RECEPTOR-TARGETED TRANSFECTION USING STABLE MALEIMIDO-TRANSFERRIN THIO-POLY-L-LYSINE CONJUGATES

Cell surface ligand-receptor systems provide favorable routes for DNA transfection due to target cell specificity, transfer efficiency, and low toxicity. Using the transferrin receptor system as a model, an approach to transfection is developed herewithin which involves the complexing of DNA to stable maleimido-transferrin/thio-poly-L-lysine conjugates. These studies establish the importance of precise stoichiometry for activity of ligand:poly-L-lysine conjugates, as well as a chemistry for their controlled conjugation. Also considered quantitatively are effects of the following related parameters on the efficiency of receptor-mediated transfection: Lysine polymer length, conjugate concentration, DNA:conjugate ratio, and treatment of target cells with chloroquine and desferrioxamine. Compared directly to standard procedures (electroporation, modified DEAE-dextran, lipofection, and modified Ca2PO4 protocols), transfection via this transferrin receptor-mediated system was ≥10-fold more efficient, and essentially nontoxic to erythroleukemic F-MEL and J2E cells. Following transfection these cells retained the physiological capacity to undergo induced differentiation in response to dimethyl sulfoxide (F-MEL cells), or to erythropoietin (J2E cells), the natural hormonal regulator of erythropoiesis. Thus, an optimized approach to transferrin receptor-mediated transfection is developed which should be widely applicable for alternate cells and ligand-receptor systems both in vitro and in vivo. © 1994 Academic Press, Inc. All rights reserved.