应用三维培养技术体外重建角膜组织的初步研究

目的 探讨三维培养技术体外重建角膜组织的理论基础及临床应用价值。方法 原代培养人角膜上皮、基质及内皮细胞、通过胶原凝胶三维培养系统,体外重建角膜结构,应用裂隙灯检测人工角膜的透明度,采用常规病理组织学及透射电镜观察细胞在三维培养系统中生长的特性。结果 重建的角膜组织为良好的三层结构;角膜上皮细胞形成复层结构;内皮细胞形成单层结构,且排列规则;角膜基质细胞呈散在分布。电镜观察、细胞在Ⅰ型胶原中存活并合成胶原纤维。结论 利用组织工程技术,能够体外重建结构较规则,透明度较高的角膜组织。     

兔角膜缘干细胞体外壳聚糖共混膜上培养的形态学观察

目的 探讨壳聚糖作为兔角膜缘干细胞体外培养载体的可行性。方法 应用消化培养法在壳聚糖材料上对兔角膜缘细胞进行原代培养，倒置显微镜观察细胞生长情况，并在电子显微镜下观察壳聚糖的结构以及第7d时细胞的形态。结果 壳聚糖呈现三维多孔结构相互连接成网状，孔径直径大小约90μm，其上有细胞生长，7d左右形成单层次，9d后细胞培养开始出现老化现象。结论 壳聚糖上可成功地对兔角膜缘组织进行原代培养，可用作组织工程角膜的载体材料。     

组织工程技术体外重建角膜上皮层的实验研究

目的 利用组织工程技术体外重建角膜上皮组织，为眼表重建提供良好的移植材料及方法。方法 以去除上皮细胞的羊膜基底膜为载体，分别种植兔角膜缘组织块及原代培养扩增的角膜缘上皮细胞，体外培养重建角膜上皮层，并进行形态、组织学、超微结构观察及免疫细胞化学检测。结果 角膜缘上皮细胞在羊膜上粘附生长并增殖，体外培养10天左右即形成3～4层上皮细胞，复合角膜上皮组织由羊膜基底膜和复层上皮细胞组成，细胞表达特异性角蛋白CK3，与生理状态下的角膜上皮组织相近。结论 以羊膜为载体培养角膜缘上皮细胞可体外重建组织工程化角膜上皮组织，作为眼表重建移植材料良好的来源。     

深低温保存的角膜缘组织CD40的表达以及体外培养增生活性的研究

目的探讨深低温保存的角膜缘组织CD40的表达情况以及培养后增生活性的变化。方法取角膜移植术后角膜缘组织20例（20眼）,其中10例新鲜组织直接进行体外培养,另10例经深低温冷冻保存后再进行体外培养,对比观察两组细胞生长情况,并用免疫组化方法检测CD40在二者的表达。结果新鲜角膜缘组织块接种后3d可见细胞贴壁生长,培养至6d时细胞基本形成单层;深低温保存角膜缘组织块接种后在7d可见细胞贴壁生长,培养至10d时细胞基本形成单层。CD40在两组角膜缘上皮基底细胞层均有着色,为棕褐色,在深低温保存角膜缘组织表达明显减弱。结论深低温保存的角膜缘组织具有良好的增生活性,利用深低温保存的角膜缘组织进行角膜缘干细胞移植可以降低移植排斥率。     

角膜缘组织定位培养和冷冻后培养的实验研究

目的验证角膜缘干细胞的组织学定位,探讨低温冷冻保存对其增殖活性的影响。方法取新鲜角膜缘上皮组织和相应部位浅层巩膜组织各10块进行体外细胞培养,对比观察细胞生长情况。取冷冻保存的角膜缘上皮组织14例,观察体外培养后细胞生长情况。通过免疫组化方法检测冷冻保存的角膜缘上皮细胞的增殖活性和培养后单层细胞K3角蛋白的表达。结果10例新鲜角膜缘上皮组织培养后,7例有上皮细胞生长,1周形成细胞单层;10例浅层巩膜组织培养后未见细胞生长。14例冷冻角膜缘上皮组织培养后,4例有上皮细胞生长,9d形成细胞单层。5例冷冻角巩膜环组织冰冻切片中,3例可见角膜缘上皮基底细胞PCNA表达阳性。培养细胞对K3角蛋白特异性的AE-5单克隆抗体免疫反应阳性。结论角膜缘干细胞定位于角膜缘上皮基底部,低温冷冻保存的角膜缘干细胞组织可以保持增殖活性,体外培养后生长分化成为角膜上皮。     

