Applications of the amniotic membrane in tissue engineering and regeneration: the hundred-year challenge

Comparative analysis of aligned and random amniotic membrane-derived cryogels for neural tissue repair

The ordered arrangement of cells and extracellular matrix facilitates the seamless transmission of electrical signals along axons in the spinal cord and peripheral nerves. Therefore, restoring tissue geometry is crucial for neural regeneration. This study presents a novel method using proteins derived from the human amniotic membrane, which is modified with photoresponsive groups, to produce cryogels with aligned porosity. Freeze-casting was used to produce cryogels with longitudinally aligned pores, while cryogels with randomly distributed porosity were used as the control. The cryogels exhibited remarkable injectability and shape-recovery properties, essential for minimally invasive applications. Different tendencies in proliferation and differentiation were evident between aligned and random cryogels, underscoring the significance of the scaffold's microstructure in directing the behaviour of neural stem cells (NSC). Remarkably, aligned cryogels facilitated extensive cellular infiltration and migration, contrasting with NSC cultured on isotropic cryogels, which predominantly remained on the scaffold's surface throughout the proliferation experiment. Significantly, the proliferation assay demonstrated that on day 7, the aligned cryogels contained eight times more cells compared to the random cryogels. Consistent with the proliferation experiments, NSC exhibited the ability to differentiate into neurons within the aligned scaffolds and extend neurites longitudinally. In addition, differentiation assays showed a four-fold increase in the expression of neural markers in the cross-sections of the aligned cryogels. Conversely, the random cryogels exhibited minimal presence of cell bodies and extensions. The presence of synaptic vesicles on the anisotropic cryogels indicates the formation of functional synaptic connections, emphasizing the importance of the scaffold's microstructure in guiding neuronal reconnection.

The landscape of clinical trials in corneal regeneration: A systematic review of tissue engineering approaches in corneal disease

The limited availability of a healthy donor cornea and the incidence of allograft failure led researchers to seek other corneal substitutes via tissue engineering. Exploring the trend of clinical trials of the cornea with the vision of tissue engineering provides an opportunity to reveal future potential corneal substitutes. The results of this clinical trial are beneficial for future study designs to overcome the limitations of current therapeutic approaches. In this study, registered clinical trials of bio-based approaches were reviewed for corneal regeneration on March 22, 2024. Among the 3955 registered trials for the cornea, 392 trials were included in this study, which categorized in three main bio-based scaffolds, stem cells, and bioactive macromolecules. In addition to the acellular cornea and human amniotic membrane, several bio-based materials have been introduced as corneal substrates such as collagen, fibrin, and agarose. However, some synthetic materials have been introduced in recent studies to improve the desired properties of bio-based scaffolds for corneal substitutes. Nevertheless, new insights into corneal regenerative medicine have recently emerged from cell sheets with autologous and allogeneic cell sources. In addition, the future perspective of corneal regeneration is described through a literature review of recent experimental models.

The Categorization of Perinatal Derivatives for Orthopedic Applications

Musculoskeletal (MSK) pathology encompasses an array of conditions that can cause anything from mild discomfort to permanent injury. Their prevalence and impact on disability have sparked interest in more effective treatments, particularly within orthopedics. As a result, the human placenta has come into focus within regenerative medicine as a perinatal derivative (PnD). These biologics are sourced from components of the placenta, each possessing a unique composition of collagens, proteins, and factors believed to aid in healing and regeneration. This review aims to explore the current literature on PnD biologics and their potential benefits for treating various MSK pathologies. We delve into different types of PnDs and their healing effects on muscles, tendons, bones, cartilage, ligaments, and nerves. Our discussions highlight the crucial role of immune modulation in the healing process for each condition. PnDs have been observed to influence the balance between anti- and pro-inflammatory factors and, in some cases, act as biologic scaffolds for tissue growth. Additionally, we assess the range of PnDs available, while also addressing gaps in our understanding, particularly regarding biologic processing methods. Although certain PnD biologics have varying levels of support in orthopedic literature, further clinical investigations are necessary to fully evaluate their impact on human patients.

