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。     

Transplantation of tissue-engineered human corneal epithelium in limbal stem cell deficiency rabbit models

AIM: To evaluate the biological functions of tissue-engineered human corneal epithelium (TE-HCEP) by corneal transplantation in limbal stem cell deficiency (LSCD) rabbit models. METHODS: TE-HCEPs were reconstructed with DiI-labeled untransfected HCEP cells and denuded amniotic membrane (dAM) in air-liquid interface culture, and their morphology and structure were characterized by hematoxylin-eosin (HE) staining of paraffin-sections, immunohistochemistry and electron microscopy. LSCD models were established by mechanical and alcohol treatment of the left eyes of New Zealand white rabbits, and their eyes were transplanted with TE-HCEPs with dAM surface outside by lamellar keratoplasty (LKP). Corneal transparency, neovascularization, thickness, and epithelial integrality of both traumatic and post transplantation eyes were checked once a week by slit-lamp corneal microscopy, a corneal pachymeter, and periodic acid-Schiff (PAS) staining. At day 120 post surgery, the rabbits in each group were sacrificed and their corneas were examined by DiI label observation, HE staining, immunohistochemistry and electron microscopy. RESULTS: After cultured for 5 days on dAM, HCEP cells, maintaining keratin 3 expression, reconstructed a 6-7 layer TE-HCEP with normal morphology and structure. The traumatic rabbit corneas, entirely opaque, conjunctivalized and with invaded blood vessels, were used as LSCD models for TE-HCEP transplantation. After transplantation, obvious edema was not found in TE-HCEP-transplanted corneas which became more and more transparent, the invaded blood vessels reduced gradually throughout the monitoring period. The corneas decreased to normal thickness on day 25, while those of dAM eyes were over 575μm in thickness during the monitoring period. A 4-5 layer of epithelium consisting of TE-HCEP originated cells attached tightly to the anterior surface of stroma was reconstructed 120 days after TE-HCEP transplantation, which was similar to the normal control eye in morphology and structure. In contrast, intense corneal edema, turbid, invaded blood vessels were found in dAM eyes, and no multilayer epithelium was found but only a few scattered conjunctiva-like cells appeared. CONCLUSION: The TE-HCEP, with similar morphology and structure to those of innate HCEP, could reconstruct a multilayer corneal epithelium with normal functions in restoring corneal transparency and thickness of LSCD rabbits after transplantation. It may be a promising HCEP equivalent for clinical therapy of corneal epithelial disorders.     

Conjunctival MUC5AC+ goblet cell index: relationship with corneal nerves and dry eye

Graefe's Archive for Clinical and Experimental Ophthalmology - To evaluate the relative proportion of conjunctival MUC5AC+ and MUC5AC− goblet cells in a post-LASIK population and their...     

角膜缘干细胞的研究

角膜缘干细胞是位于角膜缘基底上皮层底的一类特殊类型的上皮细胞,随着细胞培养技术的发展,角膜缘干细胞体外培养后移植用于治疗由于角膜缘干细胞缺乏或者功能不全引起的眼表疾病成为研究的热点。本文就其解剖学定位、生物学特性、组织工程化角膜的基础性研究及其临床应用做一综述。     

Regulation of corneal angiogenesis in limbal stem cell deficiency

Corneal angiogenesis is associated with a variety of corneal diseases, and is sometimes vision threatening. In recent years, with the discovery of major pro- and anti-angiogenic factors in the cornea, details of the angiogenic process are gradually unveiled. Of note, corneal inflammation and neovascularization associated with severe limbal stem cell (LSC) deficiency is a clinically challenging issue in that the condition persists long after the initial insult, and will not improve without transplantation of LSCs. However, to date the molecular mechanism by which LSC transplantation restores corneal avascularity is not fully understood. In addition to discussing major pro-angiogenic factors involved in corneal neovascularization, this review article also focuses on possible molecular mechanisms underlying persistent inflammation and neovascularization following severe LSC deficiency, and anti-angiogenic factors expressed by human limbo-corneal epithelial cells (HLCECs).

Most of the recently discovered corneal anti-angiogenic factors belong to extracellular matrix proteins that aquire angio-inhibitory activity only after proper proteolytic processing. Our recent findings showed that the secretion of endostatin (derived from basement membrane collagen XVIII) and restin (from collagen XV) by HLCECs were enhanced when HLCECs were cultivated on amniotic membrane (AM). This adds to the advantage of transplanting ex vivo expanded HLCECs cultivated on AM in that the anti-angiogenic activity of the epithelial cells is augmented in a physiological way. Furthermore, proteomic profiling of HLCECs and human conjunctival epithelial cells (HCECs) identified a 14-3-3 protein (stratifin) preferentially expressed by HLCECs. In addition to functioning as a cell cycle controller, keratinocyte-derived stratifin induces MMPs which are involved in the generation of restin (by MMP-1) and endostatin (by MMP-3). These findings highlight the significance of delicate epithelial–matrix interactions in the maintenance of corneal avascularity.     

