全髋关节置换者骨髓间充质干细胞中成骨细胞相关因子的基因表达

背景：全髋关节置换后假体的使用寿命与假体周围有效的骨生成密切相关,这包括骨髓间充质干细胞的募集。碱性磷酸酶、Runx2、MSX2、骨形态发生蛋白2及骨形态发生蛋白受体1a,b的基因表达可反映出骨髓间充质干细胞的成骨潜能。 目的：分析全髋关节置换患者骨髓间充质干细胞相关成骨基因的表达水平与性别、年龄及体质量指数的关系。 方法：选取12例接受全髋关节置换的患者,术中取患者股骨近端的骨髓组织于体外在α-MEM与体积分数20%胎牛血清培养基中扩增至子一代(Passage 1),取出细胞进行流式细胞学或RNA检测,应用反转录-聚合酶链反应用检测成骨相关信号因子SOST、碱性磷酸酶、Runx2, MSX2、骨形态发生蛋白2及骨形态发生蛋白受体1a,b的RNA表达水平。骨形态发生蛋白2与骨形态发生蛋白1a,b的关系应用线性回归分析;成骨相关因子与SOST的关联性应用Pearson分析。 结果与结论：骨髓间充质干细胞成骨相关信号因子与患者的性别、年龄及体质量指数无明显相关性。线性回归分析表明,骨形态发生蛋白2与骨形态发生蛋白受体1a存在显著相关性(P < 0.01),但与骨形态发生蛋白受体1b无相关性。SOST与碱性磷酸酶、MSX2及骨形态发生蛋白受体1a有相关性(P < 0.05)。提示全髋关节置换后假体的稳定性可能与患者的成骨能力相关。尽管性别、年龄及体质量指数等与成骨潜能无明显联系,但这些因素仍然可能影响假体的稳定性。

Expression of osteoblast-related genes in bone marrow mesenchymal stem cells following total hip replacement

BACKGROUND: Prosthesis longevity after total hip replacement (THR) requires an efficient periprosthetic ossification. This includes the recruitment of bone marrow mesenchymal stem cells (BMSCs) to the site. The expression of the genes for alkaline phosphatase (ALP), Runx2, MSX2, bone morphogenetic protein 2 (BMP2), and two of its receptors (BMPR-1a and BMPR-1b) indicates the bone forming potential of a population of BMSC. We propose that a comprehensive analysis of the bone marrow osteogenic potential is helpful in predicting the strength of prosthesis fixation. OBJECTIVE:To investigate the expression of osteoblast-related genes in BMSCs derived from human bone marrow aspirate and the possible linkage of these gene expression levels with patient age, sex and body mass index (BMI) in a group of THR patients. METHODS:The study was approved by the Institutional Review Board at Providence Hospital. BMSC were prepared from bone marrow aspirate obtained from the proximal femur metaphysis during THR surgery. Twelve patients were included in this study (8 men and 4 women, aged 50-84 years, BMI 21.5-50). The isolated BMSC were culture-expanded in basal α-MEM/10% fetal bovine serum medium. Passage 1, non-confluent, undifferentiated cells were harvested for flow cytometry or for RNA isolation. Real time RT-PCR with Taqman or SYBR green was used to measure the mRNA level of genes (SOST, ALP, Runx2, MSX2, BMP2, BMPR-1a, and BMPR-1b). RESULTS AND CONCLUSION:The expression of osteoblast-related genes varied greatly in these 12 patients. Statistical analysis using SPSS showed no significant relationship between osteogenic markers and either age, sex or BMI. Linear regression analysis of the gene expression of BMP2 and BMPR-1a demonstrated a significant relationship (P < 0.01), whereas there was no significant relationship between BMP2 and BMPR-1b. There was also a significant positive association between SOST mRNA expression and ALP, MSX2 and BMPR-1a mRNA expression. Detection of the cell surface marker Stro1 by flow cytometry confirmed the mesenchymal cell characteristics of the BMSC. Theses indicated that a patient’s osteogenic potential at the time of joint replacement may determine the success of the implant fixation. Although patient’s sex, age or BMI did not correlate with osteogenic potential, all may impact the success of the implant. Moreover, given the probability that some implants will fail, the wide variation in mRNA expression of osteogenic-relevant genes also provides an opportunity to correlate gene expression with the likelihood of implant failure. Further study with these BMSC cultures should validate the use of these osteogenic markers in predicting osteoblastogenesis and potentially prosthesis success.