Comparison of Amniotic Membrane Transplantation and Umbilical Cord Serum in Acute Ocular Chemical Burns: A Randomized Controlled Trial

Efficacy of Amniotic Membrane Grafting for the Treatment of Chemical and Thermal Ocular Surface Injuries: A Report by the American Academy of Ophthalmology

OBJECTIVE

To evaluate the published literature on the efficacy of amniotic membrane grafting (AMG) in the management of acute chemical and thermal ocular surface burns with respect to the rate of corneal re-epithelialization and improvement of visual acuity or corneal clarity.

METHODS

Literature searches were conducted in the PubMed database in May 2023 and updated in January 2024 and were limited to the English language without date restrictions. The searches yielded 474 citations; 58 were reviewed in full text, and 9 met the inclusion criteria. Four studies were rated level II, and 5 studies were rated level III. This assessment focuses on 3 level II articles that provided consistent primary and secondary outcomes but demonstrated suboptimal study design with respect to power calculations and lacked a priori sample-size calculations.

RESULTS

Amniotic membrane grafting significantly improved corneal re-epithelialization compared with medical therapy alone in eyes with moderate-grade burns. For severely burned eyes, AMG demonstrated no advantage over medical therapy. Additionally, AMG demonstrated no significant advantage over medical therapy for improved visual acuity or corneal clarity for moderate or severe ocular surface burns.

CONCLUSIONS

The best available level II evidence suggests that AMG in the setting of acute ocular surface burns has efficacy in hastening re-epithelialization in moderate burns. As an adjuvant to medical therapy, it did not demonstrate a benefit in improving re-epithelialization in severe burns or visual acuity or corneal clarity in either moderate or severe burns.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

The effect of platelet-rich plasma and sodium alginate hydrogel on corneal wound healing after corneal alkali burns in rats with computer-assisted anterior segment optical coherence tomography image analysis

Our objective was to determine the effect of a semi-synthetic sodium alginate hydrogel and its combination with platelet-rich plasma (PRP) on histopathological, biochemical, clinical, and anterior segment optical coherence tomography (AS-OCT) data. Alkali chemical burn of the cornea was induced. Injured rats were randomly divided into five equal groups and topically treated with phosphate-buffered saline (sham), platelet-rich plasma (PRP), 0.5% sodium citrate, a semi-synthetic sodium alginate hydrogel, or a combination of PRP and hydrogel (combined group) three times daily. The degree of corneal opacity (CO), corneal epithelial staining (CES), percentage of corneal epithelial defects (CEDP), degree of ciliary hyperemia (CH), neovascularization size (NVS), and extent of neovascularization (NVE) were evaluated. AS-OCT was performed at nine days, and then rats were sacrificed. Histological examination and enzyme-linked immunosorbent assays were performed to detect the concentrations of IL-1β and MMP-9 in the cornea. There were no significant differences between the groups regarding CEDP, CO, CES, CH, NVS, or NVE on the first day after corneal alkali burn injury (p > 0,05). At the last examination, CO was significantly lower in the PRP group than in the sham group (p = 0,044), while the CO concentrations were similar in terms of NVS (p > 0,05). Similarly, in terms of tissue MMP-9 levels, there were no significant differences between groups (p > 0,05). However, there was a significant difference in tissue IL-1β levels between the groups (p < 0,001). In the PRP and combined groups, the level of IL-1β was significantly lower than that in the sham group (p = 0,043 and p = 0,036, respectively). There was a significant difference in epithelial necrosis between the PRP, and it was the lowest in the combined group (p = 0,003). Epithelial thickness was highest in the combined group (p = 0,002). CEDP was significantly different at the last visit between the groups (p = 0.042). The fastest epithelial closing rate was observed for the combined group (p = 0,026). There was a significant negative correlation between tissue MMP-9 levels and corneal solidity and between tissue MMP-9 levels and the corneal area according to the AS-OCT measurements (p = 0,012 and p = 0,027, respectively). When used alone, topical hydrogel application did not significantly enhance the healing of corneal wounds. However, when combined with PRP, it leads to an increased rate of epithelial closure and neovascularization. This combination did not exacerbate inflammation or corneal opacity compared to PRP alone. The anticoagulant citrate solution in the PRP tube did not prove effective. The synergistic use of PRP and hydrogel could enhance epithelial thickness and reduce epithelial necrosis. The use of new parameters for corneal wound healing assessment was facilitated through AS-OCT image processing.

Management of Ocular Surface Inflammation with Persistent Epithelial Defects Using a Sutureless Human Amniotic Membrane Dehydrated Matrix: A Prospective Study Utilizing a Digital Ocular Surface Assessment Tool

Purpose

To report the outcomes of using a sutureless human amniotic membrane dehydrated matrix (HAMDM) in the management of a range of ocular surface conditions utilizing a digital ocular surface disease assessment tool.

Methods

Two UK NHS Trusts - Queen Victoria Hospital Foundation Trust (East Grinstead and Maidstone) and Tunbridge Wells Trust (Kent) - prospectively treated patients with ocular surface disease with sutureless HAMDM. The patient cohort was assessed for resolution of epithelial defects, ocular surface inflammation, and best-corrected visual acuity pre- and posttreatment. Measurements of ocular surface inflammation and epithelial defect size were assessed using AOS digital imaging software, a validated tool for objective grading of bulbar conjunctival redness and measurement of corneal epithelial defects.

Results

A total of 47 applications of sutureless HAMDM on 46 eyes of 46 patients (25 male, 21 female, age 9-94 years) were assessed across various etiologies for an average of 24.0±14.1 days. Patients with limbal stem-cell deficiency (n=17), persistent epithelial defects (n=16), neurotrophic corneal disease (n=7), filamentary keratitis (n=2), corneal erosion (n=1), corneal thinning (n=1), ocular surface inflammation (n=1), and traumatic corneal laceration (n=1) were included in the study. Across all patents, 63% of eyes showed complete healing of epithelial defects and 32.6% of eyes showed partial resolution. The average rate of healing (wound closure) was 0.36 mm2 per day across the overall patient cohort, and the rate of healing in cases with complete resolution of epithelial defects was 0.41 mm2 per day. Inflammation across all four quadrants of the ocular surface remained stable. Visual acuity across the patient cohort remained stable (61%) and improved in 26% of patients (0.06±0.51 logMAR).

