Visual improvement after cultivated oral mucosal epithelial transplantation

Strategic combination of cultivated oral mucosal epithelial transplantation and postoperative limbal-rigid contact lens-wear for end-stage ocular surface disease: a retrospective cohort study

PURPOSE

To provide the long-term outcome of patients with end-stage severe ocular surface disease (OSD) consecutively treated with cultivated oral mucosal epithelial transplantation (COMET) followed by limbal-rigid contact lens (CL)-wear therapy.

DESIGN

Retrospective cohort.

METHODS

In 23 eyes of 18 patients with severe OSD who underwent COMET surgery between 2002 and 2019 and who were followed with limbal-rigid CL-wear therapy for at least 1 year postoperative, patient demographics, best-corrected visual acuity (BCVA, logMAR), Ocular Surface Grading Scores (OSGS), surgical indication and adverse events were reviewed. Primary and secondary outcomes were BCVA and OSGS changes at baseline and final examination, respectively.

RESULTS

This study involved 16 patients with Stevens-Johnson syndrome and 2 patients with mucous membrane pemphigoid (mean age: 59±15 years). The indications for COMET were as follows: corneal reconstruction for vision improvement (10 eyes (43.5%)), corneal reconstruction for persistent epithelial defect (4 eyes (17.4%)) and conjunctival (fornix) reconstruction for symblepharon release (9 eyes (39.1%)). The mean duration of CL-wear postsurgery was 6.4±3.9 years (range: 1.4 to 13.3 years). The mean BCVA at baseline and at final follow-up was logMAR 1.9±0.5 and 1.3±0.7, respectively (p<0.05). Compared with those at baseline, the OSGSs for symblepharon and upper and lower fornix shortening showed significant improvement at each follow-up time point post treatment initiation. No serious intraoperative or postoperative adverse events were observed.

CONCLUSION

In patients afflicted with severe OSD, COMET combined with limbal-rigid CL-wear therapy postsurgery was found effective for vision improvement and ocular surface stabilisation.

Improvement of the Ocular Prognosis of Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis: A National Survey in Japan

PURPOSE

To investigate the incidence and prognostic factors of ocular sequelae in Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) cases arising between 2016 and 2018 in Japan, and compare the findings with those presented in the previous 2005-2007 survey.

DESIGN

Retrospective, national trend survey.

METHODS

Dermatologic case report forms (CRFs) (d-CRFs) were sent to 257 institutions that treated at least 1 SJS/TEN case, and 508 CRFs were collected from 160 institutions. Ophthalmologic CRFs (o-CRFs) regarding patient demographic data, onset date, ocular findings (first appearance, day of worst severity, and final follow-up), topical treatment (betamethasone), outcome (survival or death), and ocular sequelae (visual disturbance, eye dryness) were sent to the ophthalmologists in those 160 institutions. The results of this survey were then compared with that of the previous 2005-2007 survey.

RESULTS

A total of 240 cases (SJS/TEN: 132/108) were included. The incidence of ocular sequelae incidence was 14.0%, a significant decrease from the 39.2% in the previous survey (SJS/TEN: 87/48). In 197 (82.1%) of the cases, systemic treatment was initiated within 3 days after admission, an increase compared to the previous survey (ie, treatment initiated in 82 [60.7%] of 135 cases). Of the 85 cases with an Acute Ocular Severity Score of 2 and 3, 62 (72.9%) received corticosteroid pulse therapy and 73 (85.9%) received 0.1% betamethasone therapy; an increase compared to the 60.0% and 70.8%, respectively, in the previous survey. Ocular-sequelae-associated risk factors included Acute Ocular Severity Score (P < .001) and specific year in the survey (P < .001).

CONCLUSIONS

The ophthalmologic prognosis of SJS/TEN has dramatically improved via early diagnosis, rapid assessment of acute ocular severity, and early treatment.

Biologicals and Biomaterials for Corneal Regeneration and Vision Restoration in Limbal Stem Cell Deficiency

The mammalian cornea is decorated with stem cells bestowed with the life-long task of renewing the epithelium, provided they remain healthy, functional, and in sufficient numbers. If not, a debilitating disease known as limbal stem cell deficiency (LSCD) can develop causing blindness. Decades after the first stem cell (SC) therapy is devised to treat this condition, patients continue to suffer unacceptable failures. During this time, improvements to therapeutics have included identifying better markers to isolate robust SC populations and nurturing them on crudely modified biological or biomaterial scaffolds including human amniotic membrane, fibrin, and contact lenses, prior to their delivery. Researchers are now gathering information about the biomolecular and biomechanical properties of the corneal SC niche to decipher what biological and/or synthetic materials can be incorporated into these carriers. Advances in biomedical engineering including electrospinning and 3D bioprinting with surface functionalization and micropatterning, and self-assembly models, have generated a wealth of biocompatible, biodegradable, integrating scaffolds to choose from, some of which are being tested for their SC delivery capacity in the hope of improving clinical outcomes for patients with LSCD.

Severity Classification of Limbal Stem Cell Failure Due to Steven Johnson Syndrome in the Light of the Classification Consensus of Limbal Stem Cell Deficiency

OBJECTIVES

To examine and to understand the limbal stem-cell deficiency (LSCD) because of Steven-Johnson syndrome (SJS) in line with the new classification system for the first time in the literature.

METHODS

Medical records of patients with LSCD because of SJS were reviewed retrospectively. In addition to demographic data and ophthalmologic or systemic findings, anterior segment photographs of the patients were reviewed retrospectively. Limbal stem-cell deficiency severity was graded according to the classification published by the Limbal Stem Cell Working Group.

RESULTS

Twenty-four eyes of 14 patients with eye involvement secondary to SJS were included in the study. The mean age of the patients was 36.09±16.70 (9-58) years and the female-to-male ratio was 11:3. The anterior segment photographs of the patients were evaluated by two independent masked observers. Limbal stem-cell deficiency severity was graded according to the classification published by Deng et al. Corneal opacity was divided into three stages according to the area of involvement. Corneal opacity was classified as Stage I if the central 5 mm region of the cornea was not affected, as Stage II if the central 5 mm region of the cornea was affected, and as Stage III if the entire corneal surface was affected. Limbal involvement was classified as Stage A if it was below 50%, as Stage B if it was between 50% and 100%, and as Stage C if it was 100%.

CONCLUSION

This is the first study in the literature to describe and classify LSCD because of SJS, according to the new LSCD classification. Consistent with the results, LSCD follows a bimodal distribution. Most patients demonstrated severe (Stage III-32.14%) or mild (Stage IA-21.42%) LSCD.

Topical Betamethasone Treatment of Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis with Ocular Involvement in the Acute Phase

PURPOSE

To clarify the importance of administering topical steroids for the treatment of Stevens-Johnson syndrome (SJS) / toxic epidermal necrolysis (TEN) with ocular involvement in the acute phase.

DESIGN

Retrospective case series.

METHODS

Using the medical records of acute SJS/TEN patients treated at the Kyoto Prefectural University of Medicine Hospital, Kyoto, Japan, between July 2006 and July 2017, the ocular findings, topical steroid dosage, systemic steroid dosage, and ocular sequelae were retrospectively examined. The level of cytokines in tear fluid and serum samples was also analyzed.

RESULTS

This study involved 13 cases. In 10 cases in whom the clinical courses were recorded before the start of steroid therapy, the mean acute ocular severity score (AOSS: 3 = very severe; 2 = severe; 1 = mild; 0 = none) was 2.8 ± 0.4 points in the severest phase. The mean systemic steroid dose after steroid pulse therapy was 694 ± 386 mg and the mean topical steroid (0.1% betamethasone eye drop and ointment) dose was 13.4 ± 3.3 times daily in the severest phase. Analysis of cytokine levels of 4 cases showed that a cytokine storm occurred in the tear fluid after the steroid pulse therapy. At final follow-up, 16 eyes of 8 patients had a logMAR visual acuity of ≤0, and no serious ocular sequelae were observed.

