Cell electrophoresis on a chip: what can we know from the changes in electrophoretic mobility?

An overview of both experimental and theoretical studies of cell electrophoresis mobility (EPM) over the past fifty years and the relevance of cell EPM measurement are presented and discussed from the viewpoint of exploring the potential use of cell EPM as an index of the biological condition of cells. Physical measurements of the optical and/or electrical properties of cells have been attracting considerable attention as noninvasive cell-evaluation methods that are essential for the future of cell-based application technologies such as cell-based drug screening and cell therapy. Cell EPM, which can be measured in a noninvasive manner by cell electrophoresis, reflects the electrical and mechanical properties of the cell surface. Although the importance of cell EPM has been underestimated for a long time, mostly owing to the technical difficulties associated with its measurement, recent improvements in measurement technology using microcapillary chips have been changing the situation: cell EPM measurement has become more reliable and faster. Recent studies using the automated microcapillary cell electrophoresis system have revealed the close correlation between cell EPM and important biological phenomena including cell cycle, apoptosis, enzymatic treatment, and immune reaction. In particular, the converged EPM distribution observed for synchronized cells has altered the conventional belief that cell EPMs vary considerably. Finding a new significance of cell EPM is likely to lead to noninvasive cell evaluation methods essential for the next-generation of cell engineering.