Conclusion

Sutureless HAMDM application can be accomplished in just a few minutes and effectively treat a range of ocular surface disease in a clinical, nonsurgical setting. The AOS imaging software offered a quantitative methodology for measuring epithelial defect size and inflammation state.

Comparative evaluation of platelet-rich plasma, autologous blood serum, and umbilical cord serum for corneal healing after penetrating keratoplasty in New Zealand rabbits

This study aimed to evaluate the effects of platelet-rich plasma (PRP), autologous blood serum (ABS), and umbilical cord serum (UCS) on corneal healing following penetrating keratoplasty (PK). A total of 120 New Zealand white rabbits, forty were designated as donors, while the remaining eighty rabbits were randomly divided into four groups after undergoing PRP Group (n = 20), ABS Group (n = 20), UCS Group (n = 20) and Control Group (n = 20). Corneal opacity score, corneal vascularization, corneal staining, histopathological analysis, and immunohistochemical analysis (including CD4+, CD8+, and major histocompatibility complex [MHC] II) were assessed at postoperative 1, 2, 3, and 12 weeks. The results showed that corneal opacity score and corneal vascularization did not differ significantly among the groups. However, corneal staining was found to be statistically higher in the PRP group (0.40 ± 0.60) compared to the other groups (p = 0.011). Immunohistochemical examination revealed no significant differences in CD4+, CD8+, and MHC II levels among the groups. Notably, in all groups, CD4+, CD8+, and MHC II levels were significantly higher at 12 weeks compared to other time points. PRP, ABS, and UCS demonstrated positive effects on corneal healing after PK. However, among the three products, PRP exhibited a superior healing effect compared to ABS and UCS crucial in the postoperative period following PK procedures, as they significantly impact visual quality, graft transparency, graft survival, and prevention of stromal resorption caused by infections. Despite the avascular nature of the cornea and its immune privilege, failure to resolve epithelial defects (ED) commonly observed after PK can result in irreversible scarring and ulceration, leading to graft rejection. While epithelial defects are observed in 14-100% of cases on the first postoperative day, approximately 3-7% of them persist as non-healing ED in subsequent periods. In conclusion, our study demonstrated that PRP, ABS, and UCS have a positive effect on corneal healing after PK.

Quantification of Analgesic and Anti-Inflammatory Lipid Mediators in Long-Term Cryopreserved and Freeze-Dried Preserved Human Amniotic Membrane

The aim of this study was to compare concentrations of endogenous N-acylethanolamine (NAE) lipid mediators-palmitoylethanolamide (PEA), oleoylethanolamide (OEA), and anandamide (AEA)-in fresh, decontaminated, cryopreserved, and freeze-dried amniotic membrane (AM) allografts, thereby determining whether AM's analgesic and anti-inflammatory efficiency related to NAEs persists during storage. The concentrations of NAEs were measured using ultra-high-performance liquid chromatography-tandem mass spectrometry. Indirect fluorescent immunohistochemistry was used to detect the PEA PPAR-α receptor. The concentrations of PEA, OEA, and AEA were significantly higher after decontamination. A significant decrease was found in cryopreserved AM compared to decontaminated tissue for PEA but not for OEA and AEA. However, significantly higher values for all NAEs were detected in cryopreserved samples compared to fresh tissue before decontamination. The freeze-dried AM had similar values to decontaminated AM with no statistically significant difference. The nuclear staining of the PPAR-α receptor was clearly visible in all specimens. The stability of NAEs in AM after cryopreservation was demonstrated under tissue bank storage conditions. However, a significant decrease, but still higher concentration of PEA compared to fresh not decontaminated tissue, was found in cryopreserved, but not freeze-dried, AM. Results indicate that NAEs persist during storage in levels sufficient for the analgesic and anti-inflammatory effects. This means that cryopreserved AM allografts released for transplant purposes before the expected expiration (usually 3-5 years) will still show a strong analgesic effect. The same situation was confirmed for AM lyophilized after one year of storage. This work thus contributed to the clarification of the analgesic effect of NAEs in AM allografts.

An in vitro comparison of human corneal epithelial cell activity and inflammatory response on differently designed ocular amniotic membranes and a clinical case study

Amniotic membrane (AM) is a naturally derived biomaterial with biological and mechanical properties important to Ophthalmology. The epithelial side of the AM promotes epithelialization, while the stromal side regulates inflammation. However, not all AMs are equal. AMs undergo different processing with resultant changes in cellular content and structure. This study evaluates the effects of sidedness and processing on human corneal epithelial cell (HCEC) activity, the effect of processing on HCEC inflammatory response, and then a case study is presented. Three differently processed, commercially available ocular AMs were selected: (1) Biovance®3L Ocular, a decellularized, dehydrated human AM (DDHAM), (2) AMBIO2®, a dehydrated human AM (DHAM), and (3) AmnioGraft®, a cryopreserved human AM (CHAM). HCECs were seeded onto the AMs and incubated for 1, 4 and 7 days. Cell adhesion and viability were evaluated using alamarBlue assay. HCEC migration was evaluated using a scratch wound assay. An inflammatory response was induced by TNF-α treatment. The effect of AM on the expression of pro-inflammatory genes in HCECs was compared using quantitative polymerase chain reaction (qPCR). Staining confirmed complete decellularization and the absence of nuclei in DDHAM. HCEC activity was best supported on the stromal side of DDHAM. Under inflammatory stimulation, DDHAM promoted a higher initial inflammatory response with a declining trend across time. Clinically, DDHAM was used to successfully treat anterior basement membrane dystrophy. Compared with DHAM and CHAM, DDHAM had significant positive effects on the cellular activities of HCECs in vitro, which may suggest greater ocular cell compatibility in vivo.

[Corneal regeneration: is there a place for tissues of perinatal origin?]

The article reviews the main properties of the cornea and the mechanisms of its physiological regeneration and repair in response to damage and describes the most promising methods of treatment aimed at stimulating limbal stem cells and based on the use of native tissues of perinatal origin, umbilical cord mesenchymal stromal cells, and cell-free therapeutic products.

Therapeutic Potential of Honey and Propolis on Ocular Disease

Honey and propolis have recently become the key target of attention for treating certain diseases and promoting overall health and well-being. A high content of flavonoids and phenolic acids found in both honey and propolis contributes to the antioxidant properties to scavenge free radicals. Honey and propolis also exhibited antibacterial effects where they act in two ways, namely the production of hydrogen peroxide (H2O2) and gluconic acids following the enzymatic activities of glucose oxidase, which exerts oxidative damage on the bacteria. Additionally, the anti-inflammatory effects of honey and propolis are mainly by reducing proinflammatory factors such as interleukins and tumor necrosis factor alpha (TNF-α). Their effects on pain were discovered through modulation at a peripheral nociceptive neuron or binding to an opioid receptor in the higher center. The aforementioned properties of honey have been reported to possess potential therapeutic topical application on the exterior parts of the eyes, particularly in treating conjunctivitis, keratitis, blepharitis, and corneal injury. In contrast, most of the medicinal values of propolis are beneficial in the internal ocular area, such as the retina, optic nerve, and uvea. This review aims to update the current discoveries of honey and propolis in treating various ocular diseases, including their antioxidant, anti-inflammatory, antibacterial, and anti-nociceptive properties. In conclusion, research has shown that propolis and honey have considerable therapeutic promise for treating various eye illnesses, although the present study designs are primarily animal and in vitro studies. Therefore, there is an urgent need to translate this finding into a clinical setting.

Amniotic membrane transplantation for acute ocular burns

BACKGROUND

Ocular surface burns can be caused by chemicals (alkalis and acids) or direct heat. One effect of the burn is damage to the limbal epithelial stem cells of the ocular surface with delayed re-epithelialisation, stem cell failure, and conjunctivalisation of the cornea. Amniotic membrane transplantation (AMT) performed in the acute phase (day 0 to day 7) following an ocular surface burn is claimed to reduce pain and accelerate healing. The surgery involves securing a layer of amniotic membrane (AM) to the eyelid margins as a patch to cover the entire ocular surface. However, there is debate about the severity of an ocular burn that may benefit from AMT and uncertainty of whether AMT improves outcomes.

OBJECTIVES

To compare the effect of AMT with medical therapy in the first seven days after an ocular surface burn, compared to medical therapy alone.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; which contains the Cochrane Eyes and Vision Trials Register; 2021, Issue 9); Ovid MEDLINE; Ovid Embase; LILACS; the ISRCTN registry; ClinicalTrials.gov and the WHO ICTRP. We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 29 September 2021.

SELECTION CRITERIA

We included randomised trials that compared an AMT applied in the first seven days following an ocular surface burn in addition to medical therapy with medical therapy alone. The outcome measures were failure of re-epithelialisation by day 21 post injury, visual acuity at final follow-up, corneal neovascularisation, symblepharon, time to re-epithelialisation and adverse effects.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened search results, assessed the included studies for risk of bias and extracted relevant data. We contacted trial investigators for missing information. We summarised data using risk ratios (RRs) and mean differences (MDs) as appropriate.

MAIN RESULTS

We analysed two RCTs, but excluded individual patients who had been treated outside the acute phase in one of the studies (data provided by study authors). In total, 36 moderate burns from one RCT and 92 severe burns from two RCTs were evaluated separately. For both categories, the certainty of the evidence was downgraded principally as a result of high risks of performance and detection biases, and because of imprecision indicated by very wide confidence intervals. In addition, follow-up was insufficiently frequent to calculate time-to-epithelialisation precisely. Moderate severity ocular burns (Roper-Hall classification II-III) The relative risk of AMT on failure of epithelialisation by day 21 was 0.18 (0.02 to 1.31), and LogMAR visual acuity was 0.32 lower (0.55 to 0.09 lower) in the treatment group (i.e. better), suggesting a possible benefit of AMT. The GRADE assessment for failure of epithelialisation by day 21 was downgraded to very low due to the risk of bias and imprecision (very wide confidence intervals including no effect). The GRADE assessment for visual acuity at final follow-up was downgraded to low due to the risk of bias and imprecision (optimal information size not met). The relative effects of AMT on corneal neovascularisation (RR 0.56; 0.21 to 1.48), symblepharon (RR 0.41; 0.02 to 9.48) and time-to-epithelialisation (13 days lower; 26.30 lower to 0.30 higher) suggest possible benefit of AMT, but the wide confidence intervals indicate that both harm and benefit are possible. GRADE assessments for these outcomes were once again downgraded to very low due to the risk of bias and imprecision. Since adverse effects are rare, the small sample would have fewer occurrences of rare but potentially important adverse effects. The GRADE assessment for adverse effects was therefore considered to be low.  Severe ocular burns (Roper-Hall classification IV) The relative risk of AMT on failure of epithelialisation by day 21 was 1.03 (0.94 to 1.12), and LogMAR visual acuity was 0.01 higher (0.29 lower to 0.31 higher) in the treatment group (i.e, worse), indicating no benefit of AMT. GRADE assessments for failure of epithelialisation by day 21 and final outcomes were downgraded to low. The relative effects of AMT on corneal neovascularisation (RR 0.84; 0.66 to 1.06), symblepharon (RR 0.89; 0.56 to 1.42) and time-to-epithelialisation (1.66 days lower; 11.09 lower to 7.77 higher) may include both benefit and harm. GRADE assessments for corneal neovascularisation, symblepharon and time-to-epithelialisation were downgraded to low due to risk of bias and imprecision. For adverse effects, the GRADE assessment was downgraded to low, reflecting the small sample sizes in the RCTs.

AUTHORS' CONCLUSIONS

There is uncertain evidence to support the treatment of moderate acute ocular surface burns with AMT in addition to standard medical therapy as a means of preventing failure of epithelialisation by day 21, improving visual outcome and reducing corneal neovascularisation, symblepharon formation and time-to-epithelialisation. For severe burns, the available evidence does not indicate any significant benefit of treatment with AMT.

