定量超声技术评估组织工程骨修复家兔桡骨的骨强度

Quantitative ultrasound for assessing bone strength of rabbit radius repaired by tissue-engineered bone

目的:应用定量超声技术评估应用组织工程骨修复的家兔桡骨骨强度,探讨其成骨活性以及矿化规律。方法:实验于2004-04/2005-01在第四军医大学唐都医院骨实验室完成。选取健康30d龄家兔40只,随机分为两组,即聚乳酸-聚乙醇酸+骨髓基质细胞组,聚乳酸-聚乙醇酸组,20只/组。聚乳酸-聚乙醇酸+骨髓基质细胞组家兔自体骨髓基质细胞移植到预制形状的聚羟乙酸-乳酸中,体外复合培养1周后移植修复家兔桡骨15mm的缺损;聚乳酸-聚乙醇酸组采用单纯聚乳酸-聚乙醇酸对家兔桡骨骨缺损进行修复,未加入骨髓基质干细胞。对两组家兔的新生组织进行组织学、生物化学及放射线检查,12周后见新生骨完全填充了缺损,组织学显示其成骨过程为软骨内成骨。然后分别于12,16,22周对两组进行骨超声评估,测量超声波在桡骨中的传播速度。结果:实验纳入40只家兔全部进入结果分析。两组家兔骨缺损模型不同时期超声波在桡骨中的传播速度值的比较:①聚乳酸-聚乙醇酸+骨髓基质细胞组与聚乳酸-聚乙醇酸组在骨修复后12,16,22周均逐渐升高[(2890±99),(3010±108),(3106±116)m/s;(2720±96),(2910±101),(3100±98)m/s;P均<0.05]。②第12,16周聚乳酸-聚乙醇酸+骨髓基质细胞组传播速度值明显比聚乳酸-聚乙醇酸组快(P均<0.05);而第22周时两组传播速度值基本接近(P>0.05)。结论:应用定量超声技术检测到家兔桡骨骨缺损修复后不同时期的超声波在骨骼中的传播速度值,成骨活性呈动态变化,矿物质含量及骨强度均随时间的延长而升高,反映了修复后的骨髓基质细胞其组织工程骨的成骨能力增加。聚乳酸-聚乙醇酸+骨髓基质细胞组成骨活性、骨内矿物质含量及骨强度在骨修复后12,16周明显高于聚乳酸-聚乙醇酸组,至22周时两组成骨活性接近稳定,其骨强度大致相同。提示定量超声技术为组织工程骨的生物力学强度检测确定了一种新的方法。

AIM： To evaluate the bone strength of rabbit radius repaired by tissue-engineered bone with quantitative ultrasound and study the activity of ossification and the rule of mineralization. METHODS： The experiment was conducted in the Bone Laboratory, Tangdu Hospital, the Fourth Military Medical University of Chinese PLA, from April 2004 to January 2005. Forty 30-day rabbits were randomly divided into two groups with 20 rabbits in each group： poly（lactic-co-glycolic acid） （PLGA）＋bone marrow cell （BMC） group and PLGA group. Autologous BMCs were obtained from the rabbits in the PLAG＋BMC group to place into PLGA and then co-cultured in vitro 1 week to repair a 15-mm defect of radius. In the PLGA group, bone defect was only repaired by PLGA without BMC. Histological examination, biochemical examination and X-ray were adopted. Twelve weeks later, new hone formed as cartilaginous ossification. An Omnisense ultrasonic bone sonometer was applied to measure the radius speed of ultrasound at 12, 16 and 22 weeks. RESULTS： All the 40 rabbits were involved in the result analysis. ①The radius speed of sound in the PLGA＋BMC group and PLGA group became faster gradually 12, 16 and 22 weeks after defect repair [（2 890±99）, （3 010±108）, （3 106±116）m/s; （2 720±96）, （2 910±101 ）, （3 100±98）m/s, P 〈 0.05].②） At 12 and 16 weeks, the speed of sound in PLGA＋BMC group was significantly faster that in PLGA group （P 〈 0.05）; however, at 22 weeks, there was no significant difference in the speed of sound between the two groups （P 〉 0.05）. CONCLUSION： The capability of bone formation is increased after radius defect repair through detection of ossification activity, increased mineral products and bone strength, and speed of sound with quantitative ultrasound. Quantitative ultrasound provides a new way to detect biomechanical strength of tissue-engineered bone.