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。     

The diagnosis of limbal stem cell deficiency

Limbal stem cells (LSCs) maintain the normal homeostasis and wound healing of corneal epithelium. Limbal stem cell deficiency (LSCD) is a pathologic condition that results from the dysfunction and/or an insufficient quantity of LSCs. The diagnosis of LSCD has been made mainly based on medical history and clinical signs, which often are not specific to LSCD. Methods to stage the severity of LSCD have been lacking. With the application of newly developed ocular imaging modalities and molecular methods as diagnostic tools, standardized quantitative criteria for the staging of LSCD can be established. Because of these recent advancements, effective patient-specific therapy for different stages of LSCD may be feasible.     

组织工程角膜上皮治疗兔角膜缘干细胞缺乏症的研究

目的 评价以纤维凝胶膜为载体,体外培养自体角膜缘干细胞移植术治疗角膜缘干细胞缺乏症的临床效果。方法 制作兔眼角膜缘干细胞完全缺乏模型,取对侧眼角膜缘组织进行干细胞培养,并以纤维凝胶膜为载体制成组织工程角膜上皮。将实验动物随机分为4组,其中Ⅰ-Ⅲ组为实验组,行组织工程角膜上皮移植术,Ⅰ组移植术后观察3个月,Ⅱ组移植术后观察1个月,Ⅲ组移植术后观察2周。Ⅳ组为对照组,移植不含干细胞的凝胶膜,术后观察3个月。以角膜上皮染色、角膜混浊及新生血管3项指标进行临床疗效评定,通过病理检查评估术后不同时期角膜上皮修复情况,印迹细胞学检查移植前后角膜上皮的细胞表型,免疫组织化学染色观察角膜上皮特异性角蛋白K3、MUCSAC及转录因子p63在移植角膜上皮的表达。结果 实验组角膜上皮逐渐愈合,透明度提高,新生血管减退或消失;对照组角膜呈持续混浊,上皮缺损迁延不愈,最终大量新生血管长入,上皮结膜化。临床指标评分比较,差异有统计学意义（P=0．021）。角膜上皮印迹细胞学检查显示对照组为PAS（＋）的结膜细胞表型,而实验组上皮细胞PAS（-）。组织病理学显示实验组为正常角膜上皮结构,对照组为结膜化生的上皮,可见血管和杯状细胞。免疫组织化学显示实验组角膜上皮表达角膜上皮特异性角蛋白l（3（AE5）,不表达结膜特异性MUCSAC,在上皮基底部表达转录因子p63。对照组上皮持续表达MUCSAC。结论 组织工程角膜上皮移植术是一种有效的治疗角膜缘干细胞缺乏症的方法,可重建眼表,修复角膜上皮的损伤,抑制角膜上皮结膜化和新生血管。纤维凝胶膜为一种新型的组织工程材料,吸收快,透明度高,具有良好的组织相容性,是一种较理想的移植载体材料。（中华眼科杂志．2006．42：679-685）     

