diseases or stents due to its selective activity, completely suppressing the proliferation and migration of VSMCs, but not adversely affecting VECs migration in blood vessels.

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.

Fabrication of three-dimensional poly(lactic-co-glycolic acid) mesh by electrospinning using different solvents with dry ice

AbstractScaffolds used in tissue engineering are usually porous for providing a passage and cell infiltration. In this study, we have investigated the effects of vapor pressure of solvents during electrospinning with dry ice on the pore sizes of the poly(lactic-co-glycolic acid) (PLGA) meshes and the cell behaviors in these meshes. The meshes fabricated with dry ice using 1,1,1,3,3,3,-hexafluoro-2-propanol (HFIP), which was the lowest vapor pressure of the experimental solvents, were not significantly different on the fiber connections as compared to those fabricated without dry ice. When electrospinning was processed using acetone with dry ice, numerous beads were observed in the meshes. The meshes which were fabricated using the tetrahydrofuran/dimethylformamide (THF/DMF) admixture with dry ice had loose connections between the fibers and showed large voids. In addition, the infiltration and the attachment of cells increased on these meshes due to large voids. Therefore, dry ice during electrospinning could cause an increase in pore size; however, these electrospinning processing was sensitive to the vapor pressure of the experimental solvent.

Plasma treatment induces internal surface modifications of electrospun poly(L-lactic) acid scaffold to enhance protein coating

Advanced biomaterials should also be bioactive with regard to desirable cellular responses, such as selective protein adsorption and cell attachment, proliferation, and differentiation. To enhance cell-material interactions, surface modifications have commonly been performed. Among the various surface modification approaches, atmospheric pressure glow discharge plasma has been used to change a hydrophobic polymer surface to a hydrophilic surface. Poly(L-lactic acid) (PLLA)-derived scaffolds lack cell recognition signals and the hydrophobic nature of PLLA hinders cell seeding. To make PLLA surfaces more conducive to cell attachment and spreading, surface modifications may be used to create cell-biomaterial interfaces that elicit controlled cell adhesion and maintain differentiated phenotypes. In this study, (He) gaseous atmospheric plasma glow discharge was used to change the characteristics of a 3D-type polymeric scaffold from hydrophobic to hydrophilic on both the outer and inner surfaces of the scaffold...

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.