大鼠前腭缝扩张中细胞凋亡与骨缝改建的关系

Identification of cell apoptosis during premaxillary suture expansion in rat

目的:观察大鼠前腭缝扩张中细胞凋亡的发生,探讨细胞凋亡与骨缝改建的关系。方法:取35天龄SD大鼠40只,随机分为对照组和实验组。实验组动物用扩大簧施加(200±10)g力,扩大前腭缝,对照组不作处理。2组动物分别于扩弓后第1、2、3、5天后处死(每组5只)。使用HE染色和甲苯胺蓝染色,观察骨缝的组织学变化,ssDNA免疫组织化学染色检测凋亡细胞。采用SPSS15.0软件包对数据作t检验,比较实验组和对照组间的差异。结果:实验组动物在扩弓后1天,前腭缝扩大,骨缝边缘成骨细胞增殖明显;第2天成骨细胞数目最多,第3天有明显的新骨沉积,成骨细胞数目减少;第5天新骨大量形成呈树突状。ssDNA免疫组化染色显示,对照组前腭缝组织中鲜有凋亡细胞,而扩张后的前腭缝中细胞凋亡发生明显增多。凋亡细胞主要分布在骨缝边缘的成骨细胞和前腭骨内的骨细胞中,并在扩张后的第2天和第3天最明显(P<0.01)。结论:在大鼠前腭缝扩张成骨中有细胞凋亡发生,细胞凋亡参与了牵张力下上颌骨缝的骨改建。

PURPOSE：To identify the incidence of cell apoptosis during premaxillary suture expansion. METHODS： Forty SD rats were randomly allotted into experimental and control groups. The experimental animals were subjected to premaxillary suture expansion by a helix spring with （200±10）g initial force. They were sacrificed on day 1, 2, 3 and 5（n=5）. The sequence of histological changes and osteoblast proliferation in the premaxillary suture were evaluated by hematoxylin and eosin（HE） and toluidine blue staining. Cellular apoptosis was identified by ssDNA immunostaining. The difference between experimental and control groups was analyzed by Student＇s t test with SPSS 15.0 software package. RESULTS： The width of premaxillary suture was enlarged 1 day after expansion and osteoblasts were accumulated along the suture. After 2 days of stretching, the number of the osteoblasts increased to the peak. New bone deposition was identified on day 3 and projection of suture with bone trabeculae was apparent on day 5. ssDNA immunostaining showed few apoptotic cells in premaxillary suture during natural growth. Upon expansion, cell apoptosis was identified in osteoblasts along the suture and the osteocytes embedded in premaxillary bone, especially on day 2 and day 3 （P〈0.01）. CONCLUSION： Apoptotie cell death might regulate the growth modification of premaxillary suture upon mechanical stretching. Supported by National Natural Science Foundation of China （Grant No.30500572）, Research Fund of Science and Technology Commission of Shanghai Municipality （Grant No. 08DZ2271100） and Shanghai Leading Academic Discipline Project （Grant No. S30206）.