Chemical modification of red blood cells and hemoglobins with methoxy-polyethylene glycol

Abstract

Because mPEG modified proteins show both reduced antigenic and immunogenic properties and extended blood circulating life times, attachment of polyethylene glycol to proteins has found wide applications for biomedical and biotechnological purposes. In this experiments. Sheep Red blood Cells and Sheep Hemoglobins were modified with mPEG to develop the potential blood substitute. Osmotic fragility of SRBC-mPEG conjugates was determined by degree of hemolysis against salt concentrations, and antigenicity of SRBC-mPEG conjugates was determined by Blood grouping and Cross-matching test. mPEG modified SRBCs show no aggregation by blood grouping and cross-matching test, and are resistant to osmotic hemolysis. mPEG modified SHb show altered electrophoretic mobility, and modification degrees of the conjugates were calculated from TNBS free amino group titration results. Oxygen carrying capacity of SHb-mPEG conjugates was determined by tonometrically. 6.3\% modified conjugate show increased oxygen affinty and increased saturation end point. Antigenicity of SHb-mPEG conjugates was determined by double immunodiffusio test. mPEG-SHb conjugate show no antigenicity at 34\% of the free amino groups modified. But, only slightly modified mPEG-SHb conjugates (6.3\%) show oxygen transport activity similar to unmodified hemoglobin.