Human amniotic membrane as a delivery vehicle for stem cell-based therapies

Exosomes derived from human amniotic mesenchymal stem cells promotes angiogenesis in hUVECs by delivering novel miRNA N-194

BACKGROUND

To investigate the effect and mechanism of exosomes derived from human amniotic mesenchymal stem cells (hAMSC-Exos) promoting angiogenesis.

METHODS

HAMSC-Exos were isolated using ultracentrifugation and characterized by transmission electron microscopy, NTA, and Western blot. The uptake of hAMSC-Exos by hUVECs was analyzed using PKH-26 labeling, and the effect of hAMSC-Exos on angiogenesis was analyzed in human umbilical vein endothelial cells hUVECs by cell viability assay, Transwell migration assay, Matrigel tube formation assay, and Matrigel plug assays in nude mice. Bioinformatics methods were used to analyze miRNA high-throughput sequencing data of hAMSC-Exos, and RT-qPCR was used to validate the novel miRNAs. HAMSC-Exos with high and low N-194 expression were obtained by transfection, respectively. Target genes were predicted using TargetScan, and the mRNA and protein levels of potential target genes were analyzed by RT-qPCR and Western blot after N-194 mimics transfection. Interaction between miRNAs and target genes was detected using the dual-luciferase reporter assay. Target genes were overexpressed in hUVECs by transfection. The roles of target genes in the influence of N-194 on cell function were determined by analyzing angiogenesis.

RESULTS

The extracted hAMSC-Exos showed saucer-shaped under transmission electron microscopy, and the NTA results showed the particle size of 115.6 ± 38.6 nm. The positive expression of CD9, CD63, and CD81 were verified using Western blot. The treatment of hUVECs with hAMSC-Exos significantly increased cell proliferation, migration, and angiogenesis. HAMSC-Exos contained the novel miRNAs N-194, N-314, N-19, N-393, and N-481, and the expression of N-194 was higher. The Exos derived from hAMSCs which were transfected with FAM-N-194 mimics were able to deliver FAM-N-194 mimics to hUVECs. The hAMSC-Exos with high N-194 significantly promoted angiogenesis in hUVECs. N-194 mimics transfection significantly reduced mRNA and protein levels of potential target gene ING5, and N-194 mimics significantly reduced the luciferase activities expressed by wild-type reporter gene vectors for ING5. The ING5 overexpression significantly reduced the angiogenic capacity of hUVECs. ING5 overexpression suppressed the expression of HSP27 and PLCG2.

CONCLUSIONS

HAMSC-Exos promotes angiogenesis in hUVECs by delivering novel miRNA N-194 which targets ING5.

Decellularised amniotic membrane-TDSCs composite promotes Achilles tendon healing

Adhesions and poor healing are major complications after Achilles tendon injury, and there is no effective solution to this problem. The purpose of this study is to determine whether the biomimetic peritoneurosis can solve the above problems in the process of Achilles tendon healing; This study investigated the adhesion and proliferation of tendon-derived stem cells (TDSCs) on dAM in vitro, as well as their tenogenic differentiation. The effects of Achilles tendon rupture on tendon regeneration were assessed in vivo by using an Achilles tendon rupture model in rats; Finally, from in vitro mRNA transcriptome sequencing combined with in vivo Achilles tendon protein to omics analysis to explore the repair mechanism of Achilles tendon rupture. Student's t-tests were used to assess the significance of observed differences between the two experimental groups. Multiple groups were compared using one-way analysis of variances (ANOVAs), followed by post hoc Bonferroni comparisons. The main findings of this study are that cell adhesion, proliferation, and differentiation of TDSCs were enhanced by dAM. Implanted dAM + TDSCs significantly accelerated tendon regeneration in vivo. In addition, extracellular matrix-related differential genes and proteins were screened by mRNA transcriptometry in vitro and proteomic analysis of Achilles tendon in vivo, and ERK signaling pathway was further explored to participate in the repair of Achilles tendon rupture. The dAM-TDSCs composite biomimetic peritendinous membrane material can effectively promote the healing of Achilles tendon. It provides a new direction for the development of biomimetic peritendinous membrane materials.

