Effects of penetrating keratoplasty rejection on the endothelium of the donor cornea and the recipient peripheral cornea

PURPOSE: To determine the effects of penetrating keratoplasty rejection on the recipient endothelium. METHODS: Twenty transplanted corneas of 20 keratoconus patients were enrolled in this study. Ten of the corneas had undergone allograft rejection and the other 10 grafts had an uneventful postsurgical course. The endothelium of the donor cornea and the endothelium of the recipient peripheral cornea were evaluated by wide-field specular microscopy. RESULTS: The transplanted corneas that underwent allograft rejection showed a marked decrease in endothelial cell density not only in central donor cornea but also in the recipient peripheral cornea compared with that in the uneventful transplanted corneas. Additionally, the recipient endothelium had significant pleomorphism in the rejection group. There were no morphologic differences in the peripheral donor cornea between the control group and the rejection group. CONCLUSIONS: Our findings indicate that the recipient peripheral endothelium is also affected by allograft rejection, perhaps because of the contribution of recipient endothelium to the wound healing process after allograft rejection.     

Effects of posterior chamber lens implantation on the endothelium of transplanted corneas

AIMS—The morphological changes of the corneal endothelium after posterior chamber lens implantation in the transplanted corneas were investigated.
METHODS—36 patients underwent extracapsular cataract extraction with posterior chamber lens implantation. Among these, penetrating keratoplasty had been performed in 18 patients before cataract surgery. The indications for penetrating keratoplasty in these cases included keratoconus, herpetic keratitis, and macula cornea. 18 cataract patients with normal corneas were also studied as controls. The central corneal endothelium in each subject was examined with a wide field specular microscope at a few days before and 3 months after cataract surgery.
RESULTS—Although the transplanted corneas showed lower endothelial cell densities, marked polymegethism, and pleomorphism in the baseline variables, the endothelial morphological changes in the transplanted corneas after posterior chamber lens implantation were comparable with those in the normal corneas. Also, there was no clinical evidence, especially, of corneal epithelial and/or endothelial rejections and corneal decompensation in all corneas.
CONCLUSION—Even though the transplanted corneas have a lower endothelial cell density and marked polymegethism, it is believed that cataract surgery does not induce corneal decompensation in cases where the peripheral recipient endothelium can be considered to have normal morphology.

     

Keratocyte activation and apoptosis in transplanted human corneas in a xenograft model

PURPOSE: To study keratocyte activation and cellular apoptosis in transplanted human corneas during the early postoperative period. METHODS: Ten human donor corneas preserved for 6 days at 4 degrees C were transplanted into the eyes of 10 adult cats. After confocal and specular microscopy in vivo 1 week after keratoplasty, the cats were killed, and the fixed corneas were examined by TUNEL assay and by scanning (SEM) and transmission electron microscopy (TEM). RESULTS: Abnormal keratocytes, in which portions of cell bodies and processes as well as nuclei were visible, were present in all corneas and occupied the anterior 16 to 562 microm of the stroma. By TEM in the same corneas, these abnormalities represented keratocytes that were activated to a repair phenotype. Only 0% to 1% of all corneal cells were apoptotic by TUNEL assay, except for the donor keratocytes near the wound, where 7% were apoptotic. The midstromal keratocyte density was decreased at 13,936 +/- 5,910 cells/mm(3) (mean +/- SD), and the endothelial cell density was 2,298 +/- 688 cells/mm(2), representing an endothelial cell loss of 7% +/- 16%. CONCLUSIONS: Substantial keratocyte activation and low levels of cellular apoptosis occur 1 week after human corneal transplantation. The human-to-cat xenograft model of corneal transplantation demonstrated endothelial cell loss and other clinical findings similar to human allografts. The model will be useful for preclinical testing of new methods of long-term corneal preservation and of donor endothelial cell augmentation, as well as the study of human corneal wound healing and keratocyte replacement during the early postoperative period.     

