title: A method to optimize PEG-coating of red blood cells.
abstract: Alloimmunization to donor blood group antigens remains a significant problem in transfusion medicine. A proposed method to overcome donor-recipient blood group incompatibility is to mask the blood group antigens by the covalent attachment of poly(ethylene glycol) (PEG) to the red blood cell (RBC) membrane. Despite much work in the development of PEG-coating of RBCs, there is a paucity of data on the optimization of the PEG-coating technique; it is the aim of this study to determine the optimum conditions for PEG coating using a cyanuric chloride reactive derivative of methoxy-PEG as a model polymer. Activated PEG of molecular mass 5 kDa was covalently attached to human RBCs under various reaction conditions. Inhibition of binding of a blood-type specific antiserum (anti-D) was employed to evaluate the effect of the PEG-coating, quantified by hemocytometry and flow-cytometry. RBC morphology was examined by light and scanning electron microscopy. Statistical analysis of experimental design together with microscopy results showed that the optimum PEGylation conditions are pH = 8.7, temperature = 14 degrees C, and reaction time = 30 min. An optimum concentration of reactive PEG could not be determined. At high polymer concentrations (>25 mg/mL) a predominance of type III echinocytes was observed, and as a result, a concentration of 15 mg/mL is the highest recommended concentration for a linear PEG of molecular mass 5 kDa.
authors.affiliation: Biotechnology Group, Chemical Engineering Department, Tarbiat Modares University, Tehran, P. O. Box 14115-143, IR Iran.
authors.forename: Sameereh
authors.initials: S
authors.lastname: Hashemi-Najafabadi
authors.forename: Ebrahim
authors.initials: E
authors.lastname: Vasheghani-Farahani
authors.forename: Seyed Abbas
authors.initials: SA
authors.lastname: Shojaosadati
authors.forename: Mohammad Javad
authors.initials: MJ
authors.lastname: Rasaee
authors.forename: Jonathan K
authors.initials: JK
authors.lastname: Armstrong
authors.forename: Mostafa
authors.initials: M
authors.lastname: Moin
authors.forename: Zahra
authors.initials: Z
authors.lastname: Pourpak
mesh_terms: D000371:Agglutination; D001789:Blood Group Antigens; D048430:Cell Shape; D003432:Cross-Linking Reagents / Q000737:chemistry; D004910:Erythrocyte Membrane / Q000737:chemistry*; D004912:Erythrocytes / Q000737:chemistry* / Q000166:cytology; D006801:Humans; D011092:Polyethylene Glycols / Q000737:chemistry*; D013499:Surface Properties; D014227:Triazines / Q000737:chemistry
chemical_list: D001789:Blood Group Antigens; D003432:Cross-Linking Reagents; D014227:Triazines; D011092:Polyethylene Glycols; C019309:cyanuric chloride