Total pathology score showed progressive correction of sickle pathology. Total pathologic score (y-axis) versus percentage of normal Hb levels in the peripheral blood (x-axis). The total pathology score includes the following individual parameters: (1) cardiac vascular ectasia, (2) pulmonary artery medial thickness, (3) pulmonary vascular ectasia, (4) remote hepatic infarct, (5) recent hepatic infarct, (6) hepatocyte iron deposition, (7) hepatic Kupffer cell iron deposition, (8) renal glomerular hypertrophy, (9) renal mesangial hypercellularity, (10) renal tubular iron deposition, (11) splenic loss of architectural integrity and vascular congestion, and (12) evidence of ongoing multiorgan injury. This evidence includes primarily small-vessel changes (ectasia, perivascular fibrosis, and congestion), parenchymal chronic ischemic changes, pericentral vein sclerosis and hepatocytic ischemic changes in the liver, and evidence of ongoing hemolysis (especially in the liver and kidneys). Each of these parameters received a pathology score from 0 to 4 (Table 1). The summed scores were plotted against the percentage of donor Hb.