脱细胞角膜基质为支架构建组织工程角膜上皮组织的实验研究

目的 比较氯化钠(NaCl)-十二烷基硫酸钠(SDS)-胰蛋白酶与分散酶(Dispase)-聚乙二醇辛基苯基醚(Triton-X-100)两种角膜组织脱细胞方法的效果,探讨以脱细胞角膜基质为支架构建组织工程化角膜上皮组织的可行性.方法 实验研究.采用完全随机化设计的方法,分别用NaCl-SDS-胰蛋白酶和Dispase-Triton-X-100处理兔角膜组织,使用裂隙灯显微镜、光学显微镜及透射电镜观察经两种方法处理后的角膜基质特性和脱细胞效果.以兔角膜缘上皮细胞为种子细胞,Dispase-Triton-X-100处理的猪角膜前弹力层与基质为支架,体外重建兔角膜上皮细胞层,并进行形态学、组织病理学及免疫组织化学检测.结果 两种方法处理过的兔角膜基质大体形态相似,灰白色不透明,水肿明显,质地柔软.组织病理学和超微形态学观察显示两种方法处理的兔角膜基质胶原排列规整,NaCl-SDS-胰蛋白酶处理的角膜组织残留了部分基质细胞碎片,而Dispase-Triton-X-100处理的角膜组织未见基质细胞碎片.兔角膜缘上皮组织块接种于脱细胞猪角膜前弹力层与基质上,24 h角膜上皮细胞开始游出,3～4 d融合呈片状,7～8 d形成单细胞层.组织工程化角膜上皮细胞表达CK3.结论 Dispase-Triton-X-100处理方法的角膜组织脱细胞效果良好.以脱细胞猪角膜前弹力层与基质为支架.可在体外构建组织工程化兔角膜上皮组织.     

异种角膜脱细胞基质为供体进行角膜前板层移植的初步研究

目的探讨以异种猪角膜脱细胞基质为供体植片,分析兔角膜进行前板层移植后的生物相容性：设计实验研究。研究对象新西兰白兔。方法应用1％TritonX-100及冷冻干燥处理制备猪角膜脱细胞基质载体,切取1／3厚度前板层作为供体角膜植片,对兔眼角膜前板层切除后进行移植,同时以新鲜猪角膜板层为供体对兔进行前板层移植作对照。通过术后角膜透明度、组织结构观察,评价猪角膜脱细胞基质的生物相容性及植片转归的情况。主要指标角膜透明度和组织学HE染色。结果制备的猪角膜脱细胞基质植片作前板层移植到兔眼后,未见明显的新生血管、炎症反应、角膜坏死等排斥现象,观察期内植片较透明;脱细胞基质表面上皮化良好,植片基质板层与植床逐渐融合,植片内有宿主细胞迁入生长,板层结构与正常角膜相似。结论猪角膜脱细胞基质具有良好的生物相容性、安全性和低抗原性,有望成为角膜板层移植的供体材料。     

猪脱细胞角膜基质组织结构特点与生物相容性研究

背景构建组织工程化角膜时,载体的选择十分重要。目前有多种载体可供选用,但脱细胞角膜基质是公认的较好载体。目的观察猪脱细胞角膜基质的组织结构特点,评价其与异种角膜基质和上皮细胞的生物相容性。方法取猪角膜组织进行组织块培养,经胰蛋白酶-EDTA酶消化角膜上皮、基质、内皮细胞,支架组织于-20℃冷冻干燥后灭菌保存。猪脱细胞角膜基质石蜡切片行常规苏木精一伊红染色,光学显微镜下观察组织的形态学特征;扫描电镜下观察其组织结构特点;并对其物理特性,如抗拉性、膨胀性、含水量和透明度进行评价。将猪脱细胞角膜基质移植到兔角膜基质层内,同时与体外培养的兔角膜上皮细胞共培养4周,分析其组织和细胞生物相容性。结果经酶消化处理后猪角膜组织中未见上皮、基质和内皮细胞,其胶原纤维直径大小、排列与正常角膜组织相同,抗拉性、膨胀性、含水量和透明度等物理特性与正常猪角膜相似。猪脱细胞角膜基质行异种兔角膜基质层间移植1周时可见轻度水肿,2周后水肿基本消退,4周时透明度较好。猪脱细胞角膜基质与兔角膜基质之间贴附良好,未见炎症反应及新生血管。兔角膜上皮细胞接种于猪脱细胞角膜基质上共培养4周后CK3表达阳性。猪脱细胞角膜基质脱水前与脱水2h、4h后及正常猪角膜基质间的抗拉性、膨胀性、含水量的差异均无统计学意义（P〉0．05）,但脱水2h、4h后及正常猪角膜基质的透明度明显好于脱水前,差异均有统计学意义（P〈0．01）。结论猪脱细胞角膜基质组织结构与正常猪角膜相似,与兔角膜基质和上皮细胞具有良好的生物相容性。     

