Amniotic membrane in ophthalmology: properties, preparation, storage and indications for grafting-a review

A Novel Dehydrated Human Umbilical Cord Particulate Medical Device: Matrix Characterization, Performance, and Biocompatibility for the Management of Acute and Chronic Wounds

Chronic wounds present a significant socioeconomic burden forecasted to increase in prevalence and cost. Minimally manipulated human placental tissues have been increasingly employed and proven to be advantageous in the treatment of chronic wounds, showing improved clinical outcomes and cost-effectiveness. However, technological advances have been constrained by minimal manipulation and homologous use criteria. This study focuses on the characterization of a novel dehydrated human umbilical cord particulate (dHUCP) medical device, which offers a unique allogeneic technological advancement and the first human birth tissue device for wound management. Characterization analyses illustrated a complex extracellular matrix composition conserved in the dHUCP device compared to native umbilical cord, with abundant collagens and glycosaminoglycans imbibing an intricate porous scaffold. Dermal fibroblasts readily attached to the intact scaffold of the dHUCP device. Furthermore, the dHUCP device elicited a significant paracrine proliferative response in dermal fibroblasts, in contrast to fibrillar collagen, a prevalent wound device. Biocompatibility testing in a porcine full-thickness wound model showed resorption of the dHUCP device and normal granulation tissue maturation during healing. The dHUCP device is a promising advancement in wound management biomaterials, offering a unique combination of structural complexity adept for challenging wound topographies and a microenvironment supportive of tissue regeneration.

Biological ultrathin amniotic membrane flap to close refractory macular holes associated with high myopia

PURPOSE

To propose an ultrathin biological amniotic membrane (btAM) thinner than 10 μm as the graft to treat highly myopic macular holes (MH).

METHODS

This pilot study included 14 patients affected by refractory macular holes associated with high myopia. btAM was used as a bandage covering the holes. The best-corrected visual acuity (BCVA), fundus photography, and optical coherence tomography (OCT) before and after surgery were compared.

RESULTS

The mean MH size was 865.93 ± 371.72 μm and all the MHs achieved anatomical closure. The btAM located centrally and fully on MHs from fundus photography yet no obvious visual masking was complained. The average BCVA 1 month, 3, and 6 months after surgery were 0.95 ± 0.24, 0.92 ± 0.23, 0.92 ± 0.23 logMAR, respectively, improved significantly compared to pre-operative BCVA (1.24 ± 0.42 logMAR, all P < 0.05). Ten out of 14 (71.4%) exhibited 2C closure patterns (formally closed and no bare RPE) on OCT.

CONCLUSION

The btAM thinner showed a favorable anatomical success with less risk of parafoveal atrophy or iatrogenic injuries and shortened the dissolving time.

Sterilization of Human Amniotic Membrane Using an Ozone Hydrodynamic System

Human amniotic membrane (hAM) is an important biomaterial for Tissue Engineering, due to its great regenerative properties and potential use as a scaffold. The most used procedure to sterilize biomaterials is gamma-irradiation, but this method can affect several properties, causing damage to the structure and reducing the growth factors. The present work evaluated the efficiency of a new method based on ozonated dynamic water for hAM sterilization. HAM fragments were experimentally contaminated with Staphylococcus aureus, Escherichia coli, Candida albicans, Staphylococcus epidermidis, and Clostridium sporogenes (106 CFU/mL) and submitted to sterilization process for 5, 10 and 15 min. The analyses did not reveal microbial activity after 10 min for S. aureus and C. sporogenes and after 15 min for E. coli and S. epidermidis. The microbial activity of C. albicans was reduced with the exposure time increase, but the evaluated time was insufficient for complete sterilization. The depyrogenation process was investigated for different ozonation times (15, 20, 25, 30, and 35 min) to evaluate the ozone sterilization potential and presented promising results after 35 min. The ozone effect on hAM structure was evaluated by histological analysis. A decrease in epithelium average thickness was observed with the exposure time increase. Furthermore, some damage in the epithelium was observed when hAM was exposed for 10 and 15 min. It can indicate that ozone, besides being effective in sterilization, could promote the hAM sample's de-epithelization, becoming a possible new method for removing the epithelial layer to use hAM as a scaffold.

A Biosynthetic Alternative to Human Amniotic Membrane for Use in Ocular Surface Surgery

Purpose

The biosynthetic Symatix membrane (SM) was developed to replace fresh human amniotic membrane (hAM) in ocular surgical applications. The purpose of this study was to test the biocompatibility of the SM with human limbus-derived epithelial cells with regard to their physical and biological properties.

Methods

Different physical properties of SM were tested ex vivo by simulation on human corneas. In vitro, primary limbal epithelial cells from limbal explants were used to test biological properties such as cell migration, proliferation, metabolic activity, and limbal epithelial cell markers on the SM, hAM, and freeze-dried amniotic membrane (FDAM).

Results

The surgical handleability of the SM was equivalent to that of the hAM. Ultrastructural and histological studies demonstrated that epithelial cells on the SM had the typical tightly apposed, polygonal, corneal epithelial cell morphology. The epithelial cells were well stratified on the SM, unlike on the hAM and FDAM. Rapid wound healing occurred on the SM within 3 days. Immunofluorescence studies showed positive expression of CK-19, Col-1, laminin, ZO-1, FN, and p-63 on the SM, plastic, and FDAM compared to positive expression of ZO-1, Col-1, laminin, FN, and p63 and negative expression of CK-19 in the hAM.

Conclusions

These results indicate that the SM is a better substrate for limbal epithelial cell migration, proliferation, and tight junction formation. Altogether, the SM can provide a suitable alternative to the hAM for surgical application in sight-restoring operations.

Translational Relevance

The hAM, currently widely used in ocular surface surgery, has numerous variations and limitations. The biocompatibility of corneal epithelial cells with the SM demonstrated in this study suggests that it can be a viable substitute for the hAM.

Neurotrophic keratopathy: General features and new therapies

Neurotrophic keratopathy is an uncommon degenerative corneal disorder characterized by compromised corneal sensory innervation resulting in the formation of epithelial defects and nonhealing corneal ulcers. Various treatment modalities are available to stabilize disease progression, improve patient well-being, and prevent vision loss. For eligible patients, medical and surgical reinnervation have emerged as pioneering therapies, holding promise for better management. We present a comprehensive review of the disorder, providing an update relevant to ophthalmologists on pathogenesis, diagnosis, treatment options, and novel therapies targeting pathophysiological pathways.

Introduction to Amniotic Membranes in Maxillofacial Surgery-A Scoping Review

Background: Amniotic membrane (AM) holds significant promise in various medical fields due to its unique properties and minimal ethical concerns. This study aims to explore the diverse applications of the human amniotic membrane (HAM) in maxillofacial surgery. Methodology: A comprehensive search was conducted on databases, namely Google Scholar, PubMed, and Scopus, from January 1985 to March 2024. Articles in English, Polish, and Spanish were included, focusing on keywords related to amniotic membrane and oral surgery. Results: Various preservation methods for HAM were identified, namely fresh, decellularized, cryopreserved, lyophilized, and air-dried formats. Clinical studies demonstrated the efficacy of HAM in repairing oral mucosal defects, vestibuloplasty, oronasal fistula closure, cleft palate treatment, bone defect repair, and medication-related osteonecrosis of the jaw (MRONJ). Surgeon evaluations highlighted the ease of handling but noted challenges in suturing and stability during application. Conclusions: Amniotic membranes offer a versatile and effective option in maxillofacial surgery, promoting wound healing, reducing inflammation, and providing a scaffold for tissue regeneration. Further research, including randomized trials and comparative studies, is warranted to validate the efficacy and optimize the utilization of HAM in clinical practice.

