A comparison of the effectiveness between amniotic membrane homogenate and transplanted amniotic membrane in healing corneal damage in a rabbit model

Construction of living-cell tissue engineered amniotic membrane for ocular surface disease

BACKGROUND

Human amniotic membrane (AM) transplantation has been applied to treat ocular surface diseases, including corneal trauma. The focus of much deliberation is to balance the mechanical strength of the amniotic membrane, its resistance to biodegradation, and its therapeutic efficacy. It is commonly observed that the crosslinked human decellularized amniotic membranes lose the functional human amniotic epithelial cells (hAECs), which play a key role in curing the injured tissues.

METHODS AND RESULTS

In this study, we crosslinked human decellularized amniotic membranes (dAM) with genipin and re-planted the hAECs onto the genipin crosslinked AM. The properties of the AM were evaluated based on optical clarity, biodegradation, cytotoxicity, and ultrastructure. The crosslinked AM maintained its transparency. The color of crosslinked AM deepened with increasing concentrations of genipin. And the extracts from low concentrations of genipin crosslinked AM had no toxic effect on human corneal epithelial cells (HCECs), while high concentrations of genipin exhibited cytotoxicity. The microscopic observation and H&E staining revealed that 2 mg/mL genipin-crosslinked dAM (2 mg/mL cl-dAM) was more favorable for the attachment, migration, and proliferation of hAECs. Moreover, the results of the CCK-8 assay and the transwell assay further indicated that the living hAECs' tissue-engineered amniotic membranes could facilitate the proliferation and migration of human corneal stromal cells (HCSCs) in vitro.

CONCLUSIONS

In conclusion, the cl-dAM with living hAECs demonstrates superior biostability and holds significant promise as a material for ocular surface tissue repair in clinical applications.

Comparative study on corneal epithelium healing: effects of crosslinked hyaluronic acid and amniotic membrane extract eye drops in rats

Introduction

Corneal ulcers are common lesions in both human and veterinary medicine. However, only a few studies have evaluated the efficacy of cross-linked hyaluronic acid (X-HA) eye drops on corneal wound healing. To our knowledge, this is the first study to demonstrate and compare the efficacy of amniotic membrane extract eye drops (AMEED) and X-HA for corneal wound healing in rats.

Material and methods

A total of 15 male Wistar rats (30 eyes) were used in this study. Then, 10 eyes were treated with X-HA, AMEED, or 0.9% saline. After general and topical anesthesia, a superficial corneal ulcer was created using a corneal trephine. The defect was further polished with a diamond burr. Three groups of 10 eyes each were treated with either one drop of 0.75% X-HA or AMEED or 0.9% saline (control), administered every 12 h for a duration of 72 h. The median epithelial defect area (MEDA), expressed as a percentage of the total corneal surface, was measured at 0, 12, 24, 36, 48, and 72 h. Re-epithelization time scores were also evaluated. The Kruskal-Wallis test was used to compare median times for re-epithelization and histopathologic scores between groups, while the Friedman test (for paired data) was employed to compare results from the serial analysis of MEDA and vascularization scores between groups.

Results

MEDA was not significantly different between X-HA and AMEED. However, MEDA was significantly smaller in the X-HA group compared to the control group at 36 h (2.73 interquartile range (IQR) 5.52% x 9.95 IQR 9.10%, P=0.024) and 48 h (0.00 IQR 0.26% x 6.30 IQR 8.54%, P=0.030). The overall time for re-epithelization was significantly lower in the X-HA group (3.00 IQR 3.00) compared to the AMEED (6.5 IQR 3.00) and control (7.00 IQR 1.00) groups (P=0.035). Vascularization, hydropic degeneration, and epithelial-stromal separation were significantly less observed in samples in the X-HA-treated compared to samples in the AMEED- and saline-treated groups. Significantly more corneal epithelium cells were labeled for caspase3 in samples from the AMEED- and saline-treated groups compared to those from the X-HA-treated group.

Discussion

Topical X-HA has been shown to accelerate corneal epithelial healing. AMEED did not decrease corneal re-epithelialization time. X-HA may also potentially be used as an adjunct therapy for treating corneal ulcers in clinical situations.

Investigation of topical amniotic membrane suspension and ReGeneraTing Agent on early corneal stromal healing in rats

Innovative topical bioregenerative materials promoting corneal stromal healing provide valuable alternatives for treating patients with deep corneal ulcers, and particularly beneficial for those with a higher anaesthetic risk. This study aimed to investigate the effects of topical amniotic membrane suspension (AMS) and ReGeneraTing Agent (RGTA) on surgically induced deep stromal ulcers in rats. Eighteen Sprague-Dawley rats were divided into 3 treatment groups: control group (topical normal saline, TID); AMS group (topical AMS, TID); RGTA group (topical RGTA, Q2D). Corneal microsurgery was used to create deep stromal ulcer. Evaluations were performed by corneal opacity grading, spectral domain optical coherence tomography (SD-OCT), histopathology, and immunohistochemistry. One-way ANOVA and Dunnett's test were used for statistical analysis. By the seventh day of treatment, both the AMS and RGTA groups showed significantly greater thickness in corneal stroma (both p-value < 0.05) than the control group. Additionally, the RGTA group exhibited a significantly higher degree of myofibroblast infiltration in the stroma and a greater level of corneal opacity (p < 0.05). No significant differences in the count of inflammatory cells were noted. In conclusion, both AMS and RGTA have demonstrated effectiveness in promoting the early stages of stromal wound healing and wound defect recovery in our research. Both AMS and RGTA have good potential for treating deep corneal ulcers in small animals practice. Further research is necessary to investigate the long-term effects and mechanism of using topical AMS and RGTA on treating deep corneal ulcer in clinical practice.

