Quantitative Multicolor Single Cell Imaging Cytometry for High-content Drug Screening Based on Nanoprobes

Cell-based assays are essential to assess drug-mediated toxicity and cellular responses and to discover new chemical entities in the early phase of drug discovery. Cellular assays are usually based on either imaging or spectroscopic analysis. However, quantitative image-based cellular assays are still a major challenge for drug screening. In this work, quantitative multivariate  image-based cellular assays are reported. This approach is based on uniform threshold intensity distribution (TID) through quantitative multispectral and multicolor imaging cytometry. This method is capable of performing wide arrays of automated, quantitative, and multivariate cellular assays via single-cell monitoring over time. The approach of employing region selection to slightly defocused, background-nullified and threshold images facilitated rapid quantitative measurements during cellular assays by providing uniform TID over the objects (cells), necessary for automated quantitative analysis. We demonstrated its utility through quantitative cell viability and apoptosis/necrosis measurements in the drug-treated human myeloid leukemia (HL-60) cell line. This multivariate imaging also allowed efficient discrimination of simultaneous cellular events (i.e., apoptosis and necrosis) triggered by anticancer drugs by facilitating an entire emission spectrum at an individual wavelength. This high-content cellular imaging method offers imaging and quantitative analysis of targeted cellular moieties, which can be further applied to various cellular assays in combination with snapshot methods. For example, we successfully employed this method for simultaneous quantitative monitoring of drug-induced caspase cascade pathways in an intact carcinoma cell. The work has great significance for the exploration of various cellular caspases involved in apoptotic pathways as possible therapeutic targets in the process of drug discovery.

Joon Myong Song received his bachelor’s and master’s degree in Analytical Chemistry from Sogang University, Seoul, Korea, in 1991, and 1993, respectively. He completed his doctorate in Pharmaceutical Analysis at Kyushu University, Fukuoka, Japan, in 1997. He is currently an Associate Professor in the College of Pharmacy at Seoul National University, Seoul, Korea. From 1998 to 2000, he was a Research associate in the Ames Lab at Iowa State University, Iowa, USA. From 2000 to 2001, he was a Research associate in the Brookhaven National Laboratory, NY, USA. From 2001-2004 he worked as a Research associate in the Oak Ridge National Laboratory, TN, USA. From 2004-2005 he was an Assistant Professor in Analytical Chemistry in the Department of Chemistry at Chungnam National University, Dajeon, Korea. From 2005 to 2008 he was an Assistant Professor in Pharmaceutical Analysis in the College of Pharmacy at Soeul National University, Korea. He has broad interests in biomedical applications based on biochip and nanobiotechnology. His current interests include methodology development for cell-based drug screening using optical contrast agents, development of optical bioimaging system for monitoring of drug efficacy, and synthesis of new therapeutic agents such as nanopharmaceuticals and metallo- drugs.