CONCLUSIONS

In patients with SJS/TEN, ocular surface inflammation remains strong even after systemic inflammation has improved post steroid pulse therapy, thus suggesting that both systemic and topical steroid therapy should be administered appropriately.

Insights into the clinical development of regenerative medical products through a comparison of three cell-based products recently approved for limbal stem cell deficiency

Three regenerative medical products for limbal stem cell deficiency (LSCD), a rare and intractable ocular surface disease, have recently been approved in Japan. To our knowledge, this is the first time multiple stem-cell-based medical products have been approved for the same ocular disease. Development plans and study designs for each product differ, resulting in differences in indications. Since cell-based products have a heterogeneous formulation and often target rare diseases, they require a flexible approach to development. This review article describes the status and prospects of the clinical development of regenerative medical products by summarizing the issues of the three products from the Pharmaceuticals and Medical Devices Agency (PMDA) standpoint. Implementing stem cell-based products is challenging, requiring scientific and flexible review by regulatory authorities. To overcome these issues in the development process, developers and regulatory authorities need to communicate and fully discuss study protocols from the early stage of development.

Outcomes of Combined Penetrating Keratoplasty and Limbal Stem Cell Transplantation: A Meta-Analysis on Simultaneous Versus Sequential Surgery

PURPOSE

The objective of this study is to perform a systematic review and meta-analysis of the published studies on limbal stem cell transplantation (LSCT) combined with penetrating keratoplasty (PK) performed either simultaneously or sequentially.

METHODS

An extensive search was conducted in the MEDLINE and Google Scholar databases. Prospective and retrospective trials and case series reporting on the outcomes of LSCT with PK were included. Primary outcomes were the stability of the ocular surface and the rejection and/or failure of the corneal graft.

RESULTS

A total of 209 eyes from 13 studies were included in the simultaneous group and 489 eyes from 33 studies in the sequential group. Ocular surface stability was 88% [95% confidence interval (CI), 79%-96%] for sequential cases and 64% (95% CI, 43%-82%) for simultaneous cases ( P = 0.001). The graft failure rate was 15% (95% CI, 6%-26%) for sequential cases and 44% (95% CI, 31%-58%) for simultaneous cases ( P < 0.001). For cases performed sequentially, subgroup analysis revealed a stable ocular surface in 97% (95% CI, 91%-100%) of autograft cases and 63% (95% CI, 45%-80%) of allograft cases ( P < 0.001). The graft failure rate in sequential cases was 7% (95% CI, 0%-18%) for autografts and 34% (95% CI, 18%-52%) for allografts ( P < 0.001).

CONCLUSIONS

Sequential LSCT followed by PK demonstrated superior results in terms of ocular surface stability and graft retention compared with simultaneous LSCT and PK. Limbal stem cells of autologous origin fare better than allogeneic ones in sequential cases.

Early Clinical Outcomes of the First Commercialized Human Autologous Ex Vivo Cultivated Oral Mucosal Epithelial Cell Transplantation for Limbal Stem Cell Deficiency: Two Case Reports and Literature Review

The first product in the world for ex vivo cultivated oral mucosal epithelial cell transplantation (COMET) to treat limbal stem cell deficiency (LSCD), named Ocural^®, was launched in June 2021 in Japan. COMET was performed on two patients, including the first case in the post-marketing phase of Ocural^®. Pathological and immunohistochemical examinations were also carried out using specimens obtained before and after COMET and the spare cell sheet. In case 1, the ocular surface remained free from epithelial defects for approximately six months. In case 2, although defect of the cornea-like epithelia was observed after COMET for one month, it was resolved after the insertion of lacrimal punctal plugs. In case 1, adjuvant treatment was interrupted due to an accident during the second month after COMET, resulting in conjunctival ingrowth and corneal opacity. Eventually, a lamellar keratoplasty was required at six months after COMET. Immunohistochemistry revealed the presence of markers for stem cells (p63, p75), proliferation (Ki-67), and differentiation (Keratin-3, -4, and -13) in both the cornea-like tissue after COMET and a cultivated oral mucosal epithelial cell sheet. In conclusion, Ocural^® can be accomplished without major complications, and the stem cells derived from oral mucosa might be successfully engrafted.

Ophthalmic Aspects of Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis: A Narrative Review

The aim of our review article was to summarize the current literature on Stevens-Johnson syndrome (SJS) and its severe form, toxic epidermal necrolysis (TEN). SJS/TEN is a serious, rare multi-system, immune-mediated, mucocutaneous disease with a significant mortality rate that can lead to severe ocular surface sequelae and even to bilateral blindness. Restoration of the ocular surface in acute and chronic SJS/TEN is challenging. There are only limited local or systemic treatment options for SJS/TEN. Early diagnosis, timely amniotic membrane transplantation and aggressive topical management in acute SJS/TEN are necessary to prevent long-term, chronic ocular complications. Although the primary aim of acute care is to save the life of the patient, ophthalmologists should regularly examine patients already in the acute phase, which should also be followed by systematic ophthalmic examination in the chronic phase. Herein, we summarize actual knowledge on the epidemiology, aetiology, pathology, clinical appearance and treatment of SJS/TEN.

Limbal-Rigid Contact Lens Wear for the Treatment of Ocular Surface Disorders: A Review

ABSTRACT

Recently, the prescription of large-diameter rigid gas-permeable contact lenses (CLs), also known as "scleral lenses," "corneoscleral lenses," and "limbal-rigid CLs," is on the rise for the treatment of both moderate and severe ocular surface disorders (OSDs). Compared with scleral lenses, the diameter of limbal-rigid CLs is generally smaller, that is, a diameter ranging from 13.0 to 14.0 mm, and they are designed so that the peripheral edge bears on the limbus. The Suncon Kyoto-CS (Sun Contact Lens Co., Ltd.) is a novel limbal-rigid CL design with multistep curves on the peripheral edge for easy tear exchange during blinking that removes debris and prevents lens clouding or fogging, thus allowing patients to enjoy a longer daily duration of CL wear. In severe OSD cases, limbal-rigid CL wear after surgery is a noninvasive therapeutic approach that can neutralize corneal irregularities, decrease dry eye symptoms, prevent the progression or recurrence of symblepharon, and improve the patient's visual acuity and overall quality of life. Thus, surgeries such as amniotic membrane transplantation and cultivated oral mucosal epithelial transplantation, as well as limbal-rigid CL wear, which is noninvasive, are valuable and effective treatment strategies that can now be applied for the management of patients afflicted with severe OSDs.

Current Advancements in Corneal Cell-Based Therapy

Corneal epithelial stem cells (CEpSCs) mostly reside at the limbal area and are responsible for tissue homeostasis throughout life. Once complete CEpSC deficiency occurs, regenerative medicine cell-based therapy using CEpSCs or their alternatives can provide successful clinical outcomes. Due to an improved understanding of CEpSCs and mucosal epithelial stem cells, major advancements have been made over the past few decades in in vivo and ex vivo cell-based ocular surface reconstruction therapies for the treatment of severe ocular surface diseases. New therapeutic concepts and clinical strategies are emerging for the treatment of corneal endothelial dysfunction. For example, unlike corneal epithelial cells, in vivo corneal endothelial cells (CECs) stop proliferating and are arrested in the G1 phase of the cell cycle due to cell-to-cell contact inhibition and exposure to a high concentration of transforming growth factor-beta in the aqueous humor. Thus, the production of CECs with good functionality in culture has consistently been difficult. To solve this problem, Rho-associated protein kinase inhibition has taken center stage, as it not only makes the production of human CECs in culture closely mimic the functional characteristics of in vivo healthy CECs possible but also helps sustain those biological properties. Thus, cultured human CEC injection therapy is now moving to the forefront for the treatment of corneal endothelial failure. Herein, we summarize key historical discoveries in corneal cell-based regenerative medicine and illustrate the concept of corneal cell therapy for the treatment of refractory corneal epithelial and endothelial diseases.

