Limbal Stem Cell Transplantation Research Articles

TACSTD2 in gelatinous drop-like corneal dystrophy: variant functional analysis and expression in the cornea after limbal stem cell transplantation

Gelatinous drop-like corneal dystrophy (GDLD) is a rare autosomal recessive eye disease. GDLD is characterized by the loss of barrier function in corneal epithelial cells (CECs) and amyloid deposition due to pathogenic variants in the TACSTD2 gene. Limbal stem cell transplantation (LSCT) has been suggested as an effective therapeutic alternative for patients with GDLD. However, despite LSCT, amyloid deposition recurs in some patients. The pathogenesis of recurrence is poorly studied. We present the case of a patient with GDLD. Genetic analysis revealed a homozygous deletion, NM_002353.3:c.653del, in the TACSTD2 gene. Functional analysis in a cell model system revealed the loss of the transmembrane domain and subcellular protein mislocalization. The patient with GDLD underwent direct allogeneic LSCT with epithelial debridement followed by deep anterior lamellar keratoplasty 10 months later due to amyloid deposition and deterioration of vision. Taken together, the results of transcriptome analysis and immunofluorescence staining of post-LSCT corneal sample with amyloid deposits obtained during keratoplasty demonstrated complete restoration of wild-type TACSTD2 expression, indicating that donor CECs replaced host CECs. Our study provides experimental evidence that amyloid deposition can recur after LSCT despite complete restoration of wild-type TACSTD2 expression.

Limbal stem cell therapy.

To highlight the progress and future direction of limbal stem cell (LSC) therapies for the treatment of limbal stem cell deficiency (LSCD). Direct LSC transplantation have demonstrated good long-term outcomes. Cultivated limbal epithelial transplantation (CLET) has been an alternative to treat severe to total LSCD aiming to improve the safety and efficacy of the LSC transplant. A prospective early-stage uncontrolled clinical trial shows the feasibility and safety of CLET manufactured under xenobiotic free conditions. Other cell sources for repopulating of the corneal epithelium such as mesenchymal stem cells (MSCs) and induced pluripotent stem cells are being investigated. The first clinical trials of using MSCs showed short-term results, but long-term efficacy seems to be disappointing. A better understanding of the niche function and regulation of LSC survival and proliferation will lead to the development of medical therapies to rejuvenate the residual LSCs found in a majority of eyes with LSCD in vivo. Prior efforts have been largely focused on improving LSC transplantation. Additional effort should be placed on improving the accuracy of diagnosis and staging of LSCD, and implementing standardized outcome measures which enable comparison of efficacy of different LSCD treatments for different severity of LSCD. The choice of LSCD treatment will be customized based on the severity of LSCD in the future. New approaches for managing different stages of LSCD are being developed. This concise review summarizes the progresses in LSC therapies for LSCD, underlying mechanisms, limitations, and future areas of development.

Сравнительный анализ механического и фемтолазер-ассистированного методов выкраивания лимбальных мини-трансплантатов в эксперименте

