Agents facilitating the electric field-induced fusion of intact rabbit erythrocytes

Melatonin Protects Rabbit Somatic Cell Nuclear Transfer (SCNT) Embryos from Electrofusion Damage

The study’s objectives were to examine the effects of electrofusion on rabbit somatic cell nuclear transfer (SCNT) embryos, and to test melatonin as a protective agent against electrofusion damage to SCNT embryos. The levels of reactive oxygen species (ROS), the epigenetic state (H3K9me3), and the content of endoplasmic reticulum (ER) stress-associated transcripts (IRE-1 and CHOP) were measured. Melatonin was added during the preimplantation development period. The total blastocyst cell numbers were counted, and the fragmentation rate and apoptotic index were determined and used to assess embryonic development. Electrofusion increased (1) ROS levels at the 1-, 2-, 4-, and 8-cell stages; (2) H3K9me3 levels at the 2-, 4-, and 8-cell stage; and (3) the expression of IRE-1 and CHOP at the 8-cell, 16-cell, morula, and blastocyst stages. The treatment of SCNT embryos with melatonin significantly reduced the level of ROS and H3K9me3, and the expression levels of IRE-1 and CHOP. This treatment also significantly reduced the fragmentation rate and apoptotic index of blastocysts and increased their total cell number. In conclusion, the electrofusion of rabbit SCNT embryos induced oxidative stress, disturbed the epigenetic state, and caused ER stress, while melatonin reduced this damage. Our findings are of signal importance for improving the efficiency of SCNT and for optimizing the application of electrical stimulation in other biomedical areas.

DC-Dielectrophoretic separation of biological cells by size

DC-Dielectrophoresis (DC-DEP), the induced motion of the dielectric particles in a spatially non-uniform DC electric field, is applied to separate biological cells by size. The locally non-uniform electric field is generated by an insulating hurdle fabricated within a PDMS microchannel. The cells experience a negative DEP (accordingly a repulsive) force at the corners of the hurdle where the gradient of local electric-field strength is the strongest. The DC-DEP force acting on the cells is proportional to the cells' size. Thus the moving cells deviate from the streamlines and the degree of deviation is dependent on the cell size. In this paper, we demonstrated by using this method that, combined with the electroosmotic flow, mixed biological cells of a few to tens of micrometers difference in diameter can be continuously separated into different collecting wells. For separating target cells of a specific size, all that is required is to adjust the voltage outputs of the electrodes.