In vitro antibacterial efficacy of autologous conditioned plasma and amniotic membrane eye drops

OBJECTIVE

To determine the in vitro antibacterial efficacy of equine and canine autologous conditioned plasma (ACP) and amniotic membrane extract eye drops (AMEED) against aerobic bacteria common to the corneal surface.

PROCEDURES

Canine (n = 4) and equine (n = 4) anticoagulated whole blood samples were sterilely collected, pooled for each species, and processed using the Arthrex ACP® Double-Syringe System. Platelet counts were performed on ACP and pooled blood. AMEED were obtained from a commercial source. An electronic medical records search (2013-2022) identified aerobic bacteria cultured from canine and equine corneal ulcers at Mississippi State University College of Veterinary Medicine (MSU-CVM). Ten commonly isolated bacteria for each species were collected from cultures submitted to the MSU-CVM Microbiology Diagnostic Service and frozen at -80°C. The Kirby-Bauer disk diffusion method was used to determine the sensitivities of these isolates to ACP and AMEED. Bacterial isolates were plated onto Mueller-Hinton +5% sheep blood agar and blank sterile discs saturated with 20 μL of ACP or AMEED were tested in duplicate. Imipenem discs served as positive controls and blank discs as negative controls. Zones of inhibition were measured at 18 h.

RESULTS

ACP platelet counts were 1.06 and 1.65 times higher than blood for equine and canine samples, respectively. Growth of a multi-drug resistant Enterococcus faecalis was partially inhibited by canine and equine ACP. AMEED did not inhibit growth of any examined bacteria.

CONCLUSIONS

Canine and equine ACP partially inhibited E. faecalis growth in vitro. Further studies using varying concentrations of ACP against bacterial isolates from corneal ulcers are warranted.

A proposed model of xeno-keratoplasty using 3D printing and decellularization

Corneal opacity is a leading cause of vision impairment and suffering worldwide. Transplantation can effectively restore vision and reduce chronic discomfort. However, there is a considerable shortage of viable corneal graft tissues. Tissue engineering may address this issue by advancing xeno-keratoplasty as a viable alternative to conventional keratoplasty. In particular, livestock decellularization strategies offer the potential to generate bioartificial ocular prosthetics in sufficient supply to match existing and projected needs. To this end, we have examined the best practices and characterizations that have supported the current state-of-the-art driving preclinical and clinical applications. Identifying the challenges that delimit activities to supplement the donor corneal pool derived from acellular scaffolds allowed us to hypothesize a model for keratoprosthesis applications derived from livestock combining 3D printing and decellularization.

Preparation of human amniotic membrane for transplantation in different application areas

The human amniotic membrane (hAM) is the inner layer of the placenta and plays protective and nutritional roles for the fetus during pregnancy. It contains multiple growth factors and proteins that mediate unique regenerative properties and enhance wound healing in tissue regeneration. Due to these characteristics hAM has been successfully utilized in ophthalmology for many decades. This material has also found application in a variety of additional therapeutic areas. Particularly noteworthy are the extraordinary effects in the healing of chronic wounds and in the treatment of burns. But hAM has also been used successfully in gynecology, oral medicine, and plastic surgery and as a scaffold for in vitro cell culture approaches. This review aims to summarize the different graft preparation, preservation and storage techniques that are used and to present advantages and disadvantages of these methods. It shows the characteristics of the hAM according to the processing and storage methods used. The paper provides an overview of the currently mainly used application areas and raises new application possibilities. In addition, further preparation types like extracts, homogenates, and the resulting treatment alternatives are described.

Microscopic corneal epithelial changes and clinical outcomes in simple limbal epithelial transplantation surgery after treatment with amniotic membrane eye drops (AMED): A case report

Purpose

To describe the microscopic epithelial changes and the clinical outcomes of a patient treated with amniotic membrane eye drops (AMED) because of a persistent epithelial defect (PED) and a partial limbal stem cell deficiency (LSCD) after simple limbal epithelial transplantation (SLET) and deep anterior lamellar keratoplasty (DALK).

Observations

A 72-year-old patient, who had previously undergone SLET and DALK due to a total LSCD, presented with a PED related to a partial LSCD, and was treated with AMED for one month. We evaluated the patient's visual acuity, the Oxford grading scale, the Wong-Baker Pain Rating Scale, and in vivo confocal microscopy, both at baseline and 3 months after the end of treatment. Visual acuity improved from 0.5 to 0.4 LogMAR, the Oxford grading scale changed from grade III to grade I and the Wong-Baker Pain Rating Scale from grade 4 to grade 1. The corneal surface, which initially showed conjunctival characteristics over approximately 50% of the whole area, consisted mainly (75%) of mature corneal epithelium 3 months after the end of treatment.

Conclusions and importance

While improving symptoms and clinical characteristics, AMED was also able to restore the normal corneal epithelium's morphology in a case of partial LSCD after SLET and DALK.