Corneal endothelial regeneration and tissue engineering

Human corneal endothelial cells (HCECs) have a limited proliferative capacity. Descemet stripping with automated endothelial keratoplasty (DSAEK) has become the preferred method for the treatment of corneal endothelial deficiency, but it requires a donor cornea. To overcome the shortage of donor corneas, transplantation of cultured HCEC sheets has been attempted in experimental studies. This review summarizes current knowledge about the mechanisms of corneal endothelial wound healing and about tissue engineering for the corneal endothelium. We also discuss recent work on tissue engineering for DSAEK grafts using cultured HCECs and HCEC precursor cell isolation method (the sphere-forming assay). DSAEK grafts (HCEC sheets) were constructed by seeding cultured HCECs on human amniotic membrane, thin human corneal stroma, and collagen sheets. The pump function of the HCEC sheets thus obtained was approximately 75%–95% of that for human donor corneas. HCEC sheets were transplanted onto rabbit corneas after DSAEK. While the untransplanted control group displayed severe stromal edema, the transplanted group had clear corneas throughout the observation period. The sphere-forming assay using donor human corneal endothelium or cultured HCECs can achieved mass production of human corneal endothelial precursors. These findings indicate that cultured HCECs transplanted after DSAEK can perform effective corneal dehydration in vivo and suggest the feasibility of employing the transplantation of cultured HCECs to treat endothelial dysfunction. Additionally, corneal endothelial precursors may be an effective strategy for corneal endothelial regeneration.     

Movement of corneal endothelium after penetrating keratoplasty. Observation of sex chromatin as a cell marker

There is a hypothesis that corneal endothelial cells migrate after penetrating keratoplasty from the areas of higher cell density to the lower cell density areas. In order to confirm this hypothesis, the author performed exchange penetrating keratoplasty in normal albino rabbits using four combinations of sex and age and examined the movement of the endothelium between donors and recipients by observing the density and sex chromatin of the endothelial cells. As a result, there was no significant difference of the rate of decrease of the endothelial cell density of the postoperative grafts between young and old grafts. In the experiment using the sex chromatin of the endothelial cells as a cell marker, it was concluded that the endothelium of the rabbit cornea migrate from the young grafts to the old recipients or from the young recipients to the old grafts. In the control study exchanging rabbit grafts between animals of different sex but the same age the count of the sex chromatin of the endothelium of the grafts and recipients did not change postoperatively. The results confirmed the above hypothesis concerning the migration of the transplanted corneal endothelial cells in the rabbit cornea.     

不同保存方法对角膜形态结构及朗格罕斯细胞的影响

角膜的正常结构及内皮细胞功能的稳定对于角膜的透明极为重要，术前供体角膜材料的处理和保存方法直接影响穿透角膜移植术后的成功与失败。良好的中长期角膜保存为适时进行穿透角膜移植手术提供了便利的条件。综述了短期、中期和长期保存的供体角膜材料在保存过程中以及使用该材料行穿透角膜移植术后角膜的厚度、内皮细胞密度及角膜缘的HLA—DR阳性朗格罕斯细胞的变化情况。     

Corneal wound healing and immunohistological features of extracellular matrix following penetrating keratoplasty in rabbits]

PURPOSE: To analyze corneal wound healing after penetrating keratoplasty (PKP). MATERIALS AND METHODS: We performed PKP on 20 white rabbit eyes, and applied immunohistochemical techniques. The distribution of type I, III and IV collagens, large proteoglycan, chondroitin 6-sulfate, chondroitin 4-sulfate, and vimentin was determined at postoperative intervals of 3 days, 1 week, 2 weeks, 1 month and 3 months. RESULTS: By day 3, staining for type IV collagen was observed along the host-graft junction. By day 7, staining for type III collagen, large proteoglycan and chondroitin 6-sulfate had increased in the repair region, and then diminished with increasing postoperative time. Epithelial wound healing required more than one month, whereas the remodeling of Descemet's membrane did not terminate at 3 months after PKP. CONCLUSION: The data from this study suggest that type III collagen, large proteoglycan and chondroitin 6-sulfate play a crucial role in the corneal wound healing after PKP.     

Corneal wound healing: Immunohistological features of extracellular matrix following penetrating keratoplasty in rabbits

PURPOSE: To study the distribution and the constituents of the extracellular matrix in the cornea during wound healing following penetrating keratoplasty (PKP). METHODS: Penetrating keratoplasty (PKP) was performed on albino rabbit eyes, and immunohistochemical techniques were used to determine the distribution of types I, III, IV collagens, large proteoglycans, chondroitin 6-sulfate, chondroitin 4-sulfate, and vimentin. The expression of these substances was determined at postoperative times of 3 days, 1 week, 2 weeks, 1 month, and 3 months. RESULTS: By day 3, staining for type IV collagen was observed along the host-graft junction. By day 7, staining for type III collagen, large proteoglycans, and chondroitin 6-sulfate had increased in the repair region but then decreased with increasing postoperative times. Epithelial wound healing required more than one month, whereas the remodeling of Descemet's membrane did not terminate until 3 months after PKP. CONCLUSION: These results suggest that type III collagen, large proteoglycans, and chondroitin 6-sulfate probably play important roles in corneal wound healing after PKP.     

