Studies Of Virus Inactivation Effect In Platelet Concentrates And The Effect On The Quality Of Platelets By Ultraviolet C Light

Platelets are mainly used for prevention and treatment of thrombocytopenia and function imbalance of platelets which may lead to bleeding and bleeding tendency.It plays an irreplaceable role in clinic.At present,platelets are mainly derived from healthy donors,which belongs to the category of allogeneic blood transfusion.Although allogeneic platelets are tested according to national regulations,there are still residual risks.First,many pathogens can be transmitted through blood.Besides the known pathogens,such as HIV,HBV,HCV and TP,there are new and unknown pathogens.Secondly,there are missed detections due to the limitations of the detection methods as well as the existence of the "window period".How to further improve the safety of allogeneic platelets is a hot topic,thus producing the pathogen inactivation technology of platelets.A UVC inactivation device was designed in our laboratory before.It was found that UVC irradiation could effectively inactivate the PRV and SNV.However,the span of the screening irradiation dose was large and the quality of the platelets treated by UVC was not evaluated in previous study.Therefore,in the study,we focused on the re-screening of radiation dose,and the effect on the quality of platelets treated by UVC,tried to ensure the quality of platelets while achieving inactivation effect.The specific content of the study was as follows.Part I Drawed the inactivation curves and selected the suitable radiation doseWe taked the PRV and SNV as indicator viruses,added viral suspension into platelet suspension,the volume ratio of these two was 1:9.After treated with series of irradiation doses of UVC,virus dropping titers were assessed by microdose cytopathogenic effect,then drawn the inactivation curves.It was observed that PRV decreased(4.33 ± 0.28)logs and SNV decreased(5.08 ± 0.80)logs at a dose of 0.22J/cm2 of UVC.which reached the requirements of technical methods and validation guidelines for removing/inactivating blood products(virus reduction log10>4 logs).So we selected the UVC irradiation dose was 0.22J/cm2,which was similar to the THERAFLEX UV-Platelets system(Macopharma).Part II Selected suitable irradiation dose of UVC to deal with the platelets and then evaluated the quality of the plateletsPlatelets were exposed to UVC with a dose of 0.22J/cm2.The scanning electron microscopy showed that more irregular shape and pseudopodiums formation after UVC irradiated.Also,it was observed that Platelet counts and HSR decreased,the volume of platelets increased(MPV and P-LCR increased)after UVC irradiated.The platelet activation markers PAC-1 and CD62p were increased after UVC irradiation,as well as apoptosis marker Annexin V.ROS generation increased.These differences were statistically significant at all(The differences of ROS was statistically significant at the fifth day).UVC irradiation had some influence on the quality of platelets.Part III A preliminarily screening of protectants during the treatment of platelet concentrates by UVCPlatelet activation and ROS production increased after UVC irradiated.Thus we chose to add platelet activation inhibitors vitamin B6,L-Arg,and antioxidants GSH,NAC,and histidine,then observed whether these agents can reduce the damage of platelets caused by UVC.It was observed that the MPV decreased on the third day and the HSR increased on the fifth day after added 300?m L-Arg(P<0.05).Add 0.25mM vitamin B6,1mM NAC and lmM histidine respectively had no obvious protective effect and no negative effect on platelet clot contraction,platelet counts,MPV,P-LCR,HSR.According to experimental results,we preliminarily screened out 300?m L-Arg as a protective agent.However,because of the small amount of experimental specimens,the detection indexes used to screen the protective agents were not much,so we also selected 0.25mM vitamin B6,1mM NAC and ImM histidine,to further investigate whether it could effectively protect the quality of platelets after treated by UVC.Part IV The effect of preliminarily screened protectants on the inactivation of PRV and SNV in platelet concentrates treated with UVCThe virus suspension of PRV or SNV was added to the platelet concentrates,added the preliminarily screened protectants,then the solution was exposed to UVC with a dose of 0.220 J/cm2,sampled and inspected the virus titers.It was found that adding 0.25mM vitamin B6,300?m L-Arg,1mM NAC,and 1mM histidine had no significant effect on the inactivation of PRV and SNV in platelet concentrates treated with UVC.In summary,the study found that platelet concentrates were exposed to UVC with a dose of 0.220 J/cm2 could effectively inactivate PRV and SNV;UVC irradiation had some effect on the quality of platelets;preliminarily screened the protectants during the treatment of platelet concentrates by UVC;preliminarily screened protectants had no significant effect on the inactivation of PRV and SNV in platelet concentrates by UVC.We also need more experiments to further confirm whether the preliminarily screened reagents can effectively protect the quality of platelets after UVC irradiated,and to explore how to ensure the quality of platelets while ensuring the effect of pathogens inactivation.