Figure 5.

VEGF₁₂₁/rGel reduced the number of osteoclasts at the tumor–bone interface but did not reduce peritumoral osteoblasts. T, prostate cancer cells; M, bone matrix; black arrows, osteoblasts; white arrows, osteoclasts. (A) Toluidine blue staining of contralateral (top) and tumor-bearing (bottom) femurs shows morphologically normal bone tissue with visible osteoblasts. Original magnification, ×200. (B, C) Toluidine blue staining of tumor cells that are surrounded by bone matrix: (B) control, (C) VEGF₁₂₁/rGel. (D) Quantitation of peritumoral osteoblasts per field. (E) TRAP-positive osteoclasts are present throughout the tumor–bone interface in control mice. Original magnification, ×100; inset original magnification, ×200. (F) TRAP (left) and toluidine blue (right) staining of identical specimens from control mice indicate the presence of both osteoclasts and osteoblasts in the vicinity of tumor cells that are surrounded by bone matrix. Original magnification, ×200. (G) TRAP and (H) toluidine blue staining of identical specimens from VEGF₁₂₁/rGel-treated mice. Fewer osteoclasts line the tumor–bone interface or are present in the vicinity of tumor cells surrounded by bone matrix, while osteoblast numbers are unchanged. Original magnification, ×100. (I) Quantification of osteoclasts at the tumor–bone interface revealed that VEGF₁₂₁/rGel significantly suppressed osteoclast numbers compared to controls. Osteoclast numbers in the contralateral leg are provided as a reference.