Abstract
We report on a method for the selective transfer of cytoplasmic contents without nuclei mixing using a PDMS microfluidic device consisting of micro-orifices embodied an insulator wall separating two feeder channels of the device. Dendritic cells and Jurkat cells separately introduced into the channels were first aligned on either side of the micro-orifices using dielectrophoresis (6 V, 1 MHz) induced by an electric field concentration at the micro-orifices. Then, the aligned cell pairs were fused one-to-one by applying an electric pulse (9 V, 100 μs) to achieve a high fusion efficiency of about 70%. The small size of the micro-orifices (〜2 μm) prevented nuclei mixing. To dissociate Jurkat cells from dendritic cells after fusion, we designed a fusion device with pockets around the orifices for trapping dendrittic cells while Jurkat cells were stripped off by shear flow. By controlling flow rate, we could successfully dissociate Jurkat cells, leaving dendritic cells intact in the trapping pockets. Performing the separation procedure rapidly (less than 1 s) was found to be crucial to avoid loss of cytoplasmic materials to Jurkat cells during separation. Thus, the method developed in this study enables one-to-one fusion and harvesting of dendritic cells for possible use in immunotherapy.