体外构建组织工程角膜的研究进展

角膜移植是目前治疗角膜盲最有效的方法,但角膜供体材料不足及角膜移植术后的免疫排斥反应限制了角膜移植的临床应用.构建具有良好生物相容性和正常生物学功能的组织工程角膜替代物是解决当前角膜供体不足最为有效的方法.近些年来,随着生物材料、细胞培养及组织工程技术的发展,组织工程角膜在支架材料、种子细胞及组织的三维构建等方面都取得了较大进展,部分组织工程产品及技术也已经应用于临床.人们有望通过组织工程技术构建出具有良好机械强度、透光性及生物相容性的组织工程角膜,真正解决临床上角膜供体缺乏及移植术后免疫排斥等问题.羊膜、脱细胞猪角膜基质、胶原、丝素蛋白及壳聚糖等是目前较常用的支架材料.组织工程角膜较常用的种子细胞主要有永生化和原代培养的角膜细胞、胚胎干细胞及成体多能干细胞.本文就组织工程角膜的支架材料、种子细胞及三维构建进行综述.     

异种脱细胞角膜基质材料的生物相容性研究

目的：研究脱细胞猪角膜基质材料在角膜组织中的生物相容性,为组织工程角膜的构建寻找一种良好的支架材料。方法：将用去垢剂联合酶的方法脱细胞处理的猪角膜基质材料植入兔角膜基质囊袋中,进行裂隙灯观察并照相。不同时间取材HE染色,进行光镜检查。结果：脱细胞猪角膜基质材料植入兔角膜基质囊袋,观察4mo,生物相容性良好,材料逐渐降解吸收。结论：脱细胞猪角膜基质材料植入兔角膜中无炎症、无免疫排斥反应,生物相容性好,可作为组织工程角膜的支架材料。     

组织工程角膜治疗兔无菌性角膜溃疡

目的:探讨利用组织工程技术制备角膜基质进行板层角膜移植治疗无菌性角膜溃疡的可行性和疗效。方法:用去垢剂联合胰酶、DNA-RNA酶去除猪角膜基质细胞后制备成组织工程角膜基质;将16只兔的角膜基质内植入壳聚糖膜使之形成角膜溃疡,随机从16只兔中选8只行组织工程角膜基质板层移植;另外8只作为对照组,行新鲜的同种异体板层角膜移植。术后对角膜进行裂隙灯、HE染色光学显微镜检查。结果:组织工程角膜基质移植后无免疫排斥发生,术后8～10wk角膜溃疡完全修复,角膜恢复透明性,与对照组疗效相同。结论:组织工程角膜基质具有良好的生物相容性和治疗作用。     

猪角膜脱细胞基质的制备及生物相容性的实验研究

目的探讨猪角膜脱细胞基质（CACM）的制备方法，评价其组织学特性和生物相容性。方法应用1％TritonX-100去垢剂振洗，经冷冻干燥处理得到猪CACM，通过苏木精-伊红染色、扫描电镜观察行组织学检测。将猪CACM植入兔角膜板层间观察10周，取材做组织切片，评价其生物组织相容性。结果组织学检测证实角膜细胞完全脱净，胶原纤维排列疏松，板层结构同正常角膜；扫描电镜CACM表面未见细胞结构，纵切面上胶原板层间出现清晰的空穴状裂隙；CACM植入兔角膜层间后，观察期内未见明显排异反应。结论TdtonX．100可以有效地脱净角膜细胞，保存胶原排列的结构特征，经过冷冻干燥可形成多孔隙且胶原排列疏松的板层结构，适合作为载体材料，猪CACM与兔角膜生物相容性好。     

脱细胞猪角膜基质体外支持皮肤细胞生长的实验研究

目的 探讨脱细胞猪角膜基质体外是否支持皮肤细胞的生长.方法 制备脱细胞猪角膜基质(前期实验已完成).体外培养人皮肤表皮细胞和成纤维细胞,取第3代人皮肤成纤维细胞接种在脱细胞猪角膜基质的中间基质面,培养3 d后,将材料翻转,取第3代人皮肤表皮细胞接种在材料的上皮面上,再培养10 d后,取细胞-支架复合体制作石蜡切片,HE染色后光镜下观察.结果 组织学观察显示皮肤的表皮细胞和成纤维细胞体外均可在脱细胞猪角膜基质上黏附生长.接种10 d后,皮肤表皮细胞在材料表面形成复层结构,可见角化的细胞.接种13 d可见成纤维细胞存活并在支架层间生长.结论 脱细胞猪角膜基质有良好的细胞相容性,在体外能支持皮肤细胞的生长和增生.     