Insights and future directions for the application of perinatal derivatives in eye diseases: A critical review of preclinical and clinical studies

Perinatal derivatives (PnD) are gaining interest as a source for cell-based therapies. Since the eye is easily accessible to local administration, eye diseases may be excellent candidates to evaluate novel therapeutic approaches. With this work, we performed a systematic review of published preclinical and clinical studies addressing PnD in the treatment of ocular diseases. We have set two specific objectives: (i) to investigate the current level of standardization in applied technical procedures in preclinical studies and (ii) to assess clinical efficacy in clinical trials. Hereto, we selected studies that applied amniotic membrane (hAM) and mesenchymal stromal cells derived from amniotic membrane (hAMSC), placenta (hPMSC), umbilical cord (hUC-MSC) and Wharton's Jelly (hUC-WJ-MSC), excluding those where cells were not transplanted individually, following a systematic PubMed search for preclinical studies and consultation of clinical studies on https://clinicaltrials.gov and https://www.clinicaltrialsregister.eu/. Our bibliographic search retrieved 26 pre-clinical studies and 27 clinical trials. There was a considerable overlap regarding targeted ocular structures. Another common feature is the marked tendency towards (i) locally administered treatments and (ii) the PnD type. In the cornea/ocular surface, hAM was preferred and usually applied directly covering the ocular surface. For neuroretinal disorders, intra-ocular injection of umbilical or placental-derived cells was preferred. In general, basic research reported favourable outcomes. However, due to lack of standardization between different studies, until now there is no clear consensus regarding the fate of administered PnD or their mode of action. This might be accountable for the low index of clinical translation. Regarding clinical trials, only a minority provided results and a considerable proportion is in "unknown status". Nevertheless, from the limited clinical evidence available, hAM proved beneficial in the symptomatic relief of bullous keratopathy, treating dry eye disease and preventing glaucoma drainage device tube exposure. Regarding neuroretinal diseases, application of Wharton's Jelly MSC seems to become a promising future approach. In conclusion, PnD-based therapies seem to be beneficial in the treatment of several ocular diseases. However, much is yet to be done both in the pre-clinical and in the clinical setting before they can be included in the daily ophthalmic practice.

Effects of commercial amniotic membrane extract on the re-epithelialization time and the early expression of matrix metalloproteinase-9 in cats with experimentally induced corneal ulcers

OBJECTIVES

To investigate whether a commercially available amniotic membrane extract (AME) can accelerate corneal wound healing and suppress the early expression of MMP-9 in the tears of cats with experimentally induced superficial ulcerative keratitis.

PROCEDURES

A total number of 16 cats were included. At the end of keratectomy, cats in the treatment group (TG, n = 8) received 40 μl of AME (EyeQ® Amniotic Eye Drops, Vetrix®) four times daily, while cats in the control group (CG, n = 8) received 40 μl of saline at the same time points. Tears were collected 24 and 48 h after keratectomy, and the total MMP-9 was quantified by ELISA.

RESULTS

The corneal re-epithelialization rate did not differ between groups (p = .26), being 0.48 ± 0.05 mm² /h in the CG and 0.41 ± 0.03 mm² /h in the TG. Similarly, the average time to achieve corneal wound healing did not differ between groups (p = .25) and was 61.50 ± 3.54 h in the CG and 70.50 ± 6.71 h in the TG. The dimensions of the ulcerated areas also did not differ at any time point between the groups (p > .05). In both groups, corneas healed without scarring, pigmentation, or vascularization. The expression of MMP-9 in the tears was similar in both groups at 24 h post-keratectomy, with a slight decrease at 48 h (p > .05).

CONCLUSIONS

The instillation of a commercial AME (EyeQ®) is safe, but it did not decrease the corneal re-epithelialization time or the early expression of MMP-9 in the tears of cats with experimentally induced superficial ulcerative keratitis in this study.

Human amniotic epithelial cell-derived extracellular vesicles provide an extracellular matrix-based microenvironment for corneal injury repair

To study the biological functions and applications of human amniotic epithelial cell-derived extracellular vesicles (hAEC-EVs), the cargos of hAEC-EVs were analyzed using miRNA sequencing and proteomics analysis. The hAECs and hAEC-EVs in this study had specific characteristics. Multi-omics analyses showed that extracellular matrix (ECM) reorganization, inhibition of excessive myofibroblasts, and promotion of target cell adhesion to the ECM were their primary functions. We evaluated the application of hAEC-EVs for corneal alkali burn healing in rabbits and elucidated the fundamental mechanisms. Slit-lamp images revealed that corneal alkali burns induced central epithelial loss, stromal haze, iris, and pupil obscurity in rabbits. Slit-lamp examination and histological findings indicated that hAEC-EVs facilitated re-epithelialization of the cornea after alkali burns, reduced scar formation and promoted the restoration of corneal tissue transparency. Significantly fewer α-SMA-positive myofibroblasts were observed in the hAEC-EV-treated group than the PBS group. HAEC-EVs effectively promoted the proliferation and migration of hCECs and hCSCs in vitro and activated the focal adhesion signaling pathway. We demonstrated that hAEC-EVs were excellent cell-free candidates for the treatment of ECM lesion-based diseases, including corneal alkali burns. HAEC-EVs promoted ECM reorganization and cell adhesion of target tissues or cells via orderly activation of the focal adhesion signaling pathway.

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

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

Determining the efficacy of the bovine amniotic membrane homogenate during the healing process in rabbits' ex vivo corneas

OBJECTIVE

To evaluate the efficacy of bovine amniotic membrane homogenate (BAMH) on wounded ex vivo rabbit corneas.

PROCEDURE

Eighteen corneas obtained from normal rabbit eyes were wounded equally using a 6 mm trephine and cultured into an air-liquid interface model. Corneas were treated with phosphate-buffered saline (PBS) (n = 6, control group), 0.2% ethylenediaminetetraacetic acid (EDTA; n = 6), or BAMH (n = 6). All treatments were applied topically 6 times/day. Each cornea was macrophotographed daily with and without fluorescein stain to assess epithelialization and haziness. After 7 days, corneal transparency was evaluated, and the tissues prepared for histologic analysis of viability, and total and epithelial thickness.

