Application of Amniotic Membrane in Skin Regeneration

The revolutionary role of placental derivatives in biomedical research

The human placenta is a transient yet crucial organ that plays a key role in sustaining the relationship between the maternal and fetal organisms. Despite its historical classification as "biowaste," placental tissues have garnered increasing attention since the early 1900s for their significant medical potential, particularly in wound repair and surgical application. As ethical considerations regarding human placental derivatives have largely been assuaged in many countries, they have gained significant attention due to their versatile applications in various biomedical fields, such as biomedical engineering, regenerative medicine, and pharmacology. Moreover, there is a substantial trend toward various animal product substitutions in laboratory research with human placental derivatives, reflecting a broader commitment to advancing ethical and sustainable research methodologies. This review provides a comprehensive examination of the current applications of human placental derivatives, explores the mechanisms behind their therapeutic effects, and outlines the future potential and directions of this rapidly advancing field.

Genetic Insights Into Epidermolysis Bullosa: Identification of Novel Variants in Tunisian Patients

Epidermolysis Bullosa (EB) is a group of genetic skin disorders characterized by extreme skin fragility and blistering. In North African countries, including Tunisia, complex genetic and phenotypic diversity is entangled with a scarcity of scientific research on EB. This lack of knowledge presents a distinct challenge in terms of diagnostic accuracy and patient care. Our study cohort includes 10 Tunisian patients with EB whose genetic profiles were investigated by exome sequencing. In silico analysis was conducted to determine the functional impact of three novel variants. We revealed ten genetic variants, including three novel ones within the COL7A1 and DST genes. The in silico analysis shed light on the potential structural and functional implications of these novel variants. By establishing the correlation between clinical features and genetic alterations, we have expanded the existing database of disease-causing variants associated with EB in Northern Africa. Our study fills a critical knowledge gap in the North African context, where the scarcity of clinical database and genetic testing in addition to the genetic diversity necessitates comprehensive research. Our findings have the potential to improve diagnosis and management strategies for EB patients in low and middle-income countries across the region, especially through the integration of exome sequencing and in silico analysis.

Elevating Dermatology Beyond Aesthetics: Perinatal-Derived Advancements for Rejuvenation, Alopecia Strategies, Scar Therapies, and Progressive Wound Healing

Dermatologists have been interested in recent advancements in regenerative therapy. Current research is actively investigating the possibility of placental tissue derivatives to decelerate the skin aging process, enhance skin regeneration, reduce scarring, and prevent hair loss. Amniotic membranes (AM) play a crucial role in regenerative medicine as they serve as a suitable means of transporting stem cells, growth hormones, cytokines, and other essential compounds. Regulating an intricate network of biological processes improves the development and repair of tissues. Studies done by dermatologists indicate that several compounds found in the decidua, umbilical cord, and amniotic membrane have the potential to be used for regeneration. Examples include mesenchymal stem cells, growth factors, and immunomodulatory pharmaceuticals. Due to research and technological developments, scientists may use placental sections to facilitate skin regeneration, minimize scarring, and expedite wound healing. This study examines the current state of dermatological therapy, with a focus on using derivatives obtained from fetal tissue as the basis. The critical areas of study focus on this strategy are the potential benefits, growth opportunities, and recovery rates. Based on a thorough examination of the available literature and clinical data, we want to make definitive conclusions on the possible influence of fetal tissue derivatives in dermatological therapy.

Chitosan-based injectable porous microcarriers with enhanced adipogenic differentiation and angiogenesis for subcutaneous adipose tissue regeneration

Chitosan is a promising biomaterial for tissue engineering, but its functionality is limited by a lack of bioactive sites. This study develops chitosan/amniotic membrane microcarriers to enhance vascularization and tissue regeneration for subcutaneous adipose tissue. The incorporation of decellularized amniotic membrane enhances the bioactivities of chitosan in promoting cell differentiation and angiogenesis. Optimized preparation yielded porous microcarriers with a particle size of 261.2 ± 28 μm and an average pore size of 19.0 ± 4 μm. In vitro degradation analysis showed accelerated degradation with higher amniotic membrane content. Cytocompatibility and adipogenic capacity assessments indicated that the microcarriers supported cell adhesion and proliferation over 7 days, with amniotic membrane facilitating adipogenic differentiation of adipose-derived stem cells. When injected subcutaneously into nude mice, these microcarriers formed neoplastic adipose tissues, which were harvested 8 weeks later. Fluorescence staining, oil-red O staining and CD31 labeling demonstrated that amniotic membrane incorporation significantly enhanced in vivo adipose tissue formation and angiogenesis.

