Decellularized Human Chorion Membrane as a Novel Biomaterial for Tissue 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.

Harnessing the Anti-Inflammatory Effects of Perinatal Tissue Derived Therapies for the Treatment of Inflammatory Skin Diseases: A Comprehensive Review

Dealing with chronic inflammatory skin conditions like atopic dermatitis and psoriasis can be extremely difficult. Current treatments, such as topical corticosteroids, often have limitations and side effects. However, researchers have discovered that the placenta's remarkable properties may provide a breakthrough in effectively addressing these skin conditions. The placenta comprises three essential tissues: decidua, placental membrane, and umbilical cord. Placental derivatives have shown significant potential in treating psoriasis by reducing inflammatory cytokines and inhibiting keratinocyte proliferation. In the case of atopic dermatitis, umbilical cord stem cells have demonstrated anti-inflammatory effects by targeting critical factors and promoting anti-inflammatory cytokines. The scope of benefits associated with placental derivatives transcends these specific applications. They also potentially address other inflammatory skin diseases, such as vitiligo, by stimulating melanin production. Moreover, these derivatives have been leveraged in the treatment of pemphigus and epidermolysis bullosa (EB), showcasing potential as a wound dressing that could eliminate the necessity for painful dressing changes in EB patients. In summary, the integration of placental derivatives stands to revolutionize our approach to inflammatory skin conditions owing to their distinct properties and the prospective benefits they offer. This comprehensive review delves into the current applications of placental derivatives in addressing inflammatory skin diseases, presenting a novel treatment approach.

Perspectives on the use of decellularized/devitalized and lyophilized human perinatal tissues for bone repair: Advantages and remaining challenges

Human amniotic membrane (hAM) has been extensively used for several decades as a bioactive scaffold for regenerative medicine. In its cryopreserved form-one of the main storage formats-the presence of viable cells has often been questioned. Furthermore, there is little published evidence of the role of endogenous amniotic cells from cryopreserved hAM in tissue repair. Some technologies, often patented and combined, have facilitated the use of hAM. Decellularization and devitalization processes have been developed to ensure its safety and prevent immune rejection. Lyophilization and dehydration methods have had a significant impact on clinical practices by enabling storage at room temperature in the operating room and making handling and cutting easier. Consequently, the commercialization of hAM has expanded, initially in the USA, and now in Europe. In the last decade, there has been growing interest in new perinatal tissues in clinical medicine. Similar processes have been adapted for these tissues to prevent immune or inflammatory reactions, and to improve storage and make them easier to use. For example, in the USA, many products marketed for wound healing undergo lyophilization, sometimes in combination with decellularization. Given our expertise, we wanted to highlight the potential of decellularized/devitalized and lyophilized perinatal tissues in regenerative medicine, particularly for bone repair. In this opinion paper, we discuss why these tissues represent the future of regenerative medicine, their potential drawbacks and strategies to overcome these challenges.

Optimizations of Placenta Extracellular Matrix-Loaded Silk Fibroin/Alginate 3D-Printed Scaffolds Structurally and Functionally for Bone Tissue Engineering

Recent interest has been focused on extracellular matrix (ECM)-based scaffolds totreat critical-sized bone injuries. In this study, urea was used to decellularize and solubilize human placenta tissue. Then, different concentrations of ECM were composited with 8% alginate (Alg) and 12% silk fibroin (SF) for printing in order to produce a natural 3D construct that resembled bone tissue. The physical and biological features of the printed structures were evaluated entirely in vitro. Finally, a rat model was employed to examine the optimal 3D printed scaffold (5% ECM) as a bone transplant for the healing of cranial bone lesions. The present investigation demonstrated that decellularizing placental tissue fragments led to efficient removal of cell debris. In addition, a remarkable improvement in the printed scaffolds' mechanical and biological properties was observed by increasing the ECM concentration. The histology studies and real-time PCR results demonstrated the acceleration of bone regeneration in the bone lesions treated with 5%ECM-SF/Alg at 4 and 8 weeks after implantation. Overall, these results proved that the placental ECM-printed scaffolds could potentially construct biomimetic grafts to reconstruct significant bone defects and now promise to proceed with clinical studies.