RESULTS

The mean epithelialization time was 6.2 ± 0.82 days for the control group, 6.2 ± 0.75 days for the EDTA-treated group, and 5.1 ± 0.40 days for the BAMH-treated group, demonstrating a significant difference between the BAMH and the other groups. The corneas that received EDTA had better transparency compared with the other groups. Histologically, all corneas had adequate morphology and architecture after healing. Analysis of corneal and epithelial thickness revealed no significant difference among groups.

CONCLUSION

Bovine amniotic membrane homogenate is an effective and promising treatment for stromal and epithelial ulcers.

Proteome Composition of Bovine Amniotic Membrane and Its Potential Role in Corneal Healing

Purpose

To investigate the protein profile of bovine amniotic membranes (bAM) and to determine putative associations between protein composition in bAM and known corneal healing pathways.

Methods

The bAM were acquired from normal full-term births (n = 10), processed, and stored at -80°C for two days. Subsequently, the frozen membranes were thawed at room temperature and prepared for proteomic exploration using high-resolution liquid chromatography-mass spectrometry, followed by bioinformatics analysis. Recently identified corneal healing pathways were contrasted with protein profiles and pathways present in bAM.

Results

The analyses identified 2105 proteins, with an interactive network of 1271 nodes (proteins) and 8757 edges (interactions). The proteins with higher betweenness centrality measurements include microfibril-associated protein 4, HSD3B1, CAPNS1, ATP1B3, CAV1, ANXA2, YARS, and GAPDH. The top four pathways in Kyoto Encyclopedia of Genes and Genomes were ribosome, metabolic pathway, spliceosome, and oxidative phosphorylation. The bAM and cornea shared abundant proteins, genome ontology, and signaling pathways.

Conclusions

The high-throughput proteomic profile of the bAM demonstrated that numerous proteins present in the cornea are also present in this fetal membrane. Our findings collectively demonstrate the similarity between bAM and the cornea's protein composition, supporting our hypothesis that bAM can be used to treat corneal diseases.

Human Amniotic Membrane Enriched with Urinary Bladder Fibroblasts Promote the Re-Epithelization of Urothelial Injury

Culturing cells in three-dimensional systems that include extracellular matrix components and different cell types mimic the native tissue and as such provide much more representative results than conventional two-dimensional cell cultures. In order to develop biomimetic bladder tissue in vitro, we used human amniotic membrane (AM) extracellular matrix as a scaffold for bladder fibroblasts (BFs) and urothelial cells. Our aims were to evaluate the integration of BFs into the AM stroma, to assess the differentiation of the urothelium on BFs-enriched AM scaffolds, and to evaluate the AM as a urothelial wound dressing. First, to achieve the optimal integration of BFs into AM stroma, different intact and de- epithelialized AM (dAM) scaffolds were tested. BFs secreted matrix metalloproteinase (MMP)-1 and MMP-2 and integrated into the stroma of all types of AM scaffolds. Second, to establish urothelial tissue equivalent, urothelial cells were seeded on dAM scaffolds enriched with BFs. The BFs in the stroma of the AM scaffolds promoted (1) the proliferation of urothelial cells, (2) the attachment of urothelial cells on AM basal lamina with hemidesmosomes, and (3) development of multilayered urothelium with expressed uroplakins and well-developed cell junctions. Third, we established an ex vivo model of the injured bladder to evaluate the dAM as a wound dressing for urothelial full-thickness injury. dAM acted as a promising wound dressing since it enabled rapid re-epithelization of urothelial injury and integrated into the bladder tissue. Herein, the developed urothelial tissue equivalents enable further mechanistic studies of bladder epithelial–mesenchymal interactions, and they could be applied as biomimetic models for preclinical testing of newly developed drugs. Moreover, we could hypothesize that AM may be suitable as a dressing of the wound that occurs during transurethral resection of bladder tumor, since it could diminish the possibility of tumor recurrence, by promoting the rapid re-epithelization of the urothelium.

Amnion membrane proteins attenuate LPS-induced inflammation and apoptosis by inhibiting TLR4/NF-κB pathway and repressing MicroRNA-155 in rat H9c2 cells

OBJECTIVE

Amnion membrane (AM) has been popular for the treatment of inflammatory disorders due to its cell repairing properties. This current study aims to find the underlying mechanisms of amnion membrane proteins (AMPs) against the pro-inflammatory miRNA, miR-155, miR-146, and anti-apoptotic microRNA, miR-21, in LPS-treated H9c2 cells.

METHODS

Cell viability and apoptosis were determined by MTT assay and annexin V/PI staining. The production of the cytokines, TNF-α and IL-6 were evaluated by using qPCR and Enzyme-linked immunosorbent assay (ELISA), respectively. In addition, the expression of miRNAs was quantified by qPCR, and also the protein level of TLR4 and NF-kβ was determined with western blotting.

RESULTS

We found that AMPs ameliorated LPS-induced reduction of cell viability and augment apoptosis in H9c2 cells. AMPs efficiently inhibited cytokine expression (IL-6 and TNF-α) and activity of TLR4/NF-κB pathway in LPS-treated H9c2 cells. Correspondingly, in parallel with the suppression of pro-inflammatory cytokines and apoptosis, AMPs mitigated pro-inflammatory miRNA, miR-155 expression, while, the expression of miR-155 was found to be increased in LPS-treated H9c2 cells. Also, AMPs activated miR-146 expression in H9c2 cells under LPS treatment. Additionally, the elevated expression of miR-21 provoked by LPS was further enhanced by AMPs.

CONCLUSIONS

In conclusion, AMPs could alleviate LPS-induced cardiomyocytes cells injury via up-regulation of miR-21, miR-146, and suppression of TLR4/NF-κB pathway, which plays a key role in the down-regulation of LPS-mediated miR-155 and inflammatory cytokine expression.

