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

Role of AUF1 in modulating the proliferation, migration and senescence of skin cells

AU-rich element RNA-binding factor 1 (AUF1) is a classical RNA-binding protein. AUF1 influences the process of development, apoptosis and tumorigenesis by interacting with adenylate-uridylate rich element-bearing mRNAs. Human skin is the largest organ of the body and acts as a protective barrier against pathogens and injuries. The aim of the present study was to explore the function and potential molecular pathways of AUF1 in human skin cells. AUF1 was overexpressed in human keratinocyte HaCaT cells and human skin fibroblast WS1 cells using adenoviruses and silenced using lentiviruses. AUF1 overexpression facilitated cell proliferation, whereas AUF1 knockdown induced the opposite effect. AUF1 reduced apoptosis but did not affect cell cycle progression. Forced AUF1 expression promoted the migration of human skin cells, as demonstrated by a scratch wound healing assay. Cell senescence was alleviated in AUF1-overexpressing skin cells, while AUF1 knockdown increased cell senescence. WS1 cells with AUF1 overexpression and silencing were used for RNA-sequencing and Kyoto Encyclopedia of Genes and Genomes-based pathway analysis to identify AUF1-affected mRNAs. A total of 18 mRNAs (eight mRNAs with positive associations and 10 mRNAs with negative associations) revealed consistent associations with both AUF1 overexpression and silencing. Enriched pathways associated with AUF1 expression included 'MAPK', 'cell adhesion molecules', 'proteasome', 'cellular senescence' and 'TGF-β signaling', indicating a complex regulatory network. Overall, the results of the present study revealed that AUF1 is involved in the proliferation, migration and senescence of skin cells in vitro and may be a potential target for cosmetic and disease treatment of skin.

Corneal Epithelial Stem Cells-Physiology, Pathophysiology and Therapeutic Options

In the human cornea, regeneration of the epithelium is regulated by the stem cell reservoir of the limbus, which is the marginal region of the cornea representing the anatomical and functional border between the corneal and conjunctival epithelium. In support of this concept, extensive limbal damage, e.g., by chemical or thermal injury, inflammation, or surgery, may induce limbal stem cell deficiency (LSCD) leading to vascularization and opacification of the cornea and eventually vision loss. These acquired forms of limbal stem cell deficiency may occur uni- or bilaterally, which is important for the choice of treatment. Moreover, a variety of inherited diseases, such as congenital aniridia or dyskeratosis congenita, are characterized by LSCD typically occurring bilaterally. Several techniques of autologous and allogenic stem cell transplantation have been established. The limbus can be restored by transplantation of whole limbal grafts, small limbal biopsies or by ex vivo-expanded limbal cells. In this review, the physiology of the corneal epithelium, the pathophysiology of LSCD, and the therapeutic options will be presented.

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.

In-situ porcine corneal matrix hydrogel as ocular surface bandage

PURPOSE

Bioactive substrates can be used therapeutically to enhance wound healing. Here, we evaluated the effect of an in-situ thermoresponsive hydrogel from decellularized porcine cornea ECM, COMatrix (COrnea Matrix), for application as an ocular surface bandage for corneal epithelial defects.

METHODS

COMatrix hydrogel was fabricated from decellularized porcine corneas. The effects of COMatrix hydrogel on attachment and proliferation of human corneal epithelial cells (HCECs) were evaluated in vitro. The effect of COMatrix on the expressions of the inflammatory genes, IL-1β, TNF-α, and IL-6 was assessed by RT-PCR. The in-situ application and also repairing effects of COMatrix hydrogel as an ocular bandage was studied in a murine model of corneal epithelial wound. The eyes were examined by optical coherence tomography (OCT) and slit-lamp microscopy in vivo and by histology and immunofluorescence post-mortem.

RESULTS

In vitro, COMatrix hydrogel significantly enhanced the attachment and proliferation of HCECs relative to control. HCECs exposed to COMatrix had less induced expression of TNF-α (P < 0.05). In vivo, COMatrix formed a uniform hydrogel that adhered to the murine ocular surface after in-situ curing. Corneal epithelial wound closure was significantly accelerated by COMatrix hydrogel compared to control (P < 0.01). There was significant increase in the expression of proliferation marker Ki-67 in wounded corneal epithelium by COMatrix hydrogel compared to control (P < 0.05).