Engineering the Immune Response to Biomaterials

Biomaterials are increasingly used as implants in the body, but they often elicit tissue reactions due to the immune system recognizing them as foreign bodies. These reactions typically involve the activation of innate immunity and the initiation of an inflammatory response, which can persist as chronic inflammation, causing implant failure. To reduce these risks, various strategies have been developed to modify the material composition, surface characteristics, or mechanical properties of biomaterials. Moreover, bioactive materials have emerged as a new class of biomaterials that can induce desirable tissue responses and form a strong bond between the implant and the host tissue. In recent years, different immunomodulatory strategies have been incorporated into biomaterials as drug delivery systems. Furthermore, more advanced molecule and cell-based immunomodulators have been developed and integrated with biomaterials. These emerging strategies will enable better control of the immune response to biomaterials and improve the function and longevity of implants and, ultimately, the outcome of biomaterial-based therapies.

Production of second-generation sheep clones via somatic cell nuclear transfer using amniotic cells as nuclear donors

Somatic Cell Nuclear Transfer (SCNT) has transformed animal genetic improvement, gene-editing in model production, xenotransplantation, and conservation efforts for endangered species. However, SCNT-derived embryos occasionally display developmental abnormalities, and following embryo transfer, the miscarriage rate is high. Gene-edited fetuses may experience birth defects, resulting in decreased survival rates. Correct selection of nuclear donor cells is essential for the success of somatic cell cloning. Fibroblasts are the most commonly used cells, but their rapid proliferation increases the risk of genetic mutation, impairing embryo development and production. Conversely, amniotic cells have slower proliferation rates, decreasing the mutation risk during cultivation. Amniotic cells are thus better SCNT candidates than fibroblasts because they offer genomic stability, low tumorigenic and teratogenic risks, reduced immunogenicity, high differentiation potential, ease of accessibility, and fewer ethical concerns. Cells derived from first-generation gene-edited animals exhibit stable genetic structures, reduced susceptibility to genetic alterations and artificial modifications, closely resembling natural cells, and enhanced compatibility with SCNT procedures. Amniotic cells derived from gene-edited sheep fetuses used as nuclear donor cells for SCNT successfully recloned three healthy second-generation gene-edited sheep. Using amniotic cells as nuclear donor cells for SCNT did not significantly alter embryo cleavage rates, blastocyst formation, or fetal birth compared to edited fibroblasts (p > 0.05). However, fetal survival rates were significantly higher than edited fibroblasts (p < 0.05). The results support the potential of amniotic cells as SCNT alternatives, suggesting a promising strategy to improve gene-edited fetus survival rates using first-generation gene-edited sheep-derived amniotic cells.

Extracellular matrix-based biomaterials in burn wound repair: A promising therapeutic strategy

Burns are common traumatic injuries affecting many people worldwide. Development of specialized burn units, advances in acute care modalities, and burn prevention programs have successfully reduced the mortality rate of severe burns. Autologous skin grafting has been considered as the gold standard for wound coverage after the removal of burned skin. For full-thickness burns of a larger scale, however, the autograft donor site may be quickly exhausted, so that alternative skin coverage is necessary. Although rapid progress has been made in the development of skin substitutes for burn wounds during the last decade, no skin substitute has fulfilled the criteria as a perfect replacement for the damaged skin. Extracellular matrix (ECM) derived components have emerged as a source for the engineering of biomaterials capable of inducing desirable cell-specific responses and one of the most promising biomaterials for burn wound healing. Among these, acellular dermal matrix, small intestinal submucosa, and amniotic membrane have been applied to treat burn wounds with acceptable outcomes. This review has explored the use of biomaterials derived from naturally occurring ECM and their derivatives for approaches aiming to promote burn wound healing, and summarized the ECM-based wound dressings products applicable in burn wound and postburn scar contracture to date.

A Novel Human Amniotic Membrane Suspension Improves the Therapeutic Effect of Mesenchymal Stem Cells on Myocardial Infarction in Rats

Mesenchymal stem cell (MSC) therapy aids cardiac repair and regeneration, but the low rate of MSC survival and engulfment in the infarcted heart remains a major obstacle for routine clinical application. Here, an injectable suspension of human acellular amniotic membrane (HAAM) that may serve as synergistic cell delivery vehicle for the treatment of myocardial infarction (MI) by improving MSC homing and survival is developed. The results demonstrate that compared with MSC transplantation alone, HAAM‐loaded MSCs have higher survival and engraftment rates in infarcted tissue, alleviated hypoxia‐induced myocardial damage, achieved higher improvements in cardiac function, promoted angiogenesis, and reduced myocardial fibrosis. In addition, HAAM‐loaded MSCs increase N‐cadherin levels and thereby enhance the efficacy of MSCs in treating MI. This study provides a new approach for MSC‐based cardiac repair and regeneration.

