Histopathologic analysis of hematopoietic tissues in long-term TNS9-treated chimeras.

Left: 4.7 g/dL Hb, 8 months after transplantation. Right: 12.0 g/dL Hb, 6 months after transplantation. (A) Bone marrow (original magnification, × 60). Left: There is still a relative increase in the erythroid lineage but with more evidence of maturation than in untreated chimeras (Figure 3). Myeloid maturation is seen. Right: Normal erythroid maturation is present; the erythroid precursors are not as densely packed. Myeloid maturation, still decreased compared with normal, is more frequently seen than in the mouse with the lower Hb level (left). (B) Spleen (original magnification, × 60). Left: There is more maturation and less degenerative changes in the erythroid lineage than in the untreated mice (Figure 3B, right). Right: In comparison to the mouse with lower Hb level, the sinuses appear to be somewhat less compressed. The sinusoidal erythroid cells are more eosinophilic, suggesting better hemoglobinization. The nuclei are not as irregular as in either the mouse with lower Hb levels (left) or in the Hbb^th3/th3 chimera. (C) Liver (original magnification, × 20). Left: Residual EMH, greater than in control Hbb^th3/+ chimeras (Figure 3C, center) and approaching that of the Hbb^th3/th3 chimeras (Figure 3C, left). Right: Minimal residual EMH, considerably less than in the Hbb^th3/+ controls (Figure 3C, center). Stain: hematoxylin and eosin. Hepatic iron deposition, as detected by a Gomori iron stain: the 4.7 g/dL Hb chimera was similar to the Hbb^th3/+ chimera (Figure 3D; center) and was minimal in the 12.0 g/dL Hb chimera (data not shown).