P09-A130†Management of an eye bank with organ-cultured and hypothermic corneas: microbiology in endothelial grafts.

PURPOSE: To analyse the microbiologic control results taken during the processing of hypothermic and cultured corneas for endothelial transplants comparing the two groups from January to September 2022. METHODS: The microbiological controls of hypothermic corneas prepared for DSAEK or DMEK are: Transport Eusol control (pre-manipulation) and new Eusol control (post-manipulation). In cultured corneas the number of controls is increased to 4: first culture medium, evaluation culture medium, transport medium 24 hours post-evaluation and transport medium post-manipulation. RESULTS: A total of 1438 corneas were processed for transplant during the 9 months studied (321 fresh corneas and 1113 cultured corneas). A total of 557 corneas were prepared for DSAEK or DMEK, from which 89 (15,98%) were hypothermic corneas and 468 (84.O2%) were cultured. From hypothermic corneas, 65 were cut for DSAEK and with 24 corneas, pre-stripping for DMEK was done. In the case of cultured corneas, 187 were cut for DSAEK and with 281 pre-stripping for DMEK was done. The number of corneas with positive results in the microbiological controls were 15 (16,85%) in the case of fresh corneas (in 7 corneas that were prepared for DSAEK and in 8 for DMEK) and 4 cases (0,85%) in cultured corneas (in 3 corneas for DSAEK and in 1 corneas for DMEK) resulting in a clear difference between both preservation methods. Bio-surveillance notifications notified during the studied period have been a total of 5, from which 2 were SAE in hypothermic corneas and other 2 were SAE and 1 SAR, in cultured corneas, all for endothelial transplantations. CONCLUSION: The number of positive results for microorganisms was higher in the case of hypothermic corneas and the Bio-surveillance notifications were also a little bit higher in hypothermic corneas (2,25%) comparing to organ cultured corneas (0.64%). The management of an eye bank with both preservation systems is challenging with its advantages and disadvantages. The main disadvantage of hypothermic corneas is the risk of not detecting contaminations because the corneas are released without any definitive results but it is compensated by the fact that they allow us to respond to emergencies, tissue returns, apart from the economic aspect.

Lyophilized amniotic membrane graft for primary pterygium surgery: preliminary results.

The aim of this study was to investigate the tolerability, safety and efficacy of new lyophilized amniotic membrane (LAM) presentation for ocular use. A prospective case-series cohort of four patients with primary nasal pterygium which undergone excision and LAM implantation was evaluated for complications and clinical outcomes. Surgical manipulation of LAM was also assessed. LAM was stiff and easy to manipulate as well as no tearing occurred during surgery or suturing. Ocular comfort was checked and similar among those patients with LAM glued or sutured. After 12 months, there were no issues about tolerability or adverse events. Lower cosmetic outcomes (recurrence) were stated in 3 patients. Our study showed that LAM could be an effective alternative to cryopreserved amniotic membrane for graft after pterygium excision surgery. Its main advantage, storage at room temperature, can make it of immediate availability. Further studies comparing clinical outcomes of pterygium surgery with cryopreserved amniotic membrane versus LAM would confirm the benefits of the last.

Amniotic membrane extract eye drops: a new approach to severe ocular surface pathologies.

A protocol for processing amniotic membrane as an extract to be re-hydrated and administered topically as eye drops (amniotic membrane extract eye drops, AMEED) has been developed. Safety and efficacy of AMEED was assessed in patients with severe ocular surface pathologies. prospective clinical follow-up of ocular surface symptoms before and after regular application of the AMEED for at least 4 weeks on patients with severe ocular surface disorders as chronic dry eye disease, limbal stem cell deficiency, neurotrophic ulcer and permanent and disabling symptomatology that were refractory to conventional treatment. Efficacy and tolerability were assessed based on patient-reported symptoms, objective measurements, and reports of adverse events. Thirty-six eyes from 25 patients were included. Although the visual quality function score, by means of a VQF25 questionnaire, was not statistically different after the treatment (p = 0.4657), there was a clear trend, statistically significant, towards the improvement in ocular symptoms like foreign body sensation, itching and stinging (p < 0.05) and clinical presentation of the pathology. All patients with corneal ulcer showed complete epithelization. Topically applied AMEED proved to be safe, well tolerated and effective in reducing the symptoms and clinical signs of severe ocular disease. Further studies are needed to confirm the best indications for AMEED use.