Efficacy of Fresh Versus Preserved Amniotic Membrane Grafts for Ocular Surface Reconstruction: Meta-analysis

Amniotic membrane transplantation is commonly employed in ophthalmology to mend corneal epithelial and stromal defects. Its effectiveness in restoring the ocular surface has been widely acknowledged in clinical practice. Nevertheless, there is ongoing debate regarding the comparative effectiveness of using fresh amniotic membranes versus preserved ones. The objective of this meta-analysis was to ascertain whether there is a disparity in the effectiveness of fresh versus preserved amniotic membrane in the restoration of the ocular surface in clinical practice. The study utilized the following keywords: "fresh amniotic membrane," "preserved amniotic membrane," "amniotic membrane transplantation," and "ocular surface reconstruction." The study conducted a comprehensive search for relevant studies published until April 18, 2024. Seven different databases, namely PubMed, Web of Science, Embase, Cochrane, China Knowledge, China Science and Technology Journal VIP database, and Wanfang database, were utilized. The search was performed using the keywords "fresh amniotic membrane," "preserved amniotic membrane," "amniotic membrane transplantation," and "ocular surface reconstruction." The process of literature review and data extraction was carried out separately by two researchers, and all statistical analyses were conducted using Review Manager 5.4.1. The final analysis comprised nine cohort studies, encompassing a total of 408 participants. The statistics included six outcome indicators: visual acuity (relative risk [RR] = 1.07, 95% confidence interval [CI] = 0.93-1.24, I2 = 0); amniotic membrane viability (RR = 1.00, 95% CI = 0.93-1.08, I2 = 0); ocular congestion resolution (RR = 1.11, 95% CI = 0.97-1.26, I2 = 0); fluorescent staining of amniotic membranes on the second day after the operation (RR = 1.31, 95% CI = 0.80-2.14, I2 = 11); postoperative recurrence rate (RR = 1.01, 95% CI = 0.50-2.03, I2 = 0); and premature lysis of amniotic membrane implants (RR = 0.96, 95% CI = 0.49-1.88, I2 = 0). The findings indicated that there was no statistically significant disparity between fresh and preserved amniotic membranes across any of the measured variables. There is no substantial disparity in the effectiveness of fresh and preserved amniotic membrane transplants in restoring the ocular surface, and both yield favorable and consistent outcomes.

Influence of the Surface Topography of Titanium Dental Implants on the Behavior of Human Amniotic Stem Cells

The dental implant surface plays a crucial role in osseointegration. The topography and physicochemical properties will affect the cellular functions. In this research, four distinct titanium surfaces have been studied: machined acting (MACH), acid etched (AE), grit blasting (GBLAST), and a combination of grit blasting and subsequent acid etching (GBLAST + AE). Human amniotic mesenchymal (hAMSCs) and epithelial stem cells (hAECs) isolated from the amniotic membrane have attractive stem-cell properties. They were cultured on titanium surfaces to analyze their impact on biological behavior. The surface roughness, microhardness, wettability, and surface energy were analyzed using interferometric microscopy, Vickers indentation, and drop-sessile techniques. The GBLAST and GBLAST + AE surfaces showed higher roughness, reduced hydrophilicity, and lower surface energy with significant differences. Increased microhardness values for GBLAST and GBLAST + AE implants were attributed to surface compression. Cell viability was higher for hAMSCs, particularly on GBLAST and GBLAST + AE surfaces. Alkaline phosphatase activity enhanced in hAMSCs cultured on GBLAST and GBLAST + AE surfaces, while hAECs showed no mineralization signals. Osteogenic gene expression was upregulated in hAMSCs on GBLAST surfaces. Moreover, α2 and β1 integrin expression enhanced in hAMSCs, suggesting a surface-integrin interaction. Consequently, hAMSCs would tend toward osteoblastic differentiation on grit-blasted surfaces conducive to osseointegration, a phenomenon not observed in hAECs.

Amniotic miracle: Investigating the unique development and applications of amniotic membrane in wound healing

BACKGROUND

The perfect repair of damaged skin has always been a constant goal for scientists; however, the repair and reconstruction of skin is still a major problem and challenge in injury and burns medicine. Human amniotic membrane (hAM), with its good mechanical properties and anti-inflammatory, antioxidant and antimicrobial benefits, containing growth factors that promote wound healing, has evolved over the last few decades from simple skin sheets to high-tech dressings, such as being made into nanocomposites, hydrogels, powders, and electrostatically spun scaffolds. This paper aims to explore the historical development, applications, trends, and research hotspots of hAM in wound healing.