Original article Experimental study of manual and femtosecond laser-assisted methods for cutting limbal mini-transplants B.E. Malyugin, S.A. Borzenok, O.N. Nefedova, D.S. Ostrovskii, M.Yu. Gerasymov, A.V. Shatskikh S. Fyodorov Eye Microsurger y Federal State Institution, Moscow, Russian Federation A. Yevdokimov Moscow State University of Medicine and Dentistr y, Moscow, Russian Federation Purpose. To define optimal parameters of femtosecond laser (FSL) (Femto LDV Z8, Ziemer, Switzerland) for cutting limbal mini-transplants to be further used for limbal stem cells (LSC) transplantation and compare the results with manual cutting technique using microsurgical blade. Material and methods. At first step, performed on 3 porcine and 3 cadaveric eyes, the optimal energy parameters of FSL were selected, which ensured the excision of limbal mini-transplants. At the second step, 8 eyes from 4 postmortem donors were used. In the lower and upper parts of the limbus, limbal fragments were cut out into 8 mini-transplants with a FSL (experimental group). Mini-grafts were also formed manually in symmetrical areas of each eye using dosed diamond blade (control group). The structure of the limbal bed after removing mini-transplants was studied by light and scanning electron microscopy. The effect of FSL energy on the viability of LSC was determined by intravital staining using Live & Dead dye. Finally, on the third step, the assessment of reversible and irreversible apoptosis was performed by culturing corneoscleral discs containing mini-transplants not separated from the limbal bed. The obtained samples were cultivated in a medium DMEM/F12 for 7 days followed by immunohistochemical examination. Results. The optimal parameters of FSL operation are determined by energy levels- 100, 110 and 120%. Histological analysis of the limbal residual bed zone showed that the smoothest surface was obtained at energies 110 and 120%. This fact was also confirmed by scanning electron microscopy. When stained with the Live & Dead dye, damage on the lateral and inner sides of limbal mini-transplants was revealed, mainly in the experimental group. After 7 days of cultivation in the cut area in both groups, no expression of apoptosis markers was observed. Conclusion. Cutting out the limbal zone containing LSCs using FSL is safe and allows obtaining limbal mini-grafts. The most optimal parameters of laser operation in the limbal zone were selected – a planar cut at depth of 250 µm using 110% laser energy. Key words: femtosecond laser, limbal stem cells, apoptosis, limbal stem cell deficiency syndrome, scanning electron microscopy, light microscopy, cultivation, histology

A Challenging Case of Simple Limbal Epithelial Transplantation (SLET) in Limbal Stem Cell Deficiency Following Chemical Injury: A Case Report

Introduction : Limbal stem cell deficiency (LSCD) often arises following trauma or inflammation that hinders corneal epithelium healing, commonly caused by chemical or thermal injuries. Despite significant advancements, treating LSCD remains challenging. This case highlights a challenging case of simple limbal epithelial transplantation (SLET) in LSCD following chemical injury.
 Case Illustration : A 20-year-old male presented with reduced vision in left eye following an alkaline chemical injury (grade III) was diagnosed with unilateral LSCD. Upon examination, conjunctivalization of the peripheral cornea, a central corneal cicatrix, and stromal neovascularization present after previous necrotomy, tenoplasty, and amniotic membrane transplantation (AMT). The patient then underwent SLET, with limbal biopsies from the collateral eye. Four months after surgery the visual acuity improved from 3/60 to 6/15 with spectacles. However, the cornea conjunctivalization still developed despite improved visual acuity.
 Discussion : To effectively manage the recurrence of stem cell deficiency, other stem cell transplantation techniques are needed to manage the problem. Combining different limbal stem cell transplantation approaches can be customised to address the problem and achieve lasting results.
 Conclusion : Prompt diagnosis and treatment of LSCD is crucial to prevent complications and blindness. SLET is a surgical option for LSCD after chemical injury, but this report highlights a challenging case and the need for the alternatives approaches.