Outcomes of penetrating keratoplasty with imported donor corneas

PURPOSE: To analyze factors influencing the surgical success of penetrating keratoplasty and long-term graft survival when using imported donor corneas. METHODS: Sixty-three donor corneas imported to Taipei from the Cincinnati Eye Bank from July 1992-June 1993 were used for penetrating keratoplasty. The corneal endothelium was examined using specular microscopy on arrival in Taiwan. The endothelial morphology and endothelial cell density (ECD) were compared with the photograph of the same cornea taken in the United States. The relationships of the surgical success rate with donor age, death to enucleation time, death to surgery time, and ECD were analyzed. The long-term graft survival and ECD of clear grafts were analyzed 4 years after surgery. RESULTS: On specular microscopic examination. the imported corneas showed diminished endothelial reflection, blurred cellular borders, and increased dark areas, which were markedly different from the pictures of the corneal endothelium taken in the United States. The average ECD before transportation was 2,525+/-267/mm2 and decreased to 1,934+/-250/mm2 after transportation (p < 0.001), with an average endothelial cell loss of 590+/-247/mm2. The overall surgical success rate was 89% and did not correlate with any of the donor factors tested except death to surgery time. The surgical success rate decreased when the time from death to surgery was >7 days (p = 0.05), mainly because of poor reepithelialization. Four years after surgery, 24 grafts remained clear. The ECD had decreased by 72+/-5% in the clear grafts. CONCLUSIONS: Our findings show that endothelial changes in imported donor corneas do occur after transportation, but the surgical success rate may not be influenced significantly if the penetrating keratoplasty is performed within 7 days after donor death. However, the ECD in the clear grafts 4 years after surgery is low.     

角膜移植术后角膜在共焦显微镜下的形态学改变

目的：研究角膜移植术后角膜组织在共焦显微镜(Confocal microscopy)下的形态学改变。方法：应用Conoscan2．0共焦显微镜对板层角膜移植术后3～7d患者12例(12只眼)，术后1a患者8例(8只眼)，穿透性角膜移植术后3～7d患者10例(10只眼)，术后1a患者11例(11只眼)进行扫描检查，记录各层角膜图像。结果：板层角膜移植术后3～7d，植片中基质细胞较小，可见裂隙状暗纹和细小神经，层间为大面积高反光区，有点状颗粒沉积，植床水肿，细胞成像不清。移植术后1a，植片中未见神经，层间反光明显减弱，但仍有点状高反光颗粒沉积，植床中出现粗大裂隙状暗纹，内皮细胞密度正常。穿透角膜移植术后3～7d，植片中基质细胞“激活”，可见神经和后基质层的粗大暗纹，内皮细胞密度正常，细胞间可镶嵌有高反光点。术后1a，植片中基质细胞仍较小，未见神经，后基质层仍有裂隙状暗纹，内皮细胞体积增大，密度减少，高反光点消失。结论：Confoscan 2．0共焦显微镜可活体检查角膜移植术后角膜组织结构和细胞的病理改变，这对评估手术效果和临床观察以及跟踪随访具有重大意义。     

Expression of basic fibroblast growth factor in rabbit corneal alkali wounds in the presence and absence of granulocytes

PURPOSE: To study the expression of basic fibroblast growth factor (bFGF) in the early phases of corneal wound healing in the presence or absence of granulocytes. METHODS: A central penetrating corneal alkali wound was inflicted to one eye in each of 14 rabbits under general anaesthesia. Subsequently, seven of the rabbits were given fucoidin i.v. for 36 hours in order to block the selectins on the vascular endothelium, thus preventing blood granulocytes from entering the tissues. Then, corneas were prepared, stained for bFGF and evaluated by light microscopy. RESULTS: Whereas normal corneal epithelium expressed bFGF weakly, conjunctival epithelium did so strongly, particularly the goblet cells. The corneal endothelium showed medium staining, while keratocytes and vascular endothelial cells did not consistently express bFGF. After 36 hours of wound healing, a marked up-regulation of bFGF expression was observed in the corneal epithelial and endothelial cells, as well as in the keratocytes, that were migrating into the wound. No other changes were noted. None of these features were modulated when granulocyte emigration was prevented by fucoidin administration. CONCLUSIONS: The difference in bFGF expression between the corneal and conjunctival epithelium suggests a role for this growth factor in the barrier function at the limbus. Moreover, the specific presence of bFGF in cells migrating into the wound indicates the participation of bFGF in corneal wound healing. Expression of bFGF was independent of granulocytes.     

