不同移植手术治疗角膜缘干细胞缺损的实验研究

目的探讨以人羊膜为载体培养的角膜缘干细胞，自体及异体移植治疗全角膜缘干细胞缺损。方法制作兔眼角膜缘干细胞完全缺损3个月的模型。实验动物随机分为自体移植组和异体移植组，前者取对侧眼角膜缘组织，后者取异体兔眼角膜缘组织，均以去除上皮细胞的羊膜基底膜为载体，培养12d后行角膜缘干细胞羊膜移植术。术后观察3个月，以角膜上皮染色、角膜浑浊和新生血管3项指标进行临床疗效评定，通过病理检查评估术后角膜上皮修复情况，印迹细胞学检查移植前后角膜上皮的细胞表型。结果体外培养的兔角膜缘干细胞可在羊膜上粘附生长并增生，体外培养12d可形成复层。自体移植组和部分异体移植组术后角膜上皮逐渐愈合，透明度提高，基质细胞浸润减轻，新生血管减退或消失。印迹细胞学检查显示：移植前角膜上皮细胞PAS阳性，而移植后转为阴性；组织病理学显示：移植前角膜上皮大部分缺损，移植后呈现角膜上皮结构。部分异体移植组术后出现了免疫排斥反应。结论兔自体角膜缘干细胞羊膜移植术可重建眼表；免疫排斥反应仍是异体角膜缘干细胞羊膜移植术失败的主要原因。     

兔同种异体角膜缘移植角膜印迹细胞学检测

目的 研究兔角膜缘干细胞缺乏和同种异体角膜缘移植后临床和角膜上皮表型的改变。方法 建立兔角膜缘干细胞缺乏模型,1个月后对治疗组进行同种异体角膜缘移植,术后联合使用免疫抑制剂。比较治疗组与非治疗组的临床表现和角膜表型的改变。结果 兔角膜缘干细胞缺乏后,角膜混浊,新生血管化,持续性上皮缺损;角膜上皮为结膜细胞表型。移植术后角膜上皮完整,新生血管减少,角膜透明度增加;上皮恢复角膜表型。结论 兔同种异体角膜缘移植联合术后使用免疫抑制剂是治疗角膜缘干细胞缺乏症的有效方法。印迹细胞学检查是角膜缘干细胞缺乏症诊断和角膜缘移植术后的评价手段。     

大鼠角膜缘上皮细胞培养与同体移植的实验研究

目的：观察以明胶为载体培养的角膜缘上皮细胞移植治疗角膜缘干细胞缺乏症的疗效。 方法：大鼠角膜缘上皮细胞在铺有明胶载体的细胞培养板上进行培养5d后,角膜上皮细胞移植术前24h用3H胸腺嘧啶核苷标记培养的角膜缘上皮细胞,培养标记的角膜缘上皮细胞对角膜缘干细胞缺乏的大鼠动物模型行角膜缘上皮细胞同体移植术,对移植术后角膜进行观察、病理学检查及同位素检测。 结果：大鼠角膜缘上皮细胞可以在明胶载体上培养、增殖、分化为密集角膜上皮细胞层;角膜缘上皮细胞移植术后角膜上皮完整、基质细胞浸润减轻、新生血管减少。病理学检查角膜缘及周边部上皮细胞为多层结构,角膜新生血管消失及基质中炎性细胞浸润减轻。角膜缘上皮细胞移植术后4wk受眼角膜仍可测到3H胸腺嘧啶核苷。 结论：角膜缘上皮细胞移植治疗角膜缘干细胞缺乏症可恢复角膜缘干细胞缺乏病变角膜上皮结构的完整性,减少角膜新生血管的形成,维持角膜缘干细胞的屏障功能,为角膜移值提供更好的条件。     

