High expression of human beta S- and alpha-globins in transgenic mice: erythrocyte abnormalities, organ damage, and the effect of hypoxia.

Abstract

A line of transgenic mice with two cointegrated transgenes, the human 1s-and a2-globin genes, linked to the 13-globin locus control region was produced and bred with mice carrying a deletion of the mouse p1iW°r-globin gene.In transgenic mice homozygous for the pOdoEr deletion (aHI3S [PMDD]; where aH is human a-globin and MD is mouse deletion), 72.5 ± 2.4% (mean ± SD) of the 1-chains are .3s and the ratio of aH_ to 1s-globin was 0.73. Introduction of a heterozygous mouse a-globin deletion into mice homozygous for the Poor deletion (aHjis[aMDI3MDDJ) resulted in 65.1 ± 8.5% %.s and a human er/P ratio of 0.89 ± 0.2. Sickling occurs in 95% of erythrocytes from aHplS [PMDD] mice after slow deoxygenation. Transmission electron microscopy revealed polymer fiber formation but not fascicles of fiber. Increased organ weight was noted in lung, spleen, and kidney of transgenic mice vs. controls that may be due to hypertrophy or increased blood volume in the lungs and/or increased tissue water content. The hemoglobin content of lung, spleen, and kidney was also elevated in transgenic animals due to trapped hemoglobin and/or increased blood volume. When transgenic and control mice were examined by magnetic resonance imaging at 9.4 tesla, some transgenic animals had enlarged kidneys with prolonged relaxation time, consistent with increased organ weight and water content. The glomerular filtration rate was elevated in transgenic animals, which is characteristic of young sickle cell patients. Furthermore, exposure to hypoxia resulted in signifcantly decreased hematocrit, increased erythrocyte density, and induced a urineconcentrating defect. We conclude that the transgenic mouse line reported here has chronic organ damage and further hematological and organ dysfunction can be induced by hypoxia.The development of several different transgenic mouse models for sickle cell disease (1-7) has the potential ofelucidating the mechanism of vasoocclusion in sickle cell anemia. Sickle cell vasoocclusion is a multifactorial event that involves obstruction of the microcirculation by irreversibly sickled cells (8), nondeformable polymer-filled deoxygenated cells, and adhesion by deformable discocytes capable of contributing to the initiation or aggravation of vasoocclusion (9-11). The time interval or delay time between deoxygenation and the onset ofpolymer formation may play a role in determining both the frequency and severity of vasoocclusion (12).Several organs are particularly susceptible to obstruction and ensuing damage in sickle cell disease. In this paper we will focus on the spleen, the kidneys, and the lungs. In the mouse, the spleen is both the site of erythrocyte (RBC) production and destruction. In sickle cell patients, the spleen is the site of infarction (13), potential sequestration (14), and autospenectomy in the second decade of life. The detailed pathophysiology of vasoocclusion need not be the same in each organ. For example, in some organs, such as the lung and kidney, the response to hypoxia is vasoconstriction...

Protective effect of arginine on oxidative stress in transgenic sickle mouse models

“…NY1DD mice show mild pathology, but exhibit multiple organ damage [7]. NY1DD mice show no hemolysis and systemic hematocrit (%) in NY1DD mice is similar to that found for C57BL control mice (mean ± SD: NY1DD mice, 47.5 ± 3; controls, 46.5 ± 2.1) [7]. Transgenicknockout BERK mice express 100% humanα, >99% human β S , and show severe pathology.…”

“…In these mice, the total β S -globin levels are ~ 75% β S of all β-globins [8]. NY1DD mice show mild pathology, but exhibit multiple organ damage [7]. NY1DD mice show no hemolysis and systemic hematocrit (%) in NY1DD mice is similar to that found for C57BL control mice (mean ± SD: NY1DD mice, 47.5 ± 3; controls, 46.5 ± 2.1) [7].…”

Noninvasive In Vivo High-Resolution Magnetic Resonance Imaging of Atherosclerotic Lesions in Genetically Engineered Mice

“…5 Currently, MRI is being used to study atherosclerotic lesions in vivo in large animals (eg, rabbits, 6 pigs, 7 nonhuman primates 8 ) and in humans 9 by use of conventional MR scanners (1.5 T) with a spatial resolution Ն300 m. To study small structures, such as the abdominal aorta of mice (less than Ϸ1 mm in luminal diameter), it is necessary to increase the signal-to-noise ratio by use of high-magnetic-field scanners equipped with small radiofrequency (RF) coils and strong magnetic field gradients. 5 Previous applications of MR microscopy to mice have focused on imaging heart, 10 kidneys, 11 or embryonic development. 12 Here we demonstrate the first, to the best of our knowledge, in vivo MR microscopy images of the arterial wall of wild-type and genetically engineered (apoE-KO) mice that noninvasively identify and characterize atherosclerotic lesion burden without a priori knowledge of the lesion location or the lesion type.…”

Microvascular blood flow and stasis in transgenic sickle mice: Utility of a dorsal skin fold chamber for intravital microscopy

“…Their RBCs change shape upon de-oxygenation [5,31], and they display blood flow abnormalities including adhesion of RBCs, rolling and adhesion of leukocytes, and stasis in post-capillary venules [4,[31][32][33]. Upon pathological analysis, there is tissue damage in multiple organs including the kidney, liver, lung, and spleen [34][35][36]. Like human SCD patients, transgenic b S mice display numerous signs of an inflammatory response such as elevated white counts and enhanced activation of NF-kB, a transcription factor critical for the inflammatory response [37].…”