Lyophilization of dehydrated human amniotic membrane: a proactive approach to preserve growth factors for enhanced wound healing

The preservation of key growth factors in the human amniotic membrane (hAM) that are involved in tissue regeneration and wound healing is the primary focus of this research work. Here, we quantified the total protein content and the major growth factors present in different sample preparations of hAM. The membrane is initially processed, dehydrated, and gamma-irradiated and subsequently subjected to histological staining, cytotoxicity assays, and total protein estimation. The ELISA method was used to quantify TGF b1, bFGF, PDGF-BB, VEGF-A, and EGF in three distinct preservation samples: tissue homogenate (AC-H), ball milled powder (AC-P), and lyophilized powder (AC-L). An in-vitro scratch assay was performed to analyse cell migration and wound healing. Higher TGF-b1 and FGF-b concentrations indicate the potential impact of HAM on re-epithelialization and granular tissue formation. For major growth factors, the quantification shows no significant differences between the samples. On treating the wound area with concentrations of 0.4 mg/ml and 0.6 mg/ml, the remaining wound area for AC-H, AC-L, and AC-P are 39.71%, 40.31%, 55.99% and 25.48%, 62.8%, and 29.65%, respectively. This indicates the presence of growth factors in the membrane promotes wound healing and facilitates cell migration and proliferation. This study provides insights into the quantity of key growth factors within the human amniotic membrane, thereby presenting the approach as a viable option for treating chronic wounds. Additionally, as lyophilization preserves more growth factors and offers greater stability and shelf life than other preservation techniques, it may be an appropriate substitute for ball milling.

A hybrid scaffold of modified human amniotic membrane with gelatine/dendrimer-protected silver nanoparticles for skin wound healing applications

The human amniotic membrane (hAM) is a biological material widely utilized to mimic the extracellular matrix in damaged skin. Despite its potential, clinical applications of hAM have been hindered by its poor mechanical properties. Furthermore, cryopreservation process used to store hAM could compromise its inherent bactericidal properties. This study explores an innovative approach by combining hAM with 2, 4, 6 and 8% w/v of gelatine (Gel) and incorporating 100, 500 and 1000 μL of poly(propylene imine) (PPI) dendrimer-protected silver nanoparticles (AgNPs) to create antibacterial-bolstered scaffolds using freeze-drying technique. Based on results, hAM/Gel2/S500 scaffold was identified as optimal specimen. It exhibited favorable properties, including an ultimate tensile strength of 16 kPa, an elastic modulus of 26.66 kPa, an elongation at break of 59.60%, an average pore size of 490 μm and a porosity of 52.93%. In vitro degradation indicated that degradation rate of the scaffold was 30% lower on the 1st day and 20% higher on the 21st day compared to commercial ChitoHeal dressing. It also demonstrated higher water absorbance of 100 and 139% at 1 and 48 hours, respectively, compared to ChitoHeal dressing. Additionally, uniform distribution of AgNPs throughout the scaffold and their release from 2.30 μg mL-1 on the 1st day to 10.40 μg mL-1 by the 3rd day, resulted in an elevated inhibition zone against S. aureus and E. coli. Finally, all antibacterial-bolstered scaffolds exhibited 85-89% cell viability after 24 hours and 80-83% after 72 hours. Consequently, hAM/Gel2/S500 scaffold showed promising results for application in wound healing.

Alginate-Based Hydrogels with Amniotic Membrane Stem Cells for Wound Dressing Application

Objective

Chronic wounds are a common clinical problem that necessitate the exploration of novel regenerative therapies. We report a method to investigate the in vitro wound healing capacity of an innovative biomaterial, which is based on amniotic membrane-derived stem cells (AMSCs) embedded in an alginate hydrogel matrix. The aim of this study was to prepare an sodium alginate-based hydrogel, cross-linked calcium chloride (CaCl2) with the active ingredient AMSC (AMSC/Alg-H) and to evaluate its in vitro effectiveness for wound closure.

Methods

This hydrogel preparation involved combining sterile solutions of AMSC, sodium alginate, and CaCl2, followed by rinsing with serum-free media. The cells were cultured in different 6-well plates, namely sodium alginate, calcium chloride, AMSC, Alg-H, and AMSC/Alg-H, in complete medium with 10% FBS. The hydrogel was successfully formulated, as confirmed by characterization techniques including Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy, Differential Scanning Calorimetry (DSC), Cytotoxicity Studies, TGF-β1 Level Measurement by ELISA, and Cell Scratch Wound Assay.