METHODS

We examined 2660 publications indexed in the Web of Science Core Collection (WoSCC) from January 1, 1975 to July 12, 2023. Utilizing bibliometric methods, we employed VOSviewer, CiteSpace, and R-bibliometrix to characterize general information, identify development trends, and highlight research hotspots. Subsequently, we identified a collection of high-quality English articles focusing on the roles of human amniotic epithelial stem cells (hAESCs), human amniotic mesenchymal stem cells (hAMSCs), and amniotic membrane (AM) scaffolds in regenerative medicine and tissue engineering.

RESULTS

Bibliometric analysis identified Udice-French Research Universities as the most productive affiliation and Tseng S.C.G. as the most prolific author. Keyword analysis, historical direct quotations network, and thematic analysis helped us review the historical and major themes in this field. Our examination included the knowledge structure, global status, trends, and research hotspots regarding the application of hAM in wound healing. Our findings indicate that contemporary research emphasizes the preparation and application of products derived from hAM. Notably, both hAM and the cells isolated from it - hADSCs and hAESCs are prominent and promising areas of research in regenerative medicine and tissue engineering.

CONCLUSION

This research delivers a comprehensive understanding of the knowledge frameworks, global dynamics, emerging patterns, and primary research foci in the realm of hAM applications for wound healing. The field is rapidly evolving, and our findings offer valuable insights for researchers. Future research outcomes are anticipated to be applied in clinical practice, enhancing methods for disease prevention, diagnosis, and treatment.

Stem-Cell-Driven Chondrogenesis: Perspectives on Amnion-Derived Cells

Regenerative medicine harnesses stem cells' capacity to restore damaged tissues and organs. In vitro methods employing specific bioactive molecules, such as growth factors, bio-inductive scaffolds, 3D cultures, co-cultures, and mechanical stimuli, steer stem cells toward the desired differentiation pathways, mimicking their natural development. Chondrogenesis presents a challenge for regenerative medicine. This intricate process involves precise modulation of chondro-related transcription factors and pathways, critical for generating cartilage. Cartilage damage disrupts this process, impeding proper tissue healing due to its unique mechanical and anatomical characteristics. Consequently, the resultant tissue often forms fibrocartilage, which lacks adequate mechanical properties, posing a significant hurdle for effective regeneration. This review comprehensively explores studies showcasing the potential of amniotic mesenchymal stem cells (AMSCs) and amniotic epithelial cells (AECs) in chondrogenic differentiation. These cells exhibit innate characteristics that position them as promising candidates for regenerative medicine. Their capacity to differentiate toward chondrocytes offers a pathway for developing effective regenerative protocols. Understanding and leveraging the innate properties of AMSCs and AECs hold promise in addressing the challenges associated with cartilage repair, potentially offering superior outcomes in tissue regeneration.

The Regenerative Microenvironment of the Tissue Engineering for Urethral Strictures

Urethral stricture caused by various reasons has threatened the quality of life of patients for decades. Traditional reconstruction methods, especially for long-segment injuries, have shown poor outcomes in treating urethral strictures. Tissue engineering for urethral regeneration is an emerging concept in which special designed scaffolds and seed cells are used to promote local urethral regeneration. The scaffolds, seed cells, various factors and the host interact with each other and form the regenerative microenvironment. Among the various interactions involved, vascularization and fibrosis are the most important biological processes during urethral regeneration. Mesenchymal stem cells and induced pluripotent stem cells play special roles in stricture repair and facilitate long-segment urethral regeneration, but they may also induce carcinogenesis and genomic instability during reconstruction. Nevertheless, current technologies, such as genetic engineering, molecular imaging, and exosome extraction, provide us with opportunities to manage seed cell-related regenerative risks. In this review, we described the interactions among seed cells, scaffolds, factors and the host within the regenerative microenvironment, which may help in determining the exact molecular mechanisms involved in urethral stricture regeneration and promoting clinical trials and the application of urethral tissue engineering in patients suffering from urethral stricture.

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.

