Yong Kwon Lee

Cellular Toxicity of Various Inhalable Metal Nanoparticles on Human Alveolar Epithelial Cells

Nanoparticles (NPs) have a greater potential to travel through an organism via inhalation than any other larger particles, and could be more toxic due to their larger surface area and specific structural/chemical properties. The aim of this study was to evaluate in vitro biological effects of various inhalable metallic NPs (TiO2, Ag, Al, Zn, Ni). Human alveolar epithelial cells (A549) were exposed to various concentrations of NPs for 24 h. The extent of morphological damage was in the order of m-TiO2 > n-TiO2 > m-silica ≫ n-Ni ≈ n-Zn ≈ n-Ag ≈ n-Al and was affected in a dose-dependent manner. The extent of apoptotic damage measured with two-color flow cytometry was in the order of n-Zn > n- Ni > m-silica ≫ n- TiO2 > m- TiO2 > n-Al > n-Ag. The extent of apoptotic damage measured with DNA fragmentation was in the order of n-Zn ≈ m-silica > n- Ni ≫ m- TiO2 ≈ n- TiO2 ≈ n-Al > n-Ag, indicating no significant difference in the damages by both m-TiO2 and n-TiO2. The extents of apoptotic damages were also affected in a dose-dependent manner. Uptake of no other NPs but n-TiO2 and m-TiO2 into the cells was observed after 24 h exposure. The intracellular generation of ROS was significant with n-Zn but not with the other particles. These results demonstrated that various inhalable metallic NPs (TiO2, Ag, Al, Zn, Ni) could cause cell damages directly or indirectly. More detailed studies on the influence of size, structure, and composition of the NPs are needed to better understand their toxic mechanisms.

Development of a varicella virus vaccine stabilizer containing no animal-derived component

Various stabilizers containing no animal-derived components were assessed for their efficacy in stabilizing live attenuated varicella virus under various storage temperatures. Stabilizers containing carrageenan, soy protein hydrolysates, or sucrose had a satisfactory performance to maintain infectivity of the cell-free virus when compared to control stabilizer containing animal-derived gelatin/gelatin hydrolysate.

Use of soybean protein hydrolysates for promoting proliferation of human keratinocytes in serum-free medium

Human keratinocytes are generally cultured in media containing bovine pituitary extract (BPE), an animal product that can be a source of infectious contaminants. We investigated whether a safer plant product could replace BPE in the culture medium. Medium containing both BPE and soy protein hydrolysates (Bacto Soytone and Soy Hydrolysate) produced the largest number of viable cells, followed in descending order by medium supplemented only with BPE, only with the hydrolysates, and without supplementation (basal medium only). Soybean protein is thus an excellent source of nutrients for the growth of adherent keratinocytes, although they do not fully substitute for BPE.

Use of plant protein hydrolysates for varicella virus production in serum-free medium

AbstractSerum-free media containing no animal-derived components were assessed for their efficacy to produce live attenuated varicella virus. Serum-free medium containing an ultrafiltrate of soy protein acid hydrolysate and lipid resulted in a viral production yield comparable to media containing fetal bovine serum, indicating that varicella virus can be produced without the risk of contamination associated with the use of bovine serum.

Retinoic acid modulates the level of nerve growth factor gene expression and proliferation of cultured human keratinocytes

Retinoic acid (RA) inhibited proliferation of cultured human keratinocytes. Southern blot analysis at 24 h showed that RA inhibited nerve growth factor (NGF) mRNA synthesis in a dose-dependent manner. However, RA stimulated the production of NGF protein up to 187% of control after 96 h and the treatment of cells with RA did not enhance apoptosis, either in the presence of low or high concentration of Ca2+, when compared to the control with DMSO.