Medical and surgical management of neurotrophic keratopathy

Neurotrophic Keratopathy (NK) is not a specific disease entity but a consequence of several conditions with varied aetiopathogenesis, of which a loss or reduction in corneal sensitivity is the hallmark. NK is clinically graded as Mild (stage1), Moderate (stage 2) and Severe (stage 3). The grading helps in understanding severity and planning treatment. Management can be considered in two parts. The first is the management of the underlying condition when active, for example herpes virus keratitis, bacterial ulcers and immune mediated ulcerative keratitis; and the second part, which deals with treatment of the non‐healing epithelial defect, stromal melting with or without vascularization and perforation that remains due to epithelial, stromal and corneal nerve pathology.Management of mild and moderate NK begins with the identification and elimination of any obvious underlying cause such as neuroleptic, antipsychotic, antihistamine and other systemic medications, preservatives in long term topical medications; and treatment of concurrent ocular surface infection. Tear substitutes and anti‐inflammatory agents both steroids and specific immunosuppressors like cyclosporin and lifitegrast should be used early. Antibiotics can be used prophylactically or to treat subclinical or overt infection. Medication with preservatives should be avoided. Prevention of progression to severe (stage 3) NK can be achieved with antiproteases such as citrate, tetracyclines and macrolides. Substrate re‐generating agents like Cacicol and promoters of epithelial regeneration like co‐enzyme Q10 target aspects of the underlying pathology. The introduction of recombinant human nerve growth factor (rh)NGF (Cenegermin/Oxervate) has provided specific therapy that addresses the basic defect related to corneal nerves. Insulin drops are proving to be useful and amniotic membrane extracts/amniotic fluid has also been tried. Autologous and pooled allo serum or plasma drops, which provide a variety of known and unknown factors have also proved useful but may at times aggravate the condition. Usually a combination of two or more of the above are required but rhNGF and insulin hold considerable promise for long term remission.Medical treatment is often augmented with non‐surgical interventions such as bandage contact lens, padding, punctal plugs, botulinum toxin, frost suture and glue. These are primarily designed to deal with exposure, dry eyes and reduce the abrasive effect of lid blinks, to promote healing. Useful surgical procedures include tarsorrhaphy, amniotic and conjunctival grafts, penetrating and lamellar keratoplasty and limbal stem cell transplants. Surgical interventions are designed to augment effects of the non‐surgical interventions, reduce scarring, deal with complications and restore sight. A key principle is that wound healing after any form of surgery or transplant, is poor if the corneal sensations remain impaired or absent.

Limbal Epithelial Stem Cells Transplantation in Cases with Unilateral Limbal Stem Cell Deficiency Syndrome

This review presents well-known surgical techniques aimed at the treatment of unilateral limbal insufficiency syndrome. Among the many available techniques, one should especially highlight the so-called “simple limbal epithelial transplantation”, which has proven to be an effective, safe and generally available method of treating unilateral limbal insufficiency syndrome (SLN). It should be noted that the risks of recurrence of SLN remain significant, and the mechanisms of engraftment of transplanted limbal epithelial stem cells on the recipient’s eye are not fully understood. The review also considers options for new promising approaches to the possible solution of existing problems in the transplantation of limbal epithelial stem cells.

Clinical Outcome of Amniotic Membrane Transplantation in Chemically Injured Eyes

Purpose: To evaluate the clinical outcome of Amniotic Membrane Transplantation (AMT) in chemically injured eyes for ocular surface reconstruction. Methods: A prospective study of 30 consecutive chemically injured eyes was performed from December 2022 to May 2023 in National Institute of Ophthalmology & Hospital (NIO&H), Dhaka, Bangladesh. Twenty-seven patients (30 eyes having corrosive chemical injuries) were included in the study according to the inclusion & exclusion criteria. AMT was performed within 21 days of injury by single surgeon with modified surgical procedure. Post operative evaluation was done by Snellen chart, slit lamp biomicroscope and Schirmer-II test. Results: After 3 months of AMT, there was no pain or inflammation. Improvement of vision found in 20 (66.67%) of 30 eyes, 4 (13.33%) eyes of rest 10 eyes showed inaccurate Projection of Rays (PR) vision and rest 6 (20.0%) eyes of rest 10 eyes found deteriorated vision. Epithelialization occurred in all eyes. Twenty-four (80.0%) eyes had limbal stem cell deficiency and they experienced superficial corneal vascularization. Symblepharon was seen in 18 (60.0%) eyes, 6 (20.0%) of these 18 eyes developed marked conjunctival shortening with ankyloblepharon. None of the eyes showed perforation. Conclusions: AMT increases patient comfort and reduces inflammation. In mild burns, AMT alone restores corneal and conjunctival surfaces. In moderate to severe burns, it reduces conjunctival scarring sequelae, but does not prevent the sequelae of limbal stem cell deficiency that requires further limbal stem cell transplantation. In the acute stage, AMT has a protective role against the progressive melting and perforation. J.Natl.Inst.Ophthalmol.2023;6(1): 21-26

Ophthalmic manifestations and management considerations for emerging chemical threats.

