AbstractsMedical & Health Science

Hematopoietic stem cell transplantation (HSCT) is an intensive treatment often complicated by organ injuries. Non-transferrin-bound iron (NTBI), as an inducer of free oxygen radicals, is a potential factor in the pathogenesis of these complications. We studied the appearance and timing of NTBI in transplant patients and the possibility to prevent the occurrence of NTBI by binding it with apotransferrin administration. We showed that NTBI appears regularly during the peritransplantation period in HSCT, both in allogeneic and autologous transplantation. We could demonstrate, for the first time, the exact timing and duration of the changes in transferrin saturation and the appearance and the length of the presence of NTBI. We could also show and confirm the 80% saturation of transferrin to be a reliable threshold for NTBI. In allogeneic HSCT fully saturated transferrin and the appearance of NTBI was observed by day -4 before HSCT (day 0). NTBI was detectable on average for 14 days. In autologous HSCT a similar steep rise was found in the transferrin saturation. The mean time for the first to the last NTBI-positive samples was 6.1 days, the intensity of the conditioning seemed to have an effect on the appearance of NTBI. The disappearance or marked reduction of the NTBI positive samples coincided with the recovery of the bone marrow function. Our studies indicate that the presence of NTBI is largely due to reduced utilization of iron by erythropoiesis and the reduction of serum transferrin levels caused by the transplantation process. As NTBI might contribute to the complications of HSCT, we assessed the possibility to bind NTBI during the peritransplant period with apotransferrin infusions. With a single apotransferrin dose given on day +3 NTBI disappeared from the sera of all the six patients, but reappeared 12-24 hours later. Twenty patients were given repeated doses of apotransferrin at three dose levels. The daily loading doses were given at the start of conditioning, followed by maintenance doses every other day given until day +7 to day +13. Five of the eight patients given the highest dose were NTBI negative through the study period. With lower doses there was a nonsignificant trend towards fewer days with demonstrable NTBI. Our in vitro study demonstrating the toxic effect of NTBI on hematopoietic progenitors and the beneficial effect of binding NTBI with apotransferrin on colony growth supports the possibility that binding of NTBI with exogenous apotransferrin may turn out to be clinically useful. Our studies showed that the appearance of NTBI could be prevented or reduced by apotransferrin. However, the clinical utility of apotransferrin administration and the effects on transplantation outcomes remain to be investigated in further studies. Kantasolujensiirto on yleensä pahanlaatuisten veritautien hoitoon käytetty hyvin intensiivinen hoitomuoto, johon usein liittyy solu- ja kudosvaurioita. Näiden vaurioiden mahdollisena osatekijänä voi olla kuljettajavalkuaiseensa transferriiniin sitoutumaton rauta.…