Cryopreserved amniotic membrane in chronic nonhealing wounds: a series of case reports

A case series of the use of amniotic membrane (AM) for treating chronic nonhealing wounds. It presents five cases of polymorbid patients with a total of nine chronic nonhealing wounds. The patient group consisted of four men and one woman with various comorbidities, aged 45-72 years. The mean initial wound size was 15.8 cm2, and the mean time from the onset of the wound to the first application of AM was 122 weeks. The wounds were caused by chronic venous insufficiency and/or peripheral arterial disease. Wounds were treated in a standardized protocol. AM was applied weekly in the first month and then every two weeks. Photo documentation of the wound and microbiological colonization was carried out at each visit. In three out of five patients, the AM treatment effectively promoted healing up to complete wound closure. In two cases, the wounds stayed unhealed despite numerous AM applications. Pain relief was noted in all patients. The success of the treatment was closely tied to patient factors, such as adherence to the prescribed treatment regimen and individual patient characteristics. In some cases, treatment failure was observed, possibly due to underlying comorbidities, wound parameters, or poor patient compliance. AM treatment has the potential to become a viable treatment option for these nonhealing wounds. However, the effectiveness of the treatment may be influenced by various patient factors and the underlying cause of the wound. Therefore, it is crucial to have an individualized treatment plan that considers these particular factors.

Outcomes and success of amniotic membrane transplantation for the treatment of corneal diseases

PURPOSE

The amniotic membrane (AM), the inner layer of the placenta, is a semitransparent, avascular, and thin tissue that is useful due to its structure. Amniotic membrane transplantation (AMT) avoids the need for keratoplasty to prevent corneal perforating. The purpose of the study was to evaluate the visual (gain of or no change in visual acuity) and corneal outcomes (closure of the ulcer or corneal healing) of AMT in patients with ocular surface diseases.

MATERIALS AND METHODS

This was a retrospective case control study (success or failure of the surgery). It was undertaken at a single academic center. The study cohort consisted of subjects with ocular surface diseases. Patients were treated with AMT for refractory ocular surface diseases. They were divided into five subgroups according to the preoperative diagnosis. The technique of AMT used was the onlay method with two layers of AM. Primary outcome measures included best corrected visual acuity (BCVA), the number of AMTs, and reepithelization of the corneal epithelium at the end of the treatment. Two weeks to six months were given to consider epithelial closure. Treatment success was defined as corneal healing within 6 months.

RESULTS

A total of the 66 eyes of 66 patients (39 male/27 female) with a mean age of 44 ± 23 years (range 1-88 years) were included in the study. A single AMT procedure achieved epithelial closure in 74.2% (n = 49) of the eyes (53% in <15 days, 19.6% in 15-30 days, and 1.5% in 1-6 months). The fastest reepithelization occurred in neurotrophic keratopathy, 76.9% of which cases occurred within 15 days after the AMT procedure. Treatment failure was observed in five patients (7.5%), four with keratitis and one with neurotrophic keratopathy. The highest closure rates were found in persistent epithelial defects, graft-versus-host disease (GvHD), and bullous keratopathy, although there was no statistically significant difference in BCVA. Pairwise comparisons were made of neurotropic keratoplasty versus bullous keratopathy (P = 0.025), neurotrophic keratopathy versus keratitis (P = 0.004), GVHD versus keratitis (P = 0.003), and lastly, GvHD versus bullous keratopathy (P = 0.023).

CONCLUSIONS

AMT is a safe, valuable, and fast treatment technique to treat corneal epithelial defects stemming from different etiologies that are refractory to conventional treatment.

A Review of Current Uses of Amniotic Membrane Transplantation in Ophthalmic Plastic and Reconstructive Surgery

PURPOSE

To review and summarize the existing literature on the clinical applications of amniotic membrane transplantation (AMT) in ophthalmic plastic and reconstructive surgery.

METHODS

A literature review was conducted on the PubMed database using the following search terms: "amniotic membrane" and "eyelid" or "orbit" or "fornix" or "socket" or "lacrimal".

RESULTS

In total 516 articles resulted from the search, of which 62 were included. Numerous cases and case series have been published on the use of amniotic membrane transplantation for ocular surface reconstruction, eyelid and forniceal reconstruction, and cicatricial eyelid abnormalities. Surgical methods of securing the graft vary. Few comparative studies exist; some show a similar or improved result when compared to oral mucous membrane grafting for certain indications.

CONCLUSIONS

Amniotic membrane transplantation can be a useful tool for the oculoplastic surgeon when faced with a case requiring reconstruction of the posterior lamellae, particularly in patients without other graft donor sites available, and uses of AMT continue to expand. Additional studies directly comparing AMT to other reconstructive techniques would be helpful in choosing between the available surgical techniques and standardizing best practices.

An important detail that is still not clear in amniotic membrane applications: How do we store the amniotic membrane best?

The use of fresh amniotic membrane (AM) is not a viable option, as it has many disadvantages. Preserving the AM reduces the risk of cross-infection and maintains its effectiveness for a long time. In order to maximize the therapeutic effects of the AM, the basic need is to preserve its vitality and the bioactive molecules it contains. However, the effect of preservation procedures on cell viability and growth factors is a still matter of debate. Optimum preservation method is expected to be cost-effective, easily-accessible, and most importantly, to preserve the effectiveness of the tissue for the longest time. However, each preservation technique has its advantages and disadvantages over the other, and each one compromises the vitality and bioactive molecules of the tissue to some extent. Therefore, the best method of preservation is still controversial, and the question of 'how to preserve the AM best?' has not yet been definitively answered.

Amniotic membrane transplantation: structural and biological properties, tissue preparation, application and clinical indications

The amniotic membrane is a single epithelial layer of the placenta. It has anti-inflammatory, anti-scarring, anti-angiogenic and possibly bactericidal properties. The basement membrane of the amniotic membrane acts as a substrate to encourage healing and re-epithelialisation. It has been used in many ocular surface diseases including persistent epithelial defects (corneal or conjunctival), chemical or thermal burns, limbal stem cell deficiency, cicatrising conjunctivitis, ocular graft versus host disease, microbial keratitis, corneal perforation, bullous keratopathy, dry eye disease, corneal haze following refractive surgery and cross-linking, band keratopathy, ocular surface neoplasia, pterygium surgery, and ligneous conjunctivitis. This review provides an up-to-date overview of amniotic membrane transplantation including the structural and biological properties, preparation and application, clinical indications, and commercially available products.

Clinical Outcomes and Indications of In-Office Sutureless Dried Gamma Ray-Sterilized Human Amniotic Membrane Transplantation With Bandage Contact Lenses in Various Ocular Surface Disorders

PURPOSE

The purpose of this study was to investigate the efficacy and indications of using dried gamma ray-sterilized amniotic membrane (AM) transplantation with bandage contact lenses for the in-office sutureless treatment of various ocular surface diseases.

METHODS

This study retrospectively included 56 eyes of 52 patients with various ocular surface diseases treated with sutureless dehydrated AM-assisted therapeutic contact lenses. The patients were followed up and assessed 1, 2, and 4 weeks after the treatment, and the therapeutic contact lenses were removed after 1 or 2 weeks. The size of the corneal lesion and the degree of pain experienced by each patient before and after the procedure were measured. Corneal re-epithelization rate and clinical aspects related to re-epithelialization were evaluated.

RESULTS

Complete corneal re-epithelialization of the epithelial defect was observed in 40 eyes. The complete re-epithelialization rates of persistent epithelial defect caused by infectious ulcers, neurotrophic ulcers, ulcers due to burn, toxic keratopathy, previous penetrating keratoplasty or other corneal surgeries, and severe dry eye disease were 69.2%, 80.0%, 77.8%, 100%, 75.0%, and 100%, respectively. Five patients with uncontrolled infectious ulcers, neurotrophic ulcer, bullous keratopathy, and ulcers associated with rheumatic disease did not show significant improvement. Patient pain scores significantly decreased after the procedure.

