Optimization of Three-Dimensional Culture Conditions of HepG2 Cells with Response Surface Methodology Based on the VitroGel System.

Objective: This study optimizes three-dimensional (3D) culture conditions of HepG2 using response surface methodology (RSM) based on the VitroGel system to facilitate the cell model in vitro for liver tissues. Method: HepG2 cell was 3D cultured on the VitroGel system. Cell viability was detected using Cell Counting Kit-8 (CCK-8) assay of HepG2 lived cell numbers. The proliferation of HepG2 cell and clustering performance was measured via fluorescence staining test. Albumin concentration in the culture medium supernatant as an index of HepG2 cell biological function was measured with ELISA kit. Independent factor tests were conducted with three key factors: inoculated cell concentration, cultured time, and dilution degree of the hydrogel. The preliminary results of independent factor tests were used to determine the levels of factors for RSM. Result: The selected optimal culture conditions are as follows: concentration of inoculated cells was 4.44 × 10 5/mL, culture time was 4.86 days, and hydrogel dilution degree was 1:2.23. The result shows that under optimal conditions, the predicted optical density (OD) value of cell viability was 3.10 and measured 2.978 with a relative error of 3.94%. Conclusion: This study serves as a reference for the 3D HepG2 culture and constructs liver tissues in vitro. Additionally, it provides the foundation for repeated dose high-throughput toxicity studies and other scientific research work.

[Study on molecular typing by pulsed-field gel electrophoresis of food Listeria monocytogenes isolates from eight province (municipalities) of China].

OBJECTIVE: To analyse the molecular types of Listeria (L.) monocytogenes, and to construct the standard China L. monocytogenes pulsed-field gel electrophoresis (PFGE) subtyping database, using the international standardized L. monocytogenes-PFGE protocol. METHODS: 118 L. monocytogenes strains isolated from 8 provinces or municipalities of China were subtyped according to L. monocytogenes-PFGE protocol. RESULTS: 118 strains of L. monocytogenes were divided into 39 subtypes. In the 39 subtypes, 37 strains (31.36%) were GX6A160004 pattern, showing it was the predominant Lm subtype in China. CONCLUSION: Data from molecular typing suggested that the predominant Lm strains were distributed in different regions of China. PulseNet China-Lm database was constructed which was valuable for the molecular subtyping-based surveillance of L. monocytogenes.

[Study of antibody enzyme with acetylcholonesteraseactivity].

AIM: To study anti-idiotype antibody(AId Ab)directed at mAb 3F3 Fab idiotypic determinant with acetylcholinesteras(AchE) activity. METHODS: Anti-AchE mAb 3F3(IgG1) was digested by papain to prepare its Fab fragments. And then the Fab fragments were purified through Ach- and SPA-Sepharose 4B columns respectively. The BALB/c mice were immunized by using purified Fab fragments as immunogen to prepare AId Abs against the Fab fragmrnts. Catalytic activity of the AId Abs was detected by ELISA. RESULTS: The purified mAb 3F3 Fab fragments were acquired by papain digestion and affinity chromatograpy successively. Enzyme catalysis ELISA detection showed that AId Abs to the Fab fragments had activity of AchE. CONCLUSION: An AId Ab to mAb 3F3 Fab fragments has been prepared successfully, which opens up a novel way for treatment of pesticides poisoning.