Advances in cell transplantation therapy for limbal stem cell deficiency.

BACKGROUND: Limbal stem cells (LSCs) are essential for maintaining corneal transparency and ocular surface integrity. Many external factors or genetic diseases can lead to corneal limbal stem cell deficiency (LSCD), resulting in the loss of barrier and corneal epithelial cell renewal functions. Stem cell transplantation is one of the primary treatments for LSCD, including limbal transplantation and cultivated limbal epithelial transplantation. In addition, a variety of non-limbal stem cell lines have been experimented with for LSCD treatment. Biological scaffolds are also used to support in vitro stem cell culture and transplantation. Here, we review the mechanisms of corneal maintenance by LSCs, the clinical stage and surgical treatment of LSCD, the source of stem cells, and the biological scaffolds required for in vitro culture. METHODS: This study is a narrative retrospective study aimed at collecting available information on various aspects of surgical treatments for LSCD. Relevant literature was searched in a range of online databases, including Web of Science, Scopus, and PubMed from 2005 to March, 2023. RESULTS: A total of 397 relevant articles were found, and 49 articles with strong relevance to the studies in this paper were obtained and analyzed. Moreover, 11 of these articles were on the concept of LSCD and the mechanism of LESCs maintaining the corneal epithelium, 3 articles on the staging and grading of LSCD, 17 articles on cell transplantation methods and donor cell sources, and 18 articles on scaffolds for delivering stem cells. We also summarized the advantages and disadvantages of different cell transplantation methods and the benefits and limitations of scaffolds based on the above literature. CONCLUSION: The treatment of LSCD is determined by the clinical stage and whether it involves monocular or binocular eyes. Appropriate surgical techniques should be taken for LSCD patients in order to reconstruct the ocular surface, relieve symptoms, and restore visual function. Meanwhile, biological scaffolds assist in the ex vivo culture and implantation of stem cells.

Advancements in Ocular Regenerative Therapies.

The use of stem cells (SCs) has emerged as a promising avenue in ophthalmology, offering potential therapeutic solutions for various vision impairments and degenerative eye diseases. SCs possess the unique ability to self-renew and differentiate into specialised cell types, making them valuable tools for repairing damaged tissues and restoring visual function. Stem cell-based therapies hold significant potential for addressing conditions such as age-related macular degeneration (AMD), retinitis pigmentosa (RP), corneal disorders, and optic nerve damage. Therefore, researchers have explored different sources of stem cells, including embryonic stem cells (ESC), induced pluripotent stem cells (iPSCs), and adult stem cells, for ocular tissue regeneration. Preclinical studies and early-phase clinical trials have demonstrated promising outcomes, with some patients experiencing improved vision following stem cell-based interventions. However, several challenges remain, including optimising the differentiation protocols, ensuring transplanted cells' safety and long-term viability, and developing effective delivery methods. The field of stem cell research in ophthalmology witnesses a constant influx of new reports and discoveries. To effectively navigate these tons of information, it becomes crucial to summarise and systematise these findings periodically. In light of recent discoveries, this paper demonstrates the potential applications of stem cells in ophthalmology, focusing on their use in various eye tissues, including the cornea, retina, conjunctiva, iris, trabecular meshwork, lens, ciliary body, sclera, and orbital fat.

Allogeneic Limbal Transplants Integrate into the Corneal Surface and Lead to an Improved Visual Acuity.

