摘要：
背景 角膜缘干细胞(LSCs)对维持角膜上皮的稳定和角膜组织透明性有重要作用.Rho关联卷曲螺旋蛋白激酶(ROCK)抑制剂Y-27632能够促进人胚胎干细胞、角质上皮细胞等的增生,减少细胞凋亡.目的 探讨Y-27632对离体兔角膜保存和体外LSCs扩增能力的影响. 方法 在细胞培养基MEM中加入质量分数12.5％硫酸软骨素、质量分数10.0％低分子右旋糖酐、20.0 mg/L地塞米松、100 mg/L妥布霉素注射液、9.5 g/L Hepes,使用时添加0.375 mg/L L-谷氨酰胺,制备成角膜活性保存液.将新西兰大白兔的角膜组织片分别置于含或不含Y-27632的角膜活性保存液中保存4、7、14d,采用质量分数0.25％锥虫蓝和质量分数0.2％茜素红染色法观察角膜内皮细胞密度及形态,采用Giemsa染色法并使用Image J图像分析软件计数克隆球数量和LSCs活性,计算LSCs存活率和克隆形成效率. 结果 角膜片保存4d时,Y-27632保存液组和单纯角膜中期保存液组角膜内皮细胞形态无明显差别,角膜片保存7d时,Y-27632保存液组角膜内皮细胞形态仍保持规则的六边形,而单纯角膜中期保存液组角膜内皮细胞的细胞膜轻微皱缩,少数细胞体积变大.角膜片保存14 d时单纯角膜中期保存液组角膜内皮细胞可见较多的茜素红斑.单纯角膜中期保存液组角膜内皮细胞计数为(2 262±75)/mm2,Y-27632保存液组角膜内皮细胞计数为(2 425 ±95)/mm2,差异有统计学意义(P＜0.001).新鲜角膜片和角膜片保存4d时,Y-27632保存液组和单纯角膜中期保存液组LSCs的克隆球均较大,其内细胞数较多,而保存7d和14 d时,与Y-27632保存液组比较,单纯角膜中期保存液组LSCs克隆球直径明显缩小.新鲜分离的角膜片和角膜片保存4d时,Y-27632保存液组与单纯角膜中期保存液组LSCs的克隆形成率和角膜上皮细胞存活率的差异均无统计学意义(均P＞0.05);角膜片保存7d和14d时,角膜缘上皮细胞的活性率分别为(73.00±2.12)％和(56.00±0.71)％,明显高于单纯角膜中期培养液组的(66.00±4.00)％和(49.00±0.71)％,差异均有统计学意义(t=3.098,P=0.018;t=9.798,P=0.000);角膜片保存7d和14 d时,Y-27632保存液组与单纯角膜中期保存液组LSCs的克隆形成效率分别为(11.05±0.21)％和(3.10±1.97)％,明显高于单纯角膜中期保存液组中的(2.05±1.20)％和(0.40±0.14)％,差异均有统计学意义(t=18.107,P=0.000;t=3.184,P=0.017).结论角膜保存液中添加Y-27632可明显提高离体角膜保存的效果,同时可维持LSCs的活性及克隆形成能力.Y-27632可作为角膜保存液的有效添加成分.%Background Limbal stem cells (LSCs) play an important role on the stability of corneal epithelium and corneal transparency.Rho-associated coiled-coil containing protein kinase (ROCK) inhibitor can promote cell proliferation and reduce apoptosis,such as human embryonic stem cells and karatin epithelial cells.Objective This study was to investigate the improving effect of Y-27632,a ROCK inhibitor,on the activity of rabbit LSCs in corneal preservation medium.Methods Corneal preservation solution was prepared by adding 12.5％ chondroitin sulfate,10.0％ low molecular dextran,20.0 mg/L dexamethasone,100 mg/L tobramycin sulfate,9.5 g/L Hepes and 0.375 mg/L L-glutamine in MEM.The corneas of New Zealand white rabbits were collected and preserved in the corneal preservation solution with or without Y-27632 for 4,7,14 days,and the density and morphology of corneal endothelial cells were examined by using 0.25％ trypan blue staining and 0.2％ alizarin red staining.Isolated corneal epithelial cells were seeded on 3T3 feeder layer and cultured for 7-10 days until colonies formation.Colony shape of LSCs was observed under the light microscope,and colony-formation efficiency was analyzed after Giemsa staining by Image J software.Results The morphology and density of corneal endothelial cells were normal in the corneal preservation solution with and without Y-27632 for 4 days.In the seventh day after preservation,the cells remained the regular hexagon in shape in the preservation solution with Y-27632,however,the cellular membrane was slightly shrinking with the positive staining for alizarin red in the preservation solution without Y-27632.The density of corneal endothelial cells in the corneal preservation solution without Y-27632 was (2 262-± 75) cells /mm2,while in the preservation solution with Y-27632 was (2 425 ±95) cells/mm2(P＜0.001).The cloning spheres of LSCs were similar in preservation solution both with and without Y-27632 in the freshly isolated cornea or preserved corneas and exhibited more cells inside.But in 7 days and 14 days after preservation,the cloning spheres were much smaller in the preservation solution without Y-27632 group than those in the preservation with Y-27632 group.No significant differences were found in the cloning-formation rate and survival rate of corneal epithelial cells in corneas freshly isolated or preserved for 4 days in both groups (all at P＞0.05).In 7 days and 14 days after preservation,the active rates of corneal epitheli.al cells were (73.00±2.12)％ and (56.00±0.71)％ in the preservation solution with Y27632,which were significantly higher than (66.00 ± 4.00) ％ and (49.00 ± 0.71) ％ in the preservation solution without Y-27632,showing statistically significant differences between them (t =3.098,P =0.018;t =9.798,P =0.000).In addition,the cloning-formation rates of LSCs were (11.05±0.21)％ and (3.10±1.97)％ in the preservation solution with Y-27632 in 7 days and 14 days after preservation,revealing significantly elevation in comparison with (2.05 ± 1.20) ％ and (0.40 ±0.14) ％ in the preservation solution without Y-27632 (t =18.107,P =0.000;t=3.184,P=0.017).Conclusions Y-27632 promotes the vitality and cloning-formation ability of LSCs in corneal preservation medium,suggesting its potential use during storage of cornea.