Functional hydrogels for the repair and regeneration of tissue defects

Tissue defects can be accompanied by functional impairments that affect the health and quality of life of patients. Hydrogels are three-dimensional (3D) hydrophilic polymer networks that can be used as bionic functional tissues to fill or repair damaged tissue as a promising therapeutic strategy in the field of tissue engineering and regenerative medicine. This paper summarises and discusses four outstanding advantages of hydrogels and their applications and advances in the repair and regeneration of tissue defects. First, hydrogels have physicochemical properties similar to the extracellular matrix of natural tissues, providing a good microenvironment for cell proliferation, migration and differentiation. Second, hydrogels have excellent shape adaptation and tissue adhesion properties, allowing them to be applied to a wide range of irregularly shaped tissue defects and to adhere well to the defect for sustained and efficient repair function. Third, the hydrogel is an intelligent delivery system capable of releasing therapeutic agents on demand. Hydrogels are capable of delivering therapeutic reagents and releasing therapeutic substances with temporal and spatial precision depending on the site and state of the defect. Fourth, hydrogels are self-healing and can maintain their integrity when damaged. We then describe the application and research progress of functional hydrogels in the repair and regeneration of defects in bone, cartilage, skin, muscle and nerve tissues. Finally, we discuss the challenges faced by hydrogels in the field of tissue regeneration and provide an outlook on their future trends.

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

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

Application of Amniotic Membrane in Skin Regeneration

Amniotic membrane (AM) is an avascular structure composed of three different layers, which contain collagen, extracellular matrix, and biologically active cells (stem cells). Collagen, a naturally occurring matrix polymer, provides the structural matrix/strength of the amniotic membrane. Tissue remodeling is regulated by growth factors, cytokines, chemokines, and other regulatory molecules produced by endogenous cells within AM. Therefore, AM is considered an attractive skin-regenerating agent. This review discusses the application of AM in skin regeneration, including its preparation for application to the skin and its mechanisms of therapeutic healing in the skin. This review involved collecting research articles that have been published in several databases, including Google Scholar, PubMed, Science Direct, and Scopus. The search was conducted by using the keywords ‘amniotic membrane skin’, ‘amniotic membrane wound healing’, ‘amniotic membrane burn’, ‘amniotic membrane urethral defects’, ‘amniotic membrane junctional epidermolysis bullosa’, and ‘amniotic membrane calciphylaxis’. Ultimately, 87 articles are discussed in this review. Overall, AM has various activities that help in the regeneration and repair of damaged skin.

Research progress of stem cell therapy for endometrial injury

Endometrial damage is an important factor leading to infertility and traditional conventional treatments have limited efficacy. As an emerging technology in recent years, stem cell therapy has provided new hope for the treatment of this disease. By comparing the advantages of stem cells from different sources, it is believed that menstrual blood endometrial stem cells have a good application prospect as a new source of stem cells. However, the clinical utility of stem cells is still limited by issues such as colonization rates, long-term efficacy, tumor formation, and storage and transportation. This paper summarizes the mechanism by which stem cells repair endometrial damage and clarifies the material basis of their effects from four aspects: replacement of damaged sites, paracrine effects, interaction with growth factors, and other new targets. According to the pathological characteristics and treatment requirements of intrauterine adhesion (IUA), the research work to solve the above problems from the aspects of functional bioscaffold preparation and multi-functional platform construction is also summarized. From the perspective of scaffold materials and component functions, this review will provide a reference for comprehensively optimizing the clinical application of stem cells.

Prospects and Challenges of Electrospun Cell and Drug Delivery Vehicles to Correct Urethral Stricture

Current therapeutic modalities to treat urethral strictures are associated with several challenges and shortcomings. Therefore, significant strides have been made to develop strategies with minimal side effects and the highest therapeutic potential. In this framework, electrospun scaffolds incorporated with various cells or bioactive agents have provided promising vistas to repair urethral defects. Due to the biomimetic nature of these constructs, they can efficiently mimic the native cells’ niches and provide essential microenvironmental cues for the safe transplantation of multiple cell types. Furthermore, these scaffolds are versatile platforms for delivering various drug molecules, growth factors, and nucleic acids. This review discusses the recent progress, applications, and challenges of electrospun scaffolds to deliver cells or bioactive agents during the urethral defect repair process. First, the current status of electrospinning in urethral tissue engineering is presented. Then, the principles of electrospinning in drug and cell delivery applications are reviewed. Finally, the recent preclinical studies are summarized and the current challenges are discussed.