Challenges in the management of bilateral eyelid closure in Stevens-Johnson Syndrome

Purpose

Observations

Conclusion and importance

Signaling Pathways Impact on Induction of Corneal Epithelial-like Cells Derived from Human Wharton’s Jelly Mesenchymal Stem Cells

Corneal epithelium, the outmost layer of the cornea, comprises corneal epithelial cells (CECs) that are continuously renewed by limbal epithelial stem cells (LESCs). Loss or dysfunction of LESCs causes limbal stem cell deficiency (LSCD) which results in corneal epithelial integrity loss and visual impairment. To regenerate the ocular surface, transplantation of stem cell-derived CECs is necessary. Human Wharton’s jelly derived mesenchymal stem cells (WJ-MSCs) are a good candidate for cellular therapies in allogeneic transplantation. This study aimed to test the effects of treatments on three signaling pathways involved in CEC differentiation as well as examine the optimal protocol for inducing corneal epithelial differentiation of human WJ-MSCs. All-trans retinoic acid (RA, 5 or 10 µM) inhibited the Wnt signaling pathway via suppressing the translocation of β-catenin from the cytoplasm into the nucleus. SB505124 downregulated the TGF-β signaling pathway via reducing phosphorylation of Smad2. BMP4 did not increase phosphorylation of Smad1/5/8 that is involved in BMP signaling. The combination of RA, SB505124, BMP4, and EGF for the first 3 days of differentiation followed by supplementing hormonal epidermal medium for an additional 6 days could generate corneal epithelial-like cells that expressed a CEC specific marker CK12. This study reveals that WJ-MSCs have the potential to transdifferentiate into CECs which would be beneficial for further applications in LSCD treatment therapy.

OUP accepted manuscript

The corneal epithelium serves to protect the underlying cornea from the external environment and is essential for corneal transparency and optimal visual function. Regeneration of this epithelium is dependent on a population of stem cells residing in the basal layer of the limbus, the junction between the cornea and the sclera. The limbus provides the limbal epithelial stem cells (LESCs) with an optimal microenvironment, the limbal niche, which strictly regulates their proliferation and differentiation. Disturbances to the LESCs and/or their niche can lead to the pathologic condition known as limbal stem cell deficiency (LSCD) whereby the corneal epithelium is not generated effectively. This has deleterious effects on the corneal and visual function, due to impaired healing and secondary corneal opacification. In this concise review, we summarize the characteristics of LESCs and their niche, and present the current and future perspectives in the management of LSCD with an emphasis on restoring the function of the limbal niche.

Outcomes of surgical interventions for the treatment of limbal stem cell deficiency

Background & objectives:

In the current scenario, with availability of different surgical procedures for limbal stem cell deficiency (LSCD), there exists no common consensus as to the standardization of the management protocol for the same. In addition, there also exists diversity in the views about the clinical diagnosis, ancillary investigations and clinical parameters. The objective of the present study was to evaluate the reported outcomes of surgical interventions for the management of LSCD.

Methods:

A systematic review of published literature on limbal stem cell transplantation (LSCT) was performed using Ovid Medline, Embase and PubMed for a duration of 2009 to 2019. Original studies including prospective, retrospective case series and randomized controlled trials, articles in English language, articles with access to full text and studies with more than or at least 10 patients were included in this review. Data related to clinical and visual outcomes were evaluated, and pool estimates of different surgeries were calculated using random-effects model and individually using Pearson’s Chi-square test.

Results:

A total of 1133 abstracts were evaluated. Finally, 17 studies were included for the analysis. Among these 17 studies, direct limbal lenticule transplantation was performed in five studies, of which autologous tissue from the fellow eye [conjunctival limbal autograft (CLAU)], allograft from a cadaver/live donor [keratolimbal allograft (KLAL)/conjunctival limbal allograft (CLAL)] and combination of CLAU plus KLAL were done in one, three and one studies, respectively. The ex vivo expanded cultivated limbal epithelial transplantation (CLET) was reported in six studies and simple limbal epithelial transplantation (SLET) in four studies. Two were comparative studies comparing CLET and CLAL (living-related CLAL) with cadaveric KLAL, respectively. Outcome analysis of the included studies showed significant heterogeneity. Calculated pool rate for various types of surgeries was calculated. The pool estimate for CLAL was 67.56 per cent [95% confidence interval (CI), 41.75-93.36; I²=83.5%, P=0.002]. For KLAL, this value was 63.65 per cent (95% CI, 31.38-95.91; I²=92.4%, P=0.000). Pool estimate for CLET was 78.90 per cent (95% CI, 70.51-87.28; I²=73.6%, P=0.001). Corresponding values for SLET were 79.08 per cent (95% CI, 74.10-84.07; I²=0.0%, P=0.619). CLAU and combination of CLAU plus KLAL were done in one study each; hence, statistical analysis could not be done. The functional outcome in terms of gain in visual acuity post-operatively was better in KLAL (P<0.005) and SLET group as compared to CLET group.

Interpretation & conclusions:

The present analysis suggests that though the anatomical success rates were almost identical between SLET, CLET, CLAL, and KLAL procedures, the functional success rates were better following KLAL and SLET procedures as compared to CLET. Decision for LSCT for cases of ocular burns based on either clinical judgement of the surgeon or individual diagnosis remains a suitable option.

Long-term survival of cultivated oral mucosal epithelial cells in human cornea: generating cell sheets using an animal product-free culture protocol

Previously, we reported a collagenase-based, animal product-free protocol for cultivated oral mucosal epithelial cell sheets for transplantation (COMET). Here, we reported the long-term outcomes of first 2 clinical cases. A 27-year-old man suffered from thermal burn, which resulted in symblepharon of lower fornix OD. COMET was performed, and the cornea remained clear with few peripheral NV and no more symblepharon 34 months postoperatively. Another 42-year-old man suffered from severe alkaline burn OD. He underwent COMET, followed by corneal transplantation half a year later. A biopsy taken two years after COMET showed stratified epithelium positive for keratin 4, 13, and 3 in the suprabasal layer. Staining for p63 and p75^NTR was both positive in the basal layer. The graft remained clear up to post-OP 4 years. Our study confirmed the long-term survival of the transplanted OMECs, suggesting that collagenase-based spheroidal suspension culture is a promising technique for COMET.

Trial registration ClinicalTrials.gov, ClinicalTrials.gov ID: NCT03943797 Registered 9 May 2019-Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT03943797.

Oral Mucosal Epithelial Transplantation and Limbal-Rigid Contact Lens: A Therapeutic Modality for the Treatment of Severe Ocular Surface Disorders

Stevens-Johnson syndrome, ocular cicatricial pemphigoid, and severe thermal or chemical injury are considered severe ocular surface disorders (OSDs) because they affect the entire ocular surface, including corneal and conjunctival epithelial stem cells. In patients with severe OSDs, the long-term prognosis for limbal transplantation is poor, and the related corneal opacity and cicatrization lead to devastating visual impairment. To date, there is no standardized treatment to improve vision in cases with severe OSD. Investigating novel treatment methods for severe OSDs, our group began cultivated oral mucosal epithelial transplantation in 2002 and developed a limbal-supported rigid-type contact lens that can be applied as a nonsurgical treatment. When used in combination, these treatment methods make it possible to successfully restore vision in cases with severe OSDs.

Referral Patterns of Patients with Limbal Stem Cell Deficiency to a Specialized Tertiary Center in the United Kingdom

INTRODUCTION

Limbal stem cell deficiency (LSCD) is a potentially blinding disease; hence, referral to a specialist service is becoming increasingly common. Our aim was to investigate the referral patterns and associated details.