Limbal stem cell deficiency (LSCD) severely impairs vision and can lead to blindness. LSCD causes include chemical burns, infections, multiple previous operations and congenital malformations. Allogeneic limbal transplantation is a procedure for treating LSCD where prepared limbal tissue is attached using a double running suture during allogeneic penetrating keratoplasty (PKP). A total of 22 patients underwent ALT surgery between February 2019 and June 2022 at the University Hospital Halle (Saale). Regular follow-up was performed postoperatively every three months and included visual acuity testing, pressure measurement, slit lamp microscopic examination, fundoscopy, corneal topography and anterior segment optical coherence tomography (AS-OCT). The mean patient age was 69.5 years, and the mean follow-up was 19 months. All included patients had LSCD and multiple previous surgeries. Patient LSCD etiology was 59% infectious and 41% traumatic. ALTs integrated into corneal surfaces in all patients, demonstrated on AS-OCT. Since most patients initially received allogeneic limbal transplants, none of the operated eyes had surgical complications. Overall, visual acuity improved postoperatively from an initial 2.06 to 1.44 logarithm of the minimum angle of resolution (logMAR). Allogeneic limbal transplantation can be used to treat LSCD and its integration into the surrounding corneal tissue can be observed on AS-OCT.

ALT (allogeneic limbal transplantation): a new surgical technique for limbal stem cell deficiency.

PURPOSE: Limbal stem cell deficiency (LSCD) is a rare but extremely relevant disease of the eye. LSCD patients often require a variety of surgical procedures, including keratoplasty in some cases. However, the outcome of these surgeries, including opacification and revascularization, is often frustrating due to LSCD relapse. METHODS: We developed a new surgical technique for the treatment of LSCD in which partial allogenic limbal transplantation (ALT) is carried out as part of penetrating keratoplasty (PK). After the PK, 1-8 slices from the limbal tissue of the donor graft are prepared and placed under the double running sutures attaching the corneal graft. This procedure was performed on 14 patients with LSCD, caused by severe ocular burn in 5 cases and by infection in 9. Between one and eight limbal transplants were used depending on the extension of the LSCD. RESULTS: All 14 patients showed stable or increased visual acuity after the ALT surgery compared to their preoperative visual acuity. All of the grafts were integrated into the superficial corneal layers without progression of corneal vascularization beyond the limbal grafts. The median follow-up period was 12 months on average. CONCLUSION: The ALT method seems to be a promising surgical procedure for the treatment of patients with LSCD. It can be properly carried out in the context of keratoplasty and does not require a separate donor tissue. The ALT grafts may offer the possibility of constructing a new limbal region, resulting in stable or even increased visual acuity and the absence of corneal vascularization.

Mini-conjunctival autograft combined with deep anterior lamellar keratoplasty for chronic sequelae of severe unilateral chemical burn: A case report.

INTRODUCTION AND IMPORTANCE: This case describes a novel technique combining a mini-conjunctival limbal autograft (CLAU) with a deep anterior lamellar keratoplasty (DALK) in a case of chemical injury sequelae. CASE PRESENTATION: A 19-year-old female presented with total limbal stem cell deficiency (LSCD) and a vascularized corneal scar in the visual axis of the left eye, 4 years following a chemical injury. In order to treat the LSCD and simultaneously visually rehabilitate the patient, a mini-CLAU with DALK was carried out. Two separate one clock-hour CLAUs were harvested from the right eye and secured in the left. The graft was clear in the initial postoperative period and maintained its clarity over 15 months of follow period with a visual acuity of 20/30 with scleral contact lenses. The mini-CLAUs sustained a stable and well epithelialized corneal surface during the same period. CLINICAL DISCUSSION: The use of the mini-CLAUs instead of the traditional CLAU circumvents the complication of an iatrogenic LSCD in the donor eye as the size of the donor grafts is smaller (1-2 clock hours versus 6-8 clock hours). Despite the smaller size, these grafts are efficacious in maintaining a well epithelialized corneal surface even in cases of total LSCD. The autologous nature of the graft defers the need for immunosuppression and its peripheral location facilitates ease of the surgical technique when combined with a keratoplasty. CONCLUSION: This novel single-staged procedure is an effective technique to reestablish a stable ocular surface and to visually rehabilitate cases of chronic chemical injury with good long-term outcomes.

A Decellularized Human Limbal Scaffold for Limbal Stem Cell Niche Reconstruction.