组织工程角膜研究和应用进展

中国角膜供体材料的严重缺乏导致众多的角膜盲患者不能通过角膜移植来复明仍是临床棘手的问题。近年来,细胞生物学、组织工程学和材料学的发展为替代人角膜材料开辟了更广阔的前景;而且以深板层移植和内皮移植为代表的成分板层移植的推陈出新从临床技术上有力地推动了组织工程角膜的研发。现就脱细胞角膜基质板层材料、上皮细胞和内皮细胞组织工程的基础研究和临床应用进展进行述评。     

复合自体脂肪干细胞的脱细胞猪角膜基质移植治疗兔角膜碱烧伤

目的:研究复合脂肪干细胞的脱细胞猪角膜基质对碱烧伤角膜的治疗效果。方法:制备晾干的脱细胞猪角膜基质,取第3代体外培养的兔自体脂肪干细胞,体外种植到脱细胞猪角膜基质上,培养3d后用于板层角膜移植。结果:板层角膜移植2mo后,术眼角膜基本恢复透明,未发生排斥反应,新生血管较少,3mo后新生血管基本消退。结论:复合自体脂肪干细胞的脱细胞猪角膜基质对兔碱烧伤角膜具有良好的修复能力。     

组织工程角膜片移植治疗无菌性角膜溃疡的实验研究

目的探讨组织工程角膜片治疗角膜溃疡的可行性及疗效。方法将16只新西兰大白兔制作成角膜溃疡模型,随机分为2组,每组8只,分别作单纯羊膜移植和以羊膜为载体的组织工程角膜片移植。术后进行大体观察、裂隙灯观察、组织学观察、扫描电镜观察。结果羊膜为载体组织工程角膜片移植治疗角膜溃疡,平均7.5周溃疡完全愈合,角膜恢复透明性和屈光性,较单纯羊膜移植组(平均9周)角膜溃疡修复快,效果好结论羊膜为载体构建的组织工程角膜片可以有效治疗角膜溃疡。     

组织工程角膜基质的体外构建及移植的实验研究

目的探讨利用组织工程技术体外构建角膜基质进行板层角膜移植的可行性和有效性。方法将猪角膜基质去细胞处理后制备成组织工程角膜基质载体;取幼兔角膜基质细胞体外培养,将其种植在载体上,体外构建成组织工程角膜基质,用PKH26荧光标记兔角膜基质细胞示踪角膜基质的构建;将16只兔的角膜基质内植入壳聚糖膜使之形成无菌性角膜溃疡,随机从16只兔中选8只,进行组织工程角膜基质移植;另外8只作为对照组,进行新鲜的同种异体兔板层角膜移植。术后对角膜进行裂隙灯、光学显微镜、透射电镜观察。结果体外构建的组织工程角膜的基质细胞具有活性,其结构与正常角膜基质相近。移植治疗无菌性角膜溃疡术后,1~2周有新生血管侵入组织工程角膜基质植片边缘,植片为灰白色半透明状;3~4周随着新生血管减退,组织工程角膜基质植片局部开始透明变薄;术后8~10周角膜溃疡完全修复,角膜恢复透明性,角膜神经可再生;观察最长达10月,角膜仍保持透明,无免疫排斥发生,与对照组疗效相同。结论体外构建的组织工程角膜基质无免疫原性、具有良好的生物相容性,可作为临床治疗角膜溃疡的移植材料。     

Acellular ostrich corneal stroma used as scaffold for construction of tissue-engineered cornea