Human Chorionic Membrane-derived Tunable Hydrogels for Vascular Tissue Engineering Strategies

One of the foremost targets in the advancement of biomaterials to engineer vascularized tissues is not only to replicate the composition of the intended tissue but also to create thicker structures incorporating a vascular network for adequate nutrients and oxygen supply. For the first time, to the best of current knowledge, a clinically relevant biomaterial is developed, demonstrating that hydrogels made from the human decellularized extracellular matrix can exhibit robust mechanical properties (in the kPa range) and angiogenic capabilities simultaneously. These properties enable the culture and organization of human umbilical vein endothelial cells into tubular structures, maintaining their integrity for 14 days in vitro without the need for additional polymers or angiogenesis-related factors. This is achieved by repurposing the placenta chorionic membrane (CM), a medical waste with an exceptional biochemical composition, into a valuable resource for bioengineering purposes. After decellularization, the CM underwent chemical modification with methacryloyl groups, giving rise to methacrylated CM (CMMA). CMMA preserved key proteins, as well as glycosaminoglycans. The resulting hydrogels rapidly photopolymerize and have enhanced strength and customizable mechanical properties. Furthermore, they demonstrate angio-vasculogenic competence in vitro and in vivo, holding significant promise as a humanized platform for the engineering of vascularized tissues.

Development and Biocompatibility Assessment of Decellularized Porcine Uterine Extracellular Matrix-Derived Grafts

Biomaterials derived from biological matrices have been widely investigated due to their great therapeutic potential in regenerative medicine, since they are able to induce cell proliferation, tissue remodeling, and angiogenesis in situ. In this context, highly vascularized and proliferative tissues, such as the uterine wall, present an interesting source to produce acellular matrices that can be used as bioactive materials to induce tissue regeneration. Therefore, this study aimed to establish an optimized protocol to generate decellularized uterine scaffolds (dUT), characterizing their structural, compositional, and biomechanical properties. In addition, in vitro performance and in vivo biocompatibility were also evaluated to verify their potential applications for tissue repair. Results showed that the protocol was efficient to promote cell removal, and dUT general structure and extracellular matrix composition remained preserved compared with native tissue. In addition, the scaffolds were cytocompatible, allowing cell growth and survival. In terms of biocompatibility, the matrices did not induce any signs of immune rejection in vivo in a model of subcutaneous implantation in immunocompetent rats, demonstrating an indication of tissue integration after 30 days of implantation. In summary, these findings suggest that dUT scaffolds could be explored as a biomaterial for regenerative purposes, which is beyond the studies in the reproductive field.

Harnessing Macromolecular Chemistry to Design Hydrogel Micro- and Macro-Environments

Cell encapsulation within three-dimensional hydrogels is a promising approach to mimic tissues. However, true biomimicry of the intricate microenvironment, biophysical and biochemical gradients, and the macroscale hierarchical spatial organizations of native tissues is an unmet challenge within tissue engineering. This review provides an overview of the macromolecular chemistries that have been applied toward the design of cell-friendly hydrogels, as well as their application toward controlling biophysical and biochemical bulk and gradient properties of the microenvironment. Furthermore, biofabrication technologies provide the opportunity to simultaneously replicate macroscale features of native tissues. Biofabrication strategies are reviewed in detail with a particular focus on the compatibility of these strategies with the current macromolecular toolkit described for hydrogel design and the challenges associated with their clinical translation. This review identifies that the convergence of the ever-expanding macromolecular toolkit and technological advancements within the field of biofabrication, along with an improved biological understanding, represents a promising strategy toward the successful tissue regeneration.