人角膜上皮干细胞生物学特性的研究

目的 建立人角膜上皮干细胞体外培养体系，并探讨体外培养的人角膜干细胞的鉴定方法，从其生物学特性方面，为角膜上皮干细胞移植奠定基础。方法 采用低钙培养法对人角膜缘基底层细胞组织块进行培养。从生长特性、光镜特征、超微结构特点以及免疫细胞化学方面进行鉴别。结果 培养细胞呈多边形典型上皮细胞形态生长。电镜下可见张力丝等典型上皮细胞结构。单克隆抗体4Gl0．3染色，大部分阳性；AE5染色，绝大多数为阴性。结论 用无钙培养基与低钙培养基结合可获得较纯的、未分化的角膜干细胞。其鉴定应综合鉴别。     

模拟微重力条件下兔角膜基质细胞在复合材料上的三维培养

目的 探讨在模拟微重力条件下兔角膜基质细胞在复合材料上的三维生长特性,为构建组织工程角膜提供新的途径.方法 Ⅱ型胶原酶消化法获取原代兔角膜基质细胞,以密度为1×105/mL将第5代细胞种植于无菌复合载体材料上.以模拟微重力条件下培养兔角膜基质细胞为实验组与传统静态培养系统进行细胞培养作对照.分别在6、12、18 d取细胞和载体行苏木精-伊红染色光镜观察和扫描电镜观察;在3、6、9、12、15、18 d取出行CCK-8法检测细胞增生功能.结果 对照组只在材料表面可见单层细胞;实验组大量细胞与载体黏附紧密且生长入载体内部,载体材料降解显著.扫描电镜下实验组可见细胞胞体小且突触丰富,培养第18 d细胞在材料表面分泌大量胶原膜样物;模拟微重力系统促进了细胞增生(P=0.004).结论 模拟微重力环境中在复合材料上培养的兔角膜基质细胞接近生理状态,更适用于组织工程三维构建,为构建更接近生理状态的组织工程角膜提供了依据.     

组织工程化角膜组织的研究新进展

随着细胞培养技术及组织工程技术的发展 ,角膜组织的体外培养和重建有了突破性进展。从种子细胞来源的选择到各种载体的应用 ,重建的三维角膜模型及上皮层在结构及功能上都极近似于人体角膜 ,并应用于基础及临床角膜移植的研究     

人角膜内皮细胞的体外培养及其鉴定的研究进展

角膜内皮细胞对维持角膜的透明性和厚度起着关键性的作用。人体内角膜内皮细胞有限的增殖能力及角膜供体的短缺,使组织工程人角膜内皮的体外重建受到了关注。目前,人角膜内皮细胞的培养方法已基本成熟。但是体外培养的人角膜内皮细胞的功能评价及鉴定标准却尚未建立。本文就人角膜内皮细胞的体外培养及其鉴定的研究进展进行综述。     

组织工程化角膜组织的研究新进展

随着细胞培养技术及组织工程技术的发展。角膜组织的体外培养和重建有了突破性进展。从种子细胞来源的选择到各种载体的应用,重建的三维角膜模型及上皮层在结构及功能上都极近似于人体角膜,并应用于基础及临床角膜移植的研究。     

组织工程技术构建兔角膜基质组织的实验研究

目的 探讨应用组织工程技术构建兔角膜基质层组织的可行性。方法 新西兰大白免40只,即母兔及其亲生子兔共20对。分离获取新生子兔角膜基质细胞,扩增、培养,汇合后,接种于聚羟基乙酸(PGA),形成细胞-生物材料复合物,移植于对应的母兔角膜基质层。绿色荧光蛋白(GFP)标记角膜基质细胞,示踪角膜基质构建过程。同时,对侧角膜仅行PGA移植,作为材料对照组。8周后取材,行组织学切片,Western blot检测Ⅰ型胶原及电镜下测定胶原纤维直径分布。结果术后8周,实验侧角膜逐渐恢复透明,形成新生角膜基质样组织,胶原与角膜表面平行,排列较整齐,组织学结构接近正常基质组织。实验组Western blot检测提示新生组织中基质细胞表达Ⅰ型胶原;电镜下胶原纤维直径[(29.0±4.7)nm]与正常角膜基质组织比较[(28.5±3.5)nm],差异无显著意义(P>0.05)。对照组正常角膜无新生基质组织形成。GFP标记角膜基质细胞,示踪角膜基质第8周时,荧光显微镜下可见新生组织呈绿色,提示GFP表达。结论 应用组织工程技术可以在兔受体角膜内构建角膜基质层组织。(中华眼科杂志,2004,40:517-521)     