CONCLUSIONS

Dehydrated AM transplantation with a bandage contact lens is minimally invasive and easily applicable through in-office procedures. This approach is expected to be more actively applied in various ocular surface disorders, not only in severe corneal diseases but also in relatively mild corneal surface diseases.

Advances in the ocular complications after hematopoietic stem cell transplantation

Hematopoietic stem cell transplantation (HSCT) has benefited an increasing number of patients with hematological disease in the clinic. It is a curative therapy for malignant and nonmalignant hematological diseases. With the advancement and further clinical application of HSCT in recent years, the life expectancy of patients has increased, but complications have become more common. The occurrence of ocular complications is receiving increasing attention because they can seriously affect the quality of life of patients. Ocular complications require increased attention from clinicians because of their negative impact on patients and increasing incidence. Most of recent reports on posttransplant ocular complications involve ocular manifestations of graft-versus-host disease (GVHD), and a few ocular complications that do not originate from GVHD have also been reported. This review summarizes the diagnosis, scoring criteria, pathophysiology, and clinical manifestations of and common therapies for ocular graft-versus-host disease(oGVHD) after HSCT, and includes a description of some rare cases and novel therapies.

New advances in medical management of dry eye: optimizing treatment strategies for enhanced relief

PURPOSE

Dry eye disease (DED) is a prevalent ocular surface disease that is conventionally characterized by tear film hyperosmolarity and instability. This review presents a summarized classification of DED, followed by a comprehensive discussion of the most recent topical and systemic medications and clinical recommendations for selecting the most appropriate option for each patient.

METHODS

An extensive literature search was conducted on electronic databases, such as PubMed, Scopus, and Web of Science, using keywords including "dry eye syndrome," "ocular surface disease," "medical management," "artificial tears," "topical immunomodulators," and "meibomian gland dysfunction."

RESULTS

The underlying reasons for DED can range from insufficient aqueous tear production to increased tear evaporation. Recent literature has provided a more in-depth understanding of the pathophysiology of DED by examining the tear film's lipid, aqueous, and mucin layers. However, despite these advancements, medical management of patients with symptomatic DED has not fully reflected this modernized knowledge of its pathophysiology.

CONCLUSION

To develop a rationalized strategy for treating DED, it is crucial to have updated knowledge of therapeutic options, their mechanisms of actions, and indications based on the DED type and underlying causes.

Ocular Lichen Planus: A clinicopathologic review

Lichen planus is a chronic inflammatory dermatosis that can affect the skin, mucous membranes and nails. Cutaneous lichen planus lesions are best described by the "six Ps" - purple pruritic polygonal planar papules and plaques. Mucous membrane lesions are commonly associated with cutaneous lichen planus. Ocular involvement with lichen planus is rare and conjunctival involvement usually predominates, it can however be visually devastating. Ocular lichen planus often progresses to extensive conjunctival scarring which can be impossible to distinguish clinically from other cicatrising conjunctivitis, requiring histopathological confirmation. Here we review the ocular pathology of this condition.

Polymers and Biomaterials for Posterior Lamella of the Eyelid and the Lacrimal System

The application of biopolymers in the reconstruction of the posterior lamella of the eyelid and the lacrimal system marks a significant fusion of biomaterial science with clinical advancements. This review assimilates research spanning 2015 to 2023 to provide a detailed examination of the role of biopolymers in reconstructing the posterior lamella of the eyelid and the lacrimal system. It covers the anatomy and pathophysiology of eyelid structures, the challenges of reconstruction, and the nuances of surgical intervention. This article progresses to evaluate the current gold standards, alternative options, and the desirable properties of biopolymers used in these intricate procedures. It underscores the advancements in the field, from decellularized grafts and acellular matrices to innovative natural and synthetic polymers, and explores their applications in lacrimal gland tissue engineering, including the promise of 3D bioprinting technologies. This review highlights the importance of multidisciplinary collaboration between material scientists and clinicians in enhancing surgical outcomes and patient quality of life, emphasizing that such cooperation is pivotal for translating benchtop research into bedside applications. This collaborative effort is vital for restoring aesthetics and functionality for patients afflicted with disfiguring eyelid diseases, ultimately aiming to bridge the gap between innovative materials and their clinical translation.

INTRARETINAL HUMAN AMNIOTIC MEMBRANE AFTER MACULAR HOLE REPAIR

PURPOSE

To describe a unique complication of macular hole repair surgery using a subretinal human amniotic membrane plug.

METHODS

Retrospective, interventional case report.

RESULTS

A 71-year-old man presented with a chronic full-thickness macular hole in his left eye. Conventional 23-gauge pars plana vitrectomy with internal limiting membrane peeling and implantation of a subretinal human amniotic membrane plug was performed. In the postoperative period, centripetal growth of external retinal layers was observed under the plug. Six months after the surgery, the human amniotic membrane plug was completely integrated into the retina.

CONCLUSION

This is the first reported case of intraretinal integration of a human amniotic membrane plug after macular hole repair surgery.

Development of Thermoplastic Polyurethane Films for the Replacement of Corneal Endothelial Function of Transparency Maintenance

Endothelial keratoplasty is the main surgical procedure for treating corneal endothelial dysfunction (CED), which is limited by the global shortage of donor corneas. Herein, we developed and evaluated the modified thermoplastic polyurethane (M-TPU) films with gelatin-glycidyl methacrylate to replace the corneal endothelial function and maintain corneal transparency. The films displayed comparable light transmission characteristics with normal corneas and clinically favorable mechanical properties for surgical manipulation. After surface modification, the hydrophilicity and biocompatibility of M-TPU films were significantly improved. In the rabbit CED model, the M-TPU implants exhibited firm adhesion to the exposed stromal surface. The rabbit corneal transparency and thickness could be restored completely within 1 week of M-TPU film implantation. There was no significant inflammatory reaction and immune rejection during the follow-up of 1 month. Proteomic analysis suggested that the complement inhibition, the increase of mineral absorption, and the decrease of P53 apoptosis signaling pathway and lysine degradation might be beneficial in maintaining the corneal transparency. Overall, our study demonstrated the potential of M-TPU films as artificial implants for the replacement of corneal endothelial function to restore corneal thickness and transparency.

New Frontiers in Acanthamoeba Keratitis Diagnosis and Management

Acanthamoeba Keratitis (AK) is a severe corneal infection caused by the Acanthamoeba species of protozoa, potentially leading to permanent vision loss. AK requires prompt diagnosis and treatment to mitigate vision impairment. Diagnosing AK is challenging due to overlapping symptoms with other corneal infections, and treatment is made complicated by the organism's dual forms and increasing virulence, and delayed diagnosis. In this review, new approaches in AK diagnostics and treatment within the last 5 years are discussed. The English-language literature on PubMed was reviewed using the search terms "Acanthamoeba keratitis" and "diagnosis" or "treatment" and focused on studies published between 2018 and 2023. Two hundred sixty-five publications were initially identified, of which eighty-seven met inclusion and exclusion criteria. This review highlights the findings of these studies. Notably, advances in PCR-based diagnostics may be clinically implemented in the near future, while antibody-based and machine-learning approaches hold promise for the future. Single-drug topical therapy (0.08% PHMB) may improve drug access and efficacy, while oral medication (i.e., miltefosine) may offer a treatment option for patients with recalcitrant disease.