Chemical agents have been utilized for centuries in warfare and pose a health threat to civilians and military personnel during armed conflict. Despite treaties and regulations against their use, chemical agent exposure remains a threat and measures to understand their effects and countermeasures for systemic and organ-specific health are needed. Many of these agents have ocular complications, both acute and chronic. This mini-review focuses on key chemical agents including vesicants (mustards, lewisite), nerve agents (sarin, VX), knockdown gasses (hydrogen cyanide), and caustics (hydrofluoric acid). Their ophthalmic manifestations and appropriate treatment are emphasized. Acute interventions include removal of the source and meticulous decontamination, as well as normalization of pH to 7.2-7.4 if alteration of the ocular pH is observed. Besides vigorous lavage, acute therapies may include topical corticosteroids and non-steroid anti-inflammatory therapies. Appropriate personal protective equipment (PPE) and strict donning and doffing protocols to avoid healthcare provider exposure are also paramount in the acute setting. For more severe disease, corneal transplantation, amniotic membrane graft, and limbal stem cell transplantation may be needed. Orbital surgery may be required in patients in whom cicatricial changes of the ocular surface have developed, leading to eyelid malposition. Multidisciplinary care teams are often required to handle the full spectrum of findings and consequences associated with emerging chemical threats.

Экспериментальное исследование биодеградации синтетических полимерных матриц как перспективных подложек для лимбальных стволовых клеток

Aim. To study in experimental conditions and conduct a comparative assessment of the terms of biodegradation of three different types of synthetic polyester matrices as promising carriers of limbal stem cells. Material and methods. We performed matrices from poly(lactide-glycolide) (PLG), poly(lactide-caprolactone) (PLC) and poly(ε-caprolactone) (PCL). On the basis of the S.M. Kirov Military Medical Academy (St. Petersburg) estimated the timing of the biodegradation of matrices from the PLG, PLC and PCL with a thickness of 5; 10 and 15 microns by binding in vitro to the ocular surface of laboratory animals. Results. During the study, the terms of biodegradation of matrices from PLG, PLC and PCL of various thickness were studied. The time of complete biodegradation of PCL matrices with a thickness of 5 μm was about 30 days, which is the most acceptable for the purpose of their transplantation to the eye surface. Conclusion. The obtained results indicate the possibility of using PLC as a material for the manufacture of matrix carriers with a thickness of 5 μm for the cultivation and transplantation of limbal stem cells. Keywords: poly (lactide-glycolide), poly (lactide-caprolactone), poly (ε-caprolactone), biodegradation, limbal stem cells.

Ocular Surface Regeneration by Limbal Stem Cells Therapies: State of the Art, Challenges, and Perspectives.

Limbal stem cells (LSCs) are adult stem cells located at the limbus ensuring the continuous renewal of the corneal epithelium, critical to maintain an optimal visual function. Damages to the LSCs or their niche microenvironment lead to limbal stem cell deficiency (LSCD), a potentially blinding disease. Transplantation of LSCs as a treatment for severe to total LSCD has gained popularity since 1980s, owing to the clinical success of the first direct limbal autograft transplantation. Recent advances in the understanding of the LSCs' molecular identity and regulation have enabled preclinical and clinical advancements of promising LSCs therapies. However, lack of standardization of the diagnostic methods, staging of the disease severity, manufacturing process, and clinical outcome measures have hindered the advancement of the therapy. To move these therapies to the clinic, optimization and standardization of the diagnostic strategy, cell product manufacturing, and assessment of clinical efficacy with potency assays are key points to the development of customized therapies. Recent findings suggest that residual LSCs exist in eyes presenting with clinical signs of total LSCD, which opens new therapeutic strategies for eyes with partial LSCD. Prospective, randomized, multicentric controlled clinical trials are necessary to determine the efficacy of different LSCs therapies for different stages of LSCD using a set of standardized outcome measures.

Case Report: Simultaneous penetrating keratoplasty with autologous simple limbal epithelial transplantation as an alternative to keratoprosthesis

Introduction and importance: This case report highlights the multidisciplinary approach required to achieve successful anatomical and functional outcomes, in an eye with total limbal stem cell deficiency (LSCD) associated with underlying corneal scarring and thinning. Presentation of case: A 59-year-old gentleman had poor visual recovery in the right eye (RE) following accidental carbide blast, 1-year before presenting to us. The visual acuity was counting fingers and clinical examination revealed cicatricial entropion involving the upper eyelid, total LSCD, corneal scarring with a central descemetocele and cataract in the RE. Prior to ocular surface reconstruction, entropion correction was performed. Three months later, penetrating keratoplasty combined with cataract surgery and intraocular lens implantation (penetrating keratoplasty (PK) triple), with autologous simple limbal epithelial transplantation (SLET) was performed. The visual acuity was 20/100, 18 months after the surgery, with a clear well-epithelized corneal graft and stable ocular surface. Discussion: LSCD is caused by a decrease in the population and /or function of the limbal epithelial stem cells. Limbal stem cell transplantation (LSCT) is warranted in eyes with total LSCD. In eyes with coexisting corneal scarring, LSCT alone may be inadequate to restore the vision. These eyes require simultaneous or sequential lamellar or full-thickness corneal transplantation for visual rehabilitation. Though, the existing literature favors a sequential approach, where LSCT is performed first followed by corneal transplantation, under certain circumstances such as a thin underlying cornea like in our case, corneal transplantation may have to be combined with LSCT to achieve optimal outcomes. Conclusion: Combining autologous SLET with PK can be performed for visual rehabilitation in eyes with unilateral total LSCD and underlying corneal thinning. Corneal and limbal graft survival is prolonged if existing adnexal comorbidities are addressed before any surgical intervention is planned and adequate time interval is allowed for the surface inflammation to subside.

Editorial introductions.

Current Opinion in Ophthalmology was launched in 1990. It is one of a successful series of review journals whose unique format is designed to provide a systematic and critical assessment of the literature as presented in the many primary journals. The field of Ophthalmology is divided into nine sections that are reviewed once a year. Each section is assigned a Section Editor, a leading authority in the area, who identifies the most important topics at that time. Here we are pleased to introduce the Journal's Section Editors for this issue. SECTION EDITORS Jimmy K. LeeJimmy K. LeeDr Jimmy Lee specializes in laser vision correction surgery. His surgical expertise also includes complex cataract surgery, anterior segment reconstruction, all forms of corneal transplantation, and limbal stem cell transplantation. Dr Lee's research interests are new technologies in refractive surgery and improving surgical techniques for endothelial keratoplasty (DSAEK and DMEK). A member of the American Academy of Ophthalmology and American Society of Cataract and Refractive Surgery, he has extensively lectured nationally and internationally on these topics. A Phi Beta Kappa graduate from Johns Hopkins University, USA, Dr Lee obtained his medical degree from Cornell University Medical College, USA. Following his residency at Albert Einstein Montefiore Hospital, he completed a fellowship in cornea, external diseases, and refractive surgery at the Wilmer Eye Institute of The Johns Hopkins Hospital and is a Diplomate of the American Board of Ophthalmology. Shahzad I. MianShahzad I. MianShahzad I. Mian, M.D., is a professor of ophthalmology and visual sciences in the University of Michigan Medical School. He also serves the Department as Vice Chair for Clinical Sciences and Learning. Dr. Mian earned his medical degree in 1996 from the Emory University School of Medicine. He then completed a residency at the Wills Eye Hospital of Thomas Jefferson University in Philadelphia. From 2000-02, he was a fellow in cornea and refractive surgery at Harvard Medical School, Massachusetts Eye and Ear Infirmary. He joined the U-M faculty in 2002 and was promoted to associate professor with tenure in 2010. He became professor of ophthalmology and visual sciences in 2016. His research focuses on eye banking, keratoplasty techniques, and ocular graft versus host disease. He served as director of the residency training program between 2004 and 2019 and previously served as fellowship director in the department. In 2003 and 2012, he received the Bergstrom Teaching Award presented by ophthalmology residents. Dr. Mian received the 2007 Anthony Adamis Award for Outstanding Research from the U-M Kellogg Eye Center, and the Senior Achievement Award from the American Academy of Ophthalmology. He received the Straatsma Award for resident education from the Association of University Professors in Ophthalmology in 2017 and the Payton Award for Eye banking from the Eye Bank Association of America in 2019. He serves as the Senior Medical Director for Eversight Eye banks as well as on the Board of Directors. He also serves on the Board of Directors for the Cornea Society and the Eye Bank Association of America. He also serves on the Residency Review Committee for Ophthalmology.

