Narrowing slit device for high yield one-to-one electrofusion and culture of fusants without gene mixing

Somatic cell nuclei can be reprogrammed by fusion with embryonic stem cells (ESCs). For safe use of reprogrammed cells for regenerative medicine, it is desirable to reprogram somatic cells without gene mixing. In this study, we developed the new electric cell fusion device which enabled one-to-one cell fusion and cell culture after the fusion without gene mixing. The device consisting of slits on a wall separating two feeder channels. The slits had vertically varying width; wider (5μm) at the channel ceiling, and narrower (1μm) at the bottom. The electrofusion was performed on the wider slits where the cell pairs could easily contact. The field constriction induced by the slits enabled both pair formation of each cells and one-to-one electrofusion of the pairs. After the fusion, fusants were brought down toward the channel floor and cultured on the bottom side of slits which narrow enough to prevent nuclear slippage. As a result, electrofusion was successfully achieved in 90% of the aligned cell pairs. In the culture after electrofusion, fusants adhered on the channel floor where the narrow slit width was 1μm and nuclei slippage was prevented. We could culture fusants connected through the slits, preventing nuclear slippage even after culturing fusants for 24 hours.