Results

Cryo-EM characterization of the Alg-H preparation successfully demonstrated the encapsulation of MSCs. FTIR and DSC analyses indicate that crosslinking transpires in Alg-H encapsulating AMSC. The AMSC/Alg-H preparation showed no significant difference in toxicity compared to HaCaT cells (p < 0.05), indicating it was not toxic to HaCaT cells. Furthermore, in the scratch wound assay test at 24 hours, the AMSC/Alg-H preparation achieved 100% wound closure, outperforming both AMSC and Alg-H alone. In vitro assessment revealed that AMSC/Alg-H significantly enhanced key wound healing processes, including cell proliferation and migration, compared to Alg-H.

Conclusion

Our study demonstrated the promising potential of AMSC/Alg-H as an enhanced regenerative therapy for in vitro wound healing. AMSC/Alg-H was able to maintain the viability of AMSCs and facilitate the formation of tissue-like structures.

Umbilical Amniotic Tissue Graft as an Alternative Approach for Eyelid Reconstruction After Necrotizing Fasciitis Debridement

A 54-year-old female with myelodysplastic syndrome on chemotherapy presented with 10 days of periocular erythema and edema worsening on oral antibiotics. Computed Tomography scan showed periorbital soft tissue swelling without postseptal extension or abscess. Intravenous broad-spectrum antibiotics were administered. However, she developed necrosis of the upper eyelid requiring aggressive debridement. Nine days after debridement, the defect measuring 5.5 × 3 cm was covered using an umbilical amniotic tissue graft (AmnioGuard, BioTissue, Miami, FL). At postoperative week 4, 5-fluorouracil was injected to prevent the shortening of anterior lamella. At postoperative week 20, the graft had dissolved and been replaced by regenerated skin. Final eyelid exam demonstrated normal eyelid elevation and minimal lagophthalmos. Herein, we present a case of umbilical amniotic membrane as a substrate graft to support the healing of the eyelid defect by secondary intention.

Amniotic membrane, a novel bioscaffold in cardiac diseases: from mechanism to applications

Cardiovascular diseases represent one of the leading causes of death worldwide. Despite significant advances in the diagnosis and treatment of these diseases, numerous challenges remain in managing them. One of these challenges is the need for replacements for damaged cardiac tissues that can restore the normal function of the heart. Amniotic membrane, as a biological scaffold with unique properties, has attracted the attention of many researchers in recent years. This membrane, extracted from the human placenta, contains growth factors, cytokines, and other biomolecules that play a crucial role in tissue repair. Its anti-inflammatory, antibacterial, and wound-healing properties have made amniotic membrane a promising option for the treatment of heart diseases. This review article examines the applications of amniotic membrane in cardiovascular diseases. By focusing on the mechanisms of action of this biological scaffold and the results of clinical studies, an attempt will be made to evaluate the potential of using amniotic membrane in the treatment of heart diseases. Additionally, the existing challenges and future prospects in this field will be discussed.

Evaluation of the effect of an amniotic membrane derived bio-nano product (LifeCell) on human endometrial cells proliferation and gene expression: An in-vitro study

OBJECTIVE

Successful assisted reproductive technology (ART) requires a receptive endometrium with appropriate thickness and the presence of specific cytokines, chemokines, and growth factors. Despite advancements in ART, the success rates remain suboptimal, particularly in individuals with thin endometrium resistant to treatment. In this study, we evaluated the potential effects of LifeCell, a product of BioNano Technology, on the growth, development, and acceptance of endometrial cells.

STUDY DESIGN

We cultured endometrial cells in a defined medium with different concentrations of LifeCell and examined cell growth, development, and the expression of genes involved in endometrial receptivity.

RESULTS

Co-culture of primary human endometrial cells with 5 % Life cell solution significantly stimulated the endometrial cell growth, development and receptivity genes expression. The expression levels of FGF2 and CSF in the 72 h co-cultured were significantly increased compared with other groups (P < 0.01). HOXA10 and LIF significantly increased in the 72 h co-cultured compared with 24 h co-cultured and control groups but had no significant level compared with 48 h cocultured. HOXA10 significantly increased in the 48 h cocultured compared with control group. IL-6 and Hb-EGF increased in the 48 h co-cultured compared to other groups but had no significant level. VEGF increased in the treated groups compared to control but had no significant level. The expression of OPN, unlike the other genes, decreased in the treated group compared to the control, which was not significant.

