Skeletal effects of novel CSF1R-inhibitors in ovariectomized rats and mice – a pilot study
Estrogen loss after menopause increases the risk of musculoskeletal disorders, such as sarcopenia and osteoporosis. Osteoporosis is a major health problem and a disease that is underdiagnosed and undertreated. Macrophage colony-stimulating factors (M-CSF) enhances the differentiation of osteoclastic precursors and up-regulates the receptor activator of nuclear factor kappa-B (RANK) expression in bone marrow. CSF1 receptor (CSF1R) which is expressed in macrophages, microglia, and osteoclasts is one type of receptor for M-CSF, and this receptor plays an important role in initiating inflammatory, cancer, and bone disorders when it binds with its ligand.
Previous studies have shown that the inhibition of this receptor CSF1R can reduce neuroinflammation, cartilage damage, bone erosion, and bone loss. In the current pilot-study we want to investigate the potential bone preserving effects of two novel CSF1R-inhibitors in ovariectomized rat and mice models of osteoporosis.
We will use 24 female rats (Sprague Dawley) and 24 mice (BalbC) in this study. Animals will be ovariectomized to induce osteoporosis (n=20 of each species) or sham operated (n=4 of each species). The ovariectomized animals will be allocated into groups of n=4 and given chow containing the two CSF1R-inhibitors (A and B) in two different doses (high and low) for six weeks, while ovariectomized controls (n=4) and sham controls (n=4) will be given control chow (without CSFR1-inhibitors). Bone mineral density (BMD), fat and muscle mass are analyzed with Dual X-Ray Absorpiometry (DXA) under inhalation anesthesia at the beginning of the study (day 0, before aloocation) and before sacrifice after 6 weeks/42 days. Blood samples for analyses of circulating substance concentrations will be drawn at day 7 and day 35. Animals will be injected subcutaneously with calcein for bone labeling 5 and 2 days before sacrifice. Micro CT of tibia and femur and measurement of breaking strength in femurs, measurements of biomarkers in blood and gene expression analyzes of bone and muscle will be performed ex vivo. Our studies can contribute to new insights into the understanding of the pathogenesis behind osteoporosis and will contribute to development of new treatment strategies.
This pilot-study is designed to investigate the effects of two novel CSF1R-inhibitors, and to compare the effects of two different doses of these substances for future studies, and we have minimized the number of animals, but still enough to receive valuable information. We excluded sham-control groups given the substances, as the substances in the intended used doses have been studied earlier. The compounds have previously been used in feeding experiments with mice in a 7-day experiment with a similar amount of substance (1160 mg/kg chow ) at Dr. Clare Pridans, Institute for Regeneration and Repair, Center of Inflammation Research, University of Edinburgh. No toxic effects were observed during the experiment and the compounds had a clear inhibitory effect on M2 macrophages.
This DXA measurements will be performed under inhalation anesthesia, and blood sampling during the study will be performed by skilled personnel to avoid stress and a minimum of strain. This study is categorized to moderate severity.
Previous studies have shown that the inhibition of this receptor CSF1R can reduce neuroinflammation, cartilage damage, bone erosion, and bone loss. In the current pilot-study we want to investigate the potential bone preserving effects of two novel CSF1R-inhibitors in ovariectomized rat and mice models of osteoporosis.
We will use 24 female rats (Sprague Dawley) and 24 mice (BalbC) in this study. Animals will be ovariectomized to induce osteoporosis (n=20 of each species) or sham operated (n=4 of each species). The ovariectomized animals will be allocated into groups of n=4 and given chow containing the two CSF1R-inhibitors (A and B) in two different doses (high and low) for six weeks, while ovariectomized controls (n=4) and sham controls (n=4) will be given control chow (without CSFR1-inhibitors). Bone mineral density (BMD), fat and muscle mass are analyzed with Dual X-Ray Absorpiometry (DXA) under inhalation anesthesia at the beginning of the study (day 0, before aloocation) and before sacrifice after 6 weeks/42 days. Blood samples for analyses of circulating substance concentrations will be drawn at day 7 and day 35. Animals will be injected subcutaneously with calcein for bone labeling 5 and 2 days before sacrifice. Micro CT of tibia and femur and measurement of breaking strength in femurs, measurements of biomarkers in blood and gene expression analyzes of bone and muscle will be performed ex vivo. Our studies can contribute to new insights into the understanding of the pathogenesis behind osteoporosis and will contribute to development of new treatment strategies.
This pilot-study is designed to investigate the effects of two novel CSF1R-inhibitors, and to compare the effects of two different doses of these substances for future studies, and we have minimized the number of animals, but still enough to receive valuable information. We excluded sham-control groups given the substances, as the substances in the intended used doses have been studied earlier. The compounds have previously been used in feeding experiments with mice in a 7-day experiment with a similar amount of substance (1160 mg/kg chow ) at Dr. Clare Pridans, Institute for Regeneration and Repair, Center of Inflammation Research, University of Edinburgh. No toxic effects were observed during the experiment and the compounds had a clear inhibitory effect on M2 macrophages.
This DXA measurements will be performed under inhalation anesthesia, and blood sampling during the study will be performed by skilled personnel to avoid stress and a minimum of strain. This study is categorized to moderate severity.