Case Report: Simultaneous penetrating keratoplasty with autologous simple limbal epithelial transplantation as an alternative to keratoprosthesis

Introduction and importance: This case report highlights the multidisciplinary approach required to achieve successful anatomical and functional outcomes, in an eye with total limbal stem cell deficiency (LSCD) associated with underlying corneal scarring and thinning. Presentation of case: A 59-year-old gentleman had poor visual recovery in the right eye (RE) following accidental carbide blast, 1-year before presenting to us. The visual acuity was counting fingers and clinical examination revealed cicatricial entropion involving the upper eyelid, total LSCD, corneal scarring with a central descemetocele and cataract in the RE. Prior to ocular surface reconstruction, entropion correction was performed. Three months later, penetrating keratoplasty combined with cataract surgery and intraocular lens implantation (penetrating keratoplasty (PK) triple), with autologous simple limbal epithelial transplantation (SLET) was performed. The visual acuity was 20/100, 18 months after the surgery, with a clear well-epithelized corneal graft and stable ocular surface. Discussion: LSCD is caused by a decrease in the population and /or function of the limbal epithelial stem cells. Limbal stem cell transplantation (LSCT) is warranted in eyes with total LSCD. In eyes with coexisting corneal scarring, LSCT alone may be inadequate to restore the vision. These eyes require simultaneous or sequential lamellar or full-thickness corneal transplantation for visual rehabilitation. Though, the existing literature favors a sequential approach, where LSCT is performed first followed by corneal transplantation, under certain circumstances such as a thin underlying cornea like in our case, corneal transplantation may have to be combined with LSCT to achieve optimal outcomes. Conclusion: Combining autologous SLET with PK can be performed for visual rehabilitation in eyes with unilateral total LSCD and underlying corneal thinning. Corneal and limbal graft survival is prolonged if existing adnexal comorbidities are addressed before any surgical intervention is planned and adequate time interval is allowed for the surface inflammation to subside.

The role of eye banking with cell-based therapies.

Cell-based therapies are an exciting new frontier in managing corneal diseases. The introduction of these novel therapies may provide new alternatives to corneal transplantation and decrease the dependence on donor corneal tissue. These changes have the potential to significantly impact eye banking in the future. The current article reviews current research involving cell-based therapy for treating corneal disorders, including cultivated limbal stem cell transplantation, limbal mesenchymal stem cells for stromal regeneration, and the use of human-cultivated endothelial cells. We will look at barriers to the development and implementation of these therapies. As corneal surgery expands to include cell-based therapies; eye banks will need to redefine their role to support the everchanging landscape of corneal surgery and the decreased demand for corneal donor tissue.

Midterm Outcomes of Autologous Glueless Simple Limbal Epithelial Transplantation for Unilateral Limbal Stem Cell Deficiency.

The aim of this study was to report the midterm outcomes of glueless simple limbal epithelial transplantation (G-SLET) as a novel modification of limbal stem cell transplantation in patients with unilateral limbal stem cell deficiency (LSCD). This was a single-center, retrospective, interventional case series. Analysis of the 6 months interim outcomes was performed for 11 patients with unilateral LSCD who underwent G-SLET without simultaneous keratoplasty. The primary outcome measure was clinical success, which was defined as a completely epithelialized, avascular, and stable corneal surface. Secondary outcome measures included LSCD staging, improvement in visual acuity, and corneal grading of the recipient eye before and after the intervention. Adverse events were monitored throughout the study period. At 6-month follow-up, clinical success was achieved in 9 of the 11 cases (81.8%) and partial success was observed in 2 cases (18.2%). Among the patients in the cohort, 54.5% improved to stage 0 LSCD. Seven patients experienced enhancement in visual acuity. All corneal grading parameters improved significantly. Six adverse events were registered in 5 cases and were successfully managed. An extended scar in the donor eye was observed in 1 patient. This study demonstrated the high efficacy and safety of the G-SLET technique in the management of unilateral LSCD. G-SLET should be considered as a viable alternative to the"classic" SLET technique, specifically in the geographic areas where the availability of the fibrin glue is limited due to regulatory, economical, or any other reasons.

Keratoprosthesis in dry eye disease.

Bilateral corneal blindness with severe dry eye disease (DED), total limbal stem cell deficiency with underlying corneal stromal scarring and vascularization, combined with adnexal complications secondary to chronic cicatrizing conjunctivitis is a highly complex situation to treat. In such eyes, procedures such as penetrating keratoplasty alone or combined with limbal stem cell transplantation are doomed to fail. In these eyes, keratoprosthesis (Kpro) or an artificial cornea is the most viable option, eliminating corneal blindness even in eyes with autoimmune disorders such as Stevens-Johnson syndrome, ocular mucous membrane pemphigoid, Sjogren's syndrome, and nonautoimmune disorders such as chemical/thermal ocular burns, all of which are complex pathologies. Performing a Kpro in these eyes also eliminates the need for systemic immunosuppression and may provide relatively early visual recovery. In such eyes, the donor cornea around the central cylinder of the Kpro needs to be covered with a second layer of protection to avoid desiccation and progressive stromal melt of the underlying cornea, which is a common complication in eyes with severe DED. In this review, we will focus on Kpro designs that have been developed to survive in eyes with the hostile environment of severe DED. Their outcomes in such eyes will be discussed.

Understanding Ocular Surface Inflammation in Tears Before and After Autologous Cultivated Limbal Epithelial Stem Cell Transplantation.

We aimed to determine the expression of inflammatory cytokines in the tears of patients with unilateral total limbal stem cell deficiency (TLSCD) caused by chemical burns before and after autologous cultivated limbal epithelial stem cell transplantation (CLET). Tear samples were collected from both eyes of 23 patients with unilateral TLSCD and 11 healthy controls, at fixed timepoints before and after CLET. Dissolved molecules were extracted from Schirmer's strips using a standardised method and analysed on an array plate of ten inflammatory cytokines (V-Plex Proinflammatory Panel 1 Human Kit, MSD). IL1β expression was significantly elevated in the TLSCD eye compared with the unaffected eye at baseline (p < 0.0001) but decreased to normal 3months post-CLET (p = 0.22). IL6 and IL8 were unaffected at baseline but significantly elevated in the TLSCD eyes at 1month post-CLET (p = 0.001 and p < 0.0001, respectively). IL6 returned to normal at 3months and IL8 at 6months post-CLET. There was a significant renewed increase in IL1β, IL6 and IL8 expression at 12months post-CLET (p < 0.0001, p = 0.0001 and p = 0.0003, respectively). IFNγ, IL10 and IL12p70 expression were significantly reduced in both eyes of patients with unilateral TLSCD at all timepoints. IL1β is a specific marker of inflammation in TLSCD eyes that could be therapeutically targeted pre-CLET to improve stem cell engraftment. At 12months post-CLET the spike in levels of IL1β, IL6 and IL8 coincides with cessation of topical steroids, suggesting ongoing subclinical inflammation. We therefore recommend not discontinuing topical steroid treatment in cases where penetrating keratoplasty is indicated; however, further investigation is needed to ascertain this. European Union Drug Regulating Authorities Clinical Trials Database (EuDRACT 2011-000608-16); ISRCTN (International Standard Randomised Controlled Trial Number (isrctn51772481).