CONCLUSIONS

These findings suggest that LifeCell may be a potential option for patients with treatment-resistant thin endometrium in cases of infertility.

Analysis of morphology, cytotoxicity, and water content characteristics of freeze-dried amnion membrane from human and bovine

Placenta tissue has biological advantages, including anti-inflammatory, anti-bacterial, anti-fibrotic formation, and immunomodulatory properties. The amnion membrane (AM) is an inner side membrane of the placenta that faces the fetus. The main sources of amnion are humans and animals, with bovine being one of the significant sources. The aim of this study was to analyze the morphology, cytotoxicity, and water content characteristic of freeze-dried amnion membrane (FD-AM) from humans and bovines to measure the safety and compatibility of bovine FD-AM as an alternative to human FD-AM. This study is an observational cross-sectional study. Samples were divided into two groups: human FD-AM and bovine FD-AM groups. Both groups were examined for morphology characteristics by scanning electron microscopy (SEM), cytotoxicity by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) analysis, and water content by drying through moisture analyzer device. The morphology characteristics of bovine FD-AM and human FD-AM, as observed through SEM, showed similar results of a smooth, flat surface with no cavity and were well dehydrated. MTT assay analysis on both groups demonstrated cytocompatibility with cell viability exceeding 70% in the control group. However, human FD-AM showed a higher number of viable cells (0.19±0.01) compared to bovine FD-AM (0.12±0.03), with a statistically significant difference (p<0.05). The water content analysis revealed that both groups met the standard, with levels below 10%. While bovine FD-AM (7.19±0.45%) had slightly higher water content than human FD-AM (6.79±1.0%), the difference was not significant (p>0.05). Both human FD-AM and bovine FD-AM showed good results in morphology, cytotoxicity, and water content characteristics and compatibility. In conclusion, bovine FD-AM might be considered as an alternative to human FD-AM.

Advances and impact of human amniotic membrane and human amniotic-based materials in wound healing application

Wound healing is a complicated process, especially when surgical, traumatic, burn, or pathological injury occurs, which requires different kinds of dressing covers including hydrogels, hydrocolloids, alginates foams and films for treatment. The human amniotic membrane (hAM) is a biodegradable extracellular matrix with unique and tailorable physicochemical and biological properties, generated by the membrane itself or other cells that are located on the membrane surface. It is noted as a promising aid for wound healing and tissue regeneration due to the release of growth factors and cytokines, and its antibacterial and immunosuppressive properties. Moreover, hAM has optimal physical, biological, and mechanical properties, which makes it a much better option as a regenerative skin treatment than existing alternative materials. In addition, this layer has a structure with different layers and cells with different functions, which act as a regenerative geometry and reservoir of bioactive substances and cells for wound healing. In the present work, the structural and biological features of hAM are introduced as well as the application of this layer in different forms of composites to enhance wound healing. Future studies are recommended to detect possible further functionalization to enhance the hAM effectiveness on wound healing.

De-Epithelization of the Human Amniotic Membrane Using a System Involving Ozonated Water and Ultrasound

The aim of this study was to evaluate whether a system involving ozonated water and ultrasound causes de-epithelization of the human amniotic membrane (HAM). The experiment protocol was carried out in four stages. Stage I was carried out to determine the duration of the experiment. Stage II comprised the first experiment, involving four groups of samples studied in triplicate: control/natural (IN), processed with ultrasound in a liquid medium (US), processed with ozonated water (O3), and processed with ozonated water combined with ultrasound (US_O3). Stage III was performed to confirm the results, following the same steps present in Stage II. Stage IV involved the use of oxygen to confirm the hypothesis. Histological analysis was carried out to verify whether the effects of O2 were similar to those of O3. The system was activated, and ozonation was carried out for 10 min, as in the previous experiment, reaching a concentration level of 3.0 mg/L. The samples were submerged and positioned in the reservoir and processed separately for 55 min. The biochemical properties were assessed using Fourier transform infrared spectroscopy, and the morphology was examined using histology and scanning electron microscopy. The spectra of the samples exhibited similarities; however, subtle changes were highlighted, such as smooth band shifts and intensity changes. The morphology indicated that ultrasound achieved more efficient HAM de-epithelialization compared to ultrasound combined with ozonated water and ozonated water alone. One plausible hypothesis for this observation is that cavitation represents the primary mechanism responsible for de-epithelialization. When ultrasound is combined with ozone, the bubbles generated by ozone gas reduce the cavitation effect. This study is pioneering as it demonstrates an ultrasound system capable of the efficient de-epithelialization of the HAM.

