Reduced incidence of thrombosis in mice with hereditary spherocytosis following neonatal treatment with normal hematopoietic cells

Abstract

Thrombosis is a life-threatening complication of hemolytic anemia in humans. Cardiac thrombi are present in all adult ␣-spectrin-deficient (sph/sph) mice with severe hereditary spherocytosis, providing a model for events preceding thrombosis. The current study evaluated (1) the timing of thrombosis initiation and (2) the effect of postnatal transplantation of normal cells on life span and thrombotic incidence in adult mice. Thrombi are detected histologically following necropsy in untreated sph/sph mice of various ages and are not observed until 6 weeks of age. Thrombotic incidence increases from 50% at 6 to 7 weeks of age to 100% at 9 weeks of age. As a potential therapy, nonablated sph/sph neonates were transfused with either genetically marked normal peripheral blood (PB), bone marrow (BM) , IntroductionOne of the more serious complications of heritable hemolytic anemias in humans is thrombosis. Thrombotic events affect approximately 20% of patients with sickle cell disease, 5% to 10% of patients with ␤-thalassemia, and a small number of patients with hereditary spherocytosis (HS). [1][2][3][4][5][6][7][8][9][10] In adult mice with severe hemolytic anemia caused by deficiency of red blood cell (RBC) cytoskeletal components, cardiac thrombi are prevalent. 11,12 The mutant mice have severe HS typified by misshapen RBCs that are destroyed within a single day of entry into the peripheral blood (PB). 11 Reticulocytes compose 75% to 95% of the total circulating erythroid cells; mean cell volume (MCV) is increased, reflecting the larger, immature cells in the circulation. [13][14][15] Spleen and liver, sources of newly generated RBCs in anemic mice, are grossly enlarged. [13][14][15] Iron deposits accumulate in the kidney and liver. 11 Mice with HS are much more severely affected than most humans with HS, many of whom are not diagnosed until an unrelated health crisis arises.There are few models for thrombosis in experimental animals with hemolytic anemia. The mice with HS adequately fill that void. The incidence of coronary thrombosis is highest (85% to 100%) in HS mice with mutations in ␣-spectrin (Spna1), and lowest (15% to 22%) in HS mice with ␤-spectrin and ankyrin mutations. 11,12 These mice, except for the mutation they carry, share identical genetic backgrounds and environments, permitting comparative analyses. Adult Spna1 sph / Spna1 sph (hereafter, sph/sph) mice have the highest incidence (100%) of thrombosis. They provide a model for determining thrombus ontogeny, pathological consequences, precipitating agents, and efficacy of therapeutic interventions. Death of 30% of untreated sph/sph mice occurs before 3 weeks of age; the average life span of the survivors is 26.8 weeks. It is not clear whether the postnatal deaths are caused by thrombosis or other pathology. Here, the temporal development of thrombosis is established in sph/sph mice.To date, we have shown that bone marrow (BM) hematopoietic cells transplanted from sph/sph mice to normal recipients are sufficient for thrombogenesis 12 and that inversi...

The hypercoagulable state in thalassemia

“…The exact order of these events is still unclear, and the murine models of congenital hemolytic anemias may shed some light on the role of these anomalies in the induction of the hypercoagulable state. [71][72][73] Venous thrombosis is more prevalent in ␤-TI patients who are not receiving regular transfusions and who have undergone splenectomy. These patients may be more susceptible to thromboembolism because they have more circulating damaged RBCs and increased platelet counts.…”

“…72 Thrombosis incidence in these animals was significantly reduced following the transfusion of normal RBCs or transplantation of normal bone marrow. 73 The presence of normal RBCs in the peripheral circulation of these ␣-spectrin-deficient mice prolonged the survival of young animals and abrogated the development of thrombosis in adult animals. 73 …”

“…73 The presence of normal RBCs in the peripheral circulation of these ␣-spectrin-deficient mice prolonged the survival of young animals and abrogated the development of thrombosis in adult animals. 73 …”

“…19 The contribution of the abnormal RBCs to the thrombotic process has been also demonstrated in animal models of congenital hemolytic anemias. [71][72][73][74] A lethal hypercoagulable state manifested by large thrombotic lesions in the heart and the liver and large venous thrombi was found in mice in which the expression of erythroid band 3 had been eliminated via targeted mutagenesis. 71 The abnormal RBCs from these mice significantly shortened the Russell viper venom clotting time of normal plasma in a dosedependent fashion, whereas RBCs from normal mice had no effect.…”

Hypercoagulability and thrombotic complications in hemolytic anemias

“…External exposure of phosphatidylserine alters the adhesive properties of RBC 12 and appears to be involved in the hemostatic changes observed in hemolytic anemias. [13][14][15][16] The number of phosphatidylserine-positive RBC has been reported to be significantly correlated with plasma markers of thrombin generation, such as prothrombin fragment 1+2 (F1+2), D-dimer and plasmin-antiplasmin complexes in SCD, but no correlation was found between phosphatidylserine-positive platelets and any of these hemostatic markers, 13,14 suggesting a role for RBC in coagulation activation.…”