METHODS

We conducted an audit of 100 consecutive patients with LSCD who were referred to our service from 2011 to 2018. Patient demographics, geographical location, cause of LSCD, coexisting ocular diseases, best corrected visual acuity (BCVA), and extent of LSCD were recorded. The following two subgroups were further analyzed: (1) burns and (2) other causes of LSCD.

RESULTS

Out of the 100 patients (138 eyes), 70% were male, with a mean age of 45 years (SD 19). LSCD was unilateral in 62% of the cases. The most common ocular comorbidity was glaucoma, in 21 patients (33 eyes). Burns were the most frequent cause of referral (61%). The mean BCVA of the involved eye was 1.22 (SD 0.8) LogMAR, and total LSCD was present in 75 eyes (54%). There were statistically significant age, gender and eye-involved differences between the burns group and other causes group, mean 39 (SD 17) and 53 (SD 19) years (p < 0.001); 85% were men versus 48.7%, (p = 0.001); and 82% were unilateral versus 31% (p < 0.001), respectively.

CONCLUSIONS

LSCD was more common in men and usually unilateral. Overall, the main cause of LSCD was burns. There were significant differences between the burns group and other causes of LSCD group in terms of age, gender and unilateral involvement that may help to guide management decisions.

Japan: Diagnosis and Management of Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis With Severe Ocular Complications

In 2005, the “Japanese Research Committee on Severe Cutaneous Adverse Reaction” (J-SCAR) presented the official “Diagnostic Criteria” for SJS/TEN, and the specific ocular findings are included in these very important criteria. In SJS/TEN cases involving ocular disorder, conjunctivitis often occurs prior to the onset of the high fever. In a Japanese survey, ocular involvement was observed in 77% of the cases, and the incidence of ocular sequelae increased depending on the score of the acute ocular severity findings. Pseudo-membrane formation and epithelial defects are considered to be high-risk signs of ocular sequelae. At the chronic stage, limbal stem cell deficiency, visual disturbance, and severe dryness of the ocular surface are the primary disease characteristics. In 2002, we started performing Cultivated Oral Mucosal Epithelial Transplantation (COMET) for the treatment of severe ocular disorders, including SJS/TEN. As an additional treatment method, we developed a new type of rigid contact lens (CL) that is 13 to 14.0-mm in diameter, known as the “Limbal Rigid Contact Lens (Limbal CL).” Our Limbal Rigid CL greatly enhances the postoperative outcome of COMET. The detection rate of ocular surface bacteria is high in SJS/TEN cases. Thus, appropriate use of topical antibiotics reduces the risk of ocular surface inflammation. Moreover, rebamipide is an ophthalmic solution for dry eye that was developed in Japan, and it also has the effect of suppressing ocular surface inflammation. From disease onset until the chronic stage, the control of inflammation and stem cell loss is key to successfully treating eyes afflicted with SJS/TEN.

Stem Cells in the Path of Light, from Corneal to Retinal Reconstruction

The future of eye reconstruction invariably includes stem cells transplantation. Corneal limbus, corneal stroma, trabeculum, retinal cells, optic nerve, and all structures that are irreversibly damaged and have no means to be repaired or replaced, through conventional treatment or surgery, represent targets for stem cell reconstruction. This review tries to answer the question if there is any clinical validation for stem therapies, so far, starting from the cornea and, on the path of light, arriving to the retina. The investigation covers the last 10 years of publications. From 2385 published sources, we found 56 clinical studies matching inclusion criteria, 39 involving cornea, and 17 involving retina. So far, corneal epithelial reconstruction seems well validated clinically. Enough clinical data are collected to allow some form of standardization for the stem cell transplant procedures. Cultivated limbal epithelial stem cells (CLET), simple limbal epithelial transplant (SLET), and oral mucosa transplantation are implemented worldwide. In comparison, far less patients are investigated in retinal stem reconstructions, with lower anatomical and clinical success, so far. Intravitreal, subretinal, and suprachoroidal approach for retinal stem therapies face specific challenges.

Long-term outcome of cultivated oral mucosal epithelial transplantation for fornix reconstruction in chronic cicatrising diseases

BACKGROUND/AIMS

To investigate the long-term outcomes of cultivated oral mucosal epithelial transplantation (COMET) for fornix reconstruction in eyes with chronic cicatrising disease.

METHODS

This retrospective cohort study involved 16 eyes of 15 patients who underwent COMET for symblepharon release and fornix reconstruction between June 2002 and December 2008. The mean postoperative follow-up period was 102.1±46.0 months (range: 32-183 months). The treated cicatrising disorders included ocular cicatricial pemphigoid (OCP, five eyes), thermal/chemical injury (three eyes) and other chronic diseases (seven eyes; including recurrent pterygium (two eyes), Stevens-Johnson syndrome (one eye) and graft-versus-host disease (one eye)). Ocular-surface appearance was evaluated before surgery, at 1, 4, 12 and 24 weeks postoperative, and then annually based on the previously reported scoring system. Main outcome measures included overall and disease-specific fornix-reconstruction success probabilities analysed by the Kaplan-Meier survival curve. Symblepharon/fornix-shortening recurrence at 24 weeks postoperative, and its relationship to long-term surgical success was also examined.

RESULTS

At 5 years postoperative, the mean±SD overall fornix-reconstruction success probability was 79.6%±10.7%, and success probability for thermal/chemical injury and OCP was 100% and 53.3%±24.8%, respectively (p=0.53, log-rank test). The 3-year success probability was significantly higher in the no-disease-recurrence group at 24 weeks postoperative (13 eyes) than in the disease-recurrence group (three eyes) (100% and 33.3%±27.2%, respectively) (p=0.0073, log-rank test).

CONCLUSION

COMET was found to be safe and effective for symblepharon release and long-term fornix reconstruction in eyes with chronic cicatrisation. Although the 5-year success probability differed depend on the underlying disease, ocular-surface appearance at 24 weeks postoperative is a factor for predicting long-term outcome.

The effect of cultured autologous oral mucosal epithelial cells on ocular surface reconstruction

Introduction

Oral epithelial cells were recently shown to be able to differentiate into corneal epithelium, and the efficacy of cultured autologous oral mucosal epithelial cells (CAOMEC) has been suggested by the presence of epithelium replacement. Therefore, the aim of this study was to evaluate the treatment outcome in limbal stem cell deficiency (LSCD) by adding CAOMEC to regular amniotic membrane (AM) treatment.

Material and methods

Eyes with LSCD were randomized to two groups to undergo either autologous oral mucosal epithelial cell sheet (CAOMECS) combined with AM transplantation (A group) or AM transplantation alone (B group). Clinical outcome measures were corneal epithelium healing, best corrected visual acuity, symblepharon, corneal transparency, corneal neovascularization and ocular surface inflammation.

Results

The normal corneal epithelialization rate in group A (73.33%) was higher than that in group B (35.48%), and the average healing time was shorter (3.45 ±2.12 weeks vs. 4.64 ±1.63 weeks). The symblepharon in the above two groups was improved in the first 3 months after surgery, but after 6 months, part of the B group had recurrence. In improving corneal transparency, group A has obvious advantages. Corneal neovascularization (CNV) was improved to some extent in the first 3 months after surgery, but group A (1.47 ±0.64) was better than group B (1.94 ±0.85) after 6 months. Both groups can improve the inflammatory state to some extent.

Conclusions

The transplantation of CAOMECS offers a viable and safe alternative in the reconstruction of a stable ocular surface. The effect is better than that of traditional AM transplantation, mainly in promoting corneal epithelialization, improving ocular surface structure, and reducing fiber and vascular infiltration.

Systematic review of clinical research on regenerative medicine for the cornea

PURPOSE

To conduct a systematic review of clinical research on the use of regenerative medicine for the cornea in human patients.

METHODS

A systematic literature search of MEDLINE and the Cochrane Library was performed in May 2020.

