ABSTRACT

Introduction: With age, the number of adipocytes and osteoclasts increases, the number of osteoblasts decreases, and mechano-adaptation is impaired.

Objectives: Using marrow aspiration, which has a known osteogenic effect in young mice, we sought to recruit osteoblast progenitors to mediate the mechano-adaptive response to in vivo tibial loading.

Methods: First, we assessed bone formation and marrow adiposity in the tibiae of old mice (>20 months) sacrificed 1, 2, and 4 weeks after unilateral marrow aspiration. Then, we examined the effects of marrow aspiration on mechano-adaptation in aged mice using tibial loading.

Results: Two weeks after aspiration, aspirated tibiae had more bone than contralateral tibiae due to the formation of bone in the medullary canal. Two weeks and four weeks after marrow aspiration, the volume of marrow adipose tissue was higher in the aspirated tibiae, compared to contralateral tibiae. Histomorphometry indicated that aspiration increased non-periosteal (endosteal, intracortical, intramedullary) bone formation, compared to the contralateral tibia. Mice with marrow aspiration had reduced periosteal bone formation in the contralateral tibia, compared to mice that had loading alone. Loading-induced periosteal bone formation was higher in mice that had loading alone, compared to mice that had aspiration + loading, indicating that aspiration further reduced the mechano-adaptive response.

Conclusion: These data demonstrate that, in old mice, bone forms in the medullary canal following aspiration. Adiposity is increased following marrow aspiration, and periosteal mechano-adaptation is reduced.

摘要

简介：随着年龄的增长，脂肪细胞和破骨细胞的数量增加，成骨细胞的数量减少，机械适应性受损。

目的：使用骨髓抽吸，它在年轻小鼠中具有已知的成骨作用，我们试图招募成骨细胞祖细胞来介导对体内胫骨负荷的机械适应性反应。

方法：首先，我们评估了单侧骨髓抽吸后 1、2 和 4 周处死的年老小鼠（>20 个月）胫骨的骨形成和骨髓肥胖。然后，我们使用胫骨负荷检查了骨髓抽吸对老年小鼠机械适应的影响。

结果：抽吸后两周，由于髓管中骨的形成，抽吸的胫骨比对侧胫骨有更多的骨。骨髓抽吸后两周和四周，与对侧胫骨相比，抽吸胫骨中骨髓脂肪组织的体积更高。组织形态测量表明，与对侧胫骨相比，抽吸增加了非骨膜（骨内、皮质内、髓内）骨形成。与单独负重的小鼠相比，进行骨髓抽吸的小鼠对侧胫骨的骨膜骨形成减少。与吸入+负荷的小鼠相比，负荷诱导的骨膜骨形成在单独负荷的小鼠中更高，表明吸入进一步降低了机械适应性反应。

结论：这些数据表明，在老年小鼠中，抽吸后髓管中会形成骨骼。骨髓穿刺后肥胖增加，骨膜机械适应性降低。