Introduction of functional objects into live cells is one of the hot topics in bioengineering research. Here, we report a novel method for introducing large objects, up to a micrometer level, into living cells by electrofusion with an artificial giant unilamellar vesicle (GUV or Liposome). We prepared the GUVs using the water-in-oil (w/o) emulsion centrifugation method, by which artificial objects were encapsulated in them. HeLa cells and GUVs were placed into an electrofusion chamber, then exposed to an AC field to align cells and GUVs linearly. After this positioning, DC pulses were applied to induce transient electrofusion and rapid transfer of objects from GUVs into cells.
We successfully demonstrated that plasmids, designed DNA nanostructure (DNA origami) and magnetic beads can be introduced into live cells by this approach. We also confirmed that multiple artificial objects (for example, an expression plasmid for mCherry protein and 1 µm-sized fluorescent beads) can be transferred simultaneously into live cell. The treated cells divided normally and reached confluency in culture without significant damages. In addition, Hela cells, in which magnetic beads were introduced by this method, can be moved externally by a neodymium magnet.
Based on these results, we believe that our method can be used for simultaneous transfer of multiple genes and artificial objects, which paves a new way for elucidation of cell mechanisms and even creation of artificial cells.