Inter-placental variability is not a major factor affecting the healing efficiency of amniotic membrane when used for treating chronic non-healing wounds

This study aimed to evaluate the efficacy of cryopreserved amniotic membrane (AM) grafts in chronic wound healing, including the mean percentage of wound closure per one AM application, and to determine whether the healing efficiency differs between AM grafts obtained from different placentas. A retrospective study analyzing inter-placental differences in healing capacity and mean wound closure after the application of 96 AM grafts prepared from nine placentas. Only the placentas from which the AM grafts were applied to patients suffering from long-lasting non-healing wounds successfully healed by AM treatment were included. The data from the rapidly progressing wound-closure phase (p-phase) were analyzed. The mean efficiency for each placenta, expressed as an average of wound area reduction (%) seven days after the AM application (baseline, 100%), was calculated from at least 10 applications. No statistical difference between the nine placentas' efficiency was found in the progressive phase of wound healing. The 7-day average wound reduction in particular placentas varied from 5.70 to 20.99% (median from 1.07 to 17.75) of the baseline. The mean percentage of wound surface reduction of all analyzed defects one week after the application of cryopreserved AM graft was 12.17 ± 20.12% (average ± SD). No significant difference in healing capacity was observed between the nine placentas. The data suggest that if there are intra- and inter-placental differences in AM sheets' healing efficacy, they are overridden by the actual health status of the subject or even the status of its individual wounds.

Human amniotic membranes as an allogenic biological dressing for the treatment of burn wounds: Protocol for a randomized-controlled study

Background

Burn wounds pose significant challenges in medical treatment due to their devastating nature and resource-intensive requirements. Temporary coverage of burn wounds using synthetic or biological dressings allows for reepithelization before definitive skin grafting. Allogenic skin grafts have been widely used but come with drawbacks such as rejection and disease transmission. The use of amniotic membranes (AMs) offers a promising alternative for temporary coverage, as they possess biological properties that promote faster healing and improved scar quality. The various components of the amniotic membrane, including pluripotent stem cells, extracellular matrix proteins, and regenerative factors, contribute to cell growth, migration, and differentiation, as well as preservation of the original epithelial phenotype.

Objective

Reliable information on the treatment of burn wounds with AM is needed. The knowledge gained in this project may help to include this advantageous modern concept of biological dressings in clinical practice. The purpose of this study is to use human amniotic membranes from our in hospital laboratory, as an allogenic biological dressing after enzymatic debridement in superficial partial thickness, deep partial thickness or full thickness burn wounds.

Methods

We will include 30 patients in a randomized-controlled trial with each patient receiving the study intervention and the control intervention. Two 7 × 7 cm burn wound areas will be compared regarding percentage of skin graft take, healing time, healing percentage value and total healing time. Human amniotic membranes will be compared to allogenic skin grafts.

Amniotic membrane transplantation combined with conjunctival flap covering surgery for the treatment of corneal perforations in fungal keratitis

Purpose

To investigate the efficiency of amniotic membrane transplantation (AMT) combined with conjunctival flap covering surgery (CFCS) for patients with corneal perforations in fungal keratitis (FK).

Methods

In this non-comparative, retrospective case series, 16 participants of corneal perforation in FK were successfully treated by a combination of multilayer AMT and bipedicle conjunctival flap with partial tenon's capsule. Corneal healing, recurrence of FK, visual acuity, and relevant complications were reported as outcome measures.

Results

Sixteen patients (13 male, 3 female) had a mean age of 58.8 ± 10.3 (range 29-72) years. The mean diameter of corneal perforation was 1.9 ± 0.7 (range 0.5-2.8) mm. Corneal perforations healed and all the patients preserved their eyeballs. During the 11.0 ± 4.4 (range 6-18) months of follow-up, there was no recurrence of FK in any of these cases. Visual acuity improved in 15 eyes (93.8 %) and remained unchanged in 1 patient (6.3 %) who had no light perception when first admitted. All 6 patients who accepted secondary keratoplasty showed improved best corrected visual acuity of more than 4 lines. The most frequently found fungi were Aspergillus species (6 of 16, 37.5 %) and Fusarium species (4 of 16, 25.0 %), followed by 1 Scedosporium apiospermum (1 of 16, 6.3 %).

Conclusions

Combination AMT with CFCS is a safe and effective surgery for patients with corneal perforations in FK, particularly where eye banks and fresh corneas are not available. This surgery could preserve the integrity of the eyeball and avoid the recurrence of FK. Besides, it provides a greater opportunity for further optical keratoplasty.

Application of the Human Amniotic Membrane as an Adjuvant Therapy for the Treatment of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related morbidity and mortality worldwide. Current therapeutic approaches suffer significant side effects and lack of clear understanding of their molecular targets. Recent studies reported the anticancer effects, immunomodulatory properties, and antiangiogenic effects of the human amniotic membrane (hAM). hAM is a transparent protective membrane that surrounds the fetus. Preclinical studies showed pro-apoptotic and antiproliferative properties of hAM treatment on cancer cells. Herein, we present the latest findings of the application of the hAM in combating HCC tumorigenesis and the underlying molecular pathogenies and the role of transforming growth factor-beta (TGFβ), P53, WNT/beta-catenin, and PI3K/AKT pathways. The emerging clinical applications of hAM in cancer therapy provide evidence for its diverse and unique features and suitability for the management of a wide range of pathological conditions.

The Preparation and Clinical Efficacy of Amnion-Derived Membranes: A Review

Biological tissues from various anatomical sources have been utilized for tissue transplantation and have developed into an important source of extracellular scaffolding material for regenerative medicine applications. Tissue scaffolds ideally integrate with host tissue and provide a homeostatic environment for cellular infiltration, growth, differentiation, and tissue resolution. The human amniotic membrane is considered an important source of scaffolding material due to its 3D structural architecture and function and as a source of growth factors and cytokines. This tissue source has been widely studied and used in various areas of tissue repair including intraoral reconstruction, corneal repair, tendon repair, microvascular reconstruction, nerve procedures, burns, and chronic wound treatment. The production of amniotic membrane allografts has not been standardized, resulting in a wide array of amniotic membrane products, including single, dual, and tri-layered products, such as amnion, chorion, amnion-chorion, amnion-amnion, and amnion-chorion-amnion allografts. Since these allografts are not processed using the same methods, they do not necessarily produce the same clinical responses. The aim of this review is to highlight the properties of different human allograft membranes, present the different processing and preservation methods, and discuss their use in tissue engineering and regenerative applications.

Biological importance of human amniotic membrane in tissue engineering and regenerative medicine

The human amniotic membrane (hAM) is the innermost layer of the placenta. Its distinctive structure and the biological and physical characteristics make it a highly biocompatible material in a variety of regenerative medicine applications. It also acts as a supply of bioactive factors and cells, which indicate the advantages over other tissues. In this review, we firstly discussed the biological properties of hAM-derived cells in vivo or in vitro, along with their stemness of markers, pointing out a promising source of stem cells for regenerative medicine. Then, we systematically summarized current knowledge on the collection, preparation, preservation, and decellularization of hAM, as well as their characteristics helping to improve the understanding of applications in tissue engineering. Finally, we highlighted the recent advances in which hAM has undergone additional modifications to achieve an adequate perspective of regenerative medicine applications. More investigations are required in utilizing appropriate modifications to enhance the therapeutic effectiveness of hAM in the future.

Corneal Descemetocele Management with Multi-Layer Amniotic Membrane Transplantation in an Ocular Graft-versus-Host Disease Case

Background: Chronic ocular graft-versus-host disease (oGVHD) is a common ocular complication following allogeneic hematopoietic stem cell transplantation (allo-HSCT), characterized by progressive inflammation of the ocular surface and refractory dry eye. In severe cases, sterile corneal perforation can occur, which poses a significant challenge, due to the low survival rate of grafts after corneal transplantation. Case Presentation: A 47-year-old female presented to our hospital with persistent dryness, foreign body sensation, and blurred vision in her left eye. Diagnosis of graft-versus-host disease with corneal descemetocele in the left eye was made after detailed history review and thorough examination. Multi-layer amniotic membrane transplantation was performed in the affected eye, resulting in amelioration of the patient's symptoms. This amelioration of symptoms provided the patient with a level of comfort that permitted additional time while awaiting corneal transplantation. Conclusions: We report a successful case of multi-layer amniotic membrane transplantation for the management of corneal descemetocele following allo-HSCT.