Determining MMP-2 and MMP-9 reductive activities of bovine and equine amniotic membranes homogenates using fluorescence resonance energy transfer

INTRODUCTION

Matrix metalloproteinases (MMPs)-2 and -9 are present in corneal ulcers, and an imbalance between MMPs and tissue inhibitors of metalloproteinases (TIMPs) leads to further corneal degradation. Amniotic membrane homogenate (AMH) has proteolytic properties beneficial for corneal healing, but it is unknown whether AMH possesses TIMPs or effectively inhibits MMP-2 and MMP-9 activity.

OBJECTIVE

To determine if bovine and equine AMH reduce in vitro MMP-2 and MMP-9 activities associated with the presence of TIMPs.

PROCEDURES

Undiluted and diluted twofold series (0-fold to 16-fold dilutions) of equine amniotic membrane homogenates (EAMH, n = 8) and bovine amniotic membrane homogenates (BAMH, n = 8) were subjected to fluorescence resonance energy transfer, and the fluorescence emitted was recorded over time. Average fluorescence was calculated versus recombinant concentration. Enzyme-linked immunosorbent assays for TIMPs 1-4 were applied to quantify TIMPs in the samples.

RESULTS

AMH from both species were able to inhibit MMP-2 and MMP-9 activities in vitro, and the inhibition efficacy decreased gradually with dilution. BAMH was significantly more effective than EAMH at inhibiting MMP-2 and MMP-9 in vitro. TIMPs -2 and -3 were present in EAMH and BAMH. TIMP-1 was detected only in BAMH, and TIMP-4 was not detected in any samples.

CONCLUSION

Both EAMH and BAMH directly inhibited MMP-2 and MMP-9 in vitro without dilution, and BAMH showed better inhibition of MMP-2 and MMP-9 before and after dilution compared to EAMH.

Commercial amniotic membrane extract for treatment of corneal ulcers in adult horses

BACKGROUND

Amniotic membrane extract enhances the rate of epithelialisation after corneal ulceration in several species but has not been studied in the equine cornea.

OBJECTIVES

To evaluate the effect of amniotic membrane extract on re-epithelialisation of equine corneal ulcers compared with ulcers treated with antibiotic, antifungal and mydriatic medical therapy alone, and to evaluate equine corneal healing after experimentally induced superficial ulceration.

STUDY DESIGN

Masked, randomised, controlled experimental trial.

METHODS

Superficial, 8 mm corneal ulcers were created bilaterally in each horse. One eye was treated with amniotic membrane extract and the opposite was control. Both eyes were treated with medical therapy. Treatment eyes received amniotic membrane extract, and control eyes received the amniotic membrane extract vehicle. Ulcers were stained with fluorescein and photographed in 12-hour increments until completely healed. Ulcer surface area was determined by analysing photographs with ImageJ. A mixed linear model was used to compare ulcer surface area and hours until healing between treatment groups. A regression model was also used to calculate corneal re-epithelialisation rate over time.

RESULTS

Regardless of therapy, healing occurred in two phases: an initial rapid phase of 0.88 mm² /hr (95% CI: 0.81-0.94 mm² /hr) for approximately 48-54 hours followed by a second, slow phase of 0.07 mm² /hr (95% CI: 0.04-0.09 mm² /hr). Most eyes healed within 135.5 ± 48.5 hours. Treatment (amniotic membrane extract vs. control) was not significantly associated with size of ulcers over time (P = .984). Discomfort was minimal to absent in all horses.

MAIN LIMITATIONS

Results achieved experimental studies may differ from outcomes in the clinical setting.

CONCLUSIONS

There was no significant difference in healing rate with addition of amniotic membrane extract to medical therapy for equine superficial corneal ulcers. A biphasic corneal healing process was observed, with an initial rapid phase followed by a slow phase. Further study will be needed to determine whether amniotic membrane extract will be helpful for infected or malacic equine corneal ulcers.

Evaluation of pigment epithelium-derived factor concentration in equine amniotic membrane homogenate and its in-vitro vascular endothelial growth factor inhibition effect in tears of dogs with vascularized ulcerative keratitis

Background:

Corneal neovascularization can result from many pathological processes affecting the ocular surface leading to disturbances and opacifications that reduce corneal clarity and may impact vision. In veterinary medicine, the use of topical corticosteroid is contraindicated in the presence of ulcerative keratitis, and there is sparse research regarding safe medical alternatives to inhibit corneal neovascularization in dogs to improve visual outcome.

Aim:

To investigate the pigment epithelium-derived factor (PEDF) concentration in equine amniotic membrane homogenate (EAMH) and its in-vitro vascular endothelial growth factor (VEGF) inhibition in tears of dogs with vascularized ulcerative keratitis.

Methods:

Homogenates from 10 equine amniotic membranes (AM) were analyzed by sandwich enzyme-linked immunosorbent assay (ELISA) for quantification of equine PEDF and VEGF. Forty tear samples were collected from both eyes of dogs diagnosed with vascularized ulcerative keratitis, and 50 samples from healthy dogs. Samples from affected eyes were allocated to G1 – affected undiluted tears; G2 – affected tears diluted with phosphate-buffer solution; G3 – affected tears treated with low-concentrated EAMH; and G4 – affected tears treated with high-concentrated EAMH. Tears from the unaffected contralateral eyes were composed in G5, while G6 was composed by tears from healthy dogs (control). The presence and levels of VEGF were evaluated in all groups by Western blot and ELISA.

Results:

The PEDF:VEGF ratio in EAMH was 110:1. An increase in VEGF levels was observed in tears from eyes with vascularized corneal ulcers (G1) as well as in contralateral tears (G5), compared to normal dogs (G6). High-concentrated EAMH provided a greater decrease in VEGF levels in-vitro compared to low-concentrated EAMH.

