<p>A method for delivering a polypeptide to the interior of a cell of a vertebrate ex vivo is provided comprising the steps of: removing live cells from the vertebrate, contacting the cells with a preparation comprising an effective amount of polynucleotide operatively coding for the polypeptide and lipid effective to deliver the polynucleotide in the cells; and freezing or returning the cells to the vertebrate within 48 hours after the contacting step so that the cells express the polynucleotide in vivo. The method additionally can comprise substantially separating the cells from the surrounding extracellular matrix.</p>