Emerging Strategies for the Biofabrication of Multilayer Composite Amniotic Membranes for Biomedical Applications

The amniotic membrane (AM) is the innermost part of the fetal placenta, which surrounds and protects the fetus. Due to its structural components (stem cells, growth factors, and proteins), AMs display unique biological properties and are a widely available and cost-effective tissue. As a result, AMs have been used for a century as a natural biocompatible dressing for healing corneal and skin wounds. To further increase its properties and expand its applications, advanced hybrid materials based on AMs have recently been developed. One existing approach is to combine the AM with a secondary material to create composite membranes. This review highlights the increasing development of new multilayer composite-based AMs in recent years and focuses on the benefits of additive manufacturing technologies and electrospinning, the most commonly used strategy, in expanding their use for tissue engineering and clinical applications. The use of AMs and multilayer composite-based AMs in the context of nerve regeneration is particularly emphasized and other tissue engineering applications are also discussed. This review highlights that these electrospun multilayered composite membranes were mainly created using decellularized or de-epithelialized AMs, with both synthetic and natural polymers used as secondary materials. Finally, some suggestions are provided to further enhance the biological and mechanical properties of these composite membranes.

Evaluation of colonic anastomosis healing using hybrid nanosheets containing molybdenum disulfide (MOS2) scaffold of human placental amniotic membrane and polycaprolactone (PCL) in rat animal model

Anastomosis is a standard technique following different conditions such as obstruction, tumor, and trauma. Obstruction, adhesion, or anastomosis leakage can be some of its complications. To improve healing and prevent postoperative complications, we design a hybrid scaffold containing acellular human amniotic membranes and polycaprolactone-molybdenum disulfide nanosheets for colon anastomosis. The animal model of colocolonic anastomosis was performed on two groups of rats: control and scaffold. The hybrid scaffold was warped around the anastomosis site in the scaffold group. Samples from the anastomosis site were resected on the third and seventh postoperative days for histopathological and molecular assessments. Histopathologic score and burst pressure had shown significant improvement in the scaffold group. No mortality and anastomosis leakage was reported in the scaffold group. In addition, inflammatory markers were significantly decreased, while anti-inflammatory cytokines were increased in the scaffold group. The result indicates that our hybrid scaffold is a proper choice for colorectal anastomosis repair by declining postoperative complications and accelerating healing.

Corneal regeneration strategies: From stem cell therapy to tissue engineered stem cell scaffolds

Corneal epithelial defects and excessive wound healing might lead to severe complications. As stem cells can self-renew infinitely, they are a promising solution for regenerating the corneal epithelium and treating severe corneal epithelial injury. The chemical and biophysical properties of biological scaffolds, such as the amniotic membrane, fibrin, and hydrogels, can provide the necessary signals for stem cell proliferation and differentiation. Multiple researchers have conducted investigations on these scaffolds and evaluated them as potential therapeutic interventions for corneal disorders. These studies have identified various inherent benefits and drawbacks associated with these scaffolds. In this study, we provided a comprehensive overview of the history and use of various stem cells in corneal repair. We mainly discussed biological scaffolds that are used in stem cell transplantation and innovative materials that are under investigation.

Surgical Time and Postoperative Symptoms Study in Pterygium Excision and Amniotic Membrane Graft Using Celularity Triple Layer Dehydrated Amniotic Membrane

Purpose

To evaluate a novel sutureless glueless technique using a triple-layer dehydrated amniotic membrane (TLDAM) for pterygia excisions in surgical time, postoperative pain, epiphora, irritation, and FBS.

Methods

Twenty eyes with pterygia underwent excision with mitomycin C. The conjunctival defect was closed with TLDAM placed on the dried scleral bed with the edges of the amniotic membrane tucked under the edges of the conjunctival defect. Surgical times were measured from injection of lidocaine to final placement of bandage contact lens. After a bandage contact lens was placed, the eye was patched until POD1. Patients graded self-administered questionnaires to rate pain, FBS, irritation, and epiphora on a scale of 1-5 (1-none; 5-severe) at POD1 and POW1.

Results

Surgical times ranged from 6:55 to 12:00, with mean of 8:29. Compared with a previous study of sutureless glueless methodology, the difference in mean surgical time was 11.9 (p < 0.0001). Mean questionnaire scores were as follows: POD1 pain 1.8, FBS 2.3, irritation 1.0, and epiphora 2.6; POW1 pain 1.5, FBS 1.6, irritation 1.6, and epiphora 1.6. Compared to previous studies, this technique showed significantly improved pain at POD1 (p=0.0086, p<0.0001, p<0.0001, p<0.0001) and POW1 (p=0.0002, p=0.0016, p<0.0001). Significant improvement in irritation and FBS was noted at POD1 and POW1. See Table 1 for full analysis.

Conclusion

The sutureless glueless technique using TLDAM is a safe and effective technique compared to current standard methods. There appears to be a significant benefit regarding surgical time and postoperative pain, irritation, epiphora, and FBS compared to previous studies.

Revisiting the Role of Amniotic Membrane Dressing in Acute Large Traumatic Wounds: A Randomized Feasibility Study at a Level 1 Trauma Centre

Introduction

Acute large traumatic wounds require temporary dressing prior to the definitive soft tissue reconstruction, as the physiological derangement during the immediate postinjury period delays the definitive surgical intervention. Selecting an ideal dressing material from numerous available synthetic dressings and skin substitutes poses a challenge. Although amniotic membrane (AM) scaffold has a definitive role in promoting wound healing in burns and chronic wounds, however, its efficacy in acute large traumatic wound is lacking. The present trial aimed to evaluate the safety and efficacy of AM in wound bed preparation before the definitive soft-tissue reconstruction in acute large traumatic wounds.

Methods

Sixty patients with acute large traumatic wounds (>10 cm × 10 cm) were divided into two groups (conventional dressing and AM dressing) using simple mixed block randomization. Wounds were assessed using the Bates Jensen Score at various timelines for the signs of early wound healing. The primary outcome was to evaluate the time taken for the wound bed preparation for definitive soft-tissue reconstruction. The secondary outcome was the pain assessment and complications, if any.

Results

There was significant reduction in the wound exudate as well as peripheral tissue edema in the intervention group (P = 0.01). AM dressing was significantly less painful (P = 0.01). The incidence of wound infection and need for debridement was decreased in the intervention group. However, the time interval to definitive soft-tissue coverage was statistically insignificant and comparable in both the groups. No adverse reactions were seen in either group.

Conclusion

AM dressings are safe and efficacious with significant reduction in wound exudates and peripheral edema. However, these dressings do not hasten the wound maturation as compared to conventional dressings. AM dressings can be used as a less painful alternative to conventional dressing in the management of large acute posttraumatic wounds.

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.

