老年人骨髓内皮祖细胞数量及分布与骨量及骨代谢的相关性

Correlation between number and population of bone marrow endothelial progenitor cells with bone mass and bone metabolism in the elderly

目的从老年人髋关节置换手术骨髓中抽取内皮祖细胞,研究分析内皮祖细胞数量及分布与骨密度和钙磷代谢的相关性,并比较骨质疏松和非骨质疏松老年人骨髓内皮祖细胞数量及分布的差异。方法收集11例股骨颈脆性骨折和8例骨关节炎患者,行人工髋关节置换手术,用箱型骨刀在股骨颈截骨平面截取松质骨骨块,体外培养液冲洗得到骨髓混悬液,分离骨髓内皮祖细胞,并进行流式细胞检测,比较两组患者的年龄、体质量指数、骨髓内皮祖细胞数量及分布、骨密度、骨代谢标志物等临床参数,并分析各临床指标与骨髓内皮祖细胞数量及分布的关系。结果两组老人年龄比较,差异无统计学意义(P>0.05),脆性骨折组的骨髓内皮祖细胞总数量及成熟的内皮祖细胞数量明显少于骨关节炎组(0.48±0.35 vs.1.80±1.01,P=0.001和52.28±21.20 vs.77.13±19.15,P=0.042),且前者的股骨颈、全髋骨密度(0.54±0.14 g/cm2vs.0.76±0.21 g/cm2,P=0.021和0.65±0.14 g/cm2vs.0.84±0.15 g/cm2,P=0.026)和血25羟维生素D(25 hydroxy vitamin D,25OHD)水平(4.50±1.56 ng/m L vs.23.80±2.88 ng/m L,P=0.033)明显低于后者,而血甲状旁腺素(parathyroid hormone,PTH)水平(73.60±1.84 ng/L vs.32.20±0.98 ng/L,P=0.035)明显高于后者,差异均具有统计学意义(P<0.05)。年龄与骨髓分化成熟内皮祖细胞数量存在显著性负相关(r=-0.594,P=0.015),而股骨颈和全髋骨密度与骨髓分化成熟内皮祖细胞数量呈显著性正相关(r=0.847,P=0.008和r=0.925,P=0.034),全髋骨密度与骨髓分化早期内皮祖细胞数量呈显著性负相关(r=-0.817,P=0.047)。结论老年人骨髓内皮祖细胞的数量及成熟分化与骨密度呈显著性正相关,提示骨髓内皮祖细胞可能直接或间接地调节骨组织新陈代谢而影响老年人的骨量。

Objective To isolate endothelial progenitor cells（ EPCs） from bone marrow during orthopaedic surgery,studying the correlation between number and population of EPCs with bone mass,bone metabolism,and trying to figure out the differences of number and population of EPCs in elderly patients with or without osteoporosis. Methods Trabecular bone near trochanter were extracted from 11 patients with fragility fracture and 8 patients with osteoarthritis during artificial hip replacement surgery,and EPCs separated from bone marrow were prepared for flow cytometry analysis. All the patients took dual energy X-ray absorptiometry（ DXA） scan and bone metabolism marker detection. We compared the age,body mass index（ BMI）,number and population of bone marrow EPCs,bone mass and bone metabolism between fragility fracture and osteoarthritis patients,and analyzed the impact of clinical data such as age,BMI,bone mass and bone metabolism markers on the number and population of bone marrow EPCs in the elderly. Results There was no significant difference of age and BMI between fragility fracture patients and osteoarthritis patients. The total number of bone marrow EPCs and number of mature EPCs in fragility fracture patients were significantly less than that in osteoarthritis patients（ 0. 48 ± 0. 35 vs. 1. 80 ± 1. 01,P = 0. 001; 52. 28 ± 21. 20 vs. 77. 13 ± 19. 15,P = 0. 042）,and the bone mass of femur neck and total hip（ 0. 54 ± 0. 14 g / cm2 vs. 0. 76 ± 0. 21 g / cm2,P = 0. 021; 0. 65 ± 0. 14 g/cm2 vs. 0. 84 ±0. 15 g / cm2,P = 0. 026） as well as serum 25 hydroxy vitamin D（ 25OHD） level（ 4. 50 ± 1. 56 ng/m L vs. 23. 80 ±2. 88 ng / m L,P = 0. 033） in fragility fracture patients were significantly lower than those in osteoarthritis patients,however serum PTH level（ 73. 60 ± 1. 84 ng / L vs. 32. 20 ± 0. 98 ng / L,P = 0. 035） was significantly higher in fragility fracture patients than that in osteoarthritis patients. There were significantly negative correlation between age with number of mature EPCs（ r =- 0. 594,P = 0. 015）,and positive correlation between bone mass in femoral neck and total hip with number of mature EPCs（ r = 0. 847,P = 0. 008; r = 0. 925,P = 0. 034）,and negative correlation between bone mass in total hip with number of premature EPCs（ r =- 0. 817,P = 0. 047）. However,BMI,serum alkaline phosphatase,25 OHD and PTH didn＇t show any correlation with number of bone marrow EPCs. Conclusion The number of bone marrow total EPCs and mature differentiated EPCs were significantly correlated with bone mass,which suggested that bone marrow EPCs could influence bone mass via regulating bone metabolism directly or indirectly in the elderly.