Establishment of a SCID mouse model having circulating human red blood cells and a possible growth of Plasmodium falciparum in the mouse.

Our previous study has demonstrated that repeated transfusions of bovine red blood cells (RBCs) into SCID mice resulted in a complete substitution of their circulating RBCs. Identical experiments with human (Hu) RBCs, however, gave rise to a poor RBC-substitution because of the rapid elimination of Hu-RBCs from the circulation of SCID mice. Search for substances to decelerate the Hu-RBC clearance picked up some effective polysaccharides, such as sulfated chitin and mannan, but they were not effective enough to achieve a high level of Hu-RBC-substitution. In the present study, we found that Hu-serum significantly extended the lifetime of Hu-RBC in SCID mice and that repeated transfusions of the mice with Hu-RBCs, in combination with Hu-serum administration, resulted in an almost complete substitution of their circulating RBCs. An Hu-RBC-substituted SCID mouse inoculated with Plasmodium falciparum had a parasitemia persisting for two weeks, indicating a possible growth of this parasite in the mouse. Thus, this report gave the first demonstration of a complete substitution of the circulating RBCs in SCID mice with Hu-RBCs and of a successful P. falciparum infection in the mice.