Amniotic Membrane-Derived Multichannel Hydrogels for Neural Tissue Repair

In the pursuit of advancing neural tissue regeneration, biomaterial scaffolds have emerged as promising candidates, offering potential solutions for nerve disruptions. Among these scaffolds, multichannel hydrogels, characterized by meticulously designed micrometer-scale channels, stand out as instrumental tools for guiding axonal growth and facilitating cellular interactions. This study explores the innovative application of human amniotic membranes modified with methacryloyl domains (AMMA) in neural stem cell (NSC) culture. AMMA hydrogels, possessing a tailored softness resembling the physiological environment, are prepared in the format of multichannel scaffolds to simulate native-like microarchitecture of nerve tracts. Preliminary experiments on AMMA hydrogel films showcase their potential for neural applications, demonstrating robust adhesion, proliferation, and differentiation of NSCs without the need for additional coatings. Transitioning into the 3D realm, the multichannel architecture fosters intricate neuronal networks guiding neurite extension longitudinally. Furthermore, the presence of synaptic vesicles within the cellular arrays suggests the establishment of functional synaptic connections, underscoring the physiological relevance of the developed neuronal networks. This work contributes to the ongoing efforts to find ethical, clinically translatable, and functionally relevant approaches for regenerative neuroscience.

Silica nanoparticles enhance interfacial self-adherence of a multi-layered extracellular matrix scaffold for vascular tissue regeneration

PURPOSE

Based on the clinical need for grafts for vascular tissue regeneration, our group developed a customizable scaffold derived from the human amniotic membrane. Our approach consists of rolling the decellularized amniotic membrane around a mandrel to form a multilayered tubular scaffold with tunable diameter and wall thickness. Herein, we aimed to investigate if silica nanoparticles (SiNP) could enhance the adhesion of the amnion layers within these rolled grafts.

METHODS

To test this, we assessed the structural integrity and mechanical properties of SiNP-treated scaffolds. Mechanical tests were repeated after six months to evaluate adhesion stability in aqueous environments.

RESULTS

Our results showed that the rolled SiNP-treated scaffolds maintained their tubular shape upon hydration, while non-treated scaffolds collapsed. By scanning electron microscopy, SiNP-treated scaffolds presented more densely packed layers than untreated controls. Mechanical analysis showed that SiNP treatment increased the scaffold's tensile strength up to tenfold in relation to non-treated controls and changed the mechanism of failure from interfacial slipping to single-point fracture. The nanoparticles reinforced the scaffolds both at the interface between two distinct layers and within each layer of the extracellular matrix. Finally, SiNP-treated scaffolds significantly increased the suture pullout force in comparison to untreated controls.

CONCLUSION

Our study demonstrated that SiNP prevents the unraveling of a multilayered extracellular matrix graft while improving the scaffolds' overall mechanical properties. In addition to the generation of a robust biomaterial for vascular tissue regeneration, this novel layering technology is a promising strategy for a number of bioengineering applications.

A hybrid construct of decellularized matrix and fibrin for differentiating adipose stem cells into insulin-producing cells, an optimized in vitro assessment

The generation of insulin-producing cells (IPCs) is an attractive approach for replacing damaged β cells in diabetic patients. In the present work, we introduced a hybrid platform of decellularized amniotic membrane (dAM) and fibrin encapsulation for differentiating adipose tissue-derived stem cells (ASCs) into IPCs. ASCs were isolated from healthy donors and characterized. Human AM was decellularized, and its morphology, DNA, collagen, glycosaminoglycan (GAG) contents, and biocompatibility were evaluated. ASCs were subjected to four IPC differentiation methods, and the most efficient method was selected for the experiment. ASCs were seeded onto dAM, alone or encapsulated in fibrin gel with various thrombin concentrations, and differentiated into IPCs according to a method applying serum-free media containing 2-mercaptoethanol, nicotinamide, and exendin-4. PDX-1, GLUT-2 and insulin expression were evaluated in differentiated cells using real-time PCR. Structural integrity and collagen and GAG contents of AM were preserved after decellularization, while DNA content was minimized. Cultivating ASCs on dAM augmented their attachment, proliferation, and viability and enhanced the expression of PDX-1, GLUT-2, and insulin in differentiated cells. Encapsulating ASCs in fibrin gel containing 2 mg/ml fibrinogen and 10 units/ml thrombin increased their differentiation into IPCs. dAM and fibrin gel synergistically enhanced the differentiation of ASCs into IPCs, which could be considered an appropriate strategy for replacing damaged β cells.

