Inactivation of Trypanosoma cruzi trypomastigote forms in blood components with a Psoralen and Ultraviolet A light.

Inactivation of the blood-borne parasite Trypanosoma cruzi by UVA and 4'-aminomethyl-4,5',8-trimethylpsoralen (AMT) was studied in the blood components fresh frozen plasma (FFP) and platelet concentrate (PC). The AMT was utilized at a concentration of 50 micrograms/mL and the inactivation procedure included the flavonoid rutin (at 0.35 mM), a quencher of type I and type photo-reactants, which we have previously found to maintain platelet integrity during this treatment regimen. Within both FFP and PC, complete inactivation of the infective form of T. cruzi, the trypomastigote, was achieved at a UVA (320-400 nm radiation) fluence of 4.2 J/cm2. We note that while the infectivity of the parasite is eliminated at 4.2 J/cm2 the trypomastigote motility continues for at least 16 h-post-treatment and is inhibited only after much higher light doses. Isolation of total DNA from the parasite cells after treatment in the presence of 3H-AMT indicated that at the lethal UVA influence about 0.5 AMT adducts per kilobase pairs occurred. These results suggest that this psoralen plus UVA methodology which shows promise in enhancing the viral safety of PC, may in addition eliminate bloodborne T. cruzi, the causative agent of Chagas disease.

Inactivation of Trypanosoma cruzi trypomastigote forms in blood components by photodynamic treatment with phthalocyanines.

Three phthalocyanine dyes HOSiPcOSi(CH3)2(CH2)3N(CH3)2 (Pc 4), HOSiPcOSi(CH3)2(CH2)3N+(CH3)3I- (Pc 5) and aluminum tetrasulfophthalocyanine hydroxide (AlOHPcS4) were evaluated for their ability to inactivate the trypomastigote form of Trypanosoma cruzi in fresh frozen plasma (FFP) and red blood cell concentrates (RBCC). The compound Pc 4 was found to be highly effective in killing T. cruzi, Pc 5 less effective and AlOHPcS4 ineffective. With FFP as the medium, a complete loss of parasite infectivity in vitro (> or = 5 log10) was found to occur with 2 microM Pc 4 after irradiation with red light (> 600 nm) at a fluence of 7.5 J/cm2, while with RBCC as the medium, a complete loss was found to occur at a fluence of 15 J/cm2. Even without illumination, Pc 4 at 2 microM also killed about 3.7-4.1 log10 of T. cruzi in FFP during 30 min. Observed differences in T. cruzi killing by the various phthalocyanines may related to differences in binding; Pc 4 binds to the parasites about twice as much as Pc 5. Ultrastructural analysis of treated parasites suggests that mitochondria are a primary target of this photodynamic treatment. The data indicate that Pc 4 combined with exposure to red light could be used to eliminate bloodborne T. cruzi parasites from blood components intended for transfusion. The inactivation of T. cruzi by Pc 4 in the dark suggests a possible therapeutic application.