组织工程口腔黏膜上皮治疗角膜缘干细胞缺陷症的实验研究

目的探讨体外培养的自体组织工程口腔黏膜上皮重建兔角膜上皮的可行性。方法制作兔角膜缘干细胞缺陷模型32只,实验组Ⅰ～Ⅲ以自体口腔黏膜上皮细胞为种子细胞制作组织工程上皮,移植到实验组模型兔角膜表面,分别观察2周、1个月、3个月,对照组移植空白载体膜,观察3个月。术后裂隙灯显微镜下观察,以角膜新生血管、混浊度及上皮染色评分评价移植效果。用组织病理、免疫组织化学和印迹细胞技术评价角膜上皮重建的可能性。结果模型兔角膜混浊,有大量新生血管和杯状细胞。实验组移植后角膜透明,印迹细胞检查PAS(-)。实验组与对照组术后角膜总评分差异有统计学意义(P=0.000),p63表达阳性,角膜上皮的组织特点及角蛋白的表达与正常角膜上皮相似。结论组织工程口腔黏膜上皮在角膜基质微环境的诱导下可分化为角膜样上皮细胞,有重建角膜上皮的作用。     

自体角膜缘干细胞移植治疗角膜缘功能衰竭症

目的　探讨自体角膜缘干细胞移植在角膜缘功能衰竭症治疗中的作用。方法　将 83例 90眼初发性翼状胬肉、外伤性角膜缘板层缺损及角膜缘碱烧伤患者随机分为A、B组。A组为自体角膜缘干细胞移植组 (干细胞治疗组 ) 4 2例 4 5眼 ,其中 30眼翼状胬肉行翼状胬肉切除联合自体角膜缘干细胞移植术 ,外伤性角膜板层损伤 10眼、角膜缘碱烧伤 5眼行自体角膜缘干细胞移植术 ;B组为传统单纯翼状胬肉切除 ,外伤性角膜缘板层损伤、碱烧伤行结膜瓣移植术 (对照组 ) ,4 1例 4 5眼 ,其中翼状胬肉 30眼行单纯翼状胬肉切除 ,外伤性角膜缘板层缺损 11眼、碱烧伤 4眼行结膜瓣移植术 ,术后观察角膜上皮修复时间、角膜缘新生血管、角膜透明度、泪膜破裂恢复时间以及胬肉复发率 ,术后随诊 6～ 2 4月。结果　A组术后角膜上皮修复时间 2～ 4d、BUT(6 .7± 0 .8)d ,无角膜缘新生血管生长 ,术后翼状胬肉复发率为 0 ,角膜透明 ;B组术后角膜上皮修复时间 5～ 7d ,BUT(7.9± 0 .5 )d ,角膜缘有 3～ 8支新血管生长 ,角膜有不同程度的云翳 ,翼状胬肉复发率 13.33% ,A、B 2组各项指标比较有统计学差异。结论　自体角膜缘干细胞移植治疗角膜缘功能衰竭症是一种简单、安全、有效的手术方法。     

组织工程上皮移植对碱烧伤角膜新生血管的影响

目的：评价组织工程上皮移植在碱烧伤角膜缘干细胞缺乏症中对角膜新生血管的抑制作用。

方法：回顾性非随机的病例研究。2006/2011年我院收治的19例(23眼)完全性角膜缘干细胞缺乏症的碱烧伤患者, 10例13眼行组织工程上皮移植,9例10眼行羊膜移植。所有患者在手术前后均用裂隙灯观察角膜新生血管情况,在术后第21,60d对角膜新生血管进行评分比较。

结果：术后第21d和术后第60d组织工程上皮移植组和羊膜移植组角膜新生血管均较术前明显减少( P<0.05),在术后两个评价时间点,组织工程上皮移植组平均角膜新生血管分数明显低于羊膜移植组。

结论：对碱烧伤所致角膜缘干细胞缺乏的患者,组织工程上皮移植抑制角膜新生血管的作用明显好于羊膜移植。     

角膜缘干细胞缺乏对角膜上皮损伤修复的影响

目的探讨角膜缘干细胞的功能。方法采用生物医学图像分析系统,计算切除角膜缘上皮组织的兔眼的角膜上皮愈合速率;用光学显微镜观察角膜上皮损伤修复过程的组织学变化。结果在角膜上皮损伤８～３２小时内,实验组与对照组角膜上皮愈合速率分别为１．２２±０．１９ｍｍ２／ｈ和１．４５±０．２０ｍｍ２／ｈ（ｔ＝３．８９,Ｐ＜０．０１）,实验组角膜上皮损伤愈合速度明显比对照组慢。实验组角膜可见大量的杯状细胞和新生血管,并随时间而逐渐向中央区发展。结论实验结果进一步证实了角膜上皮干细胞存在于角膜缘,角膜缘干细胞缺失,可使角膜上皮增殖能力丧失,角膜缘屏障功能下降,导致持续性角膜上皮糜烂、结膜组织长入和新生血管形成。     

