Prevention of Nuclear Mixing of Fused Cells Interconnected through a Microslit Using Rock Inhibitor Y-27632 for Direct Cytoplasmic Transfer between Live Single Cells

We previously reported a cell fusion method using a microfluidic device, in which paired single cells were fused through a microslit [1]. Although our approach realized direct cytoplasmic transfer between live single cells and thus is a promising method to induce cellular reprogramming or transdifferentiation, prevention of nuclear mixing with the microslit was unsatisfactory (~15%). We herein report that the nuclear mixing was almost perfectly prevented (~95%) by addition of ROCK inhibitor Y-27632 in NIH3T3 fibroblast. Furthermore, Y-27632 raised the probability of cell fusion through the microslit. As a result, we obtained 16.5-fold increase in the number of nuclear-separated fused cell pairs.