30†A new step on amniotic membrane extract eye drops (AMEED) development for the treatment of severe ocular surface pathologies.

INTRODUCTION: Our tissue establishment developed a protocol for processing amniotic membranes as extracts to be re-hydrated and administered topically as eye drops, becoming a new approach to treat severe ocular surface pathologies. From 2015 to 2017 the safety and efficacy of the amniotic membrane extract eye drops (AMEED) were assessed in patients with severe ocular surface pathologies through clinical follow-up of ocular surface symptoms before and after regular application of the extract.Between 2018 and 2019 a study of 36 patients (50 eyes) treated with topical AMEED was conducted comparing 2 groups of patients: Dry Eye Disease (DED) and Wound Healing Delay (WHD) showing global similar symptomatic improvement in both groups (DED 88.9% vs WHD 100%; p= 0.486) with the WHD group especially consisting in general relief (78%) and DED group reporting more pain improvement (44%) (p=0.011). Regarding patients with autologous serum as previous treatment, no statistical differences were found in subjective or objective improvement. An overall success was achieved in 94.4% of the cases and no adverse events were found. From January 2020 to November 2021 a growth stage has been observed including more patients while optimizing and scaling the process from donation to clinical use. MATERIALS AND METHODS: We record data of placenta donation and preparation of AMEED vials from 1/1/2020 to 30/11/2021 and its clinical use including the indications for treatment, number of requesting ophthalmologists and number of patients. RESULTS: In the study period a total of 378 placentas were processed to obtain AMEDD (61 in 2020 and 317 in 2021). The number of suitable vials obtained were: 1845 and 6464 respectively and 1946 vials are stored in quarantine pending release for clinical use.A total of 9365 vials were sent for treatment of ocular surface pathologies to 31 hospitals (98% in Catalonia) and 69 requesting ophthalmologists.The total number of patients treated was 204 and the indications for treatment were 82% DED and 18% WHD. CONCLUSION: After the new product development and introduction stages, a significant increase in the use of AMEED in Catalan hospitals was observed in 2020-2021. Follow-up data of these patients should be assessed to demonstrate its efficacy and achieve the maturity stage.

38†Lyophilized amniotic membrane for pterygium surgery: long-term outcomes.

PURPOSE: To investigate the tolerability, security and long-term efficacy of lyophilized amniotic membrane (LAM) as an alternative to cryopreserved amniotic membrane in pterygium surgery. MATERIAL AND METHODS: Prospective case series of patients with primary nasal pterygium who undergone pterygium surgery and LAM implant either with sutures or glue. Postoperative follow-up was until month 24. Clinical and cosmetic outcomes, quality of life (as ocular comfort), and complications were evaluated. RESULTS: LAM was stiff and easy to manipulate as well as no tearing occurred during surgery or suturing. 4 patients (3 males) had pterygium surgery and LAM implant two with sutures and the other two with glue. Ocular comfort was checked and similar among those patients with LAM glued or sutured. After 24 months, there were no issues about tolerability or adverse events. Lower cosmetic outcomes (recurrence) were stated in 3 patients. CONCLUSION: Our study showed that LAM could be an effective alternative to cryopreserved amniotic membrane for graft after pterygium excision surgery. Its main advantage, storage at room temperature, can make it of immediate availability. Further studies comparing clinical outcomes of pterygium surgery with cryopreserved amniotic membrane versus LAM would confirm the benefits of the last.

4†New strategies in the barcelona eye bank to minimize the impact of the COVID-19 pandemic.

