Red blood cells as carriers for delivering of proteins

The potential use of red blood cells as a carrier system for transport and delivery of pharmacological substances is well documented. Various methods have been attempted for encapsulation of drugs; in this review we evaluate critically all the procedures illustrating their advantages and disadvantages. Moreover, we present kinetic studies of protein encapsulation by moderate hypotonic dialysis, which allows entrapment of molecules with MW less than 50,000 Da with negligible stress of the erythrocyte membrane. Furthermore data reveal that the resealing procedure commonly used is insufficient to completely seal pores of loaded erythrocytes, allowing entrapped proteins with MW less than 12-14,000 Da to escape. However, only 20-30% of the entrapped material is released, depending on the final cytocrit, while the remaining is associated to the inner membrane or to cytosolic components. Although the method of hypotonic dialysis is known to be the one that minimally affects the biophysical and immunological properties of the red blood cell membrane, the interaction of encapsulated material with cell costituents would need to be further assessed when considering red cells as macromolecular carriers.