Alignment and counting of mitochondria based on capillary electrophoresis

The mitochondria are referred to as the 'power houses' of the cell. The number of mitochondria is considered to be related to various diseases (e.g., obesity, degenerative diseases, and aging), and thus counting the number of mitochondria in per cell is helpful for the elucidation of the rare cells. Here, we report a mitochondria-aligning system that can realize mitochondrion counting based on capillary electrophoresis technology. By electrophoresis of fluorescent microsphere in a capillary with internal diameter approximated to the size of mitochondrion (0.5-1.5 μm), we find that the microsphere aggregated under DC voltage mode, corresponding to the peak intensity appeared much larger than that of one microsphere. After applying square-wave pulsed electric field, the fluorescence signal from one microsphere immediately appeared, indicating that the microsphere aligned one-dimensionally and migrated through a narrow capillary. Based on the above phenomenon, we evaluated the mitochondria in per cell of COS-1, NIH3T3, brown fat precursor cell, and brown fat cell, respectively.