Neurotrophic keratopathy: General features and new therapies

Neurotrophic keratopathy is an uncommon degenerative corneal disorder characterized by compromised corneal sensory innervation resulting in the formation of epithelial defects and nonhealing corneal ulcers. Various treatment modalities are available to stabilize disease progression, improve patient well-being, and prevent vision loss. For eligible patients, medical and surgical reinnervation have emerged as pioneering therapies, holding promise for better management. We present a comprehensive review of the disorder, providing an update relevant to ophthalmologists on pathogenesis, diagnosis, treatment options, and novel therapies targeting pathophysiological pathways.

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.

Effect of amniotic membrane/collagen scaffolds on laryngeal cartilage repair

Objectives

Laryngeal cartilage defects are a major problem that greatly impacts structural integrity and function. Cartilage repair is also a challenging issue. This study evaluated the efficacy of a collagen scaffold enveloped by amniotic membrane (AM/C) on laryngeal cartilage repair.

Study Design

Experimental animal study.

Methods

Fourteen Dutch rabbits were enrolled in the study. A 5 mm cartilage defect was created in the right and left thyroid lamina. The animals were divided into two groups randomly. Group 1 collagen scaffolds and group 2 AM/C were applied to the right side defects. Left side defects were not repaired, serving as control. Histologic evaluation was done 45 and 90 days following collagen and AM/C application with criteria of tissue and cell morphology, lacuna formation, vascularization, and inflammation.

Results

Significant improvement in cartilage repair was observed in the AM/C side compared to the control side in all histologic criteria after 45 days (p<.05). After 90 days, cartilage repair improved in cell morphology, lacuna formation, and inflammation significantly (p<.05).

Conclusion

The combination of amniotic membrane and collagen scaffolds provides a promising treatment modality for improving the repair of laryngeal cartilage defects.

Level of Evidence

NA.

Using biomaterials to improve mesenchymal stem cell therapies for chronic, nonhealing wounds

Historically, treatment of chronic, nonhealing wounds has focused on managing symptoms using biomaterial-based wound dressings, which do not adequately address the underlying clinical issue. Mesenchymal stem cells (MSCs) are a promising cell-based therapy for the treatment of chronic, nonhealing wounds, yet inherent cellular heterogeneity and susceptibility to death during injection limit their clinical use. Recently, researchers have begun to explore the synergistic effects of combined MSC-biomaterial therapies, where the biomaterial serves as a scaffold to protect the MSCs and provides physiologically relevant physicochemical cues that can direct MSC immunomodulatory behavior. In this review, we highlight recent progress in this field with a focus on the most commonly used biomaterials, classified based on their source, including natural biomaterials, synthetic biomaterials, and the combination of natural and synthetic biomaterials. We also discuss current challenges regarding the clinical translation of these therapies, as well as a perspective on the future outlook of the field.

Inter-placental variability is not a major factor affecting the healing efficiency of amniotic membrane when used for treating chronic non-healing wounds

This study aimed to evaluate the efficacy of cryopreserved amniotic membrane (AM) grafts in chronic wound healing, including the mean percentage of wound closure per one AM application, and to determine whether the healing efficiency differs between AM grafts obtained from different placentas. A retrospective study analyzing inter-placental differences in healing capacity and mean wound closure after the application of 96 AM grafts prepared from nine placentas. Only the placentas from which the AM grafts were applied to patients suffering from long-lasting non-healing wounds successfully healed by AM treatment were included. The data from the rapidly progressing wound-closure phase (p-phase) were analyzed. The mean efficiency for each placenta, expressed as an average of wound area reduction (%) seven days after the AM application (baseline, 100%), was calculated from at least 10 applications. No statistical difference between the nine placentas' efficiency was found in the progressive phase of wound healing. The 7-day average wound reduction in particular placentas varied from 5.70 to 20.99% (median from 1.07 to 17.75) of the baseline. The mean percentage of wound surface reduction of all analyzed defects one week after the application of cryopreserved AM graft was 12.17 ± 20.12% (average ± SD). No significant difference in healing capacity was observed between the nine placentas. The data suggest that if there are intra- and inter-placental differences in AM sheets' healing efficacy, they are overridden by the actual health status of the subject or even the status of its individual wounds.

Human Amniