Optical techniques for the microbiological control of blood

Blood can be the target of bacterial, viral and parasitic contamination, which can trigger serious diseases. In this study, photodynamic inactivation and ultraviolet radiation were evaluated in the in vitro decontamination of whole blood, erythrocytes, and platelet-rich plasma with S. aureus. For PDI, Photogem and 630 nm light were evaluated, and risks of toxicity of the treatment were determined by hemolysis and cell viability assays. The reductions of S. aureus in whole blood, erythrocytes, and platelet-rich plasma at 15 J/cm2 and 50 μg/mL porphyrin were 1.0 log, 1.3 log and 0.4 log CFU/mL, respectively. Hemolysis rate for erythrocytes in whole blood was 10.7%. However, erythrocytes hemolysis was 100% when in the absence of plasma. The cell viability assay showed 14% apoptosis rates in isolated erythrocytes, indicating damaging action of PDI, and no damage in platelet. For UVC radiation (254 nm), different light doses were analyzed, and the cell viability assay determined the toxicity of technique. The reductions of S. aureus in whole blood, erythrocytes and platelet-rich plasma at 23 J/cm2 were 1.7 log, 1.1 log and 2.5 log CFU/mL, respectively. Relatively small differences were observed in plasma as a function of irradiation time, suggesting some degradation of plasma proteins with 23 J/cm2. The cell viability assay showed normal rates for erythrocytes, however, in the platelets, a high apoptosis rate was observed (74%). Therefore, the optical techniques showed opposite damage effects in each blood component, and the use of one or another technique should be evaluated considering the better microbial inactivation and blood components preservation conditions.