The transplantation of ex vivo expanded limbal epithelial progenitor cells (LEPCs) on amniotic membrane or fibrin gel is an established therapeutic strategy to regenerate the damaged corneal surface in patients with limbal stem cell deficiency (LSCD), but the long-term success rate is restricted. A scaffold with niche-specific structure and extracellular matrix (ECM) composition might have the advantage to improve long-term clinical outcomes, in particular for patients with severe damage or complete loss of the limbal niche tissue structure. Therefore, we evaluated the decellularized human limbus (DHL) as a biomimetic scaffold for the transplantation of LEPCs. Corneoscleral tissue was decellularized by sodium deoxycholate and deoxyribonuclease I in the presence or absence of dextran. We evaluated the efficiency of decellularization and its effects on the ultrastructure and ECM composition of the human corneal limbus. The recellularization of these scaffolds was studied by plating cultured LEPCs and limbal melanocytes (LMs) or by allowing cells to migrate from the host tissue following a lamellar transplantation ex vivo. Our decellularization protocol rapidly and effectively removed cellular and nuclear material while preserving the native ECM composition. In vitro recellularization by LEPCs and LMs demonstrated the good biocompatibility of the DHL and intrastromal invasion of LEPCs. Ex vivo transplantation of DHL revealed complete epithelialization as well as melanocytic and stromal repopulation from the host tissue. Thus, the generated DHL scaffold could be a promising biological material as a carrier for the transplantation of LEPCs to treat LSCD.

Conjunctival limbal autografting (CLAU) combined with customised simple limbal epithelial transplantation (SLET) in a severe corneal chemical burn: Case report.

PURPOSE: The most common cause of severe limbal stem cell deficiency (LSCD) is chemical injury. We report a case of severe unilateral alkali injury complicated by total LSCD, treated with customized Simple limbal epithelial transplantation (SLET) combined with conjunctival-limbal autografting (CLAU). OBSERVATION: A 23-year-old female sustained a severe unilateral alkali chemical injury, resulting in total LSCD, treated with customized SLET combined with CLAU. We used two autologous limbal biopsies harvested from the fellow eye. One was used for CLAU and the second was split into multiple pieces, and was glued to bare stroma following resection of the corneal pannus. A stable ocular surface was achieved, and the donor eye remained healthy. Visual acuity improved from hand motion initially, to 20/20 over one year post-operatively. CONCLUSION AND IMPORTANCE: This case report demonstrates the efficacy and safety of customized SLET with supplemental CLAU to treat total LSCD in severe ocular burns.

The Surgical Outcomes of Limbal Allograft Transplantation in Eyes Having Limbal Stem Cell Deficiency.

PURPOSE: To report the limbal allograft transplantation and penetrating keratoplasty (PK) results in limbal stem cell deficiency (LSCD)-developed eyes because of chemical or thermal injury. METHODS: Medical records of 18 eyes of 14 patients who had undergone keratolimbal allograft (KLAL) or living-related conjunctival limbal allograft (lr-CLAL) with or without PK and followed up at least 1 year postoperatively were evaluated retrospectively. The preoperative LSCD grade was noted in all patients. Rejection incidents, recurrence of LSCD, and corneal graft clarity along with a visual improvement during the follow-up were noted. The complications rate due to surgery or injury itself, for instance, glaucoma and cataract, were evaluated. The limbal allograft tissue survival analysis and corneal allograft survival analysis were done to reveal the differences in both the procedures. The existence of normal corneal epithelium and improvement in visual acuity were accepted as the surgical success criteria. RESULTS: In the limbal allograft transplantation group, the survival rates of the allograft tissue were 65 ± 10.7% at 1 year and 36.6 ± 11.4% at 3 years in lr-CLAL and 66.7 ± 15.7% at 12 months and 53.3 ± 17.3% at 18 months in KLAL-transplanted eyes. The survival rate of corneal allograft at the 5th postoperative year was lower in the simultaneous procedure compared to the staged procedure, but it was not statistically significant (25.7 ± 25.8% vs. 62.5 ± 17.1%, P = 0.75). The ambulatory vision was achieved in 10 eyes (56%) after a mean follow-up time of 93.8 ± 37.8 months. The visual acuity level has increased in 12 eyes (67%) in which the limbal allograft transplantation was applied. The ambulatory visual acuity level was achieved (≤1.0 logMar [20/200]) in 10 eyes (56%). In addition, two or more Snellen lines' gain in the best corrected visual acuity was observed in 12 eyes of 18 (67%) at the last follow-up, and there was not any significant difference between the KLAL and lr-CLAL. CONCLUSIONS: Ocular surface integrity was longer in KLAL than in lr-CLAL transplantation, but it was not statistically significant. The staged procedure was more convenient than the simultaneous procedure in terms of corneal allograft clarity maintenance in limbal allograft-employed eyes.

Simple limbal epithelial transplantation (SLET): Review of indications, surgical technique, mechanism, outcomes, limitations, and impact.

Simple limbal epithelial transplantation (SLET) is an innovative limbal stem cell transplantation technique that has gained increasing popularity over the last few years. Different groups from across the world have published the clinical results of SLET in large case series with varying types and severities of limbal stem cell deficiency (LSCD). This review attempts to place all the available knowledge on SLET together in one place for the benefit of not only cornea specialists and trainees but also for residents and general ophthalmologists. It follows a balanced approach of blending evidence with experience by providing an objective analysis of published results along with helpful insights from subject experts, starting from preoperative considerations including the role of newer imaging modalities to the technical aspects of the surgery itself and the management of possible complications. Original data and novel insights on allogeneic SLET for bilateral LSCD are included in the review to address the few remaining lacunae in the existing literature on this topic. This review intends to inform, educate, and empower all aspiring and practicing SLET surgeons to optimize their clinical outcomes and to have maximal positive impact on the lives of the individuals affected by unilateral or bilateral chronic LSCD.

Interleukin-10 Gene Transfer in Rat Limbal Transplantation.

PURPOSE: To evaluate the gene transfer of the interleukin (IL)-10 cytokine as a treatment modality for prolonging limbal allograft survival in a rat model. MATERIALS AND METHODS: Adenoviral (AV) and lentiviral (LV) vectors were produced for ex vivo gene transfer into limbal graft tissue prior to orthotopic transplantation. Experimental groups comprised unmodified isografts, unmodified allografts, allografts transfected with a reporter gene, and allografts transfected with IL-10. The functional effects of the transgenes were determined by clinical assessment and by following donor cell survival in the recipient animal. Group comparisons were made using survival analysis and tested with the log-rank test. Differences in mean rejection times between groups were tested using the Wilcoxon rank-sum test. RESULTS: Isografts survived during the entire observation period of 56 days. Allografts underwent clinical rejection at a mean of 6.7 days (standard deviation 2.0) postoperatively, irrespective of the presence of transgenes (p < 0.001 for difference in rejection times). For both the AV and LV vector systems, Kaplan-Meier analysis showed a statistically significant difference with respect to time-to-graft failure when comparing allografts transfected with IL-10 with allografts transfected with reporter gene alone (p = 0.011 and p < 0.001, respectively). In the isografts, donor cells could be detected during the complete observation period. In all the allograft groups, however, donor cell detection declined after 1 week and was lost after 4 weeks. CONCLUSIONS: Under the conditions tested in the present model, both the AV and the LV vector systems were able to transfect limbal graft tissue ex vivo with biologically active IL-10, leading to delayed rejection compared to the controls.

Science and Art of Cell-Based Ocular Surface Regeneration.