Since the start of the pandemic, the tissue donation in Catalonia (Spain) has decreased drastically. At the beginning of the lockdown (from March to May 2020) there was a drop of around 70% in donation of corneas and of approximately 90% in donation of placentas. Despite the fast updating of standard operating procedures, we had big difficulties in different points. For instance, in the availability of the transplant coordinator for the donor detection and evaluation, in obtaining the necessary PPE (personal protective equipment), or in the resources available in the quality control laboratories for screening. This, added to the collapse that hospitals suffered due to the large number of patients hospitalized each day, made donation levels slowly rebound.In order to provide solutions to all patients, we tried to adapt quickly to these emerging changes.In the case of corneas, we found a scenario that we had never had before. Although the cornea transplant plummeted at the beginning of the confinement (decreased by 60% compared to 2019), we run out of corneas -even for emergency situations- at the end of March.This situation led us to develop a new type of therapeutic solution in our Eye Bank. The cryopreserved cornea for tectonic purposes is a tissue that is kept frozen at -196°C and can be preserved for up to 5 years. Therefore, it is a tissue that allows us to respond to possible emergencies in subsequent similar situations.Regarding amniotic membrane for ocular care indications, the strategy was completely different. For this kind of tissue, we carried out an adaptation of our processing with two different purposes. On the one hand, to make sure that we could inactivate the SARS-CoV-2 virus, if it was there. On the other hand, to increase the donation of placentas. For this, changes in the transport medium and in the antibiotic cocktail were performed. In addition, an irradiation step was added to the final product.Little by little, it seems that the donations of corneas and placentas have been recovering. However, it is necessary to think about future contingency strategies in case a stop in donation is repeated.

Priming human adipose-derived mesenchymal stem cells for corneal surface regeneration.

Limbal stem cells (LSC) maintain the transparency of the corneal epithelium. Chemical burns lead the loss of LSC inducing an up-regulation of pro-inflammatory and pro-angiogenic factors, triggering corneal neovascularization and blindness. Adipose tissue-derived mesenchymal stem cells (AT-MSC) have shown promise in animal models to treat LSC deficiency (LSCD), but there are not studies showing their efficacy when primed with different media before transplantation. We cultured AT-MSC with standard medium and media used to culture LSC for clinical application. We demonstrated that different media changed the AT-MSC paracrine secretion showing different paracrine effector functions in an in vivo model of chemical burn and in response to a novel in vitro model of corneal inflammation by alkali induction. Treatment of LSCD with AT-MSC changed the angiogenic and inflammatory cytokine profile of mice corneas. AT-MSC cultured with the medium that improved their cytokine secretion, enhanced the anti-angiogenic and anti-inflammatory profile of the treated corneas. Those corneas also presented better outcome in terms of corneal transparency, neovascularization and histologic reconstruction. Priming human AT-MSC with LSC specific medium can potentiate their ability to improve corneal wound healing, decrease neovascularization and inflammation modulating paracrine effector functions in an in vivo optimized rat model of LSCD.

Amniotic membrane extract eye drops for ocular surface diseases: use and clinical outcome in real-world practice.

PURPOSE: To study the indications and clinical outcomes, in a real-word setting, of amniotic membrane extract eye drops (AMEED) use for ocular surface disease (OSD). METHODS: A retrospective study of patients treated with topical AMEED between January 2018 and January 2020 was conducted. Patients were classified in two groups according to specific OSD-dry eye disease (DED) and wound healing delay (WHD) groups. Demographics, comorbidities, treatment duration and clinical outcomes were analysed. RESULTS: A total of 50 eyes of 36 patients with or without previous treatments were included. Patients in the DED group presented more systemic comorbidities (83 vs 22%; p < 0.001) and spent more mean time under AMEED treatment (10 vs 7.2 months average) than the WHD group (p = 0.0104). In four patients, long-term treatment (more than 24 months) was reported. Global similar symptomatic improvement was reported for both groups (DED 88.9% vs WHD 100%; p = 0.486), with the WHD group especially consisting in general relief (78%) and the DED group reporting more pain improvement (44%) (p = 0.011). Regarding patients with autologous serum as a previous treatment, no statistical differences were found in subjective or objective improvement. An overall success was achieved in 94.4% of the cases and no adverse events were found. CONCLUSION: AMEED administration is a promising mean to treat OSD such as dry eye, persistent epithelial defect and corneal ulcers. Although AMEED may be effective in the treatment of severe DED and persistent epithelial defect or corneal ulcers, conclusions are limited owing to the absence of controlled clinical trials.