RESULTS

Forty-two articles were identified. Thirty-eight of those articles focused on the treatment for limbal stem cell deficiency (LSCD), of which 17 articles involved autologous cultured limbal epithelial cell sheet transplantation (CLET), 13 involved allogeneic CLET, and 14 involved autologous cultured oral mucosal epithelial cell sheet transplantation (COMET). For autologous CLET, the median ocular surface reconstruction rate, visual recovery rate, incidence of immunologic rejection, infectious keratitis, and ocular hypertension/glaucoma were 74.1%, 54.5%, 0%, 4.6%, and 6.3%, respectively. For allogeneic CLET, they were 71.4%, 71.4%, 7.1%, 12.0%, and 7.1%, respectively. For autologous COMET, they were 66.7%, 66.7%, 0%, 5.3%, and 8.1%, respectively. Systemic immunosuppressants and steroid medications were predominantly used following allogeneic CLET, whereas they were not routinely used after autologous CLET. Three studies focused on the treatment of keratoconus using autologous adipose-derived adult stem cells and reported no marked adverse events. One study reported on the treatment of bullous keratopathy using allogeneic cultured corneal endothelial cells. All patients achieved an endothelial cell density of >500 cells, and the corrected distance visual acuity improved in 82% of the treated eyes.

CONCLUSIONS

The results show that regenerative medicine for the cornea demonstrated a satisfactory efficacy and safety. Through translational research, we are expecting to establish a new treatment for waiting patients.

Outcomes of Cultivated Oral Mucosal Epithelial Transplantation in Eyes With Chronic Stevens-Johnson Syndrome Sequelae

PURPOSE

To study the outcomes of cultivated oral mucosal epithelial transplantation (COMET) in eyes with chronic Stevens-Johnson syndrome (SJS) sequelae.

DESIGN

Prospective interventional case series.

METHODS

Forty-five eyes of 41 patients with chronic SJS sequelae were recruited and evaluated from 2013 to 2017 in an institutional setting. All patients underwent COMET, with an aim of fornix reconstruction and visual rehabilitation. Change in corrected distance visual acuity (CDVA), severity scores of various ocular surface parameters, and the occurrence of complications were documented during a follow up period of 2 years. Attainment and maintenance of a stable ocular surface, as assessed by change in the ocular surface severity scores was the primary outcome measure, while change in CDVA was the secondary outcome measure.

RESULTS

The mean preoperative CDVA was 2.7± 0.5 logMAR, which improved to 1.5± 0.7 logMAR and 1.49± 0.98 postoperatively, at 1- and 2-year follow-up visit. Overall, 82.2% eyes (37/45) had improvement in visual acuity, 13.3% (6/45) experienced no change, whereas 2 eyes (4.4%) had worsening of visual acuity. The total ocular surface severity scores improved from a mean preoperative value of 29.1± 9.7 to 18.7± 7.2 postoperatively, at 2-year follow-up. Two eyes developed persistent epithelial defects, with progression to corneal melting requiring keratoplasty.

CONCLUSIONS

COMET allows successful and sustained restoration of ocular surface anatomy with functional improvement, in eyes with chronic sequelae of SJS.

The progress in corneal translational medicine

Cornea tissue is in high demand by tissue donation centres globally, and thus tissue engineering cornea, which is the main topic of corneal translational medicine, can serve as a limitless alternative to a donated human cornea tissue. Tissue engineering aims to produce solutions to the challenges associated with conventional cornea tissue, including transplantation and use of human amniotic membrane (HAM), which have issues with storage and immune rejection in patients. Accordingly, by carefully selecting biomaterials and fabrication methods to produce these therapeutic tissues, the demand for cornea tissue can be met, with an improved healing outcome for recipients with less associated harmful risks. In this review paper, we aim to present the recent advancements in the research and clinical applications of cornea tissue, applications including biomaterial selection, fabrication methods, scaffold structure, cellular response to these scaffolds, and future advancements of these techniques.

Conjunctival reconstruction via enrichment of human conjunctival epithelial stem cells by p75 through the NGF-p75-SALL2 signaling axis

Severe conjunctival diseases can cause significant conjunctival scarring, which seriously limits eye movement and affects patients' vision. Conjunctival reconstruction remains challenging due to the lack of efficient methods for stem cells enrichment. This study indicated that p75 positive conjunctival epithelial cells (CjECs) were mainly located in the basal layer of human conjunctival epithelium and showed an immature differentiation state in vivo. The p75 strongly positive (p75++) CjECs enriched by immuno-magnetic beads exhibited high expression of stem cell markers and low expression of differentiated keratins. During continuous cell passage cultivation, p75++ CjECs showed the strongest proliferation potential and were able to reconstruct the conjunctiva in vivo with the most complete structure and function. Exogenous addition of NGF promoted the differentiation of CjECs by increasing nuclear localization of SALL2 in p75++ CjECs while proNGF played an opposite role. Altogether, p75++ CjECs present stem cell characteristics and exhibit the strongest proliferation potential so can be used as seed cells for conjunctival reconstruction, and NGF-p75-SALL2 signaling pathway was involved in regulating the differentiation of CjECs.

Phenotypic Characterization of Corneal Epithelium in Long-Term Follow-Up of Patients Post-Autologous Cultivated Oral Mucosal Epithelial Transplantation

PURPOSE

To analyze the phenotype of the corneal epithelium in patients with long-term follow-up who underwent autologous cultivated oral mucosal epithelial transplantation (COMET) using in vivo confocal microscopy (IVCM) and impression cytology with immunofluorescence staining (ICIF).

METHODS

Thirteen eyes from patients with severe limbal stem cell deficiency, who underwent COMET at least 48 months before, were recruited in this noncomparative cohort study. After eye examination, IVCM and ICIF were performed. Clinical manifestations of the cornea were evaluated and compared with epithelial findings detected by IVCM and ICIF [cytokeratin (CK) 3, CK7, and CK12]. Two corneal buttons derived from patients receiving the corneal transplantation post-COMET were sent for immunohistochemistry (CK3, CK6, CK7, CK12, paired box gene 6, p63, zonula occludens-1, and integrin β -1).

RESULTS

The mean age of patients was 51.2 ± 20.6 years, and the mean follow-up time since COMET was 78.7 ± 16.3 months. Six of 13 eyes showed clinically successful COMET. In these eyes, IVCM demonstrated predominant cornea-like epithelium and ICIF reported positivity for CK3 and CK12, confirming the presence of oral mucosal and corneal epithelium. Meanwhile, 7 eyes showed total conjunctivalization, corresponding with substantial conjunctival epithelium detected by IVCM and positivity for conjunctival (CK7) and oral mucosal epithelial (CK3) markers detected by ICIF. The immunohistochemistry of corneal buttons stained positive for oral mucosal, corneal epithelial, and stem cell markers (CK3, CK12, and p63).

CONCLUSIONS

In long-term follow-up of COMET, epithelium of successful patients demonstrated cornea-like phenotype, whereas failed cases revealed mainly conjunctival phenotype. However, there were evidences that oral mucosal epithelial cells remained across the cornea in both successful and failed COMET as detected by IVCM and ICIF.

A new standardized immunofluorescence method for potency quantification (SMPQ) of human conjunctival cell cultures

The aim of this study is to set up a standardized and reproducible method to determine the potency (= stem cell content) of human conjunctival cell cultures by means of immunofluorescence-based analyses. This will help the development of new Advanced Therapy Medicinal Products (ATMPs) to use in future cell therapy clinical studies when fewer cells are available to perform the quality controls. To achieve this purpose, a reference standard was investigated and the expression levels of ΔNp63α (considered as a marker of conjunctival stem cells) was correlated to cell size. The limbal hTERT cells were used as reference standard to define the expression value of ΔNp63α. The mean intensity value of limbal hTERT cells ranging between 15 and 20 µm in diameter was used to distinguish between ΔNp63α bright and not bright cells. As ΔNp63α bright expression was mainly seen in the smaller cell size group (10-15 µm), we defined as conjunctival stem cells (= potency) those cells which were bright and with sizes between 10 and 15 µm. Assays on cells from clonal analyses were used to validate the method, as they do allow to observe a decrease in potency (Holoclones > Meroclones > Paraclones). The stem cell content of conjunctival grafts was found to be 11.3% ± 5.0 compared to 21.9% ± 0.6, 9.0% ± 8.1 and 0% from Holoclones, Meroclones and Paraclones, respectively. This new method, here named as Standardized Method for Potency Quantification, will allow to detect the potency in conjunctival cell cultures, thus obtaining a quality control assay responding to the GMP standards required for ATMP release.