The potential cause of blindness worldwide includes diseases of the cornea, ocular surface (limbal stem cell deficiency, allergic conjunctivitis, dry eye diseases), and retinal diseases. The presence of stem cells (limbal stem cells) in the basal region of the limbus makes it an important tool for the ocular regeneration and also in maintaining the transparency of eye by replacing the corneal epithelium continuously. Various surgical modalities have been developed like cultured limbal epithelial transplantation, cultured oral mucosal epithelial transplantation, simple limbal epithelial transplantation, etc., utilizing the cell-based regenerative properties to treat limbal disorder. Cell-based therapies for ocular repair and regeneration comprise a major hope by therapies involving the mesenchymal stem cells, embryonic stem cells, and limbal stem cells for the restoration of vision in individuals whose ocular tissue has been irreversibly damaged by disease or trauma. This review explores critical needs in human disease mainly the ocular problem where cell-based therapeutics is exceptionally well suited and also the use of animal models, various artificial scaffolds, as well as advancement in clinical technique to challenge the current demand to overcome corneal blindness.

Corneal stem cells and tissue engineering: Current advances and future perspectives.

Major advances are currently being made in regenerative medicine for cornea. Stem cell-based therapies represent a novel strategy that may substitute conventional corneal transplantation, albeit there are many challenges ahead given the singularities of each cellular layer of the cornea. This review recapitulates the current data on corneal epithelial stem cells, corneal stromal stem cells and corneal endothelial cell progenitors. Corneal limbal autografts containing epithelial stem cells have been transplanted in humans for more than 20 years with great successful rates, and researchers now focus on ex vivo cultures and other cell lineages to transplant to the ocular surface. A small population of cells in the corneal endothelium was recently reported to have self-renewal capacity, although they do not proliferate in vivo. Two main obstacles have hindered endothelial cell transplantation to date: culture protocols and cell delivery methods to the posterior cornea in vivo. Human corneal stromal stem cells have been identified shortly after the recognition of precursors of endothelial cells. Stromal stem cells may have the potential to provide a direct cell-based therapeutic approach when injected to corneal scars. Furthermore, they exhibit the ability to deposit organized connective tissue in vitro and may be useful in corneal stroma engineering in the future. Recent advances and future perspectives in the field are discussed.

Efficacy of cultivated corneal epithelial stem cells for ocular surface reconstruction.

PURPOSE: To investigate the clinical outcomes of cultivated corneal limbal epithelial transplantation (CLET) using human amniotic membrane for corneal limbal stem-cell deficiency. METHODS: Prospective, noncomparative case series. Eighteen patients (19 eyes) with severe ocular surface diseases were chosen to undergo CLET using human amniotic membrane. Twelve eyes received auto-CLET, and seven eyes received allo-CLET. Clinical outcomes of corneal surface epithelialization, conjunctivalization, inflammation, visual acuity, graft status, and complications were observed. RESULTS: Corneal epithelium cultivated on amniotic membrane (two to four layers) was positive for molecular markers p63, ABCG2, CK3, and CK12. The mean patient age was 44.7 ± 15.2 years. A successful clinical outcome, defined as corneal epithelialization without central conjunctivalization or severe inflammation, was obtained in 14 (73.7%) of 19 eyes (mean follow-up 26.1 ± 13.5 months; range 6-47). A histopathologic success, defined as absence of goblet cells at the central cornea, was achieved in 12 (63.2%) eyes. Clinical failures occurred in five (26.3%) of 19 eyes, and histopathologic failures occurred in seven (36.8%) of 19 eyes. Survival analysis at 1 year showed that the clinical success rate was 77.9% and the pathological success rate was 72.3%. Fourteen of 19 (73.7%) eyes had visual acuity improvements after CLET. Six cases underwent penetrating keratoplasty; five of these grafts remained clear after 20.4 ± 6.9 months (range, 12-31) of follow-up. Complications included infectious keratitis (three cases) and recurrent symblepharon (one case). All complicated cases had lid abnormalities. Factors affecting the final clinical outcomes were lid abnormalities, abnormal corneal stromal beds, and complications. CONCLUSION: CLET can successfully restore ocular surface damage in most cases with corneal limbal stem cell deficiency.