Conclusion:

EAMHs exhibited high concentrations of PEDF in comparison to VEGF and were able to partially decrease VEGF levels in tears of dogs with vascularized ulcers, in-vitro. Our results suggest that VEGF concentration is elevated in tears of dogs with active vascularized ulcerative keratitis in both affected and contralateral eyes compared to that of healthy dogs.

Effects of Amniotic Membrane Extract on the Hyperplastic Response of the Middle Ear Mucosa in a Bacterially-Induced Otitis Media Rat Model: A Preliminary Study

Objectives

Human amniotic membrane extract (AME) is known to contain numerous bioactive factors and anti-inflammatory substances. However, the anti-inflammatory effects of AME on the middle ear (ME) mucosa are unclear. This study assessed the effects of AME on the growth of the ME mucosa in response to bacterially-induced otitis media (OM).

Methods

OM was induced by inoculating nontypeable Haemophilus influenzae (NTHi) into the ME cavity of rats. ME mucosal explants were cultured in AME concentrations of 0, 5, 10, or 50 μg/mL. The area of explant outgrowth was measured in culture and analyzed at 1, 3, 5, and 7 days after explantation. The expression of Ki-67, mucin 5AC (MUC5AC), tumor necrosis factor-α (TNF-α), and interleukin-10 (IL-10) in the explants was also evaluated using quantitative polymerase chain reaction (PCR) and immunocytochemistry (ICC).

Results

The NTHi-induced ME mucosa growth increased gradually over the 7-day culture period in all explants at different AME concentrations. There was a trend for mucosal growth inhibition at higher concentrations of AME, although the growth was not significantly different among the groups until day 5. The ME mucosal explants treated with the 50 μg/mL concentration of AME showed significantly suppressed growth on postexplantation day 7 compared with other explants on the same day. PCR and ICC staining revealed that the expression of Ki-67, MUC5AC, TNF-α, and IL-10 further decreased in the explants with higher concentrations of AME than in those with lower concentrations of AME.

Conclusion

Our results showed that higher concentrations of AME reduced the mucosal proliferative response in bacterial OM in rats. These findings provide evidence that AME has an influence on the inflammatory and proliferative responses to NTHi infection in ME mucosa.

Advanced Glycation End Products and Receptor (RAGE) Promote Wound Healing of Human Corneal Epithelial Cells

Purpose

We used a human corneal epithelial cell (HCE) line to determine the involvement of the advanced glycation end products (AGEs) / receptor for AGEs (RAGE) couple in corneal epithelium wound healing.

Methods

After wounding, HCE cells were exposed to two major RAGE ligands (HMGB1 and AGEs), and wound healing was evaluated using the in vitro scratch assay. Following wound healing, the HCE cells were used to study the influence of the RAGE ligands on HCE proliferation, invasion, and migration. Activation of the nuclear factor (NF)-κB signaling pathway by the AGEs/RAGE couple was tested using a luciferase reporter assay. Functional transcriptional regulation by this pathway was confirmed by quantification of expression of the connexin 43 target gene. For each experiment, specific RAGE involvement was confirmed by small interfering RNA treatments.

Results

AGEs treatment at a dose of 100 µg/mL significantly improved the wound healing process in a RAGE-dependent manner by promoting cell migration, whereas HMGB1 had no effect. No significant influence of the AGEs/RAGE couple was observed on cell proliferation and invasion. However, this treatment induced an early activation of the NF-κB pathway and positively regulated the expression of the target gene, connexin 43, at both the mRNA and protein levels.

Conclusions

Our results demonstrate that the RAGE pathway is activated by AGEs treatment and is involved in the promotion of corneal epithelial wound healing. This positive action is observed only during the early stages of wound healing, as illustrated by the quick activation of the NF-κB pathway and induction of connexin 43 expression.

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^®.

A cellular and proteomic approach to assess proteins extracted from cryopreserved human amnion in the cultivation of corneal stromal keratocytes for stromal cell therapy

Background

Human corneal stromal keratocytes propagated in culture media supplemented with human amnion extract (AME) can correct early corneal haze in an animal model. Clinical application of cultivated keratocytes is limited by infectious disease screening before amnion products can be used in humans. It remains unclear if AME from cryopreserved versus fresh human amnion can support human keratocyte propagation, and which components of the extract promote keratocyte growth.

Methods

Three placentas were collected for the preparation of fresh and cryopreserved amnion tissues followed by homogenization and protein extraction. AME protein profiles were studied using isobaric tagging for relative and absolute quantitation (iTRAQ) proteomics. Enriched gene ontology (GO) terms and functional classes were identified. Primary human keratocytes from 4 donor corneas were cultured in media supplemented with fresh AME (F-AME) or cryopreserved AME (C-AME). Cell viability, proliferation and keratocyte marker expression were examined by confocal immunofluorescence and flow cytometry.

Results

AME proteomics revealed 1385 proteins with similar expression levels (between 0.5- and 2-fold) between F- and C-AME, while 286 proteins were reduced (less than 0.5-fold) in C-AME. Enriched GO term and biological pathway analysis showed that those proteins with comparable expression between F-AME and C-AME were involved in cell metabolism, epithelial-mesenchymal transition, focal adhesion, cell-extracellular matrix interaction, cell stress regulation and complement cascades. Human corneal stromal keratocytes cultured with F-AME or C-AME showed similar morphology and viability, while cell proliferation was mildly suppressed with C-AME (P > 0.05). Expression of aldehyde dehydrogenase 3A1 (ALDH3A1) and CD34 was similar in both cultures.

Conclusion

AME from cryopreserved amnion had limited influence on keratocyte culture. It is feasible to use protein extract from cryopreserved amnion to propagate human keratocytes for potential translational applications.