AIM: To assess acellular ostrich corneal matrix used as a scaffold to reconstruct a damaged cornea. METHODS: A hypertonic saline solution combined with a digestion method was used to decellularize the ostrich cornea. The microstructure of the acellular corneal matrix was observed by transmission electron microscopy (TEM) and hematoxylin and eosin (H&E) staining. The mechanical properties were detected by a rheometer and a tension machine. The acellular corneal matrix was also transplanted into a rabbit cornea and cytokeratin 3 was used to check the immune phenotype. RESULTS: The microstructure and mechanical properties of the ostrich cornea were well preserved after the decellularization process. In vitro, the methyl thiazolyl tetrazolium results revealed that extracts of the acellular ostrich corneas (AOCs) had no inhibitory effects on the proliferation of the corneal epithelial or endothelial cells or on the keratocytes. The rabbit lamellar keratoplasty showed that the transplanted AOCs were transparent and completely incorporated into the host cornea while corneal turbidity and graft dissolution occurred in the acellular porcine cornea (APC) transplantation. The phenotype of the reconstructed cornea was similar to a normal rabbit cornea with a high expression of cytokeratin 3 in the superficial epithelial cell layer. CONCLUSION: We first used AOCs as scaffolds to reconstruct damaged corneas. Compared with porcine corneas, the anatomical structures of ostrich corneas are closer to those of human corneas. In accordance with the principle that structure determines function, a xenograft lamellar keratoplasty also confirmed that the AOC transplantation generated a superior outcome compared to that of the APC graft.     

Differences in amyloid deposition in primary and recurrent corneal lattice dystrophy type 1

PURPOSE: To report the histopathology of a case of recurrent corneal lattice dystrophy showing altered distribution of the corneal deposits in the recurrent disease compared with the original. METHODS: Clinical details and histopathology of the primary and repeat corneal grafts are reported. RESULTS: A woman originally presented at age 28 years with reduced visual acuity and classic corneal lattice lines in both corneas and underwent bilateral corneal grafts. Recurrent disease was detected 20 years later as anterior haze and various-sized subepithelial opacities but no stromal lattice lines. Histology of the original corneas demonstrated amyloid deposits throughout the corneal stroma, typical of corneal lattice dystrophy. In the repeat grafts, amyloid deposits were confined to the basement membrane region of the anterior cornea and were almost entirely absent from the stroma of the cornea. CONCLUSION: Recurrence of corneal lattice dystrophy is widely recognized to occur, but the pathology of the recurrent disease is not well documented in the literature. This case report highlights that there may be a difference in the distribution of the deposits when the disease recurs. We postulate that the reason for this difference may be that donor keratocytes survive long enough in the transplanted cornea to prevent build-up of abnormal keratoepithelin, the product of the mutated gene in type 1 corneal lattice dystrophy. By contrast, the epithelium, being replaced by host epithelium shortly after grafting, is still producing abnormal protein. The differences in the pattern of deposits may have important clinical implications, particularly regarding treatment modalities in recurrent disease.     

Decellularized porcine cornea-derived hydrogels for the regeneration of epithelium and stroma in focal corneal defects

PurposeHydrogels derived from decellularized tissues provide superior biocompatibility, tenability and tissue-specific extracellular matrix (ECM) components. Based on the preparation of decellularized porcine cornea (DPC), here we developed an injectable and transparent hydrogel for the regeneration of epithelium and stroma in focal corneal defects.MethodsThe DPC-derived hydrogel was prepared with N-cyclohexyl-N′-(2-morpholinethyl) carbodiimide metho-p-toluenesulfonate/N-hydroxysuccinimide (CMC/NHS) as cross-linkers. The characteristics of the hydrogel were analyzed and its cytocompatibility was assessed by Live/Dead and Cell Counting Kit (CCK)-8 assays. Immunofluorescence staining, quantitative PCR and Western blot analyses were performed to assess the relative protein and gene expression in corneal fibroblasts on hydrogel. The safety and efficiency of the hydrogel for repairing focal corneal defects in rabbit were measured by slit-lamp, anterior segment optical coherence tomography (AS-OCT), confocal microscopy and histological analyses.ResultsThe DPC-derived hydrogel cross-linked with CMC/NHS assumed favorable transparency, exhibited distinct mechanical properties and preserved the ECM components of native porcine cornea (NPC). In vitro experiments showed that the hydrogel maintained the phenotype, supported the proliferation and promoted the ECM synthesis of corneal fibroblasts. When injected onto rabbit corneas, the hydrogel rapidly covered, solidified and formed a smooth surface on the focal defect. Corneal epithelium was fully regenerated within 3 days. The thickness of the corneal epithelium and stroma was restored at 12 weeks after surgery without significant inflammation or scar formation. Notably, the hydrogel showed no harmful effects on the resident stroma and endothelium.ConclusionsThe DPC-derived hydrogel may represent a promising biomaterial for corneal epithelial and stromal regeneration.     

