(494b) A New Drug Screening Method for Chinese Herbal Medicines As Enhancers for Embryonic Stem Cell Proliferation

In this work, we developed a new drug screening method based on three-dimensional (3-D) cell culture for Chinese herbal medicines and for the first time discovered the potential application of a traditional herbal medicine as a new proliferation enhancer of embryonic stem cell culture through this method. This new screening method used nonwoven polyethylene terephthalate (PET) fibers as scaffolds for the 3-D culture of cells expressing enhanced green fluorescent protein (EGFP) in the medium with herbal medicine extracts. The extracts of three traditional Chinese herbal medicines, Epimedium dacidii Franch (EDF), Ganoderma lucidum spore (GLS), and Ginkgo biloba (GB), were selected as the screening targets and their effects on the proliferations of three cell lines (i.e., mouse embryonic stem (mES) D3 cells, colon cancer HT-29 cells, and breast cancer MCF-7 cells) were evaluated by measuring EGFP fluorescence intensities at a certain wave length. For each herbal medicine, the extracts were dissolved in DMEM cell culture medium at the concentrations of 0.01%, 0.1%, and 1% (w/v). Cell culture in the medium containing deoxycholic acid (DCA) (0.1 mM, 1 mM, and 10 mM) was used as the positive control for screening. The cell morphologies under different culture conditions were also characterized via scanning electron microscopy (SEM). Results showed that the growth of all three cell lines were significantly inhibited in the medium with 1% of herbal medicine exacts, which indicated that all three herbal medicines demonstrated strong cytotoxicity at 1% concentration regardless of the cell type. At a concentration of 0.1%, the herbal medicines showed different effects on cell proliferation depending on the cell type: GLS displayed a promotional effect on mES D3 cell proliferation but a reverse effect on the two cancer cell lines, while both EDF and GB inhibited the proliferation of mES D3 cells but showed no apparent impact on the two cancer cells. Those results were also supported by cell morphologies on SEM images. Based on the above results, we selected GLS as a new proliferation enhancer and for the first time used DMEM medium containing 0.1% GLS for stem cell culture. The new medium enhanced the specific growth rate and the maximum cell density of mES D3 cells by 28.6% and 29.1%, respectively, compared with the cell culture in regular DMEM medium. In summary, this 3-D cell culture-based screening method is feasible and efficient in evaluating the effects of herbal medicines on cell growth. GLS selected by this method shows its potential applications in mass production of embryonic stem cells and for treating cancers.