Figure 1
Figure 1. Osteoblast proliferation after marrow radioablation. (A) Bone (Bo) and BM section taken from a metaphysis at 48 hours after TBI shows an increased number of cells lining the bone () compared with (B) the nonirradiated control (hematoxylin-and-eosin stain). (A,B) Scale bar represents 50 μm. (C) Immunohistochemical staining (in red) to identify the bone-lining cells in panels A and B revealed an increase of collagen I (left) and osteocalcin (right) producing osteoblasts (). Scale bar (third column) represents 50 μm; scale bar (fourth column) represents 10 μm. (D) Semiquantitative RT-PCR analysis confirming an increased expression of collagen I and osteocalcin in TBI mice. The negative control (Neg, without template) is shown in the middle lane. (E) Comparison of transcript band intensities, for genes encoding collagen I and osteocalcin, expressed in irradiated and nonirradiated mice. The values were calculated relative to GAPDH levels and reported as mean percentages (± SD) of 6 mice per group. Both collagen I (P = .01) and osteocalcin (P = .001) levels are significantly increased over control values (Student t test). (F) Double staining of sections from TBI and control mice with anti-BrdU (black) and anticollagen I (red) antibodies. The typical nuclear pattern of the BrdU labeling and the simultaneous collagen I expression () demonstrates the presence of proliferating osteoblasts after TBI. The BrdU-positive cells in the control mice are predominantly present in the BM space (), with rare double-positive osteoblasts (inset). Scale bar represents 20 μm. (G) Semiquantitative RT-PCR analysis of Ki-67 expression by marrow cells from TBI and control mice demonstrates the persistence of proliferating BM cells after irradiation. (H) Comparison of transcript band intensities for Ki-67 expressed in irradiated versus nonirradiated mice. Values were calculated relative to GAPDH levels and reported as mean percentages (± SD) of 6 mice per group. Ki-67 expression was significantly decreased (P < .01) but persisted in irradiated mice.

Osteoblast proliferation after marrow radioablation. (A) Bone (Bo) and BM section taken from a metaphysis at 48 hours after TBI shows an increased number of cells lining the bone () compared with (B) the nonirradiated control (hematoxylin-and-eosin stain). (A,B) Scale bar represents 50 μm. (C) Immunohistochemical staining (in red) to identify the bone-lining cells in panels A and B revealed an increase of collagen I (left) and osteocalcin (right) producing osteoblasts (). Scale bar (third column) represents 50 μm; scale bar (fourth column) represents 10 μm. (D) Semiquantitative RT-PCR analysis confirming an increased expression of collagen I and osteocalcin in TBI mice. The negative control (Neg, without template) is shown in the middle lane. (E) Comparison of transcript band intensities, for genes encoding collagen I and osteocalcin, expressed in irradiated and nonirradiated mice. The values were calculated relative to GAPDH levels and reported as mean percentages (± SD) of 6 mice per group. Both collagen I (P = .01) and osteocalcin (P = .001) levels are significantly increased over control values (Student t test). (F) Double staining of sections from TBI and control mice with anti-BrdU (black) and anticollagen I (red) antibodies. The typical nuclear pattern of the BrdU labeling and the simultaneous collagen I expression () demonstrates the presence of proliferating osteoblasts after TBI. The BrdU-positive cells in the control mice are predominantly present in the BM space (), with rare double-positive osteoblasts (inset). Scale bar represents 20 μm. (G) Semiquantitative RT-PCR analysis of Ki-67 expression by marrow cells from TBI and control mice demonstrates the persistence of proliferating BM cells after irradiation. (H) Comparison of transcript band intensities for Ki-67 expressed in irradiated versus nonirradiated mice. Values were calculated relative to GAPDH levels and reported as mean percentages (± SD) of 6 mice per group. Ki-67 expression was significantly decreased (P < .01) but persisted in irradiated mice.

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