Stability of erythrocyte ghosts: a gamma-ray perturbed angular correlation study.

Abstract

The structural integrityof erythrocyte ghosts made by the preswell and slow-dialysis techniques has been studied in vitro by use of y-ray perturbed angular correlation (PAC) techniques and also by standard in vitro leakage methods employing sequestered labeled markers. Complexes of "'In3+ and nitrilotriacetate were encapsulated in ghosts made from human, rabbit, rat, and mouse erythrocytes, and their leakage was monitored by both methods. In addition, "2'I-labeled bovine serum albumin was encapsulated, and ghost integrity was monitored by conventional leakage measurements. With the PAC technique the percentage of material released from human ghosts was determined quantitatively, and the results were equivalent to those obtained by the conventional method. In addition, at various times after intravenous injection, tissue distribution of the ghosts in the mouse was studied. The percent injected dose per gram of tissue of the labeled surface proteins of erythrocyte ghosts in circulation approximated that of the entrapped labeled albumin. This suggests that the ghost membrane and contents are strongly associated in viva Large "MI-labeled bovine serum albumin molecules and small "'1In3+-nitrilotriacetate complexes were delivered in high quantities to the lung initially, and to the liver and spleen. Because erythrocyte ghosts have the ability to entrap a wide range of substances and deliver them to specific organs, ghosts may be preferable to other drug carriers or drug therapy for treatment of certain disorders.An attractive strategy for the in vivo delivery of biologically active molecules is the encapsulation of drugs or enzymes in erythrocytes. As carriers, erythrocytes offer several advantages over other systems: they can entrap large volumes of concentrated loading material, and they can avoid host immunologic reactions if they are from isologous or autologous blood. Different enzymes and drugs have been successfully encapsulated by erythrocytes and delivered to specific cell and tissue sites in animal models (1-3). Methods of entrapment, such as the preswell, rapid-lysis, and slow-dialysis methods, involve variations of erythrocyte osmotic lysing and resealing (4, 5); methods such as applying an external pulsed electric field or drug treatment induce membrane permeability changes or endocytic activity in erythrocytes (1,4,6). The successful entrapment of various active enzymes, transport systems, and drugs has been demonstrated (1-9). To develop theerythrocyte ghosts as practical carrier systems, we have studied the leakage of entrapped substances from ghosts of different species prepared by various methods, and we have studied the fate of the erythrocyte ghosts after administration in vivo.

Membrane phospholipid asymmetry as a determinant of erythrocyte recognition by macrophages.

“…carrierst) can be reinfused into the circulation for delivery of pharmacologically active substances (2)(3)(4). Among several advantages of this approach, one may be versatility with respect to the mode of drug delivery.…”

PAC research in biology

“…At the same time, the study of the atomic configurations around probe sites in biological systems, also both the cellular uptake and metabolism of metals [6], and cellular stability and dynamics [7] were being studied by PAC.…”