Effects of bisphosphonates and treadmill exercise on bone and kidney in adenine-induced chronic kidney disease rats.

INTRODUCTION: The increasing prevalence of osteoporosis and chronic kidney disease (CKD) due to the aging of society has highlighted the need for development of effective treatments for elderly patients. This study examined whether the combination of treadmill exercise therapy and alendronate (ALN) can improve bone mineral density (BMD) and bone strength without worsening renal function in adenine-induced CKD model rats. MATERIALS AND METHODS: 8-week-old male Wistar rats (n = 70) were divided into experimental groups based on the treatment protocol, i.e., non-CKD (control), vehicle only (CKD), ALN only, exercise only, and combined ALN plus exercise. A 0.75% adenine diet was used to induce CKD. Groups were killed at either 20 or 30 weeks of age. Comprehensive assessments included serum and urine biochemistry tests, renal histology, bone histomorphometry, BMD measurement, micro-computed tomography examinations, and biomechanical testing. RESULTS: Blood biochemistry tests, urine analyses and histological evaluations of the kidney demonstrated that ALN treatment did not worsen renal function or kidney fibrosis in moderate-stage CKD model rats. Both ALN and treadmill exercise significantly suppressed bone resorption (p < 0.05-p < 0.01). Moreover, ALN monotherapy and combined ALN and treadmill exercise significantly improved BMD of the lumbar spine and femur, bone microstructure, and trabecular bone strength (p < 0.05-p < 0.01). Treadmill exercise was also shown to decrease cortical porosity at the mid-diaphysis of the femur and improve kidney fibrosis. CONCLUSION: The combination of ALN and treadmill exercise is effective in improving BMD, the microstructure of trabecular and cortical bone, and bone strength, without compromising renal function in adenine-induced CKD model rats.

Development of a New Focal Mouse Model of Bone Metastasis in Renal Cell Carcinoma.

BACKGROUND/AIM: Developing animal models of bone metastasis in renal cell carcinoma (RCC) is challenging as immunodeficient mice are required. The aim of this study was to develop a simple immune model of RCC bone metastasis. MATERIALS AND METHODS: RENCA tumor cells were injected into the right femurs of BALB/c mice. Sixty mice were grouped into each twenty-mouse group according to the tumor cell concentration, and the presence or absence and extent of bone metastasis in the total length of the femur were compared using hematoxylin and eosin staining of the excised tissues. RESULTS: Bone metastasis was significantly higher in the high concentration group than in the other groups (p<0.05), with 10 mice developing bone metastasis at two weeks and nine mice developing bone metastasis at three weeks. The extent of bone metastasis was significantly greater in the high concentration group than in the other groups (p<0.05). Multiple logistic regression analysis was performed to examine the factors influencing bone metastasis, and only the high concentration was a significant factor (p<0.05). CONCLUSION: We developed a normal immunity mouse model of local bone metastasis from RCC. This model could prove valuable for research into the treatment of bone metastases in RCC.

Effect of Acridine Orange and Zoledronic Acid on Bone Metastasis in Renal Cell Carcinoma.

BACKGROUND/AIM: The increasing incidence of renal cell carcinoma (RCC) and its associated bone metastasis pose challenges in surgical interventions, warranting the exploration of novel therapeutic approaches. Therefore, this study aimed to assess the impact of hematogenously administering acridine orange (AO) alone and in combination with zoledronic acid (ZA) on bone metastasis in RCC. MATERIALS AND METHODS: RENCA cells (1.0×106 cells/10 µl) were directly injected into the right femur of male BALB/c mice. The mice were categorized into four groups based on the applied therapeutic intervention and were euthanized after five weeks. Micro-computed tomography was performed to quantify the extent of periosteal reaction, indicative of bone metastasis, along the entire length of the femur. Tumor weight and volume were measured at euthanization. Hematoxylin and eosin staining was used to examine the extent of tumor development in the bone. Apoptotic cell, osteoclast, and vascular endothelial growth factor (VEGF)-positive cell counts were assessed using TdT-mediated dUTP-biotin nick end labeling, tartrate-resistant acid phosphatase staining, and VEGF staining, respectively. RESULTS: The periosteal reaction was significantly reduced in the intervention groups compared to the control group (p<0.05). The apoptotic cell numbers in the intervention groups surpassed that in the control group (p<0.05), whereas those of osteoclasts and VEGF-positive cells in the intervention groups were lower than those in the control group (p<0.05). CONCLUSION: AO hinders bone metastasis progression in RCC, and combination therapy with ZA may be more effective than AO administration alone.

