Investigating the Stability of Polymer Coating of Methoxy Polyethylene Glycol Activated by Succinimidyl Valerate on the Surface of Red Blood Cells at In vitro and In vivo Conditions

Because of the host immunological system response against the minor blood groups of donor, transfusion in some cases, especially for patients require repeated transfusions (such as people with thalassemia), can be considered as a significant problem. A proposed way is coating the surface antigens on red blood cells (RBCs) by covalent binding of methoxy polyethylene glycol (mPEG). The aim of this study was to determine the storage time of PEGylated cells before injection and its effective time at in vivo condition. Methods and materials: mPEG activated by succinimidyl valerate (SVA) was used for PEGlaytion the cells. The stability of the created coating at in vitro condition was investigated using 3

counting the number of free cells, flow cytometry and qualitative investigation. Using electron microscopic investigations, the appropriate concentration of mPEG for rabbit RBC PEGylation was determined. The effective time of PEGylated rabbit RBCs was determined using flow cytometric analysis, after injection. Also, the serum biochemical properties were investigated 24 hours after injection.

The appropriate concentration of 15 mg/mL for rabbit RBC PEGlytion was determined. Forty eight hours after injection, %83 of the cells were alive in the host circulatory system and could keep their polymeric coating.

The time of 18 days was obtained as appropriate time for storage the PEGylated RBCs at in vitro condition. Also, the effective time of 14 days was determined for PEGylated RBCs, by tracking the cells at in vivo condition. Investigating the serum biochemical properties of rabbits, 24 hours after injection, showed that RBC coating, significantly inhibited the stimulation of the host immunological system and destruction the cells.