角膜碱烧伤后大鼠角膜新生血管的细胞学研究

背景微血管壁由周细胞和血管内皮细胞组成,以往人们对血管系统的研究主要集中于血管内皮细胞,而对血管周细胞的研究较少。目的观察角膜碱烧伤后新生血管形成过程中的血管内皮细胞和周细胞的变化,探讨周细胞对新生血管生长的影响。方法36只健康成年SPF级sD大鼠,浸有1mol／LNaOH的4mm自制涂药器放置于右眼角膜中央3s,制作碱烧伤动物模型,3只正常sD大鼠作为正常对照。分别于角膜烧伤后1、2、3、5、7、10d各处死6只大鼠获取平行于角膜缘的环形切片,采用双重免疫荧光染色法检测CD31和α—SMA在角膜组织的表达,以分别评估血管内皮细胞和周细胞的分布,观察角膜碱烧伤后二者在角膜组织中的动态变化。光学显微镜下分别计数抗Ot—SMA阳性的周细胞数和抗CD31阳性的内皮细胞数,以二者的比值作为周细胞包裹指数（PCI）,定量分析角膜碱烧伤后新生血管对周细胞的募集情况。结果角膜碱烧伤后1dCD31即可在角膜浅基质层表达,呈红色荧光,随着角膜碱烧伤时间的延长,CD31在角膜组织中的表达逐渐增加并进入深基质层,至角膜碱烧伤后7d表达的细胞数减少。呈绿色荧光的α一SMA在角膜碱烧伤2d于角膜浅基质层表达,在实验观察期内表达量均少于CD31,至碱烧伤后7d,残留的CD31阳性细胞被α—SMA阳性细胞包裹,未被包裹的CD31阳性细胞多数发生消退。碱烧伤后1、2、3、5、7、10d的PCI分别为0、16．07％、11．95％、43．84％、73．97％、86．21％,呈现递增的趋势。结论大鼠角膜碱烧伤后周细胞对血管内皮细胞的包绕可能对新生血管的成熟与稳定发挥重要作用。

Cytological study on rat corneal new blood vessel after alkali burn

Background Microvessels are composed of two interacting cell types: endothelial cells and pericytes. Over the past decades, studies of corneal angiogenesis have concentrated mainly on endothelial cells, while interest in pericytes has lagged behind. Objective The present study aimed to investigate the recruitment of vascular endothelial cells and pericytes in rat corneas after alkali burn. Methods Corneal alkali burn models were established in the right eyes of 36 adult SPF SD rats by putting 4 mm medicators containing a 1% 1 mol/L NaOH solution at the central corneas for 30 seconds, and 3 matched normal rats were used as controls. Corneas were excised 1,2,3,5,7 and 10 days after surgery. Frozen sections that parallel with the corneoscleral limbus were constructed. Double immunofluorescence staining was used to observe the dynamic expression of CD31 and α-smooth muscle actin (α-SMA) in corneal tissue for the evaluation of the number of endothelial cells and pericytes. The pericyte coverage index (PCI) was calculated to quantify the recruitment of pericytes to neovascular sites. The use of experimental animals followed the Statement of Association for Research in Vision and Ophthalmology. Results CD31 was expressed in the superficial stromal layer of the cornea on the 1 st day, showing the presence of red fluoresence. The positive cell number for CD31 was gradually increased with the passage of time and proceeded into the deep stromal layer from days 2 through 5 but decreased after that. However,α-SMA was positively expressed on the 2nd day in the cornea after alkali burn with the presence of green fluorescence. The positive cell number for α-SMA was less than those of CD31 throughout the experimental period. The PCI was 0, 16.07%, 11.95%, 43.84%, 73.97% and 86. 21% , respectively, 1,2,3,5,7 and 10 days after surgery. Conclusion Pericytes recruitment to corneal new vessels may play a key role in the stabilization and maturation of angiogeneis.