Two Cases of Whole Corneo-Limbal Transplantation

PURPOSE: To report the clinical outcomes of total corneolimbal transplantation in two cases. CASE SUMMARY: One patient, who previously underwent three rounds of penetrating keratoplasty and limbal transplantation for uncontrollable peripheral and central corneal melting, received total corneolimbal transplantation. The other patient who underwent penetrating keratoplasty with limbal transplanation for a chemical burn and who did not experience corneal perforation also received total corneolimbal transplantation. During the average 19 months of follow-up, cyclophotocoagulation was performed to control high intraocular pressure in both patients. Both eyes were tectonically maintained without further corneal destruction despite poor visual acuity and rejection. CONCLUSIONS: Total corneolimbal transplantation may be an effective tectonic procedure for corneal melting. This procedure can be considered as another option for patients with corneal melting after failed limbal and corneal transplantation.

Cultivated limbal stem cell transplantation for ocular surface reconstruction.

Severe damage to cell repair mechanisms of the limbal region can lead to many disorders such as vascularized conjunctivalization, keratinization, corneal scarring, and corneal opacification, collectively described as limbal stem cell deficiency (LSCD). Limbal stem cell deficiency may occur as a result of depletion of stem cells or destruction of their stromal niche. In such cases, apart from conventional corneal transplantation, limbal stem cell transplantation would be needed to restore vision. Limbal stem cells may be replenished by autologous limbal transplants from the healthy fellow eye in unilateral cases, and allografts from living related donors or cadaveric donors in bilateral cases. The induction of iatrogenic LSCD and its sequelae in donor eyes have motivated researchers to cultivate sheets of limbal epithelium ex vivo, from small fragments of donor tissue for the purpose of ocular surface reconstruction.

Limbal Transplantation: A Midterm Clinical Outcome with Continuous Systemic Immune Suppression

PURPOSE: To investigate the midterm outcome of limbal transplantation combined with continuous systemic immune suppression. METHODS: The medical records of 15 eyes in 14 patients who underwent limbal transplantation were reviewed retrospectively. All had been followed up for 6 months or more. Limbal transplantation was performed with 360 degrees of 0.19 mm partial corneal trephined tissues, accompanied with transient amniotic membrane transplantation. The procedure was accomplished with systemic cyclosporine or mycophenolate. We defined complete success as neither rejection nor epithelial defect; partial success as partial conjunctival ingrowth and neovascularization without epithelial defect; and graft failure as persistent epithelial defect or total conunctivalization with neovascularization. RESULTS: Mean age at surgery was 45.1 years. 9 eyes yielded complete success, 2 had partial success, and graft failure occurred in 4 on an average of 23.4 months postoperatively. Success including complete and partial success showed 67% incidence (4 of 6) of chemical burn, 33% (1 of 3) with Stevens-Johnson syndrome, and 100% (6 of 6) experienced another intractable ocular surface disease. Of 10 eyes (67%), which experienced graft rejection in an average of 2.7 months; 4 demonstrated full recovery with oral corticosteroid and enhanced immunosuppression, 2 presented with chronic graft rejection, and the other 4 ended in graft failure. CONCLUSIONS: Total success rate was revealed as 73.3% for on average 23.4 months in limbal transplantation with continuous systemic immune suppression, utilized for chronic intractable ocular surface disease.