Characterization of Amnion-Derived Membrane for Clinical Wound Applications

Human amniotic membrane (hAM), the innermost placental layer, has unique properties that allow for a multitude of clinical applications. It is a common misconception that birth-derived tissue products, such as dual-layered dehydrated amnion-amnion graft (dHAAM), are similar regardless of the manufacturing steps. A commercial dHAAM product, Axolotl Biologix DualGraft™, was assessed for biological and mechanical characteristics. Testing of dHAAM included antimicrobial, cellular biocompatibility, proteomics analysis, suture strength, and tensile, shear, and compressive modulus testing. Results demonstrated that the membrane can be a scaffold for fibroblast growth (cellular biocompatibility), containing an average total of 7678 unique proteins, 82,296 peptides, and 96,808 peptide ion variants that may be antimicrobial. Suture strength results showed an average pull force of 0.2 N per dHAAM sample (equating to a pull strength of 8.5 MPa). Tensile modulus data revealed variation, with wet samples showing 5× lower stiffness than dry samples. The compressive modulus and shear modulus displayed differences between donors (lots). This study emphasizes the need for standardized processing protocols to ensure consistency across dHAAM products and future research to explore comparative analysis with other amniotic membrane products. These findings provide baseline data supporting the potential of amniotic membranes in clinical applications.

Innovative approaches to wound healing: insights into interactive dressings and future directions

The objective of this review is to provide an up-to-date and all-encompassing account of the recent advancements in the domain of interactive wound dressings. Considering the gap between the achieved and desired clinical outcomes with currently available or under-study wound healing therapies, newer more specific options based on the wound type and healing phase are reviewed. Starting from the comprehensive description of the wound healing process, a detailed classification of wound dressings is presented. Subsequently, we present an elaborate and significant discussion describing interactive (unconventional) wound dressings. Latter includes biopolymer-based, bioactive-containing and biosensor-based smart dressings, which are discussed in separate sections together with their applications and limitations. Moreover, recent (2-5 years) clinical trials, patents on unconventional dressings, marketed products, and other information on advanced wound care designs and techniques are discussed. Subsequently, the future research direction is highlighted, describing peptides, proteins, and human amniotic membranes as potential wound dressings. Finally, we conclude that this field needs further development and offers scope for integrating information on the healing process with newer technologies.

3D-bioprinted GelMA/gelatin/amniotic membrane extract (AME) scaffold loaded with keratinocytes, fibroblasts, and endothelial cells for skin tissue engineering

Gelatin-methacryloyl (GelMA) is a highly adaptable biomaterial extensively utilized in skin regeneration applications. However, it is frequently imperative to enhance its physical and biological qualities by including supplementary substances in its composition. The purpose of this study was to fabricate and characterize a bi-layered GelMA-gelatin scaffold using 3D bioprinting. The upper section of the scaffold was encompassed with keratinocytes to simulate the epidermis, while the lower section included fibroblasts and HUVEC cells to mimic the dermis. A further step involved the addition of amniotic membrane extract (AME) to the scaffold in order to promote angiogenesis. The incorporation of gelatin into GelMA was found to enhance its stability and mechanical qualities. While the Alamar blue test demonstrated that a high concentration of GelMA (20%) resulted in a decrease in cell viability, the live/dead cell staining revealed that incorporation of AME increased the quantity of viable HUVECs. Further, gelatin upregulated the expression of KRT10 in keratinocytes and VIM in fibroblasts. Additionally, the histological staining results demonstrated the formation of well-defined skin layers and the creation of extracellular matrix (ECM) in GelMA/gelatin hydrogels during a 14-day culture period. Our study showed that a 3D-bioprinted composite scaffold comprising GelMA, gelatin, and AME can be used to regenerate skin tissues.

Assessing the Application and Effectiveness of Human Amniotic Membrane in the Management of Venous and Diabetic Ulcers: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

This study aimed to assess the efficacy of human amniotic membranes (HAM) in treating venous and diabetic ulcers, which often pose challenges in healing. A systematic review and meta-analysis were conducted, evaluating 10 relevant studies involving 633 participants. Findings revealed that HAM treatment significantly accelerated ulcer closure, demonstrating over 90% complete healing compared to standard care. Despite moderate heterogeneity among studies, the results strongly suggested the effectiveness and safety of HAM therapy for venous and diabetic leg ulcers. Further research with larger study cohorts is recommended to bolster the existing evidence supporting HAM in managing these challenging wounds.