Biological study of skin wound treated with Alginate/Carboxymethyl cellulose/chorion membrane, diopside nanoparticles, and Botox A

A hydrogel-based wound dressing with desirable properties is necessary for achieving functional skin integrity post-injury. This study focuses on preparing a hydrogel using Alginate/Carboxymethyl cellulose (Alg/CMC) as a base material. To evaluate its regenerative effects on full-thickness wounds, diopside nanoparticles and Botulinum toxin A (BTX-A) were incorporated into the hydrogel along with chorion membrane. The diopside nanoparticles (DNPs) act as a proangiogenic factor, promoting proliferation and regulating inflammation, while the chorion membrane facilitates these processes. Additionally, BTX-A prevents scar formation and aids in wound closure. The nanoparticles and hydrogel were characterized using various techniques, and their cytocompatibility was assessed. In vivo studies and quantitative polymerase chain reaction analysis showed that wound area reduction was significant after two weeks of treatment with the Alg/CMC/ChNPs/DNPs/BTX-A hydrogel. Overall, this scaffold demonstrated potential for promoting tissue regeneration and new epithelization formation, making it a promising candidate for enhancing skin restoration in wound treatments.

Diaphragmatic hernia repair porcine model to compare the performance of biodegradable membranes against Gore-Tex®

BACKGROUND

Patch repair of congenital diaphragmatic hernia (CDH) using Gore-Tex® is associated with infection, adhesions, hernia recurrence, long-term musculoskeletal sequels and poor tissue regeneration. To overcome these limitations, the performance of two novel biodegradable membranes was tested to repair CDH in a growing pig model.

METHODS

Twelve male pigs were randomly assigned to 3 different groups of 4 animals each, determined by the type of patch used during thoracoscopic diaphragmatic hernia repair (Gore-Tex®, polycaprolactone electrospun membrane-PCLem, and decellularized human chorion membrane-dHCM). After 7 weeks, all animals were euthanized, followed by necropsy for diaphragmatic evaluation and histological analysis.

RESULTS

Thoracoscopic defect creation and diaphragmatic repair were performed without any technical difficulty in all groups. However, hernia recurrence rate was 0% in Gore-Tex®, 50% in PCLem and 100% in dHCM groups. At euthanasia, Gore-Tex® patches appeared virtually unchanged and covered with a fibrotic capsule, while PCLem and dHCM patches were replaced by either floppy connective tissue or vascularized and floppy regenerated membranous tissue, respectively.

CONCLUSION

Gore-Tex® was associated with a higher survival rate and lower recurrence. Nevertheless, the proposed biodegradable membranes were associated with better tissue integration when compared with Gore-Tex®.

Retention of Key Characteristics of Unprocessed Chorion Tissue Resulting in a Robust Scaffold to Support Wound Healing

Placental membranes have been widely studied and used clinically for wound care applications, but there is limited published information on the benefits of using the chorion membrane. The chorion membrane represents a promising source of placental-derived tissue to support wound healing, with its native composition of extracellular matrix (ECM) proteins and key regulatory proteins. This study examined the impact of hypothermic storage on the structure of chorion membrane, ECM content, and response to degradation in vitro. Hypothermically stored chorion membrane (HSCM) was further characterized for its proteomic content, and for its functionality as a scaffold for cell attachment and proliferation in vitro. HSCM retained the native ECM structure, composition, and integrity of native unprocessed chorion membrane and showed no differences in response to degradation in an in vitro wound model. HSCM retained key regulatory proteins previously shown to be present in placental membranes and promoted the attachment and proliferation of fibroblasts in vitro. These data support the fact that hypothermic storage does not significantly impact the structure and characteristics of the chorion membrane compared to unprocessed tissue or its functionality as a scaffold to support tissue growth.

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

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

Recent advances in decellularized biomaterials for wound healing

The skin is one of the most essential organs in the human body, interacting with the external environment and shielding the body from diseases and excessive water loss. Thus, the loss of the integrity of large portions of the skin due to injury and illness may lead to significant disabilities and even death. Decellularized biomaterials derived from the extracellular matrix of tissues and organs are natural biomaterials with large quantities of bioactive macromolecules and peptides, which possess excellent physical structures and sophisticated biomolecules, and thus, promote wound healing and skin regeneration. Here, we highlighted the applications of decellularized materials in wound repair. First, the wound-healing process was reviewed. Second, we elucidated the mechanisms of several extracellular matrix constitutes in facilitating wound healing. Third, the major categories of decellularized materials in the treatment of cutaneous wounds in numerous preclinical models and over decades of clinical practice were elaborated. Finally, we discussed the current hurdles in the field and anticipated the future challenges and novel avenues for research on decellularized biomaterials-based wound treatment.