角膜缘干细胞移植的进展

角膜上皮的完整和无血管状态对维持角膜生理功能和透明性至关重要。各种致病因素造成反复上皮缺损、糜烂、溃疡、新生血管长入,导致假性胬肉形成。角膜上皮病变正成为角膜病主要致盲因素,其根本原因仍是角膜缘干细胞功能缺陷或数量不足。解决问题的根本方法是采用角膜缘含干细胞组织移植术重建角膜上皮。本文就近年来角膜缘移植方面的最新进展做一综述。1　自体角膜缘干细胞移植为了修复由于化学伤、热烧伤等引起的持续性角膜上皮缺损,Thoft[1]于1977年设计了自体结膜移植术,并取得一定疗效。然而角膜上皮细胞和结膜上皮细胞毕竟是2种不同…     

兔眼角膜缘干细胞在角膜上皮损伤愈合中作用的实验研究

利用显微手术切除＋０．２５Ｎ氢氧化钠溶液碱烧伤的方法制备动物实验模型。观察兔眼角膜缘干细胞在角膜上皮损伤愈合中的作用。结果显示：全周角膜缘上皮切除合并角膜上皮缺损组，角膜上皮愈合时间长（２５．８天）。愈合后含有大量新生血管和杯状细胞，呈现结膜上皮表型。半周角膜缘上皮切除合并角膜上皮缺损组，上皮愈合时间缩短（６．３天），含有少量新生血管和杯状细胞。保留角膜缘上皮单纯角膜上皮缺损组，上皮愈合时间最短（３天），无新生血管及杯状细胞，呈角膜上皮表型。结果表明：角膜缘上皮干细胞在角膜上皮损伤愈合中起着极重要的作用，是损伤后角膜上皮再生的源泉。     

制作角膜缘干细胞完全缺乏动物模型的新方法

目的提出一种新的角膜缘干细胞完全缺乏模型制作方法,为干细胞缺乏疾病的治疗性研究提供可靠的模型。方法利用9mm环钻划界,板层切除角膜组织,通过临床评分、印迹细胞学、组织病理及免疫组织化学验证模型的成功。结果板层切除术后30~45d,模型眼角膜混浊、上皮缺损、大量新生血管长入,印迹细胞学可见PAS( )的杯状细胞,组织病理学检查上皮符合结膜细胞表型,免疫荧光染色可见结膜杯状细胞特异性标志MUC5AC阳性表达。结论环钻划界加板层切除法为一种可靠、有效的角膜缘干细胞完全缺乏模型制作方法。     

Phenotypic study of a case receiving a keratolimbal allograft and amniotic membrane for total limbal stem cell deficiency

PURPOSE: To report the expression pattern of key molecules by the reconstructed corneal epithelium after a keratolimbal allograft (KLAL) and amniotic membrane transplantation (AMT) for total limbal stem cell deficiency. DESIGN: Interventional case report. METHOD: A 50-year-old woman with severe chemical burns in both eyes received an AMT as a temporary patch at the acute stage, and a KLAL with AMT as a graft at the chronic stage for total limbal stem cell deficiency. The corneal button removed during subsequent corneal transplantation was submitted for immunofluorescence staining with monoclonal antibodies against keratin K3, MUC5AC, connexin 43, integrins alpha3beta1 and alpha6beta4, and laminin 5 for comparison with a normal cornea. RESULTS: Histologically, a normal stratified corneal epithelium has five to six cell layers that lay on the thick amniotic membrane basement membrane. The phenotype was of a corneal origin, based on expression of positive keratin K3, negative MUC5AC, and positive connexin 43. Furthermore, intact basement membrane complexes were present, evidenced by positive staining to integrins alpha3beta1 and alpha6beta4 and to laminin 5. CONCLUSIONS: A normal corneal epithelial phenotype with normal basement membrane complexes was restored after a KLAL and AMT in a case with total limbal stem cell deficiency.     