Collagen membrane loaded with doxycycline through hydroxypropyl chitosan microspheres for the early reconstruction of alkali-burned cornea

Corneal alkali burn is one of the most devastating ophthalmic emergencies correlated with remarkable morbidity resulting in severe visual impairment. Appropriate intervention in the acute phase determines the eventual outcome for later corneal restoration treatment. Since the epithelium plays an essential role in inhibiting inflammation and promoting tissue repair, sustained anti-matrix metalloproteinases (MMPs) and pro-epithelialization are the prior remedies during the first week. In this study, a drug-loaded collagen membrane (Dox-HCM/Col) that could be sutured to overlay the burned cornea was developed to accelerate the early reconstruction. Doxycycline (Dox), a specific inhibitor of MMPs, was encapsulated in collagen membrane (Col) through hydroxypropyl chitosan microspheres (HCM) to develop Dox-HCM/Col, affording a preferable pro-epithelialization microenvironment and an in-situ controlled release. Results showed that loading HCM into Col prolonged the release time to 7 days, and Dox-HCM/Col could significantly suppress the expression of MMP-9 and -13 in vitro and in vivo. Furthermore, the membrane accelerated the corneal complete re-epithelialization and promoted early reconstruction within the first week. Overall, Dox-HCM/Col was a promising biomaterial membrane for treating alkali-burned cornea in the early stage, and our attempt may provide a clinically feasible method for the ocular surface reconstruction.

Acceleration of burn wound healing by micronized amniotic membrane seeded with umbilical cord-derived mesenchymal stem cells

Umbilical cord-derived mesenchymal stem cells (UC-MSC) are promising candidates for wound healing. However, the low amplification efficiency of MSC in vitro and their low survival rates after transplantation have limited their medical application. In this study, we fabricated a micronized amniotic membrane (mAM) as a microcarrier to amplify MSC in vitro and used mAM and MSC (mAM-MSC) complexes to repair burn wounds. Results showed that MSC could live and proliferate on mAM in a 3D culture system, exhibiting higher cell activity than in 2D culture. Transcriptome sequencing of MSC showed that the expression of growth factor-related, angiogenesis-related, and wound healing-related genes was significantly upregulated in mAM-MSC compared to traditional 2D-cultured MSC, which was verified via RT-qPCR. Gene ontology (GO) analysis of differentially expressed genes (DEGs) showed significant enrichment of terms related to cell proliferation, angiogenesis, cytokine activity, and wound healing in mAM-MSC. In a burn wound model of C57BL/6J mice, topical application of mAM-MSC significantly accelerated wound healing compared to MSC injection alone and was accompanied by longer survival of MSC and greater neovascularization in the wound.

Application of Silk-Fibroin-Based Hydrogels in Tissue Engineering

Silk fibroin (SF) is an excellent protein-based biomaterial produced by the degumming and purification of silk from cocoons of the Bombyx mori through alkali or enzymatic treatments. SF exhibits excellent biological properties, such as mechanical properties, biocompatibility, biodegradability, bioabsorbability, low immunogenicity, and tunability, making it a versatile material widely applied in biological fields, particularly in tissue engineering. In tissue engineering, SF is often fabricated into hydrogel form, with the advantages of added materials. SF hydrogels have mostly been studied for their use in tissue regeneration by enhancing cell activity at the tissue defect site or counteracting tissue-damage-related factors. This review focuses on SF hydrogels, firstly summarizing the fabrication and properties of SF and SF hydrogels and then detailing the regenerative effects of SF hydrogels as scaffolds in cartilage, bone, skin, cornea, teeth, and eardrum in recent years.

Antimicrobial Effect of the Amniotic Membrane Isolated and Associated with Photodynamic Therapy

Microbial control through alternative therapies, such as the amniotic membrane (AM) and antimicrobial photodynamic therapy (aPDT), has been gaining prominence with the advancement of bacterial resistance to conventional treatments. This study aimed to evaluate the antimicrobial effect of AM isolated and associated with aPDT using the PHTALOX® as a photosensitizer (PS) against Staphylococcus aureus and Pseudomonas aeruginosa biofilms. The groups studied were: C+; L; AM; AM+L; AM+PHTX; and AM+aPDT. The irradiation parameters were 660 nm, 50 J.cm−2, and 30 mW.cm−2. Two independent microbiological experiments were carried out in triplicate, and the results were analyzed by CFU/mL counting and a metabolic activity test, both statistically analyzed (p < 0.05). The integrity of the AM was verified after the treatments by a scanning electron microscope (SEM). The groups AM, AM+PHTX, and, mainly, AM+aPDT showed a statistical difference when compared to C+ regarding the decrease in CFU/mL and metabolic activity. SEM analysis showed significant morphological alterations in the AM+PHTX and AM+aPDT groups. The treatments with AM isolated or associated with PHTALOX® were adequate. The association had potentiated the biofilm effect, and the morphological differences presented by AM after treatment did not hinder its antimicrobial effect, encouraging its use in biofilm formation locals.

Pterygium surgery with lyophilized versus cryopreserved amniotic membrane graft

PURPOSE

To evaluate surgical outcomes (recurrence rate, aesthetics and symptoms) of pterygium surgery with two different amniotic membrane preservation approaches - lyophilized (LAM) and cryopreserved (CAM).

METHODS

Primary pterygium patients were randomized to either LAM or CAM surgery. Demographic data, ocular surface disease index (OSDI), aesthetic grading (1 to 4), recurrences and complications were recorded over a 6-month follow-up period.

RESULTS

Twenty-nine patients were recruited. Recurrence at month 6 was detected in 11 cases (37.9%) and was more prevalent with CAM grafts, without reaching statistical significance (P=0.196). Aesthetic outcome grading showed no differences between LAM and CAM at month 6 (P=0.124). Aesthetic results were mostly unsatisfactory (grade 3 and 4) without statistical differences between groups (P=0.514). Baseline OSDI was similar in both groups (P=0.888), and it significantly decreased by the last follow-up visit (P<0.001) for both the LAM and CAM groups. This decrease did not significantly differ between amniotic membrane preservation approach surgery groups (P=0.714).

CONCLUSION

LAM might be considered a legitimate alternative to CAM, showing no inferiority in outcomes, since clinical and aesthetic outcomes were similar for both groups.

An electrospun scaffold functionalized with a ROS-scavenging hydrogel stimulates ocular wound healing

Ocular alkali burn is a serious ophthalmic emergency. Highly penetrative alkalis cause strong inflammatory responses leading to persistent epithelial defects, acute corneal perforation and severe scarring, and thereby persistent pain, loss of vision and cicatricial sequelae. Early and effective anti-inflammation management is vital in reducing the severity of injury. In this study, a double network biomaterial was prepared by compounding electrospinning nanofibres of thioketal-containing polyurethane (PUTK) with a reactive oxygen species (ROS)-scavenging hydrogel (RH) fabricated by crosslinking poly(poly(ethylene glycol) methyl ether methacrylate-co-glycidyl methacrylate) with thioketal diamine and 3,3'-dithiobis(propionohydrazide). The developed PUTK/RH patch exhibited good transparency, high tensile strength and increased hydrophilicity. Most importantly, it demonstrated strong antioxidant activity against H₂O₂ and 2,2-di(4-tert-octylphenyl)-1-picryl-hydrazyl (DPPH). Next, a rat corneal alkali burn model was established, and the PUTK/RH patch was transplanted on the injured cornea. Reduced inflammatory cell infiltration was revealed by confocal microscopy, and lower expression levels of genes relative to inflammation, vascularization and scarring were identified by qRT-PCR and western blot. Fluorescein sodium dyeing, hematoxylin and eosin (H&E) staining and immunohistochemical staining confirmed that the PUTK/RH patch could accelerate corneal wound healing by inhibiting inflammation, promoting epithelial regeneration and decreasing scar formation. STATEMENT OF SIGNIFICANCE: Ocular alkali burn is a serious ophthalmic emergency, characterized with persistent inflammation and irreversible vision loss. Oxidative stress is the main pathological process at the acute inflammatory stage, during which combined use of glucocorticoids and amniotic membrane transplantation is the most widely accepted treatment. In this study, we fabricated a polyurethane electrospun nanofiber membrane functionalized with a ROS-scavenging hydrogel. This composite patch could be a promising amniotic membrane substitute, possessing with a transparent appearance, elasticity and anti-inflammation effect. It could be easily transplanted onto the alkali-burned corneas, resulting in a significant inhibition of stromal inflammation and accelerating the recovery of corneal transparency. The conception of ROS-scavenging wound patch may offer a new way for ocular alkali burn.