Human amniotic membrane as a multifunctional biomaterial: recent advances and applications

The developing fetus is wrapped by a human amniotic membrane or amnion. Amnion is a promising human tissue allograft in clinical application because of its chemical composition, collagen-based, and mechanical properties of the extracellular matrix. In addition, amnion contains cells and growth factors; therefore, meets the essential parameters of tissue engineering. No donor morbidity, easy processing and storage, fewer ethical issue, anti-inflammatory, antioxidant, antibacterial, and non-immunogenic properties are other advantages of amnion usage. For these reasons, amnion can resolve some bottlenecks in the regenerative medicine issues such as tissue engineering and cell therapy. Over the last decades, biomedical applications of amnion have evolved from a simple sheet for skin or cornea repair to high-technology applications such as amnion nanocomposite, powder, or hydrogel for the regeneration of cartilage, muscle, tendon, and heart. Furthermore, amnion has anticancer as well as drug/cell delivery capacity. This review highlights various ancient and new applications of amnion in research and clinical applications, from regenerative medicine to cancer therapy, focusing on articles published during the last decade that also revealed information regarding amnion-based products. Challenges and future perspectives of the amnion in regenerative medicine are also discussed.

Facile and versatile strategy for fabrication of highly bacteriostatic and biocompatible SLA-Ti surfaces with the regulation of Mg/Cu coimplantation ratio for dental implant applications

The low bactericidal activity and poor osteogenic activity of Ti limit the use of this metal in dental implants by increasing the risk of their periimplantitis-induced failure. To address this problem, we herein surface-modify biomedical Ti through the plasma immersion coimplantation of Mg and Cu ions and examine the physicochemical properties and bio-/hemocompatibility of the resulting materials as well as their activity against periimplantitis-causing bacteria, namely Streptococcus mutans and Porphyromonas gingivalis. The reactive oxygen species release (ROS) was assessed via the 2'7'-dichlorodihydrofluorescein diacetate (DCFH-DA) assay. The best-performing sample Mg/Cu（8/10）-Ti promotes cell proliferation and initial cell adhesion while exhibiting high hydrophilicity, outstanding activity against the aforementioned pathogens, and good bio-/hemocompatibility. Additionally, higher levels of cellular ROS generation in S. mutans and P. gingivalis could provide insight into the antibacterial mechanisms involved in Mg/Cu（8/10）-Ti. Thus, Mg/Cu coimplantation is concluded to endow the Ti surface with high bacteriostatic activity and biocompatibility, paving the way to the widespread use of Ti-based dental implants.

Modulation of Macrophage Function by Bioactive Wound Dressings with an Emphasis on Extracellular Matrix-Based Scaffolds and Nanofibrous Composites

Bioactive wound dressings that are capable of regulating the local wound microenvironment have attracted a very large interest in the field of regenerative medicine. Macrophages have many critical roles in normal wound healing, and the dysfunction of macrophages significantly contributes to impaired or non-healing skin wounds. Regulation of macrophage polarization towards an M2 phenotype provides a feasible strategy to enhance chronic wound healing, mainly by promoting the transition of chronic inflammation to the proliferation phase of wound healing, upregulating the level of anti-inflammatory cytokines around the wound area, and stimulating wound angiogenesis and re-epithelialization. Based on this, modulation of macrophage functions by the rational design of bioactive scaffolds has emerged as a promising way to accelerate delayed wound healing. This review outlines current strategies to regulate the response of macrophages using bioactive materials, with an emphasis on extracellular matrix-based scaffolds and nanofibrous composites.