Corneal innervation and cellular changes after corneal transplantation: an in vivo confocal microscopy study

PURPOSE: Although penetrating keratoplasty is generally considered a successful procedure, transplanted corneal tissue may exhibit abnormal epithelium, decreased sensation, and declining endothelial cell counts after surgery. This study aimed to use in vivo confocal microscopy to correlate corneal microstructure and recovery of the subbasal nerve plexus of the transplanted cornea with indications for, and time from, surgery. METHODS: This was a cross-sectional study comparing corneas from 42 patients after penetrating keratoplasty with those of 30 controls. Subjects were assessed by ophthalmic history and clinical examination, computerized corneal topography, and laser scanning in vivo confocal microscopy. RESULTS: Time from surgery ranged from 1 month to 40 years (mean, 85 +/- 105 months). Significant reductions in epithelial (P < 0.001), keratocyte (P < 0.001), and endothelial (P < 0.001) cell densities were noted in comparison with control corneas. Significant reductions in subbasal nerve fiber density (P < 0.001) and nerve branching (P < 0.001) were also noted. Endothelial cell density decreased with time after surgery (r = -0.472; P = 0.003), and nerve fiber density (r = .328; P = 0.034) increased. Keratoconus as an indication for transplantation was associated with higher subbasal nerve fiber densities (P = 0.003) than other indications for corneal transplantation. Neither nerve fiber nor cell density was correlated with best-corrected visual acuity. CONCLUSIONS: Laser scanning in vivo confocal microscopy highlights profound reductions in cell density at every level of the transplanted cornea and alterations to the subbasal plexus that are still apparent up to 40 years after penetrating keratoplasty.     

实验性角膜移植术后内皮创伤愈合的形态学定量分析

采用扫描电镜与计算机图象分析技术联合应用的方法，对２０只家兔进行了穿透性角膜移植术后内皮创伤愈合的形态学定量分析，结果展示了术后不同时间伤口部位角膜内皮细胞面积、周长、密度、形状系数、最大长径、变异系数的数值，并对内皮愈合机制进行了进一步探讨。     

Vascular endothelial growth factor (VEGF) and its receptor VEGFR-2 in the regulation of corneal neovascularization and wound healing

PURPOSE: To study the change in expression of vascular endothelial growth factor (VEGF) and its receptor VEGFR-2 in the rabbit cornea and limbus following a penetrating, central corneal alkali burn. The influence of different cells on VEGF and VEGFR-2 expression was studied by excluding granulocytes from the wound area. METHODS: Fourteen New Zealand white rabbits were subjected to a penetrating, 5-mm diameter, central corneal alkali burn in one eye under general anaesthesia. Seven of the rabbits were given injections of fucoidin for 36 hours. The rabbits were killed after 36 hours and the corneas were excised with a sclera rim and prepared for immunohistochemistry. RESULTS: Both VEGF and VEGFR-2 are strongly expressed in the frontline of repopulating epithelial, stromal and endothelial cells during wound healing, irrespective of granulocyte presence. Vascular endothelial cells express VEGF strongly after injury, but only in the presence of granulocytes. CONCLUSION: Corneal neovascularization requires the presence of granulocytes to stimulate vascular endothelial cells. During wound healing in this area, VEGF is a factor that stimulates proliferation and migration and that is not influenced by granulocytes.     

Cellular changes in transplanted human corneas

PURPOSE: To measure endothelial cell and keratocyte densities in transplanted corneas and the changes in these densities with time. METHODS: The endothelia of 500 consecutive penetrating corneal transplants were studied longitudinally by specular microscopy for 10 to 20 years. The keratocytes of 36 corneal transplants that varied in postoperative times from 1 month to 20 years were studied cross-sectionally by clinical confocal microscopy. The keratocytes of five transplanted corneas were studied longitudinally by confocal microscopy at 1 day, 1 week, and 1 month postkeratoplasty. RESULTS: Endothelial cell density decreased progressively at an accelerated rate for 20 years after transplantation, with concurrent increases in the coefficient of variation of cell area and corneal thickness and decreases in the percentage of hexagonal cells. Grafts with insufficient endothelial cells developed late endothelial failure, which was the primary cause of graft failure after the first 5 postoperative years. The grafts with late endothelial failure did not lose endothelial cells faster than grafts that did not fail, but instead had fewer cells immediately after transplantation, diminishing to a critically low cell density earlier. The keratocyte density was also decreased in transplanted corneas. Keratocytes became "activated" during the first week after keratoplasty and in grafts with late endothelial failure. CONCLUSION: It should be possible to prevent or delay late endothelial failure, the primary cause of graft failure, by increasing the number of endothelial cells on transplanted corneas. The status of the keratocytes appears to affect corneal transparency and, thus, visual quality in the grafted eye.     