Xenofree generation of limbal stem cells for ocular surface advanced cell therapy.

BACKGROUND: Limbal stem cells (LSC) sustain the corneal integrity and homeostasis. LSC deficiency (LSCD) leads to loss of corneal transparency and blindness. A clinical approach to treat unilateral LSCD comprises autologous cultured limbal epithelial stem cell transplantation (CLET). CLET uses xenobiotic culture systems with potential zoonotic transmission risks, and regulatory guidelines make necessary to find xenofree alternatives. METHODS: We compared two xenofree clinical grade media and two feeder layers. We used CnT07, a defined commercial medium for keratinocytes, and a modified xenofree supplemented hormonal epithelial medium with human serum (XSHEM). Optimal formulation was used to compare two feeder layers: the gold standard 3T3 murine fibroblasts and human processed lipoaspirate cells (PLA). We tested the expressions of ΔNp63α and cytokeratin 3 and 12 by qPCR and immunofluorescence. Morphology, viability, clonogenicity, proliferation, and cell growth assays were carried out. We also evaluated interleukin 6 (IL-6) and stromal-derived factor 1 (SDF-1) by qPCR and ELISA. RESULTS: XSHEM maintained better LSC culture viability and morphology than CnT07. Irradiated PLA feeder cells improved the undifferentiated state of LSC and enhanced their growth and clonogenicity stimulating IL-6 secretion and SDF-1 expression, as well as increased proliferation and cell growth when compared with irradiated 3T3 feeder cells. CONCLUSIONS: The combination of XSHEM and PLA feeder cells efficiently sustained LSC xenofree cultures for clinical application. Moreover, PLA feeder layers were able to improve the LSC potential characteristics. Our results would have direct clinical application in CLET for advanced therapy.

Limbal Stem Cells from Aged Donors Are a Suitable Source for Clinical Application.

Limbal stem cells (LSC) are the progenitor cells that maintain the transparency of the cornea. Limbal stem cell deficiency (LSCD) leads to corneal opacity, inflammation, scarring, and blindness. A clinical approach to treat this condition consists in LSC transplantation (LSCT) after ex vivo expansion of LSC. In unilateral LSCD, an autologous transplant is possible, but cases of bilateral LSCD require allogenic LSCT. Cadaveric donors represent the most important source of LSC allografts for treatment of bilateral LSCD when living relative donors are not available. To evaluate the suitability of aged cadaveric donors for LSCT, we compared three pools of LSC from donors of different ages (<60 years, 60-75 years, and >75 years). We evaluated graft quality in terms of percent of p63-positive (p63+) cells by immunofluorescence, colony forming efficiency, and mRNA and protein expression of p63, PAX6, Wnt7a, E-cadherin, and cytokeratin (CK) 12, CK3, and CK19. The results showed that LSC cultures from aged donors can express ≥3% of p63+ cells-considered as the minimum value for predicting favorable clinical outcomes after LSCT-suggesting that these cells could be a suitable source of LSC for transplantation. Our results also indicate the need to evaluate LSC graft quality criteria for each donor.

Potential Role of Induced Pluripotent Stem Cells (IPSCs) for Cell-Based Therapy of the Ocular Surface.

The integrity and normal function of the corneal epithelium are crucial for maintaining the cornea's transparency and vision. The existence of a cell population with progenitor characteristics in the limbus maintains a dynamic of constant epithelial repair and renewal. Currently, cell-based therapies for bio replacement-cultured limbal epithelial transplantation (CLET) and cultured oral mucosal epithelial transplantation (COMET)-present very encouraging clinical results for treating limbal stem cell deficiency (LSCD) and restoring vision. Another emerging therapeutic approach consists of obtaining and implementing human progenitor cells of different origins in association with tissue engineering methods. The development of cell-based therapies using stem cells, such as human adult mesenchymal or induced pluripotent stem cells (IPSCs), represent a significant breakthrough in the treatment of certain eye diseases, offering a more rational, less invasive, and better physiological treatment option in regenerative medicine for the ocular surface. This review will focus on the main concepts of cell-based therapies for the ocular surface and the future use of IPSCs to treat LSCD.

