多尺度分析骨质疏松大鼠骨微结构变化

目的 多尺度分析骨质疏松大鼠的骨微结构变化。 方法 20只5月龄雌性SD大鼠随机选取12只实施双侧去卵巢(ovariectomy, OVX)手术,术后 8 周形成骨质疏松大鼠模型,另外 8 只作为假手术( SHAM) 对照组。 利用Micro-CT 和 SR-Nano-CT 定量分析骨质疏松大鼠在组织尺度下皮质骨和松质骨以及细胞尺度下骨细胞、骨陷窝小管和细胞外基质的微结构变化。 结果 组织尺度下,OVX 组皮质骨的截面积较 SHAM 组显著增大(P<0. 05),皮质骨骨密度和厚度较 SHAM 组虽有变化,但不显著;OVX 组骨小梁的骨密度、体积分数、厚度和骨小梁数量较 SHAM组显著降低(P<0. 01),骨小梁分离度显著增加(P<0. 01)。 细胞尺度下,OVX 组骨陷窝半轴长较 SHAM 组没有显 著差异,但 OVX 组骨陷窝厚度和骨小管直径较 SHAM 组显著增大(P<0. 05);同时,细胞尺度下 OVX 组皮质骨孔隙率较 SHAM 组显著增大(P<0. 05)。 结论 OVX 大鼠骨在组织和细胞尺度出现不同程度的微结构变化。 其中,组织尺度主要是松质骨丢失,皮质骨变化不大;细胞尺度骨陷窝小管网络孔隙显著增大,将直接影响皮质骨骨密度和强度。 多尺度分析骨质疏松大鼠骨微结构变化对于骨质疏松症的临床诊断及病理分析有潜在的应用价值。

Multiscale Analysis on Changes in Bone Microstructure of Osteoporotic Rats

Objective To study changes in bone microstructure of osteoporotic rats by multiscale analysis. Methods A total of 20 5-month-old female SD rats were randomly divided into two groups, i.e., ovariectomy (OVX) group (n=12) and the SHAM group (n=8), respectively. The rats in OVX group were subjected to bilateral ovariectomy and became osteoporosis models after 8 weeks, while sham operation was performed for the SHAM group. Changes in microstructure of cortical bone and cancellous bone at tissue scale, and osteocyte lacunar-canalicular network (LCN) and extracellular matrix (ECM) at cell scale were quantitatively analyzed using Micro-CT and SR-Nano-CT. Results At tissue scale, the cross-sectional area of cortical bone in OVX group was significantly higher than that in SHAM group (P<0.05), and the bone mineral density (BMD) and thickness of cortical bone were not significantly different from those in SHAM group. The trabecular BMD, bone volume fraction, trabecular thickness and trabecular number in OVX group were significantly decreased in comparison with SHAM group (P<0.01), while the trabecular separation was significantly increased (P<0.01). At cell scale, there was no significant difference in the semiaxes of lacunae between OVX group and SHAM group, but the thickness of lacunae and the diameter of canaliculi in OVX group were significantly increased in comparison with SHAM group (P<0.05). At the same time, the porosity of cortical bone in OVX group was significantly higher than that in SHAM group at cell scale (P<0.05). Conclusions The bone microstructure in OVX group varied to different extents at tissue and cell scales. At tissue scale, the cancellous bone loss was severe, while the cortical bone had fewer changes. At cell scale, porosity of the lacunar-canalicular network significantly increased, which directly affected the BMD and strength of cortical bone. Multiscale analysis on changes in bone microstructure of OP rats has potential application value for clinical diagnosis and pathological analysis of osteoporosis.