Single cell gel electrophoresis, commonly known as comet assay, was originally developed for detecting double-strand DNA breaks in cells. Single cells are loaded in microwells in agarose chip arrays and subjected to electrophoresis. In cells with damaged DNA, a “comet tail” of DNA fragments is separated from the cell into the gel, which can be detected by staining with a nucleic acid gel stain. The technique also has been modified to allow the detection of DNA intrastrand crosslinks (ICLs) induced by anti-cancer drugs. However, a disadvantage of comet assays is the fact that cells must be trypsinized and placed in single cell suspension prior to analysis, which can alter cellular viability and integrity and affect results.
Now, Li and colleagues from Tsinghua University report a new modification of the comet assay that allows adherent cells to be evaluated for DNA damage and cellular viability in situ. By coating agarose microarray gels with extracellular matrix components, they were able to culture adherent cells in the microarray gel itself. After treating individual wells with ICL-inducing drugs, they evaluated drug toxicity using fluorescence based viability stains. Subsequently they performed comet assays and stained the arrays with GelRed™ to detect drug-induced double-strand breaks or intrastrand crosslinks (ICLs). This novel platform allows multiparameter screening of drug activity and DNA damage in individual cells in situ.
To read the original article, click here.
Lili Li, Weixing Wang, Mingyu Ding, Guoan Luo, and Qionglin Liang. Single-Cell-Arrayed Agarose Chip for in Situ Analysis of Cytotoxicity and Genotoxicity of DNA Cross-Linking Agents. Anal. Chem. DOI: 10.1021/acs.analchem.6b01008 (2016).
To learn more about Biotium’s safe and superior DNA gel stains, including GelRed™ and GelGreen™, click here.