Quantitative analyses of RBC movement in whole blood exposed to DC and ELF electric field

• Published in: Bioelectromagnetics Vol. 45; no. 4; pp. 159 - 170
• Main Authors: Kanemaki, Miki, Shimizu, Hisae O., Inujima, Hiroshi, Miyake, Takeo, Shimizu, Koichi
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.05.2024
• Subjects: Accuracy; Air gaps; Alternating current; Biological effects; Biomedical materials; Blood; Cell migration; Coupling; Dielectrophoresis; Direct current; Electric field strength; Electric fields; Electrodes; Electrophoresis; ELF electric field; Erythrocytes; Exposure; Extremely low frequencies; Image analysis; Image processing; Low frequency; Microchannels; Quantitative analysis; red blood cell; Safety; Spatial analysis; Spatial distribution; Theoretical analysis; Validity; Velocity; whole blood; dielectrophoresis; whole blood; electrophoresis; ELF electric field; biological effects; red blood cell
• ISSN: 0197-8462; 1521-186X
• DOI: 10.1002/bem.22493

For the study of biological effects of direct current (DC) and extremely low frequency (ELF) electric fields, we have quantitatively analyzed red blood cell (RBC) movement in whole blood. Considering the inhomogeneous distribution of electric fields in vivo, five different electric field distributions were generated under a microscope. For theoretical analyses, we assumed electrophoresis and dielectrophoresis as basic motive forces and obtained the spatial distribution of blood cell velocity. The RBC velocity was measured using video image analysis. The spatial dependence of the velocity showed good agreement with that predicted by theoretical analysis. This result suggests the validity of the theoretical model based on electrophoresis and dielectrophoresis for the study of ELF electric field exposure to inhomogeneous animal and human bodies. Next, using the same measurement system, we attempted to find the electric field strength at which these effects occur. The threshold values were found to be 0.40 and 1.6 kV/m, respectively, for DC and AC electric field exposures. Furthermore, we investigated the reproducibility of the field effects in more realistic conditions of human exposure. The RBCs in microchannels were exposed to the electric field generated in capacitive coupling using electrodes separated by an air gap. Even in the new condition, similar effects were observed, which also verified the validity of the analysis described above. These results will provide useful information for the safety assessment of field exposure and for the future biomedical applications of electric fields to manipulate RBCs in vivo. Highlights To evaluate the hematological effects of direct current (DC) and alternating current (AC) extremely low frequency (ELF) electric field exposure, we investigated the movement of red blood cells (RBCs) in whole blood. Video images of RBCs were captured under a microscope using specially designed electrode systems. We discovered that RBC movement is significantly influenced by ELF electric field exposure with much greater intensity than the internationally publicized guideline for human safety. In this study, we have conducted a quantitative analysis of RBC movement in whole blood, considering the inhomogeneous distribution of electric fields in vivo. The spatial dependence of RBC velocity exhibited good agreement with that predicted by the theoretical model based on electrophoresis and dielectrophoresis. The threshold values for the exposed electric field were found to be 0.40 and 1.6 kV/m for DC and AC field exposures, respectively. To investigate the effects of the electric field under more realistic conditions of human exposure, RBCs in microchannels were exposed to the electric field generated via capacitive coupling, using electrodes separated by an air gap. Even under these new conditions, we observed similar effects to those in the previous experiment, which verified the validity of the analysis described above. These results will provide valuable information for safety assessment of field exposure and for potential future biomedical applications of electric fields to manipulate RBCs in vivo.