CONCLUSIONS

COMatrix hydrogel is a naturally derived bioactive material with potential application as an ocular surface bandage to enhance epithelial wound healing.

The Influence of the Preservation Method and Gamma Irradiation Sterilization on TGF-β and bFGF Levels in Freeze-Dried Amnion Membrane (FD-AM) and Amnion Sponge

Background

Amnion grafts can be preserved as freeze-dried amnion membrane (FD-AM) and amnion sponge. Preserved grafts require to be sterilized by gamma irradiation. However, each step of the process could affect its biological properties. Even so, there are only a few studies that report the influence of the preservation method and gamma irradiation on growth factor levels in preserved amniotic grafts.

Methods

This was an in vitro experimental study with a pretest-posttest group design using a consecutive sampling technique in one batch of amnion donors at a particular time. The amnion was made into FD-AM and amnion sponge preparations, and they were sterilized with gamma irradiation (15 kGy and 25 kGy). Nonirradiated specimens served as controls, and 20 mg of each specimen was pulverized to evaluate the growth factors levels using ELISA.

Results

There were significant decreases in amnion sponge compared to the FD-AM, both in transforming growth factor beta (TGF-β) and basic fibroblast growth factor (bFGF) levels and in the preirradiated and 25 kGy postirradiated preparations (p ≤ 0.05). The growth factor levels in the preirradiated and postirradiated FD-AM (both 15 kGy and 25 kGy) showed significant differences (p ≤ 0.05). Likewise, the preirradiated amnion sponge group's growth factor levels compared with the postirradiated amnion sponge group also showed a significant decrease (p ≤ 0.05).

Conclusion

TGF-β and bFGF levels were lower in amnion sponge than FD-AM. The FD-AM and amnion sponge preparations' growth factors levels were reduced following gamma irradiation sterilization. Although the decrease in growth factor levels is significant, the number of growth factor levels is still sufficient for tissue healing.

[Modern biotechnological treatment methods of persistent corneal epithelial defects]

The article reviews modern methods of treatment of persistent corneal epithelial defects and considers the factors involved in the development of this pathology, including the limbal stem cell deficiency, which is likely to play the main role. The most promising treatment methods are described, particularly the use of blood derivatives and cell therapy.

Development of Contact Lens-Shaped Crosslinked Amniotic Membranes for Sutureless Fixation in the Treatment of Ocular Surface Diseases

Purpose

To develop a new method of manufacturing contact lens-shaped crosslinked amniotic membranes (AMs) using glutaraldehyde (GA) and dialdehyde starch (DAS) as crosslinking agents.

Methods

Amniotic membranes were placed on a curved plastic mold and crosslinked with either 4.5% DAS or 1% GA, after which their physical properties and biological safety were evaluated.

Results

The tensile strength of the GA- and DAS-crosslinked samples was much increased compared with that of normal AMs. Neither crosslinking process affected AM transparency. Although the GA-crosslinked AM showed better enzymatic resistance, its physiological structure was severely damaged after the crosslinking process. On the other hand, compared with the GA-crosslinked AM, the DAS-crosslinked AM showed higher growth factor concentrations and better biocompatibility, similar to normal AMs. In addition, the DAS-crosslinked AM was effective in the recovery of corneal epithelial wounds and was well maintained over 3 days without decentration or degradation on the ocular surface in human subjects.

Conclusions

Contact lens-shaped AMs were successfully prepared with crosslinking agents. Crosslinking with DAS did not affect the structural properties or biological activity of the AMs, and the improved mechanical properties helped the AM to maintain its curved shape. This crosslinking method allowed us to transplant AMs into patients’ eyes without sutures.

Translational Relevance

Sutureless fixation of contact lens-shaped AMs would be very convenient and safe for the treatment of corneal surface disease.

