Fig. 4

In vivo anti-myeloma and bone-formation stimulating activity of sicXer and boXer in the 5T33-myeloma mouse model. A. Concentration-dependent local control of myeloma cell accumulation as assessed by anti-CD138 immunohistochemistry (first column) and bone formation capacity as assessed by Masson–Goldner staining (second column) for A1 sicXer, A2 boXer-500, A3 boXer-2500. After implantation of sicXer, the entire distal epiphysis was intensely stained in the course of CD138 immunohistochemistry, reflecting myeloma cell infiltration. The numerous myeloma cells even spread into the defect. After implantation of boXer-materials, bortezomib-mediated suppression effects of the myeloma cells appeared, which affected the adjacent circumference of the defect in the case of boXer-500 and extend into the diaphysis in boXer-2500. The dashed line corresponds to the contour of the drill hole defect. The red line marks the respective “limit of action of bortezomib” in terms of local control of myeloma cells. Induction of bone formation in terms of osteoid was most prominent for sicXer. As shown by Masson–Goldner staining three weeks after implantation of sicXer, woven bone has grown into the defect from the edge of the drill hole (dashed black line), while the defect areas have enlarged in the presence of boXer-materials. The green lines delimit the areas not accessed by bone, while the magenta-colored lines mark the annular zone of 100 µm around the implanted material. The osteoid margins were measured within these zones. B. Boxplots summarizing the results from panel A. in terms of reduction of myeloma cell infiltration B1 in bone marrow and B2 an annular zone of 100 µm around the implanted material. C. Boxplot summarizing the results from panel A. in terms of osteoid deposition. D. Material application in drill hole defect. White colored arrows identify the drill hole. E. µCT analysis of tissue slices. Coronal multiplanar reformation shows subtotal degradation of sicXer (left panel) with an enhanced bone formation inside and outside the margin of the original drillhole. BoXer-500 shows partial material resorption and new bone formation (middle panel). Almost no bone formation and material resorption were observed for boXer-2500 (right panel). F. Quantitative analysis of µCT-data, schematic. The defect zone represents the area of the initial bone defect (1 mm diameter, quantitative analysis in I1-I3), the “ring” represents an area of 1 mm around the initial defect (quantitative analysis in J1-J3, peri-defect area). G1 percentage of bone in the initial defect area, G2 number of bone trabeculae [1/mm], G3 thickness of bone trabeculae [mm]. New bone formation in the defect is visible for all three materials, pronounced for sicXer. H1 percentage of bone in the peri-defect area, H2 number of bone trabeculae [1/mm], and H3 thickness of bone trabeculae [mm]. The peri-defect zone is not negatively affected by bortezomib-release