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。     

Study on the optical property and biocompatibility of a tissue engineering cornea

AIM: To study the optical property and biocompatibility of a tissue engineering cornea. METHODS: The cross-linker of N-(3-Dimethylaminoropyl)-N’ethylcarbodiimide hydrochloride (EDC)/ N-Hydroxysuccinimide (NHS) was mixed with Type I collagen at 10% (weight/volume). The final solution was molded to the shape of a corneal contact lens. The collagen concentrations of 10%, 12.5%, 15%, 17.5% and 20% artificial corneas were tested by UV/vis-spectroscopy for their transparency compared with normal rat cornea. 10-0 sutures were knotted on the edges of substitute to measure the corneal buttons’s mechanical properties. Normal rat corneal tissue primary culture on the collagen scaffold was observed in 4 weeks. Histopathologic examinations were performed after 4 weeks of in vitro culturing. RESULTS: The collagen scaffold appearance was similar to that of soft contact lens. With the increase of collagen concentration, the transparency of artificial corneal buttons was diminished, but the toughness of the scaffold was enhanced. The scaffold transparency in the 10% concentration collagen group resembled normal rat cornea. To knot and embed the scaffold under the microscope, 20% concentration collagen group was more effective during implantation than lower concentrations of collagen group. In the first 3 weeks, corneal cell proliferation was highly active. The shapes of cells that grew on the substitute had no significant difference when compared with the cells before they were moved to the scaffold. However, on the fortieth day, most cells detached from the scaffold and died. Histopathologic examination of the primary culture scaffold revealed well grown corneal cells tightly attached to the scaffold in the former culturing. CONCLUSION: Collagen scaffold can be molded to the shape of soft contact corneal lens with NHS/EDC. The biological stability and biocompatibility of collagen from animal species may be used as material in preparing to engineer artificial corneal scaffold.     

人脐静脉血管内皮细胞在体移植替代猴角膜内皮细胞的形态学分析

目的　使用去除后弹力层的恒河猴自体角膜为细胞载体,将培养的人脐静脉血管内皮细胞（ｈｕｍａｎｕｍｂｉｌｉｃａｌｖｅｉｎｅｎ-ｄｏｔｈｅｌｉａｌｃｅｌｌｓ,ＨＵＶＥＣ）种植到角膜内表面,观察ＨＵＶＥＣ替代恒河猴角膜内皮细胞的功能情况以及ＨＵＶＥＣ在恒河猴眼内生长的情况。方法　取恒河猴６只随机分为３组:实验组（３只）、实验对照组（２只）、空白对照组（１只）。实验组:用离心沉淀法将培养的ＨＵＶＥＣ移植到去除后弹力层的恒河猴自体角膜内表面,之后将自体角膜缝回植床;实验对照组:将撕除部分后弹力层的术眼角膜植片原位缝回植床;空白对照组:取下术眼角膜植片不做任何处理原位缝回植床。术后观察各组角膜植片透明情况;实验组及实验对照组于术后３０ｄ及６０ｄ、空白对照组于术后６０ｄ行术眼摘除,标本做病理切片、ＣＤ３４免疫组化及扫描电镜,观察房角结构及ＨＵＶＥＣ在角膜植片内表面形态分布。结果　实验组角膜植片维持了一定的厚度和透明性,而实验对照组角膜植片发生严重大泡性改变。病理切片示实验组角膜内表面可见一层细胞生长,ＣＤ３４染色阳性,提示为血管内皮细胞;实验对照组角膜内表面未见任何细胞生长;空白对照组角膜植片保留完整后弹力层及内皮细胞层。扫描电镜示实验组有ＨＵＶＥＣ单层在角膜内表面生长但有大量白细胞聚集及少量细胞碎片嵌顿于小梁网;实验对照组角膜内表面残留胶原纤维样物质,无细胞生长;空白对照组见完整六边形角膜内皮细胞层。结论　ＨＵＶＥＣ能够在撕除后弹力层的恒河猴角膜内表面生长并发挥一定的屏障作用,维持角膜的厚度和透明性,但会产生较重的排斥反应。     