Recent Advances in Stem Cell Therapy for Limbal Stem Cell Deficiency: A Narrative Review

Destruction of the limbus and depletion of limbal stem cells (LSCs), the adult progenitors of the corneal epithelium, leads to limbal stem cell deficiency (LSCD). LSCD is a rare, progressive ocular surface disorder which results in conjunctivalisation and neovascularisation of the corneal surface. Many strategies have been used in the treatment of LSCD, the common goal of which is to regenerate a self-renewing, transparent, and uniform epithelium on the corneal surface. The development of these techniques has frequently resulted from collaboration between stem cell translational scientists and ophthalmologists. Direct transplantation of autologous or allogeneic limbal tissue from a healthy donor eye is regarded by many as the technique of choice. Expansion of harvested LSCs in vitro allows smaller biopsies to be taken from the donor eye and is considered safer and more acceptable to patients. This technique may be utilised in unilateral cases (autologous) or bilateral cases (living related donor). Recently developed, simple limbal epithelial transplant (SLET) can be performed with equally small biopsies but does not require in vitro cell culture facilities. In the case of bilateral LSCD, where autologous limbal tissue is not available, autologous oral mucosa epithelium can be expanded in vitro and transplanted to the diseased eye. Data on long-term outcomes (over 5 years of follow-up) for many of these procedures is needed, and it remains unclear how they produce a self-renewing epithelium without recreating the vital stem cell niche. Bioengineering techniques offer the ability to re-create the physical characteristics of the stem cell niche, while induced pluripotent stem cells offer an unlimited supply of autologous LSCs. In vivo confocal microscopy and anterior segment OCT will complement impression cytology in the diagnosis, staging, and follow-up of LSCD. In this review we analyse recent advances in the pathology, diagnosis, and treatment of LSCD.

Ex vivo cultivated oral mucosal epithelial cell transplantation for limbal stem cell deficiency: a review

Destruction or dysfunction of limbal epithelial stem cells (LESCs) leads to unilateral or bilateral limbal stem cell deficiency (LSCD). Fifteen years have passed since the first transplantation of ex vivo cultivated oral mucosal epithelial cells (COMET) in humans in 2004, which represents the first use of a cultured non-limbal autologous cell type to treat bilateral LSCD. This review summarizes clinical outcomes from COMET studies published from 2004 to 2019 and reviews results with emphasis on the culture methods by which grafted cell sheets were prepared.

Evaluation of chronic ocular sequelae in patients with symblepharon caused by ocular burns

AIM

To evaluate chronic ocular sequelae in patients with symblepharon caused by ocular burns and propose an objective grading system.

METHODS

This was a retrospective, single-center clinical study. Patients with symblepharon caused by ocular burns at least six months later were assessed. Chronic ocular sequelae were classified into 3 categories (eyelid, conjunctiva, and cornea) and 9 chronic ocular sequelae [friction factors, exposure factors, conjunctival hyperemia, length of symblepharon, scope of adhesion, lacrimal area adhesion, loss of the palisades of Vogt (POV), corneal neovascularization, and corneal opacification]. Each ocular sequela was graded from 0 to 3, depending on the increasing severity. The 9 ocular sequelae were evaluated to obtain the total severity score for each eye. The total severity score was defined as Grade I (1-9), Grade II (10-18), and Grade III (19-27). Moreover, the correlation between the severity of chronic ocular sequelae and visual acuity, surgical strategy, and the prognosis was analyzed, respectively.

RESULTS

Cases of 79 eyes with symblepharon caused by ocular burns were included in this study. Of these, 20 (25.32%) were defined as Grade I, 43 (54.43%) as Grade II, and 16 (20.25%) as Grade III. Eyes with a high total severity score had reduced visual acuity, required complicated surgery strategies, and poor prognosis (P<0.001). Multivariate regression analysis showed that the scope of adhesion, corneal opacification, and corneal neovascularization significantly affected visual acuity, surgical strategy, and prognosis (all P<0.001).

CONCLUSION

The evaluation of chronic ocular sequelae enabled the development of an objective grading system for patients with symblepharon caused by ocular burns. This grading system can be applied to guide the treatment and predict the prognosis.

Clinical trial to evaluate the therapeutic benefits of limbal-supported contact lens wear for ocular sequelae due to Stevens-Johnson syndrome/toxic epidermal necrolysis

PURPOSE

To analyze the therapeutic benefits of limbal-supported contact lens (CL) wear in patients with ocular sequelae due to Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN).

METHODS

This interventional study enrolled 10 chronic SJS/TEN eyes with a spectacle best-corrected visual acuity (BCVA) of between 0.01 and 0.7 that were fitted with a limbal-supported CL. At baseline and at after 3-months CL use, CL-wear BCVA and the 25-item National Eye Institute Visual Function Questionnaire (NEI VFQ-25) scores were measured, and then compared. Incidence rates and severities of adverse events were also analyzed.

RESULTS

At after 3-months CL use, BCVA with the fitted CL significantly improved compared to that with spectacle correction at baseline (LogMAR: 0.76-0.15) (P = 0.0039), all NEI VFQ-25 scores improved, however, only in ocular pain and mental health showed statistically significant improvement (P = 0.0078 and 0.0039). No serious adverse events were observed during the follow-up.

CONCLUSION

Wearing of the limbal-supported CL improved vision compared to spectacles and reduced ocular pain in patients with ocular sequelae due to SJS/TEN.

Stevens-Johnson syndrome/toxic epidermal necrolysis with severe ocular complications

Introduction: Stevens-Johnson syndrome (SJS) and its severe phenotype, toxic epidermal necrolysis (TEN), are acute inflammatory vesiculobullous reactions of the skin and mucosa. Approximately 50% of SJS/TEN patients diagnosed by dermatologists and in burn units suffer from severe ocular complications (SOC) in the acute stage.Areas covered: Earlier studies on patients with SJS/TEN with SOC identified cold medicines including multi-ingredient cold medications and non-steroidal anti-inflammatory drugs as the main eliciting drugs. HLA analyzes showed that genetic predisposition might play a role in the response to these drugs. Our analysis of the association between HLA genotypes and cold medicine-related SJS/TEN (CM-SJS/TEN) with SOC revealed that certain HLA genotypes play a role in the development of SJS/TEN with SOC. Genetic predisposition and other factors contributing to the elicitation of CM-SJS/TEN with SOC and the management of patients in the acute and chronic stage of the disease are discussed.Expert opinion: The main sequelae of SJS/TEN are ocular sequelae with visual disturbance. SJS/TEN with SOC needs ophthalmic treatment in addition to systemic treatment from the onset time to reduce the ophthalmic sequelae. In addition, HLA examination and public awareness of SJS/TEN with SOC due to cold medicine use might contribute to preventing visual disturbance due to SJS/TEN.Abbreviations: SJS: Stevens-Johnson syndrome; TEN: toxic epidermal necrolysis; SOC: severe ocular complications.