Analysis of limbal stem cell deficiency by corneal impression cytology

PURPOSE: The impaired function of corneal epithelial stem cells, located in the limbus, is responsible for corneal surface damage and is clinically characterized by recurrent epithelial defects, conjunctivalization, neovascularization, and corneal opacity. The aim of this study was to investigate corneal limbal stem cell deficiency (LSCD) by means of the impression cytology (IC) technique, using antibodies against cytokeratin 19 (CK19) and cytokeratin 3 (CK3), and to evaluate the diagnostic potential of this approach. METHODS: Over a 3-year period (October 1998-June 2001), we collected 113 pairs of IC samples from the eyes of 85 patients with a range of ocular surface diseases and performed an immunocytochemical analysis of CK19 and CK3. Samples with more than 50% cellularity were considered suitable for diagnostic purposes, while samples with less than 50% cellularity were considered with caution. CK19-positive cells in corneal IC were considered an expression of LSCD. We arbitrarily scored LSCD as mild (<25% of CK19-positive cells), moderate (25-50%), and severe (>50%). RESULTS: One hundred thirteen pairs of IC specimens were obtained from 85 patients; 32 patients (37.6%) had alkaline burns, 18 (21.2%) had other chemical or physical corneal injuries, 13 (15.3%) had complications from wearing contact lenses, 8 (9.4%) had severe microbial keratitis, and 14 (16.5%) had suspicious limbal deficit due to other causes. Nine patients underwent bilateral sampling and 12 had to be resampled. Thirteen pairs of IC specimens were obtained during the follow-up of 8 patients who had undergone limbal stem cell transplantation. In 3 of these patients, IC confirmed reversion to corneal immunophenotype (CK3+/CK19-), whereas in 4, residual limbal damage was still evident; 1 patient relapsed. In the remaining 100 pairs of impressions, we found 77 cases of LSCD, whereas in 16 pairs, we did not find LSCD. Seven pairs were defined as "not valuable" because of the poor quality of both CK samples. Diffuse LSCD, moderate or severe in degree, was found in 26 of 32 patients (81.2%) with alkali burns, whereas mild diffuse LSCD or sectoral LSCD was found in 13 of 18 patients (72.2%) with other chemical-physical injuries, in 10 of 13 patients (76.9%) wearing contact lenses, in 7 of 8 patients (87.5%) with severe microbial keratitis, and in 12 of 14 patients (85.7%) with other corneal pathologies. The quality of impressions was assessed in 77 cases and found to be good or discrete for both CKs in 32 cases (41.5%) and poor in 45 (58.5%): in 46.7% of these cases, the IC was poor only for CK19 and in 45.4% only for CK3. CONCLUSIONS: Immunocytochemistry for seeking out CK19- and CK3-positive cells on corneal IC is a simple and practical method to investigate LSCD. We believe that this technique could have an important role in evaluating patients undergoing therapeutic penetrating keratoplasty to select those who would benefit from limbal stem cell transplantation. Since sampling has been shown to be a critical point, we believe that any improvement in this area will also help to improve the methodology and will contribute to its wider utilization.     

角膜缘niche细胞与基质细胞维持角膜缘干细胞功能的对比研究

目的比较角膜缘niche细胞(limbal niche cells,LNCs)与角膜缘基质细胞(limbal stromal cells,LSCs)在维持角膜缘干细胞功能上的不同特性。方法将LNCs和LSCs分别从6个角膜缘组织分离,并在相同的条件下培养、传代。LNCs与LSCs经丝裂霉素C(mitomycin C,MMC)处理后分为LNCs组与LSCs组作为饲养细胞分别与角膜缘干细胞共培养,比较两组角膜缘干细胞克隆形成率(colony-forming efficiency,CFE)、上皮细胞复层化以及细胞标志物和部分基因的表达。结果 LNCs组角膜缘干细胞CFE(6.57±1.54)%高于LSCs组(1.43±0.47)%。LNCs组细胞复层上皮数(4～5层)多于LSCs组(2～3层)。角膜缘干细胞克隆与免疫荧光染色及mRNA半定量分析结果显示,LNCs组比LSCs组表达了更多干细胞标志物ΔNp63,能更有效地维持角膜缘干细胞的细胞特性。逆转录PCR分析结果显示,LNCs组与LSCs组都分泌了一些维持角膜缘干细胞生长的生长因子,但LNCs组比LSCs组高表达上皮型钙黏蛋白(E-cad...     

Autologous limbal transplantation in patients with unilateral corneal stem cell deficiency

AIM: To describe a surgical technique for autologous limbal stem cell transplantation and the outcome of a series of patients with unilateral stem cell deficiency. METHODS: A report of six consecutive patients who underwent autologous limbal stem cell transplantation is presented. The primary diagnosis included alkali burn (n=3), conjunctival intraepithelial neoplasia (CIN) (n=1), recurrent pterygium (n=1), and contact lens induced keratopathy (n=1). The autologous transplanted tissue consisted of peripheral cornea, limbus, and conjunctiva obtained from the contralateral eye. Three of the above patients underwent penetrating keratoplasty in association with auto-limbal transplantation. A significant modification to established techniques was the close monitoring of conjunctival epithelial migration in the immediate postoperative period. If conjunctival epithelium threatened to migrate on to the corneal surface, it was mechanically removed at the slit lamp and prevented from crossing the limbus. This was required in three patients. RESULTS: The mean follow up was 18.8 months. The outcome was satisfactory in all cases: a stable corneal surface was restored and there was a substantial improvement in vision and symptoms. One patient had a primary failure of the corneal allograft associated with glaucoma, and 6 months later developed a retinal detachment. No complications were noted in the donor eye with the exception of one patient who developed filamentary keratitis along the edge of the donor site. CONCLUSION: Autologous limbal transplantation with corneal, limbal, and conjunctival carriers was found to be useful for ocular surface reconstruction, over a mid-term follow up, in patients with unilateral stem cell deficiency. Close monitoring of the migration of conjunctival epithelium in the immediate postoperative period, and preventing it from crossing the limbus, ensured that the corneal surface was re-epithelialised exclusively from epithelial cells derived from the transplanted limbal tissue. This approach should improve the success of this procedure.