以干燥脱水法保存的异种角膜基质为载体构建人工生物角膜上皮组织

目的:观察以干燥脱水法保存的鸵鸟角膜基质为载体构建人工生物角膜上皮组织的生物学特性。方法:采用组织块培养法获得新西兰大白兔角膜缘干细胞,经胰蛋白酶消化法获得细胞,种植于干燥脱水法保存的鸵鸟角膜板层基质上,采用气液界面培养法进行培养,通过倒置显微镜、透射电子显微镜、荧光显微镜观察其形态学、生长特点,超微结构及免疫学特征。结果:在干燥脱水法保存的鸵鸟角膜基质上种植兔角膜缘干细胞,接种72h后,细胞形成单层,移置气液交界面后继续培养7～10d,逐渐形成复层。经光镜、透射电镜、及免疫学检测显示其具有角膜上皮组织的生物学特性。结论:兔角膜缘干细胞能够在干燥脱水法保存的鸵鸟角膜基质载体上生长,并可形成复层,基本具有正常角膜上皮细胞的形态、超微结构和生物学特性。     

Sodium activity in the aqueous humor and corneal stroma of the rabbit.

The present study examined the free sodium concentration of the aqueous humor and corneal stroma of both transparent and non-transparent corneas to assess the transendothelial activity gradient for sodium. In the transparent cornea of the adult rabbit, the sodium activity was higher in the aqueous humor than the stroma. This difference in sodium activity would cause water to diffuse down its concentration gradient from stroma to aqueous humor. In this way corneal transparency and the deturgesced state are maintained. Removal of the corneal endothelium in the adult rabbit produced an opaque swollen cornea. Under these conditions the sodium activity was higher in the stroma than the aqueous humor. However, an osmotic gradient was not produced by the Na+ activity gradient because the endothelium was not present to act as a semi-permeable membrane. The corneal endothelium was no longer present to establish and sustain the activity gradient for sodium that is necessary for corneal transparency in the mature rabbit. The transendothelial sodium activity gradient was also measured in 13-day-old rabbits. At this age, the cornea was not yet transparent, nevertheless the free sodium concentration of the aqueous humor was higher than that of the stroma, similar to the adult transparent cornea. This suggests that forces other than the establishment of the proper transendothelial sodium gradient are responsible for the lack of corneal transparency in the young rabbit.     

羟乙基淀粉130/0.4对器官培养法保存兔角膜的脱水作用

目的：研究羟乙基淀粉的最新剂型HES 130/0.4对器官培养保存角膜的持续脱水效果。

方法：20对配对兔角膜,一半于含10% HES 130/0.4的ACF培养液中保存28d作为实验组,不再单独脱水; 另一半于ACF培养液中保存28d后再葡聚糖T500脱水48h作为对照组。内皮细胞活性和植片质量评估指标包括：内皮细胞计数、角膜厚度和含水量、角膜透明度和后弹力层皱褶程度、内皮层中肌动蛋白微丝(filament actin,F-actin)的表达,及透射电镜下内皮细胞超微结构的变化。

结果：保存结束时,实验组植片明显较薄,角膜透明度和皱褶程度也优于对照组,内皮细胞密度为2371±159个/mm²。对照组继续脱水后,角膜厚度、含水量和透明度与实验组间差别变小,内皮细胞密度却降至2138±182个/mm²。免疫印迹法证实F-actin在两组内皮层都有表达,实验组的F-actin表达水平更高。电镜下实验组的细胞超微结构改变较小。