Clinical Outcomes From Cultivated Allogenic Stem Cells vs. Oral Mucosa Epithelial Transplants in Total Bilateral Stem Cells Deficiency

Total bilateral limbal stem cell deficiency results from various pathologies, from burns (either chemical or physical) to Sjogren Syndrome, aniridia or ocular cicatricial pemphigoid. After the loss of stem cells, normal corneal epithelium is replaced by a more opaque and vascularized conjunctival epithelium, causing loss of vision. After 1997, cultivation techniques for limbal stem cells became possible. In parallel, cultivation techniques for oral mucosa epithelial cells were also available. The aim of our review was to summarize the clinical outcomes following allogenic cultured limbal stem cell transplant (allogenic CLET), and on the other hand, oral mucosa derived epithelium transplant (cultivated oral mucosa epithelial transplant-COMET or cultivated autologous oral mucosal epithelial cell sheet-CAOMECS), in the case of total bilateral limbal stem cell loss. Thirty studies matching the inclusion criteria were found. The clinical improvement in both methods was reported similar, with percentages higher than 50% of the treated cases. However, the comparison between studies was difficult to achieve due to the lack of a universal and objective grading tool for assessing post-operative results. The definition of clinical improvement was problematic, because success was defined differently, depending on the study. Moreover, some of the studies followed both autologous and allogenic CLET, but described the results together, for both procedures, and therefore it was impossible to analyze them separately. COMET presented some advantages compared to CLET. By using autologous cells, there was no risk of immune activation and no immunosuppression was needed. COMET, however, might be associated with increased risk of persistent epithelial defects and graft failure, compared with allogenic CLET.

Clinical Trials of Limbal Stem Cell Deficiency Treated with Oral Mucosal Epithelial Cells

The corneal surface is an essential organ necessary for vision, and its clarity must be maintained. The corneal epithelium is renewed by limbal stem cells, located in the limbus and in palisades of Vogt. Palisades of Vogt maintain the clearness of the corneal epithelium by blocking the growth of conjunctival epithelium and the invasion of blood vessels over the cornea. The limbal region can be damaged by chemical burns, physical damage (e.g., by contact lenses), congenital disease, chronic inflammation, or limbal surgeries. The degree of limbus damage is associated with the degree of limbal stem cells deficiency (partial or total). For a long time, the only treatment to restore vision was grafting part of the healthy cornea from the other eye of the patient or by transplanting a cornea from cadavers. The regenerative medicine and stem cell therapies have been applied to restore normal vision using different methodologies. The source of stem cells varies from embryonic stem cells, mesenchymal stem cells, to induced pluripotent stem cells. This review focuses on the use of oral mucosa epithelial stem cells and their use in engineering cell sheets to treat limbal stem cell deficient patients.

Cellular therapy of corneal epithelial defect by adipose mesenchymal stem cell-derived epithelial progenitors

Background

Persistent epithelial defects (PED), associated with limbal stem cell deficiency (LSCD), require ocular surface reconstruction with a stable corneal epithelium (CE). This study investigated CE reformation using human adipose mesenchymal stem cells (ADSC), which derived epithelial progenitors via mesenchymal-epithelial transition (MET).

Methods

STEMPRO human ADSC were cultured with specific inhibitors antagonizing glycogen synthase kinase-3 and transforming growth factor-β signaling, followed by culture under a defined progenitor cell targeted-epithelial differentiation condition to generate epithelial-like cells (MET-Epi), which were characterized for cell viability, mesenchymal, and epithelial phenotypes using immunofluorescence and flow cytometry. Tissue-engineered (TE) MET-Epi cells on fibrin gel were transplanted to corneal surface of the rat LSCD model caused by alkali injury. Epithelial healing, corneal edema, and haze grading, CE formation were assessed by fluorescein staining, slit lamp bio-microscopy, anterior segment optical coherence tomography, and immunohistochemistry.

Results

CD73^high/CD90^high/CD105^high/CD166^high/CD14^negative/CD31^negative human ADSC underwent MET, giving viable epithelial-like progenitors expressing δNp63, CDH1 (E-cadherin), epidermal growth factor receptor, integrin-β4, and cytokeratin (CK)-5, 9. Under defined epithelial differentiation culture, these progenitors generated MET-Epi cells expressing cell junction proteins ZO1 and occludin. When transplanted onto rat corneal surface with LSCD-induced PED, TE-MET-Epi achieved more efficient epithelial healing, suppressed corneal edema, and opacities, when compared to corneas without treatment or transplanted with TE-ADSC. CE markers (CK3, 12, and CDH1) were expressed on TE-MET-Epi-transplanted corneas but not in other control groups.

Conclusion

Human ADSC-derived epithelial-like cells, via MET, recovered the CE from PED associated with LSCD. ADSC can be a viable adult stem cell source for potential autologous epithelial cell-based therapy for corneal surface disorders.

Diagnostic criteria for limbal stem cell deficiency before surgical intervention-A systematic literature review and analysis

An accurate diagnosis of limbal stem cell deficiency (LSCD) is the premise of an appropriate treatment; however, there is no consensus about the diagnostic criteria for LSCD. We performed a systematic literature search of the peer-reviewed articles on PubMed, Medline, and Ovid to investigate how LSCD was diagnosed before surgical intervention. The methods used to diagnose LSCD included clinical presentation, impression cytology, and in vivo confocal microscopy. Among 131 eligible studies (4054 eyes), 26 studies (459 eyes, 11.3%) did not mention the diagnostic criteria. In the remaining 105 studies, the diagnosis of LSCD was made on the basis of clinical examination alone in 2398 eyes (62.9%), and additional diagnostic tests were used in 1047 (25.8%) eyes. Impression cytology was used in 981 eyes (24.2%), in vivo confocal microscopy was used in 29 eyes (0.7%), and both impression cytology and in vivo confocal microscopy were used in 37 eyes (0.9%). Our findings suggest that only a small portion of patients underwent a diagnostic test to confirm the diagnosis of LSCD. Treating physicians should be aware of the limitations of clinical examination in diagnosing LSCD and perform a diagnostic test whenever possible before surgical intervention.

Recovering vision in corneal epithelial stem cell deficient eyes

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Corneal limbal epithelial stem cells deficiencies cause severe ocular surface instability and visual impairment.

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These conditions, caused by injury or disease, are very difficult to treat.

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Laboratory-grown epithelial cell sheets expanded from healthy limbal tissue can be used to reconstruct the ocular surface.

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Other epithelia, such as the oral mucosa, can be used to generate the therapeutic cell sheets.

A healthy corneal epithelium, which is essential for proper vision and protection from external pathogens, is continuously replenished throughout life by stem cells located at the limbus. In diseased or injured eyes, however, in which stem cells are deficient, severe ocular problems manifest themselves. These are notoriously difficult to manage and as a result the last 20 or so years has seen a number of therapeutic strategies emerge that aim to recover the ocular surface and restore vision in limbal stem cell deficient eyes. The dominant concept involves the generation of laboratory cultivated epithelial cell sheets expanded from small biopsies of the epithelial limbus (for patient or donors) or another non-corneal epithelial tissue such as the oral mucosa. Typically, cells are grown on sterilised human amniotic membrane as a substrate, which then forms part of the graft, or specially formulated plastic culture dishes from which cells sheets can be released by lowering the temperature, and thus the adherence of the plastic to the cells. Overall, clinical results are promising, as is discussed, with new cultivation methodologies and different cell lineages currently being investigated to augment the treatment options for visual disturbance caused by a corneal epithelial limbal stem cell deficiency.

Ocular Surface Reconstruction Using Circumferentially-trephined Autologous Oral Mucosal Graft Transplantation in Limbal Stem Cell Deficiency

PURPOSE

To investigate the effects of transplantation of a circumferentially-trephined autologous oral mucosal graft using a vacuum trephine on ocular surface reconstruction in patients with limbal stem cell deficiency.

