Erythrocyte ghost-mediated microinjection into cells in monolayer cultures: a highly efficient and low toxic...

We describe a technique by which macromolecules can be microinjected into mammalian cells in monolayer cultures. This technique employs erythrocyte ghosts as the vehicle for microinjection, calcium as attachment agent and polyethylene glycol as fusogen. The use of calcium allows a reduction of the time of exposure to polyethylene glycol, and results in a high injection efficiency and a high cell viability when followed by incubation in a buffer free of divalent cations. Injecting over 90% of the cells, a reduction of cell viability is not observed and the mitotic index is never lower than 2.3%. Light and electron microscopy suggest that erythrocyte ghost-cell fusion is only a short event.