Objective: To analyze the effects of bone marrow mesenchyml stem cells (BMSCs) on bone alkaline phosphatase (BALP)/C-terminal telopeptide of type-Ⅰ collagen (CTX-1) expression and mechanical dynamics in rats with osteoporotic (OP) vertebral fracture.
Methods: A total of 60 female Sprague-Dawley rats were evenly divided into three groups, a control group that received sham operation (sham group), a group consisting of rats with OP vertebral fracture (OP group), and the last group consisting of OP vertebral fracture rats given BMSCs treatment (BMSCs group). Comparison of the three groups of animals was made in terms of bone dynamic change, bone quantitative broadband ultrasound attenuation (BUA) measurement, and bone mineral density (BMD). HE staining was done to examine the bone histological morphological parameters of the vertebral body. Serum CTX-1 and BALP levels were determined by ELISA.
Results: Mechanical comparison showed that there were significant differences in mechanical changes of L 5 vertebra body and right femur among the three experimental groups ( P<0.05). The elastic modulus and maximum load of the OP group significantly decreased compared with those of the sham group ( P<0.05). After the intervention, the maximum load and elastic modulus of the BMSCs group were significantly higher than those of the OP group ( P<0.05). Compared with the sham group, BUA and BMD values in the OP group were significantly downregulated ( P<0.05). After intervention, BUA and BMD of the BMSCs group were significantly higher than those of the OP group and were comparable to those of the sham group ( P<0.05). Compared with the sham group, the number of trabeculae in the OP group was significantly fewer, and the distribution of trabeculae was disorderly and lacked regularity. Compared with the OP group, there were more trabeculae in the BMSCs group, and their distribution was more regular. Compared with sham group, bone histological morphological parameters of the vertebral body of rats in the OP group were significantly changed--mean trabecular plate thickness (MTPT) and trabecular bone volume (TBV) parameters were significantly decreased, while mineral apposition rate (MAR) and trabecula bone surface (TRS) parameters were significantly upregulated (all P<0.05). After the experimental intervention, bone histological morphological parameters of the vertebral body in the BMSCs group showed significant improvement compared with those of the OP group ( P<0.05). Compared with the sham group, serum BALP content in the OP group was greatly decreased, while the CTX-1 level was upregulated ( P<0.05). After the intervention, the BMSCs group had higher serum BALP content than that of the OP group and substantially lower CTX-1 content than that of the OP group ( P<0.05).
Conclusion: BMSCs can improve the mechanical changes in rats with OP vertebral fracture, and can increase the maximum load and elastic modulus of bone tissue. In addition, BMSCs can upregulate the expression of BALP in serum and downregulate the expression of CTX-1, thus helping rats with OP vertebral fracture heal early.
目的: 分析骨髓间充质干细胞（BMSCs）对骨质疏松（OP）性椎体骨折大鼠骨碱性磷酸酶（BALP）/Ⅰ型胶原交联C-末端肽（CTX-1）表达与力学动态的影响。
方法: 把60只SD雌性大鼠均等划入至假手术组（sham组）、OP性椎体骨折大鼠组（OP组）、行BMSCs处理的OP性椎体骨折大鼠组（BMSCs组），对比3组动物骨动力学改变、骨定量振幅衰减（BUA）状况、骨密度（BMD），经由HE染色查看椎体骨组织形态学与参数；ELISA测定血清内CTX-1、BALP水平。
结果: 力学对比表明，在L5椎体与右侧股骨力学改变方面，对比3组实验动物发现存在显著区别（P<0.05）；在弹性模量、最大载荷上，OP组与sham组相比大幅下降（P<0.05）；经过干预，在最大载荷、弹性模量这2项指标上，与OP组相比，BMSCs组明显偏高（P<0.05）。相较于sham组，OP组动物的BUA与BMD值下调（P<0.05）；经过干预，在BUA与BMD这2项指标上，与OP组相比，BMSCs组增高（P<0.05），与sham组相当（P>0.05）。在骨小梁数量上，与sham组相比，OP组明显偏少，同时分布失调缺乏规则性；在此项指标上，与OP组相比，BMSCs组偏多，同时分布较为规则。相较于sham组，OP组椎体骨组织学形态参数出现大幅改变，MTPT与TBV这2项参数皆大幅下降，MAR与TRS参数皆大幅上调（P<0.05）；经过干预，BMSCs组椎体骨组织学形态参数与OP组相比为明显改善表现（P<0.05）。相较sham组，OP组血清内BALP含量大幅减少，CTX-1水平上调（P<0.05）；经过干预，BMSCs组血清内BALP含量与OP组相比偏高，CTX-1含量与OP组相比大幅下降（P<0.05）。
结论: BMSCs对OP性椎体骨折大鼠力学改变具改善作用，可提升骨组织最大荷载与弹性模量，同时BMSCs可上调血清内BALP表达，使CTX-1表达下调，由此帮助OP性椎体骨折大鼠早日愈合。
Keywords: Bone alkaline phosphatase (BALP); Bone marrow mesenchyml stem cells; C-terminal telopeptide of type-Ⅰ collagen (CTX-1); Dynamic mechanics; Osteoporotic vertebral fracture.
Copyright© by Editorial Board of Journal of Sichuan University (Medical Sciences).