Biological nerve conduit model with de-epithelialized human amniotic membrane and adipose-derived mesenchymal stem cell sheet for repair of peripheral nerve defects

In this study, a biological conduit, consisting of an adipocyte-derived mesenchymal stem cell (AdMSCs) sheet and amniotic membrane (AM), was designed for the reconstruction of peripheral nerve defects. To evaluate the effect of the produced conduit on neural regeneration, a 10-mm sciatic nerve defect was created in rats, and experiments were carried out on six groups, i.e., sham control group (SC), negative control group (NC), nerve autograft group (NG), the biological conduit (AdMSCs + AM) group, the commercial PGA tube conduit (PGA) group, and the conduit only consisting of AM (AM) group. The effects of different nerve repair methods on the peripheral nerve and gastrocnemius muscle were evaluated by functional, histological, and immunohistochemical tests. When the number of myelinated axons was compared between the groups of AdMSCs + AM and PGA, it was higher in the AdMSCs + AM group (p < 0.05). The percentage of gastrocnemius collagen bundle area of AdMSCs + AM group was found to be statistically lower than the PGA group (p < 0.05). The muscle fiber diameter of AdMSCs + AM group was lower than that of the NG group, but significantly higher than that of the PGA group and the AM group (p < 0.001). Muscle weight index was significantly higher in the AdMSCs + AM group compared to the PGA group (p < 0.05). It was observed that nerve regeneration was faster in the AdMSCs + AM group, and there was an earlier improvement in pin-prick score and sciatic functional index compared to the PGA group and the AM group. In conclusion, the biological conduit prepared from the AdMSCs sheet and AM is regarded as a new biological conduit that can be used as an alternative treatment method to nerve autograft in clinical applications.

Cryopreserved amniotic membrane in the treatment of limb skin defects of aplasia cutis congenita: a case study

OBJECTIVE

To report the efficacy and long-term outcomes of treating the skin defects of aplasia cutis congenita (ACC) with cryopreserved amniotic membrane (AM).

METHOD

Human amnion was obtained from the caesarean delivery of a full-term healthy pregnancy and processed in a sterile laminar flow hood, and cryopreserved in liquid nitrogen. The structure of the AM was investigated histologically and the viability of the epithelial cells was assessed after cryopreservation and compared with fresh AM and with AM preserved in phosphate-buffered saline (PBS) at 4°C. The cryopreserved AM was applied onto the lower limb skin defects of a one-month old baby with ACC. Timely AM changes were performed as necessary until the wounds healed.

RESULTS

The structure of the cryopreserved AM was intact, with little visible difference compared with fresh AM. The viability of the epithelial cells was partially lost but still much better retained than in those preserved in PBS at 4°C. The limb skin defects were gradually re-epithelialised upon application of the AM and were completely healed after one month. The 4-month and 2-year follow-ups presented good skin texture and colour, without hypertrophic scar formation.

CONCLUSION

In this case study, cryopreservation of AM presented a well preserved stromal compartment and viable epithelial layer. It also offered features such as pain relief, good attachment and adhesiveness, improved wound healing and suppressed scar formation in the treatment of ACC skin defects.

A Novel Technique of Amniotic Membrane Preparation Mimicking Limbal Epithelial Crypts Enhances the Number of Progenitor Cells upon Expansion

We aimed to investigate whether a novel technique of human amniotic membrane (HAM) preparation that mimics the crypts in the limbus enhances the number of progenitor cells cultured ex vivo. The HAMs were sutured on polyester membrane (1) standardly, to obtain a flat HAM surface, or (2) loosely, achieving the radial folding to mimic crypts in the limbus. Immunohistochemistry was used to demonstrate a higher number of cells positive for progenitor markers p63α (37.56 ± 3.34% vs. 62.53 ± 3.32%, p = 0.01) and SOX9 (35.53 ± 0.96% vs. 43.23 ± 2.32%, p = 0.04), proliferation marker Ki-67 (8.43 ± 0.38 % vs. 22.38 ± 1.95 %, p = 0.002) in the crypt-like HAMs vs. flat HAMs, while no difference was found for the quiescence marker CEBPD (22.99 ± 2.96% vs. 30.49 ± 3.33 %, p = 0.17). Most of the cells stained negative for the corneal epithelial differentiation marker KRT3/12, and some were positive for N-cadherin in the crypt-like structures, but there was no difference in staining for E-cadherin and CX43 in crypt-like HAMs vs. flat HAMs. This novel HAM preparation method enhanced the number of progenitor cells expanded in the crypt-like HAM compared to cultures on the conventional flat HAM.

Amniotic membrane application in surgical treatment of conjunctival tumors

The amniotic membrane (AM) has special properties, making it ideal for clinical applications in various surgical fields like ophthalmology. It is used more frequently to cover conjunctival and corneal defects. In our retrospective study we have been combined 68 patients with epibulbar conjunctival tumors they have been surgically treated in the period of 2011-2021. Seven (10.3%) patients have been treated with AM application after surgical removal of the tumor. 54 (79%) cases were malignant, and 14 (21%) were benign. In the analyzed dataset the males had just slightly higher chance of malignancy than females, 80% versus 78.3%. For the significancy calculation the Fisher exact test was used and the result proved no significancy (p = 0.99). Six patients with AM application were malignant. The observed difference in the number of quadrants of the bulbar conjunctiva infiltrated versus significant malignancy with p = 0.050 calculated by Fisher Exact test and with p = 0.023 calculated by Likelihood-ratio test. The results of our study indicate that AM grafts are an effective alternative to cover defects after removal of epibulbar lesions due to their anti-inflammatory properties because the conjunctiva must be preserved, and especially the most important application is in malignant epibulbar conjunctival tumors.

From bench to clinic: Emerging therapies for corneal scarring

Corneal diseases are one of the leading causes of moderate-to-severe visual impairment and blindness worldwide, after glaucoma, cataract, and retinal disease in overall importance. Given its tendency to affect people at a younger age than other blinding conditions such as cataract and glaucoma, corneal scarring poses a huge burden both on the individuals and society. Furthermore, corneal scarring and fibrosis disproportionately affects people in poorer and remote areas, making it a significant ophthalmic public health problem. Traditional medical strategies, such as topical corticosteroids, are not effective in preventing fibrosis or scars. Corneal transplantation, the only effective sight-restoring treatment for corneal scars, is curbed by challenges including a severe shortage of tissue, graft rejection, secondary conditions, cultural barriers, the lack of well-trained surgeons, operating rooms, and well-equipped infrastructures. Thanks to tremendous research efforts, emerging therapeutic options including gene therapy, protein therapy, cell therapy and novel molecules are in development to prevent the progression of corneal scarring and compliment the surgical options currently available for treating established corneal scars in clinics. In this article, we summarise the most relevant preclinical and clinical studies on emerging therapies for corneal scarring in recent years, showing how these approaches may prevent scarring in its early development.

