New technologies for the inactivation of infectious pathogens in cellular blood components and the development of platelet substitutes

Despite the increased safety of blood components, achieved through improved donor selection and testing, transfusion recipients remain at risk of tran sfusion-associated diseases. Transfusion of cellular blood components has b een implicated in transmission of viral, bacterial and protozoan diseases.( 1) While it is commonly recognized that hepatitis B virus (HBV), hepatitis C virus (HCV), cytomegalovirus (CMV), and retroviruses, such as human immun odeficiency virus (HIV) and the human lymphotrophic viruses (HTLV), can be transmitted through cellular components, other pathogens are emerging as po tentially significant transfusion-associated infectious agents. For example , transmission of protozoan infections due to trypanosomes(2-4) and Bobesia have been reported.(5) In addition to viral and protozoan infectious agent s, cases of bacterial contamination of platelet and red cell concentrates c ontinue to be reported(6,7) and may be an under-reported transfusion compli cation.(8) More importantly, new infectious agents continue to enter the do nor population, and there is an inherent time delay before the new pathogen s are definitively identified and new tests implemented in order to maintai n consistent, safety of the blood supply. The paradigm for this problem is the HIV pandemic. During the past decade a number of methods for inactivating infectious path ogens in platelet concentrates have been investigated as a strategy to impr ove the safety of platelet transfusion therapy. One method of treating plat elet concentrates to inactive pathogens has now reached the advanced clinic al trial phase in the United States and Europe. Similar efforts with a new class of compounds are underway for red cell concentrates. and two of these are in early phase trials. In addition to studies with allogeneic platelet s and red cells, a number of laboratories have described methods for develo ping platelet substitutes or modified platelets to avoid the use of traditi onal platelet concentrates as a means to improve safety.