Dynamic photodamage of red blood cell induced by CisDiMPyP porphyrin.

ABSTRACT

It is well-known that oxidative damage in red blood cell (RBC) usually causes morphological changes and increased membrane rigidity. Although many studies have focused on investigating how RBC responds to a photodynamic stimulus, the intermediate steps between membrane damage and hemolysis are not reported. To give a comprehensive insight into changes of RBC membrane property under different oxidative damage levels, we employed the photoactivation of CisDiMPyP porphyrin that primarily generates singlet oxygen 1O2 as oxidant species. We found that there were distinguishable characteristic damages depending on the 1O2 flux over the membrane, in a way that each impact of photooxidative damage was categorized under three damage levels mild (maintaining the membrane morphology and elasticity), moderate (membrane elongation and increased membrane elasticity) and severe (wrinkle-like deformation and hemolysis). When sodium azide (NaN3) was used as a singlet oxygen quencher, delayed cell membrane alterations and hemolysis were detected. The delay times showed that 1O2 indeed plays a key role that causes RBC photooxidation by CisDiMPyP. We suggest that the sequence of morphological changes (RBC discoid area expansion, wrinkle-like patterns, and hemolysis) under photooxidative damage occurs due to damage to the lipid membrane and cytoskeletal network proteins.