Corneal endothelium and postoperative outcomes 15 years after penetrating keratoplasty

PURPOSE: To determine changes in the central endothelium and thickness of grafted corneas and the cumulative probability of developing glaucoma, of graft rejection, and of graft failure 15 years after penetrating keratoplasty. DESIGN: Longitudinal cohort study of 500 consecutive penetrating keratoplasties by one surgeon. METHODS: Regrafted eyes, fellow eyes of bilateral cases, and patients not granting research authorization were excluded, leaving 388 grafts for analysis. At intervals after surgery, we photographed the endothelium and measured corneal thickness using specular microscopy. The presence of glaucoma, graft rejection, and graft failure were recorded. RESULTS: The 67 patients examined at 15 years represented 30% of the available clear grafts. Endothelial cell loss from preoperative donor levels was 71 +/- 12% (mean +/- standard deviation, n = 67), endothelial cell density was 872 +/- 348 cells/mm(2), and corneal thickness was 0.59 +/- 0.06 mm. Endothelial cell density was unchanged between 10 and 15 years, whereas corneal thickness increased (P = .001, n = 55). The mean annual rate of endothelial cell loss from 10 to 15 years after surgery was 0.2 +/- 5.7% (n = 54). The cumulative probability of developing glaucoma, graft rejection, or graft failure was 20%, 23%, and 28%, respectively, and 6 of the 8 graft failures after 10 years resulted from late endothelial failure. CONCLUSIONS: From 10 to 15 years after penetrating keratoplasty, the annual rate of endothelial cell loss was similar to that of normal corneas, corneal thickness increased, and late endothelial failure was the major cause of graft failure.     

长期干燥保存角膜穿透移植实验与应用

利用干燥保存７～５７天及１６～３０个月的兔用膜，行同种异体部分穿透角膜移植后，前者３７眼中，透明愈合８眼，后者９眼中，透明愈合３眼。保存１０～５７天猴眼角膜移植后，观察的９猴（９眼）中，透明愈合３眼，半透明２眼。用干燥保存４个月～４年９个月人角膜，行挽救眼球穿透移植的６眼中，观察２６天到１年６个月，透明愈合２眼，半透明３眼。提示：在临床上，干燥保存角膜有可能作为穿透角膜移植材料应用。     

Impact of short-term versus long-term topical steroids on corneal neovascularization after non-high-risk keratoplasty

PURPOSE: To analyze incidence and extent of corneal neovascularization (CN) after non-high-risk keratoplasty and to find out whether duration of postoperative topical steroid therapy (6 vs 12 months) affects CN, corneal endothelial cell count, pachymetry, aqueous flare values, and best-corrected visual acuity at 1 year after keratoplasty. METHODS: Patients of the prospective Erlangen non-high-risk keratoplasty study with available high-quality corneal photographs taken preoperatively and 1 year later were analyzed (n=136). Corneal photographs were evaluated by two independent observers in a standardized semiquantitative fashion. Slides were projected with 100x magnification and corneal vessels classified into five grades with regard to the limbus, sutures and host-graft junction in each of 12 corneal sectors. Incidence and extent of CN after keratoplasty and relation to short-term (0-6 months) versus long-term (0-12 months) postoperative topical steroid therapy were analyzed. The effect of duration of topical steroid therapy on corneal endothelial cell count, pachymetry, aqueous flare values, and best corrected visual acuity was also analyzed. Of the 136 patients, 69 (51%) were randomly assigned to short-term and 67 to long-term topical prednisolone acetate 1%. RESULTS: Fifty-eight percent of patients (n=79) developed a CN within 1 year after keratoplasty in at least one corneal sector (mean 3.1 +/- 2.2, range 1-10). At 1 year after keratoplasty, only in 12% of these patients did at least one vessel reach the host-graft junction or grow into the donor cornea, whereas in 51% vessels were seen beyond the outer suture ends of the double running suture without reaching the host-graft junction. In 37%, capillaries were located between limbus and outer suture ends. New vessels usually pointed directly or indirectly to the outer suture ends and usually were located around the 12 o'clock and 6 o'clock positions. There was no significant difference regarding incidence and extent of CN 1 year after keratoplasty between the long-term and the short-term group. Duration of topical steroid therapy had no significant effect on corneal endothelial cell count and thickness, aqueous flare values and best-corrected visual acuity at 6 and 12 months postoperatively (only at 12 months, corneas in the long-term treatment group were slightly thicker; P=0.03). Interobserver correlation of vessel assessment was 0.77 (Kendall's tau B). CONCLUSIONS: CN is a common phenomenon after non-high-risk keratoplasty. New vessels rarely reach the host-graft junction, most commonly develop from the 6 o'clock and 12 o'clock positions and are usually located between epithelium and Bowman's layer (i.e., at the level of the superficial suture). The direction of vessel growth from the limbus towards the outer suture ends suggests release of angiogenic factors in this area. Prolongation of topical steroid therapy after non-high-risk keratoplasty beyond 6 months in this study did not significantly influence incidence and extent of CN, corneal endothelial cell count, aqueous flare values and best-corrected visual acuity observed 1 year after keratoplasty.     