The developments in amniotic membrane transplantation in glaucoma and vitreoretinal procedures

The main reasons why Amniotic Membrane (AM) is transplanted in Ophthalmology are: to provide a substrate for cellular growth and to provide tectonic support or as a biological bandage and barrier that protects the wound to facilitate an environment for wound healing. The application of AM is well-documented in corneal disorders of various aetiologies [1], however, research within the field has highlighted how it can be used in conjunctival disorders and most recently, in glaucoma and vitreoretinal procedures. This review explores the preservation modalities of AM and summarises the current literature regarding AM transplantation in Glaucoma and Vitreoretinal conditions. AM transplantation in conjunction with trabeculectomy was reported to be used in two different surgical techniques. They differ in relation to the position of the implant: below the scleral flap or over the entire exposed sclera. The results of these studies suggest that AM transplant is a safe procedure that helps in the improvement of the intraocular pressure when associated with trabeculectomies. Moreover, it enhances trabeculectomies success rates when used along with mitomycin C [2]. The use of AM is also described for managing leaking blebs. It is mentioned to be a suitable alternative to conjunctival advancement. Regarding AM transplantation in glaucoma shunt or valve surgeries, the current literature is relatively limited. However, AM has been described as a good tectonic support for shunt procedures [3]. Successful results are described in the literature for surgical treatments using AM plug for vitreoretinal procedures. In particular macular hole closure and rhegmatogenous retinal detachment. In conclusion, AM transplant is a very promising and versatile adjutant therapy. However, further studies are also required for a better understanding and refinement of surgical techniques.

Recurrence of perforation and overall patient survival after penetrating keratoplasty versus amniotic membrane transplantation in corneal perforation

PURPOSE

The following is a comparative analysis on the treatment outcomes of corneal perforations using amniotic membrane transplantation (AMT) or penetrating keratoplasty (PK).

METHODS

This monocentric retrospective study was performed at the Department of Ophthalmology, University Hospital Ulm, Germany. A total of 78 eyes of 78 patients were included. Thirty-nine eyes received an AMT, and 39 patients were treated with a PK. Primary outcome was recurrence of perforation. Secondary outcomes were patient mortality and visual acuity.

RESULTS

No statistically significant difference was observed with regard to a recurrence of perforation between the two groups (26% in AMT vs 23% in PK, p > 0.99). The time of recurrences was within the first two years and did not differ statistically (p = 0.97). In addition, a proportional hazards model with cox regression regarding recurrent perforation showed no significant differences (p = 0.5). After AMT, 41% and after KP, 28% of the patients died during follow-up (p = 0.2), respectively. The Charlson Comorbidity Index (p < 0.0001) and the age at the time of surgery (p = 0.0002) were statistically significantly higher in those who were deceased. A mean follow-up of 485 ± 517 days was recorded.

CONCLUSION

Both surgical methods show good results and no statistically significant difference regarding recurrent perforation rate. About a third of the patients died during the follow-up period. The decision regarding the appropriate method should therefore be based on a combination of all factors.

Distribution of an analgesic palmitoylethanolamide and other N-acylethanolamines in human placental membranes

BACKGROUND

Human amniotic and amniochorionic membranes (AM, ACM) represent the most often used grafts accelerating wound healing. Palmitoylethanolamide, oleoylethanolamide and anandamide are endogenous bioactive lipid molecules, generally referred as N-acylethanolamines. They express analgesic, nociceptive, neuroprotective and anti-inflammatory properties. We assessed the distribution of these lipid mediators in placental tissues, as they could participate on analgesic and wound healing effect of AM/ACM grafts.

METHODS

Seven placentas were collected after caesarean delivery and fresh samples of AM, ACM, placental disc, umbilical cord, umbilical serum and vernix caseosa, and decontaminated samples (antibiotic solution BASE 128) of AM and ACM have been prepared. Ultra-high-performance liquid chromatography-tandem mass spectrometry was used for N-acylethanolamines analysis.

RESULTS

N-acylethanolamines were present in all studied tissues, palmitoylethanolamide being the most abundant and the anandamide the least. For palmitoylethanolamide the maximum average concentration was detected in AM (350.33 ± 239.26 ng/g), while oleoylethanolamide and anandamide were most abundant in placenta (219.08 ± 79.42 ng/g and 30.06 ± 7.77 ng/g, respectively). Low levels of N-acylethanolamines were found in serum and vernix. A significant increase in the levels of N-acylethanolamines (3.1-3.6-fold, P < 0.001) was observed in AM when the tissues were decontaminated using antibiotic solution. The increase in decontaminated ACM was not statistically significant.

CONCLUSIONS

The presence of N-acylethanolamines, particularly palmitoylethanolamide in AM and ACM allows us to propose these lipid mediators as the likely factors responsible for the anti-hyperalgesic, but also anti-inflammatory and neuroprotective, effects of AM/ACM grafts in wound healing treatment. The increase of N-acylethanolamines levels in AM and ACM after tissue decontamination indicates that tissue processing is an important factor in maintaining the analgesic effect.

Bleb analysis using anterior segment optical coherence tomography after trabeculectomy with amniotic membrane transplantation

INTRODUCTION

Little has been known about the intrableb structures associated with bleb function after trabeculectomy with amniotic membrane transplantation (AMT). The aim of this study is to analyze the characteristics of intrableb structures using anterior segment optical coherence tomography (AS-OCT) after trabeculectomy with AMT.

METHODS

A total of 68 eyes of 68 patients with primary open-angle glaucoma who underwent trabeculectomy with AMT were included. Surgical success was defined as intraocular pressure (IOP) ≤ 18 mmHg and IOP reduction of ≥ 20% without medication on AS-OCT examination. Intrableb parameters, including bleb height, bleb wall thickness, striping layer thickness, bleb wall reflectivity, fluid-filled space score, fluid-filled space height, and microcyst formation were evaluated using AS-OCT. Logistic regression analysis was performed to determine factors associated with IOP control.

RESULTS

Of the 68 eyes, 56 eyes were assigned to the success group and 12 eyes to the failure group. In the success group, bleb height (P = 0.009), bleb wall thickness (P = 0.001), striping layer thickness (P = 0.001), fluid-filled space score (P = 0.001), and frequency of microcyst formation (P = 0.001) were greater than those in the failure group. Bleb wall reflectivity was higher in the failure group than in the success group (P < 0.001). In the univariate logistic regression analysis, previous cataract surgery was significantly associated with surgical failure (odds ratio = 5.769, P = 0.032).

CONCLUSION

A posteriorly extending fluid-filled space, tall bleb with low reflectivity, and thick striping layer were characteristics of successful filtering blebs after trabeculectomy with AMT.

Management of scleral melt

Scleral melting, while rare, can lead to significant ocular morbidity. Several possible risk factors for scleral melt have been identified, such as infection, autoimmune disease, trauma, and post-surgical state, and these may act in combination with each other. Treatment should be tailored according to the etiology and severity of the scleral melt. Medical management may be indicated, especially in cases of autoimmune-related melt; however, surgical procedures are often necessary due to compromised ocular integrity and limited penetration of medications into the avascular sclera. An understanding of the surgical options available and their operative outcomes is particularly important when choosing the appropriate treatment protocol for each patient.

The progress in techniques for culturing human limbal epithelial stem cells

In vitro culture of human limbal epithelial stem cells (hLESCs) is crucial to cell therapy in the treatment of limbal stem cell deficiency, a potentially vision-threatening disease that is characterized by persistent corneal epithelial defects and corneal epithelium conjunctivalization. Traditionally, hLESCs are cultivated based on either limbal tissue explants or single-cell suspensions in culture media containing xenogenous components, such as fetal bovine serum and murine 3T3 feeder cells. Plastic culture dishes and human amniotic membranes are classical growth substrates used in conventional hLESC culture systems. The past few decades have witnessed considerable progress and innovations in hLESC culture techniques to ensure a higher level of biosafety and lower immunogenicity for further cell treatment, including complete removal of xenogenous components from culture media, the application of human-derived feeder cells, and the development of novel scaffolds. Three-dimensional artificial niches and three-dimensional culture techniques have also been established to simulate the real microenvironment of limbal crypts for better cell outgrowth and proliferation. All these progresses ensure that in vitro cultured hLESCs are more adaptable to translational stem cell therapy for limbal stem cell deficiency.