Amnion-derived hydrogels as a versatile platform for regenerative therapy: from lab to market

In recent years, the amnion (AM) has emerged as a versatile tool for stimulating tissue regeneration and has been of immense interest for clinical applications. AM is an abundant and cost-effective tissue source that does not face strict ethical issues for biomedical applications. The outstanding biological attributes of AM, including side-dependent angiogenesis, low immunogenicity, anti-inflammatory, anti-fibrotic, and antibacterial properties facilitate its usage for tissue engineering and regenerative medicine. However, the clinical usage of thin AM sheets is accompanied by some limitations, such as handling without folding or tearing and the necessity for sutures to keep the material over the wound, which requires additional considerations. Therefore, processing the decellularized AM (dAM) tissue into a temperature-sensitive hydrogel has expanded its processability and applicability as an injectable hydrogel for minimally invasive therapies and a source of bioink for the fabrication of biomimetic tissue constructs by recapitulating desired biochemical cues or pre-defined architectural design. This article reviews the multi-functionality of dAM hydrogels for various biomedical applications, including skin repair, heart treatment, cartilage regeneration, endometrium regeneration, vascular graft, dental pulp regeneration, and cell culture/carrier platform. Not only recent and cutting-edge research is reviewed but also available commercial products are introduced and their main features and shortcomings are elaborated. Besides the great potential of AM-derived hydrogels for regenerative therapy, intensive interdisciplinary studies are still required to modify their mechanical and biological properties in order to broaden their therapeutic benefits and biomedical applications. Employing additive manufacturing techniques (e.g., bioprinting), nanotechnology approaches (e.g., inclusion of various bioactive nanoparticles), and biochemical alterations (e.g., modification of dAM matrix with photo-sensitive molecules) are of particular interest. This review article aims to discuss the current function of dAM hydrogels for the repair of target tissues and identifies innovative methods for broadening their potential applications for nanomedicine and healthcare.

Clinically Actionable Topical Strategies for Addressing the Hallmarks of Skin Aging: A Primer for Aesthetic Medicine Practitioners

In this narrative review, we sought to provide a comprehensive overview of the mechanisms underlying cutaneous senescence, framed by the twelve traditional hallmarks of aging. These include genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, impaired macroautophagy, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, altered intercellular communication, chronic inflammation, and dysbiosis. We also examined how topical interventions targeting these hallmarks can be integrated with conventional aesthetic medicine techniques to enhance skin rejuvenation. The potential of combining targeted topical therapies against the aging hallmarks with minimally invasive procedures represents a significant advancement in aesthetic medicine, offering personalized and effective strategies to combat skin aging. The reviewed evidence paves the way for future advancements and underscores the transformative potential of integrating scientifically validated interventions targeted against aging hallmarks into traditional aesthetic practices.

Modification of the Human Amniotic Membrane Using Different Cross-Linking Agents as a Promising Tool for Regenerative Medicine

Human amniotic membranes (hAMs) obtained during cesarean sections have proven to be clinically useful as an interesting biomaterial in a wide range of tissue engineering applications such as ocular surface reconstruction, burn treatments, chronic wounds, or bedsore ulcers. It presents antimicrobial properties, promotes epithelization, reduces inflammation and angiogenesis, contains growth factors, and constitutes the reservoir of stem cells. However, variability in hAM stiffness and its fast degradation offers an explanation for the poor clinical applications and reproducibility. In addition, the preparatory method of hAM for clinical use can affect its mechanical properties, and these differences can influence its application. As a directly applied biomaterial, the hAM should be available in a ready-to-use manner in clinical settings. In the present study, we performed an analysis to improve the mechanical properties of hAM by the addition of various reagents used as protein cross-linkers: EDC/NHS, PEG-dialdehyde, PEG-NHS, dialdehyde starch, and squaric acid. The effect of hAM modification using different cross-linking agents was determined via infrared spectroscopy, thermal analyses, mechanical properties analyses, enzymatic degradation, and cytotoxicity tests. The use of PEG-dialdehyde, PEG-NHS, dialdehyde starch, and squaric acid increases the mechanical strength and elongation at the breaking point of hAM, while the addition of EDC/NHS results in material stiffening and shrinkage. Also, the thermal stability and degradation resistance were evaluated, demonstrating higher values after cross-linking. Overall, these results suggest that modification of human amniotic membrane by various reagents used as protein cross-linkers may make it easier to use hAM in clinical applications, and the presented study is a step forward in the standardization of the hAM preparation method.

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.