Dye solutions based on lutein and zeaxanthin: in vitro and in vivo analysis of ocular toxicity profiles.

PURPOSE: To study the safety profile of Lutein/Zeaxanthin(L/Z)-based natural dye solutions in in vitro and in vivo models. MATERIAL AND METHODS: In vitro cytotoxicity and cellular growth experiments were carried out on ARPE-19 and human corneal epithelial (HCE) cell lines using different L/Z-based dye solutions, either alone or in association with brilliant blue (BB) or trypan blue (TB). Light and transmission electron microscopy studies were performed seven days after intravitreal injection of dye solutions in rabbits. Electroretinogram (ERG) recordings were taken at baseline and before histopathology. RESULTS: In vitro cytotoxicity assays demonstrated that the different L/Z-based solutions (from 0.3 to 2%), either alone or in association with BB (0.025%) or TB (0.04%), did not significantly alter mitochondrial activity (≤15%) in the cell lines tested. In addition, in vitro cell growth was inhibited by up to 60% depending on the dye solution, and in direct proportion to the concentration assayed. There was no evidence of structural alterations in the neurosensory retina, retinal pigment epithelium (RPE), or choriocapillaris-choroidal complex. b-Wave ERG records showed no significant differences (±15.2%) in comparison with baseline. CONCLUSIONS: L/Z-based dye solutions demonstrated a safe profile in in vitro and in vivo models, and may be a useful tool for staining intraocular structures.

Progenitor cells for ocular surface regenerative therapy.

The integrity and normal function of the corneal epithelium are essential for maintaining the cornea's transparency and vision. The existence of a cell population with progenitor characteristics in the limbus maintains a dynamic of constant epithelial repair and renewal. Currently, cell-based therapies for bio-replacement, such as cultured limbal epithelial transplantation and cultured oral mucosal epithelial transplantation, present very encouraging clinical results for treating limbal stem cell deficiencies. Another emerging therapeutic strategy consists of obtaining and implementing human progenitor cells of different origins using tissue engineering methods. The development of cell-based therapies using stem cells, such as human adult mesenchymal stromal cells, represents a significant breakthrough in the treatment of certain eye diseases and also offers a more rational, less invasive and more physiological approach to ocular surface regeneration.

Characterization of ocular surface epithelial and progenitor cell markers in human adipose stromal cells derived from lipoaspirates.

PURPOSE: The goal of this study was to characterize and compare mesenchymal stem cells from adult human adipose tissue (ADS cells) with progenitor cell lines from the human corneoscleral limbus and to analyze their potential for the expression of epithelial markers. METHODS: Stem cell markers (CD34, CD90, p63, and ABCG2) and epithelial cell markers (CK3/76, CK12, CK76, CK19, and CK1/5/10/14) were analyzed by immunostaining, flow cytometry, Western blot analysis, and PCR methods. The authors assayed adhesion and proliferation on different extracellular matrix proteins. RESULTS: ADS cells expressed a set of progenitor cell markers, including p63 and ABCG2. CK12 expression in ADS cell cultures increased spontaneously and progressively by differential adhesion, which demonstrates the cells' potential and capability to acquire epithelial-like cell characteristics. The authors observed an increase in the adhesion and proliferation of ADS cells seeded onto different basement membrane extracellular matrix proteins. Laminin substrates reduced the proliferative state of ADS cells. CONCLUSIONS: The expression of putative stem cell markers (CD90, ABCG2, and p63) and cytokeratins (CK12 and CK76) supports the hypothesis that ADS cells have self-renewal capacity and intrinsic plasticity that enables them to acquire some epithelial-like characteristics. Therefore, adult ADS cells could be a potential source for cell therapy in ocular surface regeneration.