A Bioink Derived From Human Placenta Supporting Angiogenesis

Bioprinting is an emerging approach for constructing sophisticated tissue analogues with detailed architectures such as vascular networks, which requires bioink fulfill the highly printable property and provide a cell-friendly microenvironment mimicking native extracellular matrix (ECM). Here, we developed a human placental ECM-derived bioink (hp-bioink) meeting the requirements of 3D printing for printability and bioactivity. We first decellularized the human placenta, followed by enzymatic digestion, dialysis, lyophilization, and re-solubilization to convert the extracts into hp-bioink. Then, we demonstrated that 3%-5% of hp-bioink can be printed with self-standing and 1%-2% of hp-bioink can be embedded with suspended hydrogels. Moreover, hp-bioink supports HUVEC assembly in vitro and angiogenesis in mice in vivo. Our research enriched the bank of human-derived bioink, and provided a new opportunity to further accelerate bioprinting research and application.

Decellularization of Wharton’s Jelly Increases Its Bioactivity and Antibacterial Properties

The field of regenerative medicine has recently seen an emerging trend toward decellularized extracellular matrix (ECM) as a biological scaffold for stem cell-delivery. Human umbilical cord represents a valuable opportunity from both technical and ethical point of view to obtain allogenic ECM. Herein, we established a protocol, allowing the full removal of cell membranes and nuclei moieties from Wharton’s jelly (WJ) tissue. No alterations in the ECM components (i.e., collagen, GAG content, and growth factors), physical (i.e., porosity and swelling) and mechanical (i.e., linear tensile modulus) properties were noticed following WJ processing. Furthermore, no effect of the tissue processing on macromolecules and growth factors retention was observed, assuring thus a suitable bioactive matrix for cell maintenance upon recellularization. Based on the in vitro and in vivo biodegradability and stromal cell homing capabilities, decellularized WJ could provide an ideal substrate for stromal cells adhesion and colonization. Interestingly, the tissue processing increased the antibacterial and antiadhesive properties of WJ against Staphylococcus aureus and Staphylococcus epidermidis pathogens. Altogether, our results indicate that decellularized WJ matrix is able to limit Staphylococcus-related infections and to promote stromal cell homing, thus offering a versatile scaffold for tissue regenerative medicine.

Bioinks Enriched with ECM Components Obtained by Supercritical Extraction

Extracellular matrix (ECM)-based bioinks have been steadily gaining interest in the field of bioprinting to develop biologically relevant and functional tissue constructs. Herein, we propose the use of supercritical carbon dioxide (scCO₂) technology to extract the ECM components of cell-sheets that have shown promising results in creating accurate 3D microenvironments replicating the cell’s own ECM, to be used in the preparation of bioinks. The ECM extraction protocol best fitted for cell sheets was defined by considering efficient DNA removal with a minor effect on the ECM. Cell sheets of human dermal fibroblasts (hDFbs) and adipose stem cells (hASCs) were processed using a customised supercritical system by varying the pressure of the reactor, presence, exposure time, and type of co-solvent. A quantification of the amount of DNA, protein, and sulfated glycosaminoglycans (sGAGs) was carried out to determine the efficiency of the extraction in relation to standard decellularization methodologies. The bioinks containing the extracted ECM were fabricated by combining them with alginate as a support polymer. The influence of the alginate (1%, 2% w/vol) and ECM (0.5% and 1.5% w/vol) amounts on the printability of the blends was addressed by analysing the rheological behaviour of the suspensions. Finally, 3D printed constructs were fabricated using an in-house built extrusion-based bioprinter, and the impact of the extrusion process on cell viability was assessed. The optimised scCO₂ protocol allowed efficient removal of DNA while preserving a higher number of proteins and sGAGs than the standard methodologies. The characterization of extract’s composition also revealed that the ECM produced by hDFbs (fECM) and hASCs (aECM) is distinctively affected by the extraction protocols. Furthermore, rheological analysis indicated an increase in viscosity with increasing ECM composition, an effect even more prominent in samples containing aECM. 3D printing of alginate/ECM constructs demonstrated that cell viability was only marginally affected by the extrusion process, and this effect was also dependent on the ECM source. Overall, this work highlights the benefits of supercritical fluid-based methods for ECM extraction and strengthens the relevance of ECM-derived bioinks in the development of printed tissue-like constructs.