METHODS

Patients with a limbal stem cell deficiency who underwent transplantation of autologous oral mucosal graft performed by a particular surgeon in Seoul National University Hospital were included. The medical records of these five patients were retrospectively reviewed. The lower labial mucosal graft inside the inferior lip was trephined to a depth of 250 μm using a donor vacuum trephine with a 9-mm diameter. Outside markings were made using a 14-mm intraoperative keratometer. The oral mucosal graft was dissected under a microscope using a Beaver mini-blade as either a ring or a crescent-shaped strip with a 5-mm width. The mucosal graft was transplanted onto the limbus in the limbal-deficient eye. Best-corrected visual acuity and corneal status were measured during the follow-up period.

RESULTS

Four patients were diagnosed with Stevens-Johnson syndrome and one was diagnosed with atopy-associated immune keratitis. The mean follow-up period was 10.4 ± 2.9 months. After 4 months, visual acuity improved in all patients, and the mean improvement in logarithm of the minimum angle of resolution visual acuity was 0.526 ± 0.470 (range, 0.15 to 1.10). Corneal surface erosion and neovascularization decreased in four patients, and stromal opacity decreased in two patients. The engraftments maintained ocular surface stabilization in four of the five patients at the last follow-up.

CONCLUSIONS

Transplantation of circumferential autologous oral mucosal grafts may be effective for the treatment of limbal stem cell deficiency.

Comparison of the efficacy of different cell sources for transplantation in total limbal stem cell deficiency

PURPOSE

The purpose of this study was to compare the efficacy of allogeneic cultured limbal epithelial transplantation (ACLET) and cultivated oral mucosal epithelial transplantation (COMET) in treating total limbal stem cell deficiency (LSCD).

METHODS

In this retrospective cohort study, 73 patients (76 eyes) with total LSCD, including 41 patients (42 eyes) treated with ACLET and 32 patients (34 eyes) receiving COMET, were evaluated. The age, gender and injury cause of all patients were recorded.

RESULTS

The mean follow-up was 23.3 ± 9.9 months in the ACLET group and 16.1 ± 5.8 months in the COMET group. A higher incidence of persistent epithelial defect was observed after COMET (P = 0.023). The overall ocular surface grading scores were all lower in the ACLET group than in the COMET group at 3, 6, and 12 months after surgery and the last follow-up. Kaplan-Meier survival curve analysis demonstrated a significantly higher success rate of ACLET (71.4%), compared with that of COMET (52.9%; P = 0.043). The risk of graft failure was higher in patients with entropion and trichiasis, incomplete eyelid closure and treated with COMET. The graft failure risk rate after COMET was 3.5 times higher than that of ACLET.

CONCLUSIONS

For total LSCD patients, ACLET should be prioritized, since limbal epithelial cells have better ability to maintain corneal epithelial integrity and ocular surface stability and benefit the ocular surface when compared with oral mucosal epithelial cells. Preoperative and postoperative eyelid abnormalities should be corrected as early as possible.

Expression of prostaglandin E2 receptor 3 in the eyelid epidermis of patients with Stevens-Johnson syndrome/toxic epidermal necrolysis

Background/aims

In a previous genome-wide association study of Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) patients we reported the association between SJS/TEN and the prostaglandin E receptor 3 (PTGER3) gene, and that its protein PGE2 receptor 3 (EP3) was markedly downregulated in the conjunctival epithelium of SJS/TEN patients. Here we examined EP3 expression of the eyelid epidermis in SJS/TEN patients with severe ocular complications and investigated the function of EP3.

Methods

For the immunohistochemical study, we obtained eyelid samples from five SJS/TEN patients and five patients without SJS/TEN (control subjects) who were undergoing surgery to treat trichiasis, and investigated the expression of EP3 protein in the epidermis of those samples. To investigate the EP3 function in the human epidermal keratinocytes, we performed ELISA and quantitative reverse transcription polymerase chain reaction, since it is reported that PGE2 suppresses cytokine production via EP3 in human conjunctival epithelium.

Results

The results of the immunohistochemical study revealed that EP3 expression in the eyelid epidermis of the SJS/TEN patients was the same as that in the controls. PGE2 and a selective EP3 agonist suppressed cytokine production and expression induced by polyinosine-polycytidylic acid stimulation, such as chemokine ligand 5 and chemokine motif ligand 10.

Conclusion

Our findings revealed that in chronic-phase SJS/TEN, EP3 protein was expressed in the eyelid epidermis and was not downregulated, unlike in conjunctival epithelium, and that PGE2 could suppress cytokine production via EP3 in human epidermal keratinocytes. Thus, EP3 expression in the epidermis might contribute to a silencing of skin inflammation in chronic-phase SJS/TEN.

Limbal Stem Cell Transplantation: Clinical Results, Limits, and Perspectives

Limbal stem cell deficiency (LSCD) is a clinical condition characterized by damage of cornea limbal stem cells, which results in an impairment of corneal epithelium turnover and in an invasion of the cornea by the conjunctival epithelium. In these patients, the conjunctivalization of the cornea is associated with visual impairment and cornea transplantation has poor prognosis for recurrence of the conjunctivalization. Current treatments of LSCD are aimed at replacing the damaged corneal stem cells in order to restore a healthy corneal epithelium. The autotransplantation of limbal tissue from the healthy, fellow eye is effective in unilateral LSCD but leads to depauperation of the stem cell reservoir. In the last decades, novel techniques such as cultivated limbal epithelial transplantation (CLET) have been proposed in order to reduce the damage of the healthy fellow eye. Clinical and experimental evidence showed that CLET is effective in inducing long-term regeneration of a healthy corneal epithelium in patients with LSCD with a success rate of 70%–80%. Current limitations for the treatment of LSCD are represented by the lack of a marker able to unequivocally identify limbal stem cells and the treatment of total, bilateral LSCD which requires other sources of stem cells for ocular surface reconstruction.

Emerging Therapeutic Strategies for Limbal Stem Cell Deficiency

Identification and characterization of the limbal epithelial stem cells (LESCs) has proven to be a major accomplishment in anterior ocular surface biology. These cells have been shown to be a subpopulation of limbal epithelial basal cells, which serve as the progenitor population of the corneal epithelium. LESCs have been demonstrated to play an important role in maintaining corneal epithelium homeostasis. Many ocular surface diseases, including intrinsic (e.g., Sjogren's syndrome) or extrinsic (e.g., alkali or thermal burns) insults, which impair LESCs, can lead to limbal stem cell deficiency (LSCD). LSCD is characterized by an overgrowth of conjunctival-derived epithelial cells, corneal neovascularization, and chronic inflammation, eventually leading to blindness. Treatment of LSCD has been challenging, especially in bilateral total LSCD. Recently, advances in LESC research have led to novel therapeutic approaches for treating LSCD, such as transplantation of the cultured limbal epithelium. These novel therapeutic approaches have demonstrated efficacy for ocular surface reconstruction and restoration of vision in patients with LSCD. However, they all have their own limitations. Here, we describe the current status of LSCD treatment and discuss the advantages and disadvantages of the available therapeutic modalities.

Identification and In Vitro Expansion of Buccal Epithelial Cells

Ex vivo-expanded buccal mucosal epithelial (BME) cell transplantation has been used to reconstruct the ocular surface. Methods for enrichment and maintenance of BME progenitor cells in ex vivo cultures may improve the outcome of BME cell transplantation. However, the parameter of cell seeding density in this context has largely been neglected. This study investigates how varying cell seeding density influences BME cell proliferation and differentiation on tissue culture polystyrene (TCPS). The highest cell proliferation activity was seen when cells were seeded at 5×10⁴ cells/cm². Both below and above this density, the cell proliferation rate decreased sharply. Differential immunofluorescence analysis of surface markers associated with the BME progenitor cell population (p63, CK19, and ABCG2), the differentiated cell marker CK10 and connexin 50 (Cx50) revealed that the initial cell seeding density also significantly affected the progenitor cell marker expression profile. Hence, this study demonstrates that seeding density has a profound effect on the proliferation and differentiation of BME stem cells in vitro, and this is relevant to downstream cell therapy applications.