Perhaps the most brutal way of introducing nucleic acids into cells is microinjection: you make a really, really fine needle, jab it into a cell's nucleus, and

Perhaps the most brutal way of introducing nucleic acids into cells is microinjection: you make a really, really fine needle, jab it into a cell's nucleus, and inject a DNA solution. It is incredibly painstaking work, does kill a lot of the cells, and making the needles is a black art, but it works for all sorts of cells, even those resistant to chemical methods, so it is sometimes still useful.