Administration of high-dose macrophage colony-stimulating factor increases bone turnover and trabecular volume fraction

Macrophage colony-stimulating factor (M-CSF) is a hematopoietic growth factor that plays a critical role in early osteoclastogenesis. To characterize the skeletal effects of M-CSF, we administered soluble M-CSF to mice. It was hypothesized that M-CSF would stimulate bone formation through coupled activity of osteoclasts and osteoblasts. Twenty-four male C57BL/6 J mice (n = 12/group, aged 7 weeks) received subcutaneous injections of human M-CSF [5 mg/(kg day)] or inert vehicle (VEH) for 21 days. M-CSF increased serum bone turnover markers (+57% TRAP-5b and +44% osteocalcin). Microcomputed tomography revealed an anabolic effect on tibial trabecular bone, with higher bone volume fraction (+35%), connectivity density (+79%), and number (+18%), as well as lower trabecular separation (−18%). M-CSF had no significant effect on cortical bone mineral content, geometry, or strength. There was no change in quantitative histomorphometry parameters of femoral cortical bone. These results reveal the complex, site-specific effects of M-CSF. In particular, we have demonstrated an anabolic effect of M-CSF on trabecular bone achieved through coupled activation of osteoblasts. However, in contrast to previous studies, M-CSF was found to have no effect on cortical bone. M-CSF was demonstrated to significantly influence both bone modeling and remodeling in relatively young animals.     

高浓度葡萄糖对Notch2信号通路及破骨细胞分化的影响

目的 探讨高浓度葡萄糖对RANKL诱导破骨细胞分化及Notch信号通路的影响.方法 高糖(5～40 mmol/L)条件下,RANKL刺激小鼠骨髓源性破骨前体细胞向破骨细胞分化,TRAP染色检测破骨细胞分化情况,实时定量PCR检测Notch信号通路相关基因(Notch1、Notch2、Jagged1)的表达情况.结果 RANKL诱导破骨细胞分化过程中,实验组(20 mmol/L和40 mmol/L葡萄糖)破骨细胞个数分别为(110.3±6.81)和(72.0±8.0); Notch1相对表达量分别为(1.25±0.43)和(1.14±0.45),Notch2相对表达量分别为(1.65±0.23)和(1.1±0.11),Jagged1相对表达量分别为(1.16±0.38)和(1.09±0.23);对照组(20 mmol/L和40 mmol/L甘露醇)破骨细胞个数分别为(152.7±7.0)和(157±12.5),Notch1相对表达量分别为(1.84±0.38)和(1.66±0.40),Notch2相对表达量分别为(2.82±0.28)和(2.42±0.27),Jagged1相对表达量分别为(1.52±0.26)和(1.45±0.34).其中,破骨细胞数量和Notch2基因表达量在实验组与对照组间差异具有显著统计学意义(P＜0.05).结论 高浓度葡萄糖抑制Notch信号及破骨细胞分化,该结果提示Notch2信号可能参与高糖抑制破骨细胞分化过程.