组织工程角膜内皮的体外构建及在猕猴角膜移植中的应用

目的体外构建出形态结构功能正常的组织工程人角膜内皮（TE-HCE）,并以猕猴动物模型验证其维持角膜透明的作用。方法实验研究。以非转染人角膜内皮单克隆细胞株细胞（mcHCE细胞）为种子细胞,以去上皮层修饰羊膜（mdAM）为载体支架体外构建出TE-HCE,对其透明度、形态、细胞密度、组织学结构、超微结构、功能蛋白的荧光表达进行检测;采用穿透性角膜移植手术（PKP）对猕猴右眼分别移植TE-HCE（3眼,TE-HCE组）和mdAM（3眼,mdAM组）,未移植的左眼作为正常对照眼（6眼,对照组）,利用裂隙灯显微镜、角膜内皮镜、角膜测厚仪和眼压计对术后动物的角膜透明度、角膜内皮细胞密度（ECD）、中央角膜厚度（CCT）和眼压（IOP）进行在体检测,并利用荧光显微镜检测移植眼角膜内皮细胞的CM-DiI标记。数据处理均采用单因素方差分析。结果体外构建的TE-HCE透明度高,具有与活体角膜内皮近似的形态结构,单层细胞密度高达（3 602±45）个/mm2,细胞连接蛋白和膜运输蛋白呈阳性表达;术后跟踪观测结果显示,TE-HCE移植眼的角膜没有出现明显的炎症和免疫排斥反应,角膜维持透明,虽然出现了轻度角膜水肿,但随着时间的推移CCT逐渐下降,术后181 d时单层细胞密度为（2 796±157）个/mm2;而mdAM移植眼的角膜则出现了明显的炎症反应,长入了新生血管,角膜持续混浊与水肿,厚度没有明显的下降趋势;各组间IOP的变化无明显差异。CM-DiI荧光检测结果显示TE-HCE移植眼的角膜内皮移植区的细胞均带有CM-DiI标记（来自于移植的TE-HCE）。结论体外构建的高密度TE-HCE具有正常的形态结构,且功能蛋白表达正常,移植后能使猕猴角膜逐渐恢复透明度和厚度,表明TE-HCE在体内可重建出功能正常的角膜内皮,有望用于角膜内皮异常疾病的临床治疗。     

Leukocytes in the early events of corneal neovascularization

PURPOSE: To study the early events in corneal neovascularization after alkali injury and their relationship to the presence and absence of leukocytes. METHODS: A standardized 5.5-mm diameter penetrating central corneal alkali wound was induced in one eye in each of ten New Zealand white rabbits (2.5 kg). In five of the ten rabbits, 1.5 mL 5% fucoidin was given intravenously every 2 hours to prevent leukocytes from leaving the blood stream. Presence of hyaluronan (HA) and proliferating cell nuclear antigen (PCNA) in the corneas were analyzed using immunohistochemical staining 36 hours after injury. RESULTS: In the alkali wounded corneas, HA was expressed intensively in the limbal area where a massive infiltration of leukocytes was seen. PCNA was expressed in the vascular endothelium as well as in the corneal cells. In the leukocyte-free corneas, HA staining intensity and distribution were the same as in uninjured corneas. No positive PCNA staining was seen in the vascular endothelial cells in these corneas. CONCLUSIONS: Extravasated leukocytes in the alkali-burned corneas caused enhanced production of HA and proliferation of vascular endothelial cells.