Teriparatide and etelcalcetide improve bone, fibrosis, and fat parameters in chronic kidney disease model rats.

Objectives: Chronic kidney disease (CKD) complicated by secondary hyperparathyroidism (SHPT) is associated with an increased risk of fragility fractures. Etelcalcetide (EC) is a treatment for SHPT that reduces serum parathyroid hormone (PTH) levels. However, the effects of combined treatment with osteoporosis drugs such as teriparatide (TPTD) remain unclear. This study investigates the combined effects of EC and TPTD on bone in CKD model rats. Methods: The CKD model was established in 8-week-old male Wistar rats by feeding them a 0.75% adenine diet for 4 weeks. At 20 weeks of age, the rats were divided into 4 groups (N = 9-10 in each group): CKD group (vehicle administration), TPTD group (30 µg/kg, 3 times/week), EC group (0.6 mg/kg, daily), and Comb group (TPTD and EC combined). EC was injected for 12 weeks starting at 20 weeks of age, and TPTD was injected for 8 weeks starting at 24 weeks of age. After treatment, the followings were evaluated: bone mineral density, bone strength, biochemical tests, bone and fat histomorphometry, and micro-computed tomography. Results: In CKD model rats, the combination of EC and TPTD was more effective in increasing cortical bone thickness and bone strength and inhibiting porosity. In addition, the combined treatment decreased bone marrow adiposity and fibrosis, and it increased bone mass and improved bone microstructure in trabecular bone. Conclusions: With the observed benefits such as improved bone mass, bone strength, structural properties, and bone marrow adiposity, combination therapy may be a potential way to improve bone fragility in CKD.

Effects of Soft Tissue Sarcoma and Doxorubicin on Bone Metabolism in Mice.

BACKGROUND/AIM: This study aimed to evaluate the effects of doxorubicin (Dox) on bone microstructure and metabolism in a mouse model of soft tissue sarcoma. MATERIALS AND METHODS: CCRF S-180II cells (2-4×105 cells/0.2 ml) were injected subcutaneously into the back of mice. The mice were divided into four groups according to tumor and treatment status and were reared and sacrificed after 2 or 4 weeks. Micro-computed tomography (CT) was performed to calculate the architecture of the femoral bone. The proximal tibia was double stained with tartrate-resistant acid phosphatase (TRACP) and alkaline phosphatase (ALP), and bone morphometry was performed. RESULTS: Trabecular bone mass was significantly reduced in the Sarcoma and Sarcoma+Dox groups. Cortical bone thickness was reduced in the DOX group, with a stronger effect observed in the Sarcoma+Dox group. In bone morphometry, osteoclast number at the bone surface (Oc.N/BS) was significantly lower in the Dox, Sarcoma, and Sarcoma+Dox groups than in the Control group at 2 weeks. The osteoblast surface at the bone surface (Ob.S/BS) was significantly lower in the Dox and Sarcoma groups than in the Control group at 2 weeks. At 4 weeks, the differences were smaller for both Oc.N/BS and Ob.S/BS. CONCLUSION: The use of doxorubicin alone worsened the cortical bone structure; however, the presence of both soft-tissue sarcoma and doxorubicin use worsened both cortical and trabecular bone structures from an early stage.