Retracted: Acupoint Massage plus Recombinant Bovine Basic Fibroblast Growth Factor Ophthalmic Gel and Limbal Stem Cell Transplantation on Visual Quality, Corneal Refraction, and Aesthetic Outcome in Patients with Pterygium.

[This retracts the article DOI: 10.1155/2022/7103496.].

Limbal Stem Cell Deficiency: A Review Focusing on Staging, Diagnostic and Treatment Modalities

The cornea being a transparent tissue acts as a refractive surface as well as a protective barrier of the eye. The corneal epithelium is being continuously replaced and renewed by the Limbal Stem Cells (LSC). The turnover of corneal epithelium is brought about by asymmetrical differentiation and self-renewal of LSCs, their migration to the cornea and desquamation of current corneal epithelium. LSC are undifferentiated cells that acts as progenitors of corneal epithelium and maintains corneal homeostasis. LSC resides in its own microenvironment known as LSC niche, which are capable of sustaining these tissue regenerating cells. Any intrinsic factors (e.g., toxic epidermal necrolysis or mucous membrane pemphigoid), extrinsic factors (e.g., thermal burns, radiations, chemical burns) or genetic defects (e.g., aniridia) cause impairment of LSC or its niche leading to Limbal Stem Cell Deficiency (LSCD). LSCD is associated with invasion of cornea by conjunctival epithelium, corneal opacity, and visual impairment. The diagnostic modality of LSCD includes fluorescein staining and slit lamp examination, impression cytology, confocal scanning and anterior chamber optical coherence tomography. The staging of LSCD is important for deciding the treatment modalities. In LSCD, the most common treatment modality includes LSC transplant from a healthy eye. Non LSC transplantation techniques are being used to prevent allograft rejection. In this review article, the authors aim to summarise the existing knowledge of the aetiology, staging and treatment modalities of LSCD.

En Bloc Keratolimbal Allograft and Central Penetrating Keratoplasty: A Novel Surgical Technique in Severe Limbal Stem Cell Deficiency.

The purpose of this study was to present a novel surgical technique combining 360-degree keratolimbal allograft (KLAL) and simultaneous central keratoplasty termed en bloc KLAL with the central penetrating keratoplasty (PKP) performed in those cases with total limbal stem cell deficiency (LSCD) and corneal scars. Nine eyes of 9 patients underwent en bloc KLAL and central PKP between 2014 and 2016. All patients had bilateral total LSCD with total corneal opacity due to different etiologies. The exclusion criteria were previous limbal stem cell transplantation and the presence of active and uncontrolled ocular surface inflammation. The same donor globe was used for harvesting 360-degree KLAL and central PKP. The 1-piece integrity of the KLAL and PKP graft was preserved during the described technique. All patients received modified immunosuppressive regimens compatible with the Cincinnati solid organ transplantation protocol. The average age of patients was 58.6 ± 18.6 years. The diagnosis was mustard gas keratopathy in 6, herpes simplex keratitis in 1, and severe acid chemical burn in 2 patients. Seven patients were male. An integrated ocular surface without epitheliopathy and a clear cornea was achieved in 8 patients (88.8%) with an average of 6.5 years in follow-up. The average best-corrected visual acuity was 1.89 ± 0.18 (20/1600) preoperatively which improved to 1.02 ± 0.64 (20/200) logMAR in the postoperative period. Endothelial immune rejection episodes were observed in 3 patients. KLAL rejection was not observed in any patient. One patient required repeat PKP due to corneal graft failure. En bloc 360-degree KLAL and central PKP could simultaneously be performed in patients with total LSCD and corneal opacification.