种植人骨髓间充质干细胞的猪角膜板层移植治疗兔角膜损伤的初步研究

目的研究种植人骨髓间充质干细胞（MSCs）的猪角膜基质治疗兔角膜损伤的可能性。方法用全骨髓贴壁法分离纯化人MSCs并传代,流式细胞仪检测免疫表型及诱导成脂、成骨分化鉴定。12只新西兰白兔随机分为2组,实验组取第3代MSCs接种于去上皮的猪角膜基质上,培养4 d后移植到广泛损伤的兔角膜上,对照组单纯移植去上皮猪角膜基质。术后2、4、8周,取各实验眼行组织学检查,观察移植的MSCs及猪角膜基质的存活、转归及移植局部的反应。免疫组织化学、免疫荧光染色检测移植后角膜上皮细胞角蛋白12的表达。结果培养获得的MSCs中CD29阳性者占95.97%,CD44阳性者占96.49%,CD90阳性者占92.79%,CD105阳性者占94.66%,CD34阳性者占0.59%,CD45阳性者占0.36%,符合MCSs的免疫表型,并可以诱导成脂及成骨分化。实验组MSCs接种到去上皮猪角膜基质后贴附、生长迅速,术后植片在植床上存活良好,无排斥反应,角膜较对照组透明,新生血管少,而对照组在移植后发生排斥反应。实验组角膜免疫组织化学及免疫荧光染色均检测出CK12阳性细胞。结论种植MSCs的猪角膜基质移植到损伤兔角膜后可以存活,MSCs可以分化为角膜上皮样细胞,具有构建组织工程角膜的潜能。     

利用皮肤成纤维细胞重建兔角膜基质组织的初步研究

目的 探讨利用皮肤成纤维细胞替代角膜基质细胞,构建兔角膜基质组织的可行性.方法 实验研究.通过酶消化的方法分离培养同种异体新生兔皮肤成纤维细胞,用腺病毒转染绿色荧光蛋白(GFP)基因标记细胞,接种细胞于聚羟基乙酸(PGA)圆盘支架,形成细胞-PGA复合物,移植于成年兔角膜基质层.动态观察构建组织在角膜内的变化情况,并于第3、6、8周取材进行大体、组织学、GFP表达及角膜基质特异蛋白Keratocan的检测.透射电镜观察胶原纤维排列并测量其直径.应用t检验统计分析数据.结果 术后8周,实验侧角膜逐渐恢复透明,形成的新生角膜基质样组织,排列较规则.荧光显微镜检测显示GFP阳性细胞存在,形成基质板层样组织,同时该部分细胞表达Keratocan.胶原纤维排列规则,实验组胶原纤维直径为(33.08±2.47)nm,经统计学分析,与正常角膜差异无统计学意义(t=1.80,P=0.0771).结论 皮肤成纤维细胞可以替代角膜基质细胞,在兔角膜内构建组织工程角膜基质组织.     

Protective role of corneal epithelium against ultraviolet radiation damage

PURPOSE: It is known that the corneal epithelium strongly absorbs ultraviolet radiation (UVR). The aim of the present study was to examine the protective role of corneal epithelium against UVR damage by comparing the biological effect of UVR exposure on whole corneas with that on de-epithelialized corneas. METHODS: Six New Zealand albino rabbit corneas were exposed to UVR centred around 280 nm at a dose that causes biomicroscopically significant keratitis (012 J/cm(2)). Three corneas underwent manual de-epithelialization prior to UVR exposure. A control group of three rabbits underwent only manual de-epithelialization. The animals were killed 76 hours after treatment. The corneas were stained with haematoxylin and evaluated by light microscopy. RESULTS: Corneas that underwent only the exposure to UVR showed a loss of epithelial cells in the treated area. No damage to keratocytes or the stroma was detected. Corneas that underwent manual de-epithelialization showed a loss of epithelial cells, and also keratocytes in the anterior quarter of the corneal stroma. However, corneas that were exposed to UVR after manual de-epithelialization showed very deep stromal damage. The keratocytes disappeared through the entire thickness of the stroma in the UVR-exposed area. CONCLUSION: Exposure to UVR at 280 nm alone does not result in any deep damage to the corneal stroma and keratocytes. Manual de-epithelialization causes the disappearance of anterior keratocytes. However, the stromal damage caused by UVR in the de-epithelialized corneas was very deep. The corneal epithelium serves to protect the deeper corneal structures against UVR damage, probably by absorbing a substantial amount of the UVR energy applied to the eye.