Use of stem cells cultured ex vivo for ocular surface reconstruction

Lesions on the ocular surface can destroy the stem cells from the limbus and cause limbal stem cell deficiency. The limbal stem cell deficiency is marked by conjunctivalization, which can be defined as the invasion of conjunctival epithelium over the cornea. This process is accompanied by varying degrees of corneal changes such as neovascularization, inflammation, recurrent erosions, persistent epithelial defects, destruction of basement membrane of epithelium and stromal healing. Often, these changes are associated with poor visual acuity, photophobia and ocular discomfort. The best treatment for this disease is not known and varies in unilateral or bilateral cases. Among the treatments available, transplantation of limbal autograft or allograft is one of the most used. To improve the outcome of allotransplantation, some researchers use the transplantation of corneal epithelium cultured in the laboratory by ex vivo expansion of limbal stem cells, but due to limited availability of autologous tissue from the limbus and the risk of complications associated with immunosuppression in allogeneic tissue transplantation, researches of others options of stem cell cultured ex vivo have been described in experimental and clinical stage. This review describes the new types of stem cells cultured ex vivo, their current results and future potential.     

羊膜移植及丝裂霉素对碱烧伤大鼠角膜缘基质微环境的影响

目的观察羊膜移植及丝裂霉素C（MMC）对碱烧伤大鼠角膜缘基质微环境的影响。方法采用SD大鼠角膜缘碱烧伤模型。将大鼠随机分为5个组：A组为正常组,B组为羊膜移植组,C组为羊膜移植联合MMC组,D组、E组为未干预组（D组为碱烧伤1周组,E组为碱烧伤2周组）。通过苏木精-伊红染色观察病理学改变,免疫组织化学技术观察髓过氧化物酶（MPO）、肝细胞生长因子（HGF）免疫染色阳性细胞数的变化。结果干预组（B组、C组）较未干预组（D组、E组）角膜上皮完整、基质细胞浸润减轻、新生血管减少,组织病理学染色证实角膜缘及其周边上皮细胞为多层结构,角膜新生血管减少及基质中炎性细胞浸润减轻。免疫组织化学结果显示MPO及HGF含量明显减少,B组、C组之间MPO含量差别不明显,C组中的HGF含量明显减少,上皮细胞层数轻微减少。结论羊膜移植和羊膜移植联合MMC可以改善角膜缘碱烧伤大鼠模型中的角膜缘基质微环境,MMC可能通过抑制成纤维细胞分泌HGF而影响上皮细胞的增生和移行。     

Limbal stem cells of the corneal epithelium

Stem cells have certain unique characteristics, which include longevity, high capacity of self-renewal with a long cell cycle time and a short S-phase duration, increased potential for error-free proliferation, and poor differentiation. The ocular surface is made up of two distinct types of epithelial cells, constituting the conjunctival and the corneal epithelia. Although anatomically continuous with each other at the corneoscleral limbus, the two cell phenotypes represent quite distinct subpopulations. Stem cells for the cornea reside at the corneoscleral limbus. The limbal palisades of Vogt and the interpalisade rete ridges are believed to be repositories of stem cells. The microenvironment of the limbus is considered to be important in maintaining the stemness of stem cells. Limbal stem cells also act as a "barrier" to conjunctival epithelial cells and normally prevent them from migrating on to the corneal surface. Under certain conditions, however, the limbal stem cells may be partially or totally depleted, resulting in varying degrees of stem cell deficiency with resulting abnormalities in the corneal surface. Such deficiency of limbal stem cells leads to "conjunctivalization" of the cornea with vascularization, appearance of goblet cells, and an irregular and unstable epithelium. This results in ocular discomfort and reduced vision. Partial stem cell deficiency can be managed by removing the abnormal epithelium and allowing the denuded cornea, especially the visual axis, to resurface with cells derived from the remaining intact limbal epithelium. In total stem cell deficiency, autologous limbus from the opposite normal eye or homologous limbus from living related or cadaveric donors can be transplanted on to the affected eye. With the latter option, systemic immunosuppression is required. Amniotic membrane transplantation is a useful adjunct to the above procedures in some instances.     

