Method for introducing desired agents into red blood cells

Abstract

A method of introducing effectively non-anionic agents into mammalian red blood cells without unacceptable loss of cell contents, utilizing an osmotic pulse technique wherein an aqueous diluent medium is provided containing the desired effectively non-anionic agent(s) and an effective amount of water-soluble polyanion. The polyanion is non-disruptive to the lipid outer membranes of red blood cells and contains at least two anionic moieties per molecule. The method comprises suspending packed red blood cells in an aqueous solution containing a compound which readily diffuses into and out of the cells, rapidly creating a trans-membrane osmotic gradient by diluting the solution containing the cells in suspension with an essentially isotonic aqueous medium containing an effective amount of polyanion and one or more effectively non-anionic agents to be introduced, thereby causing diffusion of water into the cells with consequent swelling and increase in permeability of the outer membranes, and maintaining the increase in permeability for a period of time sufficient only to permit transport of the desired agent and polyanion into the cells and diffusion of the compound out of the cells. In another embodiment, for use where a polyanion in the aqueous diluent medium would be undesirable, the red blood cells are subjected to shear stress immediately after the osmotic pulse occurs, resulting in resealing of the outer membranes of the cells and regaining their original size and shape, with the desired agent(s) incorporated therein.