BIOCHEMICAL AND FUNCTIONAL-CHARACTERIZATION OF DNA COMPLEXES CAPABLE OF TARGETING GENES TO HEPATOCYTES VIA THE ASIALOGLYCOPROTEIN RECEPTOR

Electrostatic binding of polycations or basic polypeptides to the DNA phosphate backbone has been previously described as a one-step process which results in uncontrolled aggregation and precipitation of the DN A in solution. We describe here a multistep process in which the conde nsation of DNA in the presence of poly-L-lysine can be controlled to p roduce particles of discrete size and shape suitable for receptor-medi ated gene transfer in vivo and in vitro. The first step in this proces s involves the gradual accretion of poly-L-lysine onto the DNA phospha te backbone, until charges are neutralized, The addition of poly-L-lys ine to a concentrated solution of DNA in this fashion prevents intermo lecular aggregation of the DNA, presumably by promoting the formation of a nucleus of condensation along the length of each DNA molecule. Th e second stage of the process involves adjusting the ionic strength of the solvent to facilitate the solubilization of compact DNA-poly-L-ly sine complexes. Several physical and biochemical parameters have been studied and correlated with the efficacy of DNA/ligand-poly-L-lysine p articles in transferring genes to the liver of adult animals by recept or-mediated endocytosis.