结论：HES 130/0.4的细胞毒性小,可成为器官保存液中的持续添加组分,不仅避免角膜过度水肿,还简化了保存程序,减轻了感染风险,有希望成为新型角膜脱水剂。     

Transplantation of corneal endothelial cells

Though conventional corneal transplantation has achieved great success, it still has several drawbacks including limited availability of donor corneas, recurrent allograft rejection, and subsequent graft failure in certain cases. Reconstructing clinically usable corneas by applying the technology of regenerative medicine can offer a solution to these problems, as well as making corneal transplantation a non-emergency surgery and enabling the usage of banked corneal cells. In the present study, we focused on corneal endothelium that is critical for corneal transparency and investigated the reconstruction of cornea utilizing cultured human corneal endothelial cells (HCECs). We succeeded in steadily culturing HCECs by using culture dishes pre-coated with extracellular matrix produced by calf corneal endothelial cells and culture media that contained basic fibroblast growth factor and fetal bovine serum. We performed the following analysis utilizing these cultured HCECs. The older the donor was, the more frequently large senescent cells appeared in the passaged HCECs. The telomeres of HCECs were measured as terminal restriction fragments (TRF) by Southern blotting. HCECs, in vivo from donors in their seventies had a long TRFs of over 12 kilobases. Passaging shortened the TRFs but there was no difference in TRFs among donors of various ages. These results indicated that shortening of telomere length is not related to senescence of HCECs. We investigated the role of advanced glycation end products (AGEs) in the senescence of in vivo HCECs. The results indicated that AGE-protein in the aqueous humor is endocytosed into HCECs via AGE receptors expressed on the surface of HCECs and damages HCECs by producing reactive oxygen species and inducing apoptosis, suggesting that AGEs, at least partly, cause the senescence of HECEs. HCECs were cultured using adult human serum instead of bovine serum to get rid of bovine material that can be infected with prions. Primary and passage culture of HCECs was possible using adult human serum. We reconstructed the cornea using cultured HCECs and human corneal stroma. The corneal stroma, on which the cell suspension of HCECs was poured, was mildly centrifuged to enhance the HCECs attachment to the stroma. The cell density of HCECs on the reconstructed cornea reached 2,500 cells/mm2. The pump function of the reconstructed cornea was measured with an Ussing chamber. The potential difference in the reconstructed cornea and normal cornea was 0.30 mV and 0.40 mV, respectively; indicating that the pump function of the reconstructed cornea is 75% of that of the normal cornea. The reconstructed cornea was transplanted to a rabbit eye and stayed transparent for 6 months after the operation. Fluorescein labeled cultured HCECs remained on the graft 1 month after the transplantation, indicating that transplanted HCECs contributed to the transparency of the graft. The possibility of using artificial stroma or porcine corneal stroma as a carrier of cultured HCECs was investigated. The artificial stroma made of alkaline-treated collagen could not be sutured but showed good transparency, biocompatibility, and cell-attachability. Porcine corneal stroma, expressing little xeno-sugar antigen alpha-gal epitope, induced no super acute rejection but mild cellular rejection when transplanted in the cornea of animals possessing natural antibody to alpha-gal epitope. The cornea reconstructed with porcine corneal stroma and HCECs had an average cell density of 1721/mm2 and had approximately 60% of the pump function of a normal cornea. As new technologies in corneal transplantation, the application of self immature cells and the direct delivery of cultured HCECs into the anterior chamber were investigated. Part of rat mononuclear cells that were obtained from the bone marrow and injected into the rat anterior chamber transformed into corneal endothelium-like cells, suggesting that self immature cells can transform into corneal endothelial cells. Cultured rabbit corneal endothelial cells that endocytosed iron were injected into the anterior chamber of rabbits whose corneal endothelium was cryo-injured, and were pulled to Descemet's membrane by putting a magnet on the eyelid. In these rabbits, corneal edema decreased more quickly than in the control group and no intraocular pressure rise was observed during 8 weeks after the operation, suggesting that the direct delivery of cultured HCECs into the anterior chamber can be an alternative method of choice. The following obstacles should be addressed to make the transplantation of cultured corneal endothelial cells clinically applicable. 1. To reconstruct a cornea that is the same as or superior to the normal cornea, more innovation is necessary in the method of culturing and seeding HCECs. We should consider utilizing HCECs obtained from fetuses after clearing ethical issues. Moreover, we need to develop a method to enhance the cell density and the cell functions. 2. Porcine corneal stroma is promising as a carrier of HCECs instead of human corneal stroma, which is in very limited supply. The usefulness of porcine corneal stroma acellularized to prevent retrovirus infection should be evaluated. 3. To make the self immature cells applicable to corneal transplantation, we should elucidate the corneal endothelial cell specific markers and the factors that are necessary to induce self immature cells to become corneal endothelial cells. 4. The direct delivery of cultured HCECs into the anterior chamber can be an alternative method of choice when its long-term safety is confirmed.     

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。