Recycling Apparent Waste Into Biologicals: The Case of Umbilical Cord Blood in Italy and Spain

Most public cord blood banking programs are currently facing financial difficulties due to a progressive decline in the number of cord blood transplants performed worldwide and to a high discard rate of the donated units caused by progressively increasing thresholds of the stem cell dose required to perform safe and effective hemopoietic cord blood transplants. Recycling a proportion of unused cord blood units to prepare novel cord blood components obtained with minimal manipulation (platelets, plasma, red blood cells) and to develop more technologically complex products regulated in the US as Cellular and Gene Therapy Products and in Europe as Advanced Therapy Medicinal Products [e.g. virus-specific T cells (VST), natural killer (NK) cells, induced pluripotent stem cells (iPSCs) is a promising strategy to increase the therapeutic value and reduce the financial deficits of public cord blood banking. Based on encouraging preliminary evidences reported in the literature, additional laboratory studies, large multicenter clinical trials and international regulatory harmonization are necessary to achieve these important goals. This article describes organizational, methodological and regulatory advancements developed in Italy and Spain to promote the clinical use of cord blood platelets, plasma and red blood cells.

Wound healing of the corneal epithelium: a review

The corneal epithelium (CE) forms the outermost layer of the cornea. Despite its thickness of only 50 μm, the CE plays a key role as an initial barrier against any insults to the eye and contributes to the light refraction onto the retina required for clear vision. In the event of an injury, the cornea is equipped with many strategies contributing to competent wound healing, including angiogenic and immune privileges, and mechanotransduction. Various factors, including growth factors, keratin, cytokines, integrins, crystallins, basement membrane, and gap junction proteins are involved in CE wound healing and serve as markers in the healing process. Studies of CE wound healing are advancing rapidly in tandem with the rise of corneal bioengineering, which employs limbal epithelial stem cells as the primary source of cells utilizing various types of biomaterials as substrates.

Visual Acuity and Number of Amniotic Membrane Layers as Indicators of Efficacy in Amniotic Membrane Transplantation for Corneal Ulcers: A Multicenter Study

BACKGROUND

To evaluate new indicators in the efficacy of amniotic membrane transplantation (AMT) for non-healing corneal ulcers (NHCUs).

METHODS

Retrospective, multicenter study. In total, 223 AMTs for NHCU in 191 patients were assessed. The main outcomes studied were the success rate of AMT (complete re-epithelization), postoperative visual acuity (VA) gain, and number of AM layers transplanted.

RESULTS

The overall AMT success rate was 74.4%. In 92% of our patients VA stability or improvement. Postoperative VA was significantly higher than preoperative VA in the entire cohort (p < 0.001) and in all etiological groups of ulcers (post-bacterial, p ≤ 0.001; post-herpetic, p ≤ 0.0038; neurotrophic ulcers, p ≤ 0.014; non-rheumatic peripheral, p ≤ 0.001; and ulcers secondary to lagophthalmos and eyelid malposition or trauma, p ≤ 0.004). Most participants (56.5%) presented a preoperative VA equal to or less than counting fingers (≤0.01). Of these, 13.5% reached a postoperative VA equal to or better than legal blindness (≥0.05) after AMT. A higher success rate was observed in the monolayer than in the multilayer AMT (79.5% and 64.9%, respectively; p = 0.018). No statistically significant values were found between the number of layers transplanted and VA gain (p = 0.509).

CONCLUSION

AMT is not only beneficial in achieving complete re-epithelialization in NHCUs but also in improving postoperative VA; these improvements are independent of etiologies of ulcers. Furthermore, the use of monolayer AMT seems to be a more appropriate option than multilayer AMT for NHCU since the multilayer AMT did not present better outcomes (success rate and VA gain) compared to monolayer AMT in the different types of ulcers studied.

Global Consensus on the Management of Limbal Stem Cell Deficiency

PURPOSE

In recent decades, the medical and surgical treatment of limbal stem cell deficiency (LSCD) has evolved significantly through the incorporation of innovative pharmacological strategies, surgical techniques, bioengineering, and cell therapy. With such a wide variety of options, there is a need to establish a global consensus on the preferred approaches for the medical and surgical treatment of LSCD.

METHODS

An international LSCD Working Group was established by the Cornea Society in 2012 and divided into subcommittees. Four face-to-face meetings, frequent email discussions, and teleconferences were conducted since then to reach agreement on a strategic plan and methods after a comprehensive literature search. A writing group drafted the current study.

RESULTS

A consensus in the medical and surgical management of LSCD was reached by the Working Group. Optimization of the ocular surface by eyelid and conjunctival reconstruction, antiinflammatory therapy, dry eye and meibomian gland dysfunction treatment, minimization of ocular surface toxicity from medications, topical medications that promote epithelialization, and use of a scleral lens is considered essential before surgical treatment of LSCD. Depending on the laterality, cause, and stage of LSCD, surgical strategies including conjunctival epitheliectomy, amniotic membrane transplantation, transplantation of limbal stem cells using different techniques and sources (allogeneic vs. autologous vs. ex vivo-cultivated), transplantation of oral mucosal epithelium, and keratoprosthesis can be performed as treatment. A stepwise flowchart for use in treatment decision-making was established.

CONCLUSIONS

This global consensus provides an up-to-date and comprehensive framework for the management of LSCD.

Heparin-Modified Amniotic Membrane Combined With Growth Factors for Promoting Corneal Wound Healing After Alkali Burn

Ocular chemical burns are potentially blinding ocular injuries and require urgent management. Amniotic membrane (AM) transplantation is an effective surgical treatment, one of the reasons is because AM is a rich source of growth factors that can promote epithelialization and wound healing. However, growth factors will be gradually lost and insufficient after preparation process and long-time storage, leading to unsatisfactory therapeutic effects. Herein, we present a modified AM (AM-HEP) for the supplement and sustained release of growth factor by surface grafting heparin for treatment of ocular chemical burns. Heparin grafting rate and stability, microstructure, physical property, and sustained release of epithelial growth factor (EGF) of AM-HEP were characterized. Biocompatibility and ability to promote corneal epithelial cell growth and migration were evaluated and compared with a biological amnion, which is available on the market in vitro. The therapeutic effects of AM-HEP combined with EGF (AM-HEP@EGF) in vivo had been evaluated in a model of mouse corneal alkali burn. The results indicated that heparin was introduced into AM and maintain stability over 3 weeks at 37°C. The modification process of AM-HEP did not affect microstructure and physical property after comparing with non-modified AM. EGF could be combined quickly and effectively with AM-HEP; the sustained release could last for more than 14 days. AM-HEP@EGF could significantly promote corneal epithelial cell growth and migration, compared with non-modified AM and control group. Faster corneal epithelialization was observed with the transplantation of AM-HEP@EGF in vivo, compared with the untreated control group. The corneas in the AM-HEP@EGF group have less inflammation and were more transparent than those in the control group. The results from in vitro and in vivo experiments demonstrated that AM-HEP@EGF could significantly enhance the therapeutic effects. Taken together, AM-HEP@EGF is exhibited to be a potent clinical application in corneal alkali burns through accelerating corneal epithelial wound healing.