Chorion-derived extracellular matrix hydrogel and fibronectin surface coatings show similar beneficial effects on endothelialization of expanded polytetrafluorethylene vascular grafts

The endothelium plays an important regulatory role for cardiovascular homeostasis. Rapid endothelialization of small diameter vascular grafts (SDVGs) is crucial to ensure long-term patency. Here, we assessed a human placental chorionic extracellular matrix hydrogel (hpcECM-gel) as coating material and compared it to human fibronectin in-vitro. hpcECM-gels were produced from placental chorion by decellularization and enzymatic digestion. Human umbilical vein endothelial cells (HUVECs) were seeded to non-, fibronectin- or hpcECM-gel-coated expanded polytetrafluorethylene (ePTFE) SDVGs. Coating efficiency as well as endothelial cell proliferation, migration and adhesion studies on grafts were performed. hpcECM-gel depicted high collagen and glycosaminoglycan content and neglectable DNA amounts. Laminin and fibronectin were both retained in the hpcECM-gel after the decellularization process. HUVEC as well as endothelial progenitor cell attachment were both significantly enhanced on hpcECM-gel coated grafts. HUVECs seeded to hpcECM-gel depicted significantly higher platelet endothelial cell adhesion molecule-1 (PECAM-1) expression in the perinuclear region. Cell retention to flow was enhanced on fibronectin and hpcECM-gel coated grafts. Since hpcECM-gel induced a significantly higher endothelial cell adhesion to ePTFE than fibronectin, it represents a possible alternative for SDVG modification to improve endothelialization.

Fabrication of Decellularized Amnion and Chorion Scaffolds to Develop Bioengineered Cell-Laden Constructs

INTRODUCTION

Human mesenchymal stem cells (hMSCs) holds great promise for managing several clinical conditions. However, the low engraftment efficiency and obscurity to harvest these cells without compromising the cellular viability, structural and functional properties from the culture niche still remain major obstacles for preparing intact regenerative constructs. Although few studies have demonstrate different methods for generating cell-liberated amniotic scaffolds, a common method for producing completely cell-liberated amnion (D-HAM) and chorion (D-HCM) scaffolds and their cytocompatibility with hMSCs yet to be demonstrated.

METHODS

A common process was developed for preparing D-HAM and D-HCM scaffolds for assessing hMSCs engraftment efficiency, proliferation and molecular shifts to generate cell-laden biological discs. The structural and functional integrity of D-HAM and D-HCM was evaluated using different parameters. The compatibility and proliferation efficiency of hMSCs with D-HAM and D-HCM was evaluated.

RESULTS

Histological analysis revealed completely nucleic acid-free D-HAM and D-HCM scaffolds with intact extracellular matrix, mechanical and biological properties almost similar to the native membranes. Human MSCs were able to adhere and engraft on D-HCM better than D-HAM and expanded faster. Ultrastructural observations, crystal violet staining and expression studies showed better structural and functional integrity of hMSCs on D-HCM than D-HAM and control conditions.

CONCLUSION

A common, simple and reliable process of decellularization can generate large number of cell-liberated amniotic scaffolds in lesser time. D-HCM has better efficiency for hMSCs engraftment and proliferation and can be utilized for preparing suitable cell-laden constructs for tissue engineering applications.

