Abstract

To deliver impermeable molecules into cells, one can employ physicochemical (e.g., microinjection, liposomes, sonication, electroporation, etc.) or biological methods (e.g., virus-aided delivery).  We develop new “transfection” protocols by bombarding cells directly with highly accelerated molecules without the need to use carrier particles, as is essential for conventional “gene gun” techniques.  The molecule bombardment can be applied to well-differentiated epithelial cells that are notoriously difficult for gene transfection, or to primary cultured cells/neurons or tissue explants.  Purified or recombinant proteins can be effectively introduced to cells; even bacteria can be delivered by the bombardment assay and replicate within the eukaryotic cytoplasm.  We provide experimental evidence and physical model to argue for the mechanisms whereby accelerated molecules can directly penetrate the membrane and enter the cells.  The molecule bombardment may cause a transient (~10 min) increase of cell permeability, but such membrane leakage has only minimal adverse effect to the cell survival.