Limbal Transplantation: A Midterm Clinical Outcome with Continuous Systemic Immune Suppression

PURPOSE: To investigate the midterm outcome of limbal transplantation combined with continuous systemic immune suppression. METHODS: The medical records of 15 eyes in 14 patients who underwent limbal transplantation were reviewed retrospectively. All had been followed up for 6 months or more. Limbal transplantation was performed with 360 degrees of 0.19 mm partial corneal trephined tissues, accompanied with transient amniotic membrane transplantation. The procedure was accomplished with systemic cyclosporine or mycophenolate. We defined complete success as neither rejection nor epithelial defect; partial success as partial conjunctival ingrowth and neovascularization without epithelial defect; and graft failure as persistent epithelial defect or total conunctivalization with neovascularization. RESULTS: Mean age at surgery was 45.1 years. 9 eyes yielded complete success, 2 had partial success, and graft failure occurred in 4 on an average of 23.4 months postoperatively. Success including complete and partial success showed 67% incidence (4 of 6) of chemical burn, 33% (1 of 3) with Stevens-Johnson syndrome, and 100% (6 of 6) experienced another intractable ocular surface disease. Of 10 eyes (67%), which experienced graft rejection in an average of 2.7 months; 4 demonstrated full recovery with oral corticosteroid and enhanced immunosuppression, 2 presented with chronic graft rejection, and the other 4 ended in graft failure. CONCLUSIONS: Total success rate was revealed as 73.3% for on average 23.4 months in limbal transplantation with continuous systemic immune suppression, utilized for chronic intractable ocular surface disease.

Early Effect of Autologous Limbal Transplantation Immediately following Total Limbal Injury in Rabbits

Limbal epithelium plays a great role in reconstruction of damaged corneal epithelium and early limbal transplantation showed better results in limbal injury.However, there is no consensus about the appropriate time for limbal transplantation.We, therefore, investigated the results of autologous limbal transplantation (ALT)immediately following limbal epithelial injury in rabbits.We classified the rabbits in three groups whether the application of ALT and therapeutic contact lens were done or not.Injury of limbal and corneal epithelium was made by application of n-heptanol and tarsorrhaphy was done in all groups.ALT from the healthy fellow eye was done in Group 1 and Group 2 but not in Group 3, control group.Therapeutic soft contact lens was applied to Group 2 after ALT.We evaluated epithelial defect, haze, and neovascularization of corneas at 3 days, 1 week, and 2 weeks after operation.We also examined tissue specimen of corneas after two weeks of operation.Epithelial defect was almost healed within 2 weeks after operation in Group 1 and Group 2, but Group 3 showed persistent epithelial defect. Corneal neovascularization and haze were the most severe in Group 3, but was not so severe in Group 1 and Group 2, and there was no significant difference between the two groups.On histopathologic examination, Group 1 and Group 2 showed almost normal corneal epithelium though a few inflammatory cells and goblet cells were observed in some cases but control group showed severe inflammaton and many new vessels and goblet cells.In conclusion, ALT immediately following severe limbal injury is effective in reconstructing corneal epithelium.

Combined Surgery of the Penetrating Keratoplasty and the Limbal Cell Transplantation

If the corneal opacity and the corneal neovascularization are severe and broad, it should be taken the penetrating keratoplasty. But there is a high risk of the persistent epithelial defect, the neovascularization and the rejection. Recently, there were many reports that support the limbal stem cell theory. Based on the stem cell conception of the corneal epithelium, the authors have evaluated the clinical effects of the penetrating keratoplasty combined with the allograftic limbal transplantation or the penetrating keratoplastty combined with the autologousl imbal transplantation in 4 patients (4 eyes) whose corneas were severly opaque and heavily neovasculized. As a result, the visual improvement was achieved in 3 eyes (as a corrected vision, from hand motion to finger count, from hand motion to 0.05, from hand motion to 0.15), the prompt reepithelialization was accomplished in 3 eyes (the mean time: 5.7 days) and even in case of the failed reepithelialization, the epithelial side at which the limbal transplantion was done showed a rapid recovery. Therefore we think that the combined surgery of the panetrating keratoplasty and the limbal transplantation is useful because it can increase the success rate of the penetrating keratoplasty by the rapid and firm reepithelialization and the suppression of the neovascularization. Futhermore the donor cornea can be used effectively (the central portion is used for a penetrating keratoplasty and the limbal portion is used for a limbal transplantation), and we can expect a rapid visual recovery through a simultaneous surgery of the two other operation.