Corneal epithelial stem cells at the limbus: looking at some old problems from a new angle

Corneal epithelium is traditionally thought to be a self-sufficient, self-renewing tissue implying that its stem cells are located in its basal cell layer. Recent studies indicate however that corneal epithelial stem cells reside in the basal layer of peripheral cornea in the limbal zone, and that corneal and conjunctival epithelia represent distinct cell lineages. These ideas are supported by the unique limbal/corneal expression pattern of the K3 keratin marker for corneal-type differentiation; the restriction of the slow-cycling (label-retaining) cells in the limbus; the distinct keratin expression patterns of corneal and conjunctival epithelial cells even when they are provided with identical in vivo and in vitro growth environments; and the limbal cells' superior ability as compared with central corneal epithelial cells in undergoing in vitro proliferation and in reconstituting in vivo an intact corneal epithelium. The realization that corneal epithelial stem cells reside in the limbal zone provides explanations for several paradoxical properties of corneal epithelium including its 'mature-looking' basal cells, the preponderance of tumor formation in the limbal zone, and the centripetal cellular migration. The limbal stem cell concept has led to a better understanding of the strategies of corneal epithelial repair, to a new classification of various anterior surface epithelial diseases, to the use of limbal stem cells for the reconstruction of corneal epithelium damaged or lost as a consequence of trauma or disease ('limbal stem cell transplantation'), and to the rejection of the traditional notion of 'conjunctival transdifferentiation'. The fact that corneal epithelial stem cells reside outside of the cornea proper suggests that studying corneal epithelium per se without taking into account its limbal zone will yield partial pictures. Future studies need to address the signals that constitute the limbal stem cell niche, the mechanism by which amniotic membrane facilitates limbal stem cell transplantation and ex vivo expansion, and the lineage flexibility of limbal stem cells.     

新鲜羊膜移植对碱烧伤大鼠角膜缘干细胞增殖效应的影响

目的：观察新鲜羊膜移植对碱烧伤大鼠模型角膜缘干细胞增殖细胞核抗原(proliferating cell nuclear antigen,PCNA)表达的影响。

方法：SD大鼠40只40眼制作眼碱烧伤模型; 随机选取20只20眼行新鲜羊膜移植为实验组,对照组为不处理的烧伤模型眼。于术后1,2,3,4wk取角膜缘组织,采用免疫组化技术观察PCNA在角膜缘干细胞的表达情况。

结果：PCNA在实验组和对照组的角膜缘干细胞中均有表达,位于角膜缘上皮细胞基底层的细胞核内,但羊膜移植组显著高于对照组,两者比较有统计学意义(P<0.05); 羊膜移植术后1,2,3,4wk时PCNA蛋白在角膜缘干细胞的表达不一致,呈线性趋势,1wk达到高峰,以后逐渐降低。

结论：眼碱烧伤后行羊膜移植术可促进角膜缘干细胞的增殖表达,利于角膜上皮的修复。     

羊膜培养兔角膜缘上皮细胞及自体移植--角膜缘干细胞缺损的治疗

目的　探讨以人羊膜为载体培养兔角膜缘上皮细胞及其自体移植治疗全角膜缘干细胞缺损。方法　在8只兔右眼用正庚醇脱上皮和角膜缘环切的方法构建全角膜缘干细胞缺损模型2月。其中6只兔为实验组,活体取左眼角膜缘浅层小块,置羊膜上常规和气_液培养42天后进行自体移植治疗右眼角膜缘干细胞缺损;2只兔为对照组,直接用解冻无细胞人羊膜移植治疗右眼角膜缘干细胞缺损。进行细胞和术眼活体观察、组织学观察和电镜观察。结果　角膜缘上皮细胞在羊膜上生长良好,形成复层,细胞间的联结结构存在,细胞与羊膜组织粘附牢固。实验组移植手术后角膜迅速上皮化,恢复角膜表面光滑和透明,组织学观察和电镜观察呈现生理角膜上皮层的结构特点。但眼睑闭合不全可导致手术失败。对照组术后出现角膜缘干细胞缺损导致的角膜病变。结论　以羊膜为载体培养角膜缘上皮细胞后自体移植可有效地治疗角膜缘干细胞缺损导致的角膜病变。     