Strategies for reconstructing the limbal stem cell niche

The epithelial cell layer that covers the surface of the cornea provides a protective barrier while maintaining corneal transparency. The rapid and effective turnover of these epithelial cells depends, in part, on the limbal epithelial stem cells (LESCs) located in a specialized microenvironment known as the limbal niche. Many disorders affecting the regeneration of the corneal epithelium are related to deficiency and/or dysfunction of LESCs and the limbal niche. Current approaches for regenerating the corneal epithelium following significant injuries such as burns and inflammatory attacks are primarily aimed at repopulating the LESCs. This review summarizes and assesses the clinical feasibility and efficacy of current and emerging approaches for reconstruction of the limbal niche. In particular, the application of mesenchymal stem cells along with appropriate biological scaffolds appear to be promising strategies for long-term revitalization of the limbal niche.

Nrf2 activation and down-regulation of HMGB1 and MyD88 expression by amnion membrane extracts in response to the hypoxia-induced injury in cardiac H9c2 cells

BACKGROUND

human Amniotic Membrane (hAM) extracts contain bioactive molecules such as growth factors and cytokines. Studies have confirmed the ability of hAM in reduction of post-operative dysfunction in patients with cardiac surgery. However, the function of Amniotic Membrane Proteins (AMPs), extracted from hAM, against hypoxia-induced H9c2 cells injury have never been investigated. In this study, we aimed to appraise the protective impact of AMPs on H9c2 cells under hypoxia condition.

METHODS

Cardiomyocyte cells were pre-incubated with AMPs and subjected to 24 h hypoxia to elucidate its effects on expression of Nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1(HO-1). Furthermore, the high mobility group box-1 (HMGB1) and Myeloid differentiation primary response 88 (MyD88) expressions were detected by qPCR and western-blotting. The mitochondrial membrane potential (ΔΨm) was estimated by JC-1 using fluorescent microscopy and fluorimetry. Moreover, the cell apoptosis and intracellular calcium levels were measured by flow cytometry.

RESULTS

Pre-treatment of AMPs resulted in significant induction in cell viability and decreased the LDH release under hypoxic condition in H9c2 cells. Accordingly, these protective effects of AMPs were associated with a reduction in apoptosis rates and intracellular Ca2+, meanwhile, ΔΨm was increased. Pre-treatment with AMPs resulted in degradation of HMGB1 and MyD88 levels and depicted pro-survival efficacy of AMPs against hypoxia-induced cell damage through induction of HO-1 and Nrf2.

CONCLUSION

The data indicated that AMPs mediated HO-1 regulation by Nrf2 activation and plays critical protective effects in hypoxia-induced H9c2 injury in vitro by the inhibition of myocardial HMGB1 and MyD88 inflammatory cascade.

Amniotic Membrane Extract Eye Drop Promotes Limbal Stem Cell Proliferation and Corneal Epithelium Healing

Objective

Human amniotic membrane (HAM) is used as a supporter for limbal stem cell (LSC) expansion and corneal surgery. The aim of study is to use HAM extracts from healthy donors to enhance proliferation of LSCs in vitro and in vivo.

Materials and Methods

In this interventional experimental study, the effective and cytotoxic doses of the amniotic membrane extract eye drops (AMEED) was assessed by adding different concentrations of AMEED (0-2.0 mg/ml) to LSC cultures for 14 days. Subsequently, the expression levels of ATP-binding cassette sub-family G member 2 (ABCG2, a putative stem cell marker), cytokeratin 3 (K3, corneal maker), K12 and K19 (corneal-conjunctival cell makers) were assessed by real-time polymerase chain reaction (PCR). In the second step, the corneal epithelium of 10 rabbits was mechanically removed, and the right eye of each rabbit was treated with 1 mg/ml AMEED [every 2 hours (group 1) or every 6 hours (group 2)]. The left eyes only received an antibiotic. The corneal healing process, conjunctival infection, degree of eyelid oedema, degree of photophobia, and discharge scores were evaluated during daily assessments. Finally, corneal tissues were biopsied for pathologic evidences.

Results

In comparison to the positive control [10% foetal bovine serum (FBS)], 0.1-1 mg/ml AMEED induced LSC proliferation, upregulated ABCG2, and downregulated K3. There were no remarkable differences in the expression levels of K12 and K19 (P>0.05). Interestingly, in the rabbits treated with AMEED, the epithelium healing duration decreased from 4 days in the control group to 3 days in the two AMEED groups, with lower mean degrees of eyelid oedema, chemosis, and infection compared to the control group. No pathologic abnormalities were observed in either of the AMEED groups.

Conclusion

AMEED increases LSCs proliferation ex vivo and accelerates corneal epithelium healing in vivo without any adverse effects. It could be used as a supplement for LSC expansion in cell therapy.

Amniotic membrane extract and eye drops: a review of literature and clinical application

The amniotic membrane (AM) has a long history of use in the treatment of various diseases of the ocular surface. It contains pluripotent cells, highly organized collagen, anti-fibrotic and anti-inflammatory cytokines, immune-modulators, growth factors, and matrix proteins. It is used to promote corneal healing in severely damaged eyes. Recently, AM extract and AM extract eye drops have been successfully used in clinical applications, including dry eye and chemical burns. We provide an overview on the recent progress in the preparation, mechanisms of action, and use of AM extract/AM extract eye drops for corneal and external eye diseases.

Effect of Amniotic Membrane Suspension (AMS) and Amniotic Membrane Homogenate (AMH) on Human Corneal Epithelial Cell Viability, Migration and Proliferation In Vitro

PURPOSE

To analyze the effects of different concentrations of amniotic membrane suspension (AMS) or amniotic membrane homogenate (AMH) on human corneal epithelial cell (HCEC) viability, migration and proliferation.

