Walker 256/B malignant breast cancer cells improve femur angioarchitecture and disrupt hematological parameters in a rat model of tumor osteolysis

This study was designed to assess femur angioarchitecture and hematological effects of Walker 256/B cells in a rat model of tumor osteolysis. Tumor osteolysis was induced by in situ inoculation of Walker 256/B malignant cells. Six other rats were sham operated and served as control. Twenty days later, rats were euthanized, and femurs were collected than radiographed. Angioarchitecture [mean lumen diameter (MLD), wall thickness (WTh), Vessel number, volume, and separation (VNb, VV, and VSp respectively)] was studied by histomorphometry at 2 different positions (P1: diaphysis, and P2: metaphysis) of the operated femora. Some hematological parameters were also assessed. Walker 256/B induced marked tumor osteolysis, with cortical perforation and trabecular destruction, associated increase in bone vascularization (increases of VNb and VV and decrease of VSp). Angioarchitecture of W256/B rats was disorganized and showed large MLD and lower WTh. These effects were more prominent in P2. When compared to Sham group, significantly decreases at levels of red blood cell (RBC), hemoglobin (Hb), hematocrit (Ht), and white blood cell (WBC) were observed in W256/B rats. These results suggest that Walker 256/B cells induced tumor osteolysis, improve hypervasculature especially near the tumoral foci (P2) associated hematological disruption. Besides, tumor vessels showed abnormal (enlarged and thinner) and disorganized morphology.