Long-term survival of allogeneic donor cell-derived corneal epithelium in limbal deficient rabbits

PURPOSE: To investigate the capability of cultivated allogeneic epithelial stem cells to restore a functional ocular surface in a limbal deficient cornea; to verify the long term survival of epithelial allograft; and to examine the host immune response to heterologous cell transplant in a rabbit model. METHODS: Limbal deficiency was established by performing limbectomy on rabbits (n = 100). Corneal epithelial stem cells were obtained from the limbus and replicated in vitro without a supporting layer. The cell (3 x 10(5)) suspension was then transplanted via topical application as eye drops. Animals were divided into allograft, autograft, and control groups. Females were used as recipients and males as donors for the allograft. Corneas were collected at 7, 14, 21, 40 days as well as 2, 3, 7 and 8 months after cell transplantation. Experimental corneas were evaluated by histology, immunofluorescence, immunohistochemistry and Y chromosome analysis. RESULTS: A well-differentiated corneal epithelium was recognized at 14 to 40 days after cell transfer overlying an infiltrated corneal stroma. Corneal re-epitheliazation was confirmed in 31 of 36 allograft corneas. No significant immune rejection was noted. Stromal abnormality caused by previous limbal deficiency was mostly resolved three months after the regeneration of corneal epithelium. CONCLUSIONS: Transplanted corneal epithelial stem cells were able to differentiate into normal corneal epithelium in vivo without the use of membrane scaffolding. This non-autologous donor cell-derived corneal epithelium survived up to 8 months without immunosuppression and was able to reverse the stromal scarring. Thus, cultivated epithelial stem cells have great potential as an alternative to multiple-surgical procedures in the treatment of limbal deficiency states.     

大鼠角膜碱烧伤模型制备方法的研究

目的:探索相对稳定性强、一致性好的大鼠角膜碱烧伤动物模型。方法:将87只SD大鼠分为角膜缘碱烧伤20s组(A组,34只),角膜缘碱烧伤40s组(B组,23只),角膜中央碱烧伤40s组(C组,30只),用浸润1mol/L氢氧化钠的滤纸片,分别烧灼大鼠角膜缘和角膜中央,术后7d裂隙灯显微镜观察角膜透明度、角膜溃疡及角膜新生血管情况,并记录上述指标。结果:角膜缘碱烧伤(B组)较角膜中央烧伤(C组)溃疡发生率、角膜穿孔率和角膜上皮荧光素钠染色阳性率高,且有统计学差异(P<0.05);角膜缘烧灼时间长组(B组)溃疡发生率及角膜穿孔率高于角膜缘烧灼时间短组(A组),且有统计学差异(P<0.05);烧灼角膜缘和角膜中央(A,B,C组)均能诱导出角膜新生血管。结论:对于研究角膜新生血管的动物模型,以选择3mm圆形滤纸片角膜中央烧伤为佳;对于研究角膜缘干细胞缺乏所致角膜病变的实验,以选择环形滤纸片放置于角膜缘20s为佳。     

培养角膜缘干细胞羊膜移植治疗碱烧伤动物的实验研究

目的 观察培养生长于羊膜的角膜缘干细胞移植的治疗角膜缘碱烧伤伤的效果。方法 将兔角膜缘干细胞在的代培养后接种于羊膜,对新西兰大白兔角膜缘碱烧伤动物模型行角膜缘干细胞羊膜移植术,并对治疗后的角膜进行临床及病理学检查。结果 体外培养的兔角膜缘士细胞可在羊膜上继续增殖、分化为密集的角膜上皮细胞层;角膜缘干细胞移植术后兔角膜缘轻度充血、角膜上皮完整基质细胞浸润减轻、新生血管减少。组织病理学染色证实,角膜缘