METHODS

Amniotic membranes (AMs) of 13 placentas were prepared and stored at -80°C. For AMS preparation, following de-freezing, AM pieces were inserted in six-well plates and 5 ml Dulbecco's Modified Eagle's Medium (DMEM)/F12 (with 5% fetal bovine serum, FBS) per gram tissue was added for 96 h. After removal of the AM, the remaining supernatant was collected for experiments. For AMH preparation, following de-freezing, AMs were homogenized in liquid nitrogen and 5 ml DMEM/F12 (with 5% FBS) per gram tissue was added. Following centrifugation, the supernatant was collected for experiments. HCECs were expanded and incubated in DMEM/F12, 5% FBS supplemented by 15%, 30% or 100% AMS or 15% or 30% AMH. Viability was analyzed using Cell Proliferation Kit XTT, migration using wound healing assay and proliferation by the cell proliferation ELISA BrdU kit.

RESULTS

HCEC viability remained unchanged using 15% or 30% AMS (p = 1.0 for both); however, it decreased significantly using 100% AMS (p < 0.001) or 15% (p = 0.041) or 30% AMH (p < 0.001), compared to controls. Using 15% or 30% AMS, HCEC migration increased significantly (p < 0.001 for both). Using 15% or 30% AMH (p = 0.153; p = 0.083), HCEC migration remained unchanged and 100% AMS inhibited HCEC migration (p < 0.001). Next, 15% and 30% AMS had no effect on HCEC proliferation (p = 0.454 and p = 0.119), but 100% AMS (p < 0.001) and 15% (p = 0.002) and 30% AMH (p = 0.001) inhibited HCEC proliferation significantly.

CONCLUSION

With unchanged HCEC viability and proliferation and increased HCEC migration, 15% and 30% AMS application seems to be the most appropriate method to support epithelial healing.

Amniotic membrane: new concepts for an old dressing

The amniotic membrane is the innermost layer of fetal membranes that surrounds and protects the embryo. The amniotic epithelial cells are a rich source for biologically active factors known to promote cell proliferation and differentiation. Therefore, the amniotic membrane is considered to be an attractive wound dressing material. Despite a large number of publications reporting anti-inflammatory, bacteriostatic, reepithelializing, and scar-preventing properties of amniotic membrane, not all the molecular mechanisms underlying the beneficial actions of the amniotic membrane dressing have been fully elucidated. This review summarizes current knowledge on the properties of the amniotic membrane and its various clinical applications. It includes an overview of the main biologically active factors that may be responsible for the observed clinical effects of amnion dressings. This issue is briefly discussed in the context of the role of amnion processing and inter- and intradonor variations between amniotic membrane specimens. Finally, future directions for the use of amnion derivatives in wound care are indicated.

Amniotic Membrane Extract Preparation: What is the Best Method?

Purpose:

To compare different preparation methods for a suitable amniotic membrane (AM) extract containing a given amount of growth factors.

Methods:

In this interventional case series, we dissected the AM from eight placentas within 24 hours after delivery, under clean conditions. After washing and mixing, AM extracts (AMEs) were prepared using pulverization and homogenization methods, and different processing and storing conditions. Main outcome measures were the amount of added protease inhibitor (PI), the relative centrifugal force (g), in-process temperature, repeated extraction times, drying percentage, repeated pulverization times, and the effect of filtering with 0.2 μm filters. Extract samples were preserved at different temperature and time parameters, and analyzed for hepatic growth factor (HGF) and total protein using ELISA and calorimetric methods, respectively.

Results:

The extracted HGF was 20% higher with pulverization as compared to homogenization, and increased by increasing the PI to 5.0 μl/g of dried AM. Repeating centrifugation up to 3 times almost doubled the extracted HGF and protein. Storing the AME at −170° for 6 months caused a 50% drop in the level of HGF and protein. Other studied parameters showed no significant effect on the extracted amount of HGF or total protein.

Conclusion:

Appropriate extraction methods with an adequate amount of PI increases the level of extractable components from harvested AMs. To achieve the maximal therapeutic effects of AMEs, it is necessary to consider the half-life of its bioactive components.

Proteomic analysis of equine amniotic membrane: characterization of proteins

INTRODUCTION

Human amniotic membrane (AM) has been used as a biomaterial for surgical wound skin and ocular surface reconstruction for several years. Currently, equine AM has been used for corneal reconstruction in several animal species, and appears to have the same properties as human AM. Despite the observed positive healing abilities of this tissue in horses with ulcerative keratitis the proteins of equine AM have not been described.

OBJECTIVE

To identify proteins known to be associated with corneal healing from frozen equine AM.

PROCEDURES

Placentas were acquired from healthy live foal births from a local Thoroughbred breeding farm. The amnion was removed from the chorion by blunt dissection, washed with phosphate-buffered saline (PBS), and treated with 0.05% trypsin and 0.02% ethylene diaminetetraacetic acid in PBS. Amnion was attached to nitrocellulose paper (epithelial side up), and cut into 4 × 4 cm pieces. The sheets were frozen at -80 °C. The protein samples were solubilized, and analyzed by 2D gel electrophoresis and shotgun proteomics.

RESULTS

A reference identification map of the equine AM proteins was produced and 149 different proteins were identified. From gel-based proteomics, 49 spots were excised and 43 proteins identified by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Shotgun proteomics identified 116 proteins with an overlap of 10 proteins in both analyses.

CONCLUSIONS

We have described a reference map for equine AM proteins that may provide a background to explain the positive results found in horses with ulcerative keratopathies using this biomaterial.