Developing a pro-angiogenic placenta derived amniochorionic scaffold with two exposed basement membranes as substrates for cultivating endothelial cells

Decellularized and de-epithelialized placenta membranes have widely been used as scaffolds and grafts in tissue engineering and regenerative medicine. Exceptional pro-angiogenic and biomechanical properties and low immunogenicity have made the amniochorionic membrane a unique substrate which provides an enriched niche for cellular growth. Herein, an optimized combination of enzymatic solutions (based on streptokinase) with mechanical scrapping is used to remove the amniotic epithelium and chorion trophoblastic layer, which resulted in exposing the basement membranes of both sides without their separation and subsequent damages to the in-between spongy layer. Biomechanical and biodegradability properties, endothelial proliferation capacity, and in vivo pro-angiogenic capabilities of the substrate were also evaluated. Histological staining, immunohistochemistry (IHC) staining for collagen IV, and scanning electron microscope demonstrated that the underlying amniotic and chorionic basement membranes remained intact while the epithelial and trophoblastic layers were entirely removed without considerable damage to basement membranes. The biomechanical evaluation showed that the scaffold is suturable. Proliferation assay, real-time polymerase chain reaction for endothelial adhesion molecules, and IHC demonstrated that both side basement membranes could support the growth of endothelial cells without altering endothelial characteristics. The dorsal skinfold chamber animal model indicated that both side basement membranes could promote angiogenesis. This bi-sided substrate with two exposed surfaces for cultivating various cells would have potential applications in the skin, cardiac, vascularized composite allografts, and microvascular tissue engineering.

Membranous Extracellular Matrix-Based Scaffolds for Skin Wound Healing

Membranous extracellular matrix (ECM)-based scaffolds are one of the most promising biomaterials for skin wound healing, some of which, such as acellular dermal matrix, small intestinal submucosa, and amniotic membrane, have been clinically applied to treat chronic wounds with acceptable outcomes. Nevertheless, the wide clinical applications are always hindered by the poor mechanical properties, the uncontrollable degradation, and other factors after implantation. To highlight the feasible strategies to overcome the limitations, in this review, we first outline the current clinical use of traditional membranous ECM scaffolds for skin wound healing and briefly introduce the possible repair mechanisms; then, we discuss their potential limitations and further summarize recent advances in the scaffold modification and fabrication technologies that have been applied to engineer new ECM-based membranes. With the development of scaffold modification approaches, nanotechnology and material manufacturing techniques, various types of advanced ECM-based membranes have been reported in the literature. Importantly, they possess much better properties for skin wound healing, and would become promising candidates for future clinical translation.

Cardiac transplantation for cardiomyopathy with constrictive pericarditis

Constrictive pericarditis is a great mimic and has posed a diagnostic dilemma since its first description 300 years ago as "Concretio Cordis." It can mimic restrictive cardiomyopathy, endomyocardial fibrosis, and chronic liver and renal disease. This would perhaps be the first clinical report of constriction in patients undergoing cardiac transplantation. We report two distinct cases with cardiomyopathy requiring cardiac transplantation and the clinical implications of concomitant pericardial constriction. While the first case mimics a natural "cardiac support device," which addresses ventricular remodeling in heart failure by reducing the wall stress, the second case is a case in point against the use of "biological pericardial membrane-like the bovine pericardium," as a pericardial substitute.

New Vascular Graft Using the Decellularized Human Chorion Membrane

The increase of both arterial occlusive diseases and coronary heart diseases leads to a higher demand for small-diameter vascular grafts (<6 mm). The gold standard for small-diameter vessel replacement is the use of autologous veins. Nevertheless, up to 30% of these patients need to use vascular grafts. Although synthetic polymers have been successfully used for the replacement of large-diameter vascular grafts (>6 mm), they are associated with thrombosis, intimal hyperplasia, calcification, and chronic inflammation when used as small-diameter vascular grafts. Therefore, natural materials have been studied for this application. In this study, a decellularized human chorion membrane (dHCM) vascular graft with a 3-4 mm diameter was created. Herein, the biocompatibility of dHCM with endothelial cells was demonstrated in vitro and ex ovo. Blood biocompatibility of dHCM was also shown by studying plasma protein adsorption, platelet adhesion and activation, and its hemolytic potential. Furthermore, dHCM antibacterial properties against Staphylococcus aureus were also studied. In summary, the dHCM reticular layer side presented all the needed characteristics to be used in the inner side of a vascular graft. Additionally, the mechanical properties of the dHCM tubular construct were studied, being similar to the ones of the saphenous vein, the gold standard for autologous small-diameter vessel replacement.