Amniotic Membrane Extract Protects Islets From Serum-Deprivation Induced Impairments and Improves Islet Transplantation Outcome

Islet culture prior to transplantation is a standard practice in many transplantation centers. Nevertheless, the abundant islet mass loss and function impairment during this serum-deprivation culture period restrain the success of islet transplantation. In the present study, we used a natural biomaterial derived product, amniotic membrane extract (AME), as medium supplementation of islet pretransplant cultivation to investigate its protective effect on islet survival and function and its underlying mechanisms, as well as the engraftment outcome of islets following AME treatment. Results showed that AME supplementation improved islet viability and function, and decreased islet apoptosis and islet loss during serum-deprived culture. This was associated with the increased phosphorylation of PI3K/Akt and MAPK/ERK signaling pathway. Moreover, transplantation of serum-deprivation stressed islets that were pre-treated with AME into diabetic mice revealed better blood glucose control and improved islet graft survival. In conclusion, AME could improve islet survival and function in vivo and in vitro, and was at least partially through increasing phosphorylation of PI3K/Akt and MAPK/ERK signaling pathway.

Corneal Repair and Regeneration: Current Concepts and Future Directions

The cornea is a unique tissue and the most powerful focusing element of the eye, known as a window to the eye. Infectious or non-infectious diseases might cause severe visual impairments that need medical intervention to restore patients' vision. The most prominent characteristics of the cornea are its mechanical strength and transparency, which are indeed the most important criteria considerations when reconstructing the injured cornea. Corneal strength comes from about 200 collagen lamellae which criss-cross the cornea in different directions and comprise nearly 90% of the thickness of the cornea. Regarding corneal transparency, the specific characteristics of the cornea include its immune and angiogenic privilege besides its limbus zone. On the other hand, angiogenic privilege involves several active cascades in which anti-angiogenic factors are produced to compensate for the enhanced production of proangiogenic factors after wound healing. Limbus of the cornea forms a border between the corneal and conjunctival epithelium, and its limbal stem cells (LSCs) are essential in maintenance and repair of the adult cornea through its support of corneal epithelial tissue repair and regeneration. As a result, the main factors which threaten the corneal clarity are inflammatory reactions, neovascularization, and limbal deficiency. In fact, the influx of inflammatory cells causes scar formation and destruction of the limbus zone. Current studies about wound healing treatment focus on corneal characteristics such as the immune response, angiogenesis, and cell signaling. In this review, studied topics related to wound healing and new approaches in cornea regeneration, which are mostly related to the criteria mentioned above, will be discussed.

Effect of human autologous serum and fetal bovine serum on human corneal epithelial cell viability, migration and proliferation in vitro

AIM

To analyze the concentration-dependent effects of autologous serum (AS) and fetal bovine serum (FBS) on human corneal epithelial cell (HCEC) viability, migration and proliferation.

METHODS

AS was prepared from 13 patients with non-healing epithelial defects Dulbecco's modified eagle medium/Ham's F12 (DMEM/F12) with 5% FBS, 0.5% dimethyl sulphoxide (DMSO), 10 ng/mL human epidermal growth factor, 1% insulin-transferrin-selenium, then were incubated in serum media: DMEM/F12 supplemented by 5%, 10%, 15% or 30% AS or FBS. HCEC viability was analyzed using cell proliferation kit XTT, migration using a wound healing assay, proliferation by the cell proliferation enzyme-linked immunosorbent assay (ELISA) BrdU kit. Statistical analysis was performed using the generalized linear model, the values at 30% AS or 30% FBS were used as the baselines.

RESULTS

HCEC viability was the highest at 30% AS or 15% FBS and the lowest at 10% AS or 30% FBS application. HCEC migration was the quickest through 30% AS or 30% FBS and the slowest through 5% AS or 5% FBS concentrations. Proliferation was the most increased through 15% AS or 5% FBS and the least increased through 30% AS or 30% FBS concentrations. HCEC viability at 10% and 15% AS was significantly worse (P=0.001, P=0.023) compared to baseline and significantly better at 15% FBS (P=0.003) concentrations. HCEC migration was significantly worse (P≤0.007) and HCEC proliferation significantly better (P<0.001) in all concentration groups compared to baseline.

CONCLUSION

For the best viability of HCEC 30% AS or 15% FBS, for HCEC migration 30% AS or 30% FBS, for proliferation 15% AS or 5% FBS should be used. Therefore, we suggest the use of 30% AS in clinical practice.