Transient aplastic crisis in hereditary spherocytosis

Amelioration of severe hereditary spherocytosis in nonablated adult mice by marrow transplantation

Human severe hereditary spherocytosis (sHS) is life threatening and transfusion dependent. sHS is lethal within 6 days of birth for 99% of jaundiced (ja/ja) mice, making these mice excellent models for early therapeutic interventions. Nonablated ja/ja neonates simultaneously transfused and given intravenous injections of normal marrow become chimeric for donor cells. Significant improvement of red blood cell parameters occurs but is temporary because the donor marrow-derived cells gradually disappear from the circulation. The average lifespan, however, is increased to 8.7 months. We postulate that donor cells are diluted by rapidly proliferating host cells during postnatal growth. Here, we test this hypothesis by determining whether treatment of adults improves long-term therapy. Nonablated ja/ja adults rescued by a single neonatal transfusion were injected intravenously with 1 x 10(10) normal, genetically marked donor marrow cells/kg body weight. Donor cell implantation and blood parameters were monitored periodically and tissue histopathology was determined at necropsy.sHS recipients with 100% donor erythroid cells have significantly improved red blood cell counts throughout life when compared with ja/ja controls transfused once at birth. Total serum iron and bilirubin levels are corrected in ja/ja marrow recipients. Donor-implanted HS mice necropsied at 16 to 21 months of age have normal mean cell hemoglobin concentration and dramatically decreased tissue iron deposits. Reticulocyte counts but not red cell counts normalize, suggesting the HS mice reset their response to hypoxia. Nonablative transplantation performed after cessation of host postnatal red blood cell amplification can be therapeutic long term for transfusion-dependent hemolytic anemias.

Thrombosis and Secondary Hemochromatosis Play Major Roles in the Pathogenesis of Jaundiced and Spherocytic Mice, Murine Models for Hereditary Spherocytosis

Jaundiced mice, ja/ja, suffer from a severe hemolytic anemia caused by a complete deficiency of erythroid β-spectrin. We used these mice as a model to investigate the pathophysiological consequences of the deficiency, including the effects in the nonerythroid tissues where this protein is expressed. Because the ja/ja mice rarely survive beyond the fourth postnatal day, methods were assessed for extending lifespan into adulthood. Neonatal transfusion increased lifespan to a mean of 3.7 months, allowing a more complete characterization of the pathophysiology. Blood parameters and histopathology of the jaundiced mouse were compared with that from spherocytic mice, which have a hemolytic anemia caused by deficiency of erythroid α-spectrin, yet can survive the postnatal period transfusion free. The adult jaundiced and spherocytic mice present with greatly decreased hematocrit and red blood cell counts, reticulocytosis, and bilirubinemia, leading secondarily to hepatosplenomegaly and cardiomegaly. Jaundiced and spherocytic mice were analyzed histopathologically between 1.0 and 9.5 months of age. Interestingly, the complete absence of erythroid β-spectrin in jaundiced mice leads to no detectable structural defects in brain, cardiac, or skeletal muscles. However, fibrotic lesions and lymphocytic infiltration were observed in cardiac tissue from 4 of 13 jaundiced mice and 15 of 15 spherocytic mice, and thrombi were detected at either the atrioventricular valves or within the atria of 2 of 13 jaundiced mice and 15 of 15 spherocytic mice. In addition, all affected mice had a progressive renal hemosiderosis concurrent with hydronephrosis and glomerulonephritis. The severity of the renal disease and its presence in all moribund mice suggests kidney failure rather than the fibrotic heart lesions as the major cause of death in these mice.

Thrombosis and Secondary Hemochromatosis Play Major Roles in the Pathogenesis of Jaundiced and Spherocytic Mice, Murine Models for Hereditary Spherocytosis

Jaundiced mice, ja/ja, suffer from a severe hemolytic anemia caused by a complete deficiency of erythroid β-spectrin. We used these mice as a model to investigate the pathophysiological consequences of the deficiency, including the effects in the nonerythroid tissues where this protein is expressed. Because the ja/ja mice rarely survive beyond the fourth postnatal day, methods were assessed for extending lifespan into adulthood. Neonatal transfusion increased lifespan to a mean of 3.7 months, allowing a more complete characterization of the pathophysiology. Blood parameters and histopathology of the jaundiced mouse were compared with that from spherocytic mice, which have a hemolytic anemia caused by deficiency of erythroid α-spectrin, yet can survive the postnatal period transfusion free. The adult jaundiced and spherocytic mice present with greatly decreased hematocrit and red blood cell counts, reticulocytosis, and bilirubinemia, leading secondarily to hepatosplenomegaly and cardiomegaly. Jaundiced and spherocytic mice were analyzed histopathologically between 1.0 and 9.5 months of age. Interestingly, the complete absence of erythroid β-spectrin in jaundiced mice leads to no detectable structural defects in brain, cardiac, or skeletal muscles. However, fibrotic lesions and lymphocytic infiltration were observed in cardiac tissue from 4 of 13 jaundiced mice and 15 of 15 spherocytic mice, and thrombi were detected at either the atrioventricular valves or within the atria of 2 of 13 jaundiced mice and 15 of 15 spherocytic mice. In addition, all affected mice had a progressive renal hemosiderosis concurrent with hydronephrosis and glomerulonephritis. The severity of the renal disease and its presence in all moribund mice suggests kidney failure rather than the fibrotic heart lesions as the major cause of death in these mice.