Bioengineering Approaches for Corneal Regenerative Medicine

BACKGROUND

Since the cornea is responsible for transmitting and focusing light into the eye, injury or pathology affecting any layer of the cornea can cause a detrimental effect on visual acuity. Aging is also a reason for corneal degeneration. Depending on the level of the injury, conservative therapies and donor tissue transplantation are the most common treatments for corneal diseases. Not only is there a lack of donor tissue and risk of infection/rejection, but the inherent ability of corneal cells and layers to regenerate has led to research in regenerative approaches and treatments.

METHODS

In this review, we first discussed the anatomy of the cornea and the required properties for reconstructing layers of the cornea. Regenerative approaches are divided into two main categories; using direct cell/growth factor delivery or using scaffold-based cell delivery. It is expected delivered cells migrate and integrate into the host tissue and restore its structure and function to restore vision. Growth factor delivery also has shown promising results for corneal surface regeneration. Scaffold-based approaches are categorized based on the type of scaffold, since it has a significant impact on the efficiency of regeneration, into the hydrogel and non-hydrogel based scaffolds. Various types of cells, biomaterials, and techniques are well covered.

RESULTS

The most important characteristics to be considered for biomaterials in corneal regeneration are suitable mechanical properties, biocompatibility, biodegradability, and transparency. Moreover, a curved shape structure and spatial arrangement of the fibrils have been shown to mimic the corneal extracellular matrix for cells and enhance cell differentiation.

CONCLUSION

Tissue engineering and regenerative medicine approaches showed to have promising outcomes for corneal regeneration. However, besides proper mechanical and optical properties, other factors such as appropriate sterilization method, storage, shelf life and etc. should be taken into account in order to develop an engineered cornea for clinical trials.

Umbilical cord blood: Current uses for transfusion and regenerative medicine

The past 20 years of experience with umbilical cord blood transplantation have demonstrated that cord blood is effective in the treatment of a spectrum of diseases, including hematological malignancies, bone marrow failure, hemoglobinopathies, and inborn errors of metabolism. However, only a few number of umbilical cord blood units collected have a cell content adequate for an allogenic hematopoietic stem cell transplantation. In the meanwhile, there is an increasing interest in exploiting cord blood derivatives in different fields. In this review, we will summarize the most recent updates on clinical applications of umbilical cord blood platelet derivatives for regenerative medicine, and we will revise the literature concerning the use of umbilical cord blood for autologous or allogeneic transfusion purposes. The methodological aspect and the biological characteristics of these products also will be discussed.

Management Strategies of Ocular Chemical Burns: Current Perspectives

Ocular chemical burns are absolute ophthalmic emergencies and require immediate management to minimize devastating sequelae. Management of alkali and acid burns is started at the scene of the accident by copious irrigation. Treatment is directed at improving epithelial integrity and stromal stability, reduction of undue inflammation, and prevention or timely management of complications. To ascertain the best possible outcome, numerous biological medications and surgical interventions have been merged into conventional therapeutic regimens. These include autologous and umbilical cord serum preparations, platelet-rich plasma, amniotic membrane transplantation, limbal stem-cell transplantation, and anti-angiogenic agents.

Case Series Describing the Use of Low-Temperature Vacuum-Dehydrated Amnion (Omnigen) for the Treatment of Corneal Ulcers in Cats and Dogs: 46 Cases (2016-2017)

Amniotic membrane is widely used in the treatment of ocular surface disorders in human and veterinary patients. Preservation and storage of amnion has proven challenging, prompting the development of new preservation techniques. Omnigen, a novel low-temperature vacuum-dehydrated amnion, is reported to possess enhanced structural properties and biochemical stability in vitro, but its clinical use in veterinary patients is not well described. This study aims to document and describe the varied use of Omnigen for the surgical treatment of corneal ulceration in cats and dogs. A total of 45 patients (46 eyes) were recruited from the clinical record system of the Royal Veterinary College (London) between January 2016 and December 2017. Brachycephalic breeds were over-represented (37/45; 82.2%). Omnigen was used as a standalone graft in 5/46 (10.9%) eyes, as a supplementary graft in 29/46 (63.0%) eyes and as a patch in 12/46 (26.1%) eyes. Graft failure occurred in 10/46 eyes (21.7%). At final examination 43/46 eyes (93.5%) had healed and 31/33 eyes (93.9%) were visual. This study demonstrates the successful use of Omnigen for the surgical treatment of corneal ulceration in cats and dogs. Further studies are needed to clarify its properties and benefits in the clinical field.

Amniotic Membrane Transplantation in Ophthalmology: An Updated Perspective

Aim

The aim of this paper is to provide a succinct literature review of the different clinical applications for AMT usage in an ophthalmic setting, ranging from commonly used applications to less mainstream approaches. The hope is that this review enables the reader to have a better understanding of the biological properties of amnion as well as the indications and scenarios in which AMT can be used, whilst presenting relevant evidence from within the literature which may be of interest. We also provide an update on the methods of preservation of amniotic membrane and the application methodologies.

Methods

Literature search. A PubMed search was performed using the search terms “amniotic membrane transplant”, “amnion AND cornea”, amnion AND ophthalmology”, “amnion AND ocular surface” and “Amnion AND eye”. A full review of the literature using the PubMed database was conducted up until 01/05/20. The articles used were written in English, with all articles accessed in full. Both review articles and original articles were used for this review. All full publications related to ophthalmology were considered.

Clinical characteristics of patients hospitalized for ocular chemical injuries in Shanghai from 2012 to 2017

Purpose

To summarize the clinical characteristics of patients with ocular chemical injuries and evaluate their potential relationship with the visual outcome by analyzing the medical records of these patients from January 1, 2012, to December 31, 2017.

Methods

This is a retrospective case series study. Patient data included age, gender, occupational classification, location of ocular chemical injury, initial and final best-corrected distance visual acuity (BCDVA), intraocular pressure (IOP), nature and chemical phase, distribution and severity of chemical injury, management methods, and complications. All variables were evaluated for their potential relationship with visual outcome.

Results

A total of 160 patients were hospitalized with ocular chemical injuries. Majority of the patients were factory workers and arrived at the consultation room less than 24 h after injury. The most common ocular injury setting, classification of severity, causative chemical, chemical phase, and complications were workplace, grade II, unknown and mixed substance, liquid, and elevated IOP, respectively. The risk factors for poor final BCDVA were identified as older age, poor initial BCDVA, and irrigation 24 h after injury (P < 0.001, P < 0.001, and P = 0.011, respectively).

Conclusions

We elaborate the clinical characteristics and outcomes of patients with ocular chemical injuries in Jinshan District, Shanghai. A comprehensive education program should be established and the use of protective eyewear should be promoted to prevent occupation-related ocular chemical injuries.

Preparation of Dried Amniotic Membrane for Corneal Repair

Amniotic membrane transplantation is an established therapeutic and biological adjunct for several clinical situations, including treatment of diabetic foot ulcers and ocular surface disease. However, poorly standardized and validated clinical preparation and storage procedures can render the final product highly variable and an unpredictable biomaterial. We have therefore developed a novel, standardized method for processing and dry-preserving amniotic membrane, minimizing biochemical, compositional, and structure damage to produce a potentially superior membrane suitable for clinical use. The intellectual property associated with this methodology was patented by the University of Nottingham and licensed to NuVision^® Biotherapies which formed the basis of the Tereo^® manufacturing process which is used to manufacture Omnigen^®.

Amniotic membrane, clinical applications and tissue engineering. Review of its ophthalmic use

The use of amniotic membrane in ophthalmology has been increasing in recent years due to its multiple biological and tectonic properties, improvement in the process of obtaining, ease of use, and advancement in tissue engineering. The amniotic membrane has become one of the main adjuvant treatments, in ophthalmic surgery as well as in other medical-surgical specialties. The development of tissue engineering has allowed it to be used, not only in its classic form, but also by the use of drops and other presentations. The different steps prior to its use (preparation and conservation), the different surgical techniques, and their main clinical applications are described throughout the article.

Blood-Based Treatments for Severe Dry Eye Disease: The Need of a Consensus

The use of blood-based eye drops as therapy for various diseases of the ocular surface has become increasingly popular in ophthalmic practice during recent years. The rationale for their use is based on the promotion of cellular proliferation and migration thanks to the supply of metabolically active substances, in particular growth factors. Blood-derived eye drops have been used for the treatment of several ocular surface disorders, such as dry eye disease, corneal ulcer, persistent epithelial defect, neurotrophic keratitis, ocular surface burn, recurrent corneal erosion, and limbal stem-cell deficiency. Both autologous (from patients themselves) and heterologous (from adult donors or from cord blood sampled at birth)-derived products exist, and each source has specific pros and cons. Despite an extensive literature, several issues are still under debate and the aim of this manuscript is to review the indications, preparation methods and storage, characterization of content, rationale for clinical outcomes, patient stratification, length of treatment, and rationale for repeated treatments at disease relapse. A rationale based on a "5 Ws and 2 Hs" protocol is proposed as a way of thinking, with the attempt to clarify Who, Why, When, Where, What, and How to use these treatment options.

Acute surgical vs non-surgical management for ocular and peri-ocular burns: a systematic review and meta-analysis

Background

Burn-related injury to the face involving the structures of the eyes, eyelids, eyelashes, and/or eyebrows could result in multiple reconstructive procedures to improve functional and cosmetic outcomes, and correct complications following poor acute phase management. The objective of this article was to evaluate if non-surgical or surgical interventions are best for acute management of ocular and/or peri-ocular burns.

Methods

This systematic review and meta-analysis compared 272 surgical to 535 non-surgical interventions within 1 month of patients suffering burn-related injuries to 465 eyes, 253 eyelids, 90 eyelashes, and 0 eyebrows and evaluated associated outcomes and complications. The PubMed, Embase, Cochrane Library, Web of Science, and Scopus databases were systematically and independently searched. Patient and clinical characteristics, surgical and medical interventions, outcomes, and complications were recorded.

Results

Eight of the 14,927 studies queried for this study were eligible for the systematic review and meta-analysis, with results from 33 of the possible 58 outcomes and complications using Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) and Cochrane guidelines. Surgery was associated with standard mean differences (SMD) 0.44 greater visual acuity on follow-up, SMD 1.63 mm shorter epithelial defect diameters on follow-up, SMD 1.55 mm greater changes in epithelial diameters from baseline, SMD 1.17 mm² smaller epithelial defect areas on follow-up, SMD 1.37 mm² greater changes in epithelial defect areas from baseline, risk ratios (RR) 1.22 greater numbers of healed epithelial defects, RR 11.17 more keratitis infections, and a 2.2 greater reduction in limbal ischemia compared to no surgical intervention.

Conclusions

This systematic review and meta-analysis found that compared to non-surgical interventions, acute surgical interventions for ocular, eyelid, and/or eyelash burns were found to have greater visual acuity on follow-up, shorter epithelial defect diameters on follow-up, greater changes in epithelial diameters from baseline, smaller epithelial defect areas on follow-up, greater changes in epithelial defect areas from baseline, greater numbers of healed epithelial defects, more keratitis infections, and a greater reduction in limbal ischemia, possibility preventing the need of a future limbal stem cell transplantation.

An update on chemical eye burns

Ocular chemical injuries vary in severity, with the more severe end of the spectrum having profound visual consequences and medicolegal implications. Grading of ocular injuries is critical for determining acute treatment and visual prognosis. Poor immediate management results in more challenging treatment of acute disease. Similarly, poorly controlled acute disease results in more treatment-resistant chronic ocular disease. Despite several decades of research and public health initiatives, simple and effective interventions such as wearing protective eyewear and immediate irrigation of eyes remain as key challenges. Education and prevention are therefore important public health messages. Hurdles in the acute management of disease include poor evidence-base for commonly used treatments (e.g. based on experimental animal studies), reduced treatment adherence rates and high clinic non-attendance rates. The evolution of treatment strategies, particularly limbal stem cell transplantation, has revolutionised the visual and cosmetic outcomes in chronic phases of disease. It is therefore increasingly important to consider tertiary referral for patients with limbal stem cell failure or vision-limiting corneal scarring.

Therapeutic effects of three human-derived materials in a mouse corneal alkali burn model

Purpose: To compare the therapeutic effects of human derivatives in a mouse alkali burn model. Methods: The right eyes of mice were injured using NaOH. After alkali injury, one of the following agents was topically administered for 7 d: human amniotic membrane (hAM) suspension, human umbilical cord serum (hUCS), and human peripheral blood serum (hPBS), or saline. The epithelial defect areas on days 1, 2, and 3 degrees of opacity on days 2, 3, and 7, and corneal neovascularization (NV) areas on day 7 were evaluated. Histologic examination and mRNA expression levels of tumour necrosis factor (TNF)-α, interleukin (IL)-6, vascular endothelial growth factor (VEGF), matrix metalloproteinase (MMP)-2, MMP-8, and MMP-9 were also evaluated on day 7. Results: The epithelial defect areas in the hUCS group were smaller than those in the control and hPBS groups on day 3 (p < .05, respectively). The epithelial defect areas in the hAM suspension group showed smaller than those in the control and hPBS groups on days 1 and 2 (p < .05, respectively). The degrees of opacity were lower in all treatment groups than that of the saline control group on day 7 (p < .05, respectively). Corneal NV areas were not different among groups on day 7 (p = 0.20). The expression levels of TNF-α, IL-6, MMP-8, and MMP-9 mRNA and the infiltration of the inflammatory cells in all treatment groups were lesser than those in the control group on day 7 (p< .05, respectively). Conclusions: All treatments reduced inflammatory reactions and corneal opacity development. Corneal reepithelialization was faster in the hUCS group.

Amniotic Membrane Transplantation in Acute Severe Ocular Chemical Injury: A Randomized Clinical Trial

PURPOSE

To compare the outcomes of conventional medical treatment vs combined medical treatment and amniotic membrane transplantation (AMT) in the management of patients with Roper-Hall grade IV ocular chemical injury.

DESIGN

Randomized, parallel-controlled clinical trial.

METHODS

Setting: Single tertiary referral hospital.

PATIENTS

Sixty eyes of 60 patients with Roper-Hall grade IV ocular chemical injury with a minimum follow-up of 12 months were enrolled in the study.

INTERVENTION

Patients were randomly assigned to 2 groups: Group 1 (30 eyes) received topical preservative-free lubricating gel and drops, chloramphenicol, betamethasone, homatropine, oral vitamin C, and doxycycline; Group 2 (30 eyes) received amniotic membrane transplant (AMT) on the entire ocular surface in addition to the medical treatment provided in Group 1.

OUTCOME MEASURES

The main outcome measure was time to complete corneal epithelialization. Secondary outcome measures were best-corrected visual acuity (BCVA) and neovascularization in the central 5 mm of the cornea.

RESULTS

Mean follow-up time was 20.3 ± 2.5 months (range 13-24 months). Corneal epithelial defects healed within 72.6 ± 30.4 (21-180) days in Group 1 vs 75.8 ± 29.8 (46-170) days in Group 2 (P = .610). Mean BCVA was 2.06 ± 0.67 (0.4-2.6) logMAR vs 2.06 ± 0.57 (1-2.9) logMAR in Groups 1 and 2, respectively (P = .85). Group 1 developed more central corneal neovascularization (22 eyes; 73.3%) compared to Group 2 (16 eyes; 53.3%); however, it was not statistically significant (P = .108).

CONCLUSIONS

In comparison to conventional medical therapy, combined amniotic membrane transplantation and medical therapy does not accelerate corneal epithelialization or affect final visual acuity in severe chemical injuries.

The application of human amniotic membrane in the surgical management of limbal stem cell deficiency

The application of human amniotic membrane (AM) has a wide spectrum of indications in the treatment of ocular surface disorders. Transplantation of AM has been incorporated routinely as a component of ocular surface reconstruction in a variety of ocular pathologies. The application of human AM can be combined with nearly all types of limbal transplantation in treating limbal stem cell deficiency (LSCD). AM provides support and possible protection to the transplanted limbal tissues and limbal stem cells owing to its mechanical and biological properties, and these properties are thought to enhance the success rate of LSC transplantation. This paper reviews the current literature on the applications of AM in the surgical management of LSCD and summarizes the outcome of different surgical approaches. The current literature contains mostly low-level evidences in supporting the role of AM. The efficacy of AM in LSC transplantation needs to be confirmed by randomized controlled clinical trials.

Effects of Cryopreserved Amniotic Membrane-Umbilical Cord Allograft on Total Ankle Arthroplasty Wound Healing

Relatively high rates of wound healing complications continue to be reported with a total ankle arthroplasty (TAA) anterior incision. The amniotic membrane-umbilical cord (AM-UC) allograft is a regenerative orthobiologic adjunct that modulates wound healing by down-regulating inflammation, enhancing local healing and antimicrobial factors, and reducing scar formation. The purpose of this study was to determine whether local application of a cryopreserved AM-UC allograft enhances soft tissue healing after TAA. A total of 104 patients with symptomatic ankle arthritis who failed conservative management underwent standard TAA. At skin closure, patients were allocated to either the treatment (local application of AM-UC) or control (no allograft) group. Demographic data, patient comorbidities, and radiographic findings were collected. The primary outcome was a major complication necessitating reoperation. Secondary outcomes were time to healing, minor complications (i.e., skin dehiscence, local wound care, use of antibiotics), and patient scar assessment. Local application of an AM-UC allograft significantly decreased the overall time to skin healing (28.5 days vs 40 days; p = .03). Two patients required a reoperation for soft tissue wound complications, with no difference (p = 1.00) between the groups. No statistically significant difference was detected in terms of skin dehiscence, local wound care, or antibiotic prescriptions in the 2 groups. Regenerative technology using local application of a cryopreserved AM-UC allograft may enhance TAA outcomes by decreasing the time to healing. Larger randomized controlled trials are needed to determine whether an AM-UC allograft enhances soft tissue wound healing and ultimately reduces the incidence of devastating soft tissue complications.

Towards biobanking technologies for natural and bioengineered multicellular placental constructs

Clinical application of a large variety of biomaterials is limited by the imperfections in storage technology. Perspective approaches utilizing low-temperature storage are especially challenging for multicellular structures, such as tissues, organs, and bioengineered constructs. Placenta, as a temporary organ, is a widely available unique biological material, being among the most promising sources of various cells and tissues for clinical and experimental use in regenerative medicine and tissue engineering. The aim of this study was to analyse the mechanisms of cryoinjuries in different placental tissues and bioengineered constructs as well as to support the viability after low temperature storage, which would contribute to development of efficient biobanking technologies. This study shows that specificity of cryodamage depends on the structure of the studied object, intercellular bonds, as well as interaction of its components with cryoprotective agents. Remarkably, it was possible to efficiently isolate cells after thawing from all of the studied tissues. While the outcome was lower in comparison to the native non-frozen samples, the phenotype and expression levels of pluripotency genes remained unaffected. Further progress in eliminating of recrystallization processes during thawing would significantly improve biobanking technologies for multicellular constructs and tissues.

Biochemical characterization of pure dehydrated binate amniotic membrane: role of cytokines in the spotlight

AIM

Placental allografts used for tissue regeneration differ in membrane compositions and processing techniques. A uniquely folded dehydrated binate amniotic membrane (DBAM) was biochemically characterized to evaluate its potential role in wound healing.

METHODS

Histology, Luminex-based immunoassay and standard in vitro cell biology techniques were employed.

RESULTS

Histological staining confirmed that the DBAM was chorion free with epithelial cell layer of the respective amnion membranes facing outward. DBAM had quantifiable levels of relevant cytokines that induced proliferation and migration while bolstering secretory activity of the cells. DBAM retained biological efficacy at a broad range of temperatures.

CONCLUSION

Cytokines in DBAM stimulate bone marrow stromal and stem cells that may lead to tissue regeneration and wound healing in a clinical setup.

Comparison of Collagen Cross-Linking and Amniotic Membrane Transplantation in an Experimental Alkali Burn Rabbit Model

PURPOSE

To compare the effects of collagen cross-linking (CXL) and amniotic membrane transplantation (AMT) on acute corneal alkali burns.

METHODS

After establishment of an alkali burn model, 32 rabbits were divided into 4 groups: control group, AMT group, CXL group, and AMT + CXL (combined) group. Clinical parameters, including epithelial wound, opacity, ulceration, and neovascularization, were evaluated on postinjury days 1, 7, 14, and 18. Histological parameters were examined in hematoxylin/eosin (H&E) and Masson trichrome-stained corneal sections. Immunohistochemical analyses, including a terminal deoxynucleotidyl transferase-mediated biotin-deoxyuridine triphosphate nick-end labeling assay and cluster of differentiation 68 (CD68) labeling, were performed to determine the apoptotic index and macrophage activation.

RESULTS

On postinjury day 18, the epithelial wound of AMT {4.08% [interquartile range (IQR), 0.68%-5.22%]}, CXL [1.84% (IQR, 0.01%-3.89%)], and combined [3.44% (IQR, 0.01%-4.36%)] groups were significantly lower than the control [15.23% (IQR, 9.86%-23.06%)] group (P = 0.003). No significant difference was detected between the groups in terms of opacity (P = 0.303). Neovascularization was the least severe in the CXL group [16.18% (IQR, 8.39%-21.28%)] and the most severe in the AMT [34.47% (IQR, 17.71%-62.77%)] and combined [35.12% (IQR, 31.96%-59.98%)] groups on day 18 (P = 0.033). Significant increases in the apoptotic index and CD68 labeling were detected in the CXL and combined groups compared with those in the control group (P = 0.047 and P = 0.001, respectively).

CONCLUSIONS

CXL treatment is an effective adjuvant treatment for promoting reepithelialization, reducing inflammation and neovascularization, and preventing ulceration in acute alkali burns. Providing AMT after suppressing inflammation may be a more effective treatment.

Treatment of acute ocular chemical burns

Ocular chemical burns are an ophthalmic emergency and are responsible for 11.5%-22.1% of ocular injuries. Immediate copious irrigation is universally recommended in acute ocular burns to remove the offending agent and minimize damage. Conventional medical therapy consists of the use of agents that promote epithelialization, minimize inflammation, and prevent cicatricial complications. Biological fluids such as autologous serum, umbilical cord blood serum, platelet-rich plasma, and amniotic membrane suspension are a rich source of growth factors and promote healing when used as adjuncts to conventional therapy. Surgical treatment of acute ocular burns includes the debridement of the necrotic tissue, application of tissue adhesives, tenoplasty, and tectonic keratoplasty. Amniotic membrane transplantation is a novel surgical treatment that is increasingly being used as an adjunct to conventional treatment to promote epithelial healing, minimize pain, and restore visual acuity. Various experimental treatments that aim to promote wound healing and minimize inflammation are being evaluated such as human mesenchymal and adipose stem cells, beta-1,3 glucan, angiotensin-converting enzyme inhibitors, cultivated fibroblasts, zinc desferrioxamine, antifibrinolytic agents, antioxidants, collagen cross-linking, and inhibitors of corneal neovascularization.

Upgradation and modernization of eye banking services: Integrating tradition with innovative policies and current best practices

Purpose:

The purpose of this study is to review the history and evolution of the National Eye Bank (NEB) and analyze the impact over the years and report the outcome of the invested resources.

Methods:

Review of archival material, records, project reports, policy and procedures' manuals, and publications was done. Descriptive and analytical processing of data obtained was undertaken. Parameters evaluated included total collection, transplantation, utilization rates of donor cornea, changing trends over time in terms of numbers and duration of recipients waiting, impactful research translated into changes in standard operating protocols, new facilities, and subsequent effects on numbers or quality assurance measures and overview of major achievements. Periodic situational analysis with contextual relevance and interpretation of outcomes was done pertaining to national goals and international standards.

Results:

The NEB and cornea services have played a key leadership role in furthering the development of eye banking and corneal transplantation services. The contribution extends beyond routine patient care to education, training, generation of resources, advocacy, and policymaking. In quantifiable terms, the overall performance has steadily increased over the years. Major contributions include training of doctors, eye bank staff and corneal surgeons, introduction of innovative techniques for corneal transplantation, setting of national standards for eye banking and provision of preservation media, customized corneal, and ocular surface cell replacement therapy in collaboration with other departments and institutes.

Conclusion:

The eye banking and corneal transplantation facilities have evolved with time providing quality services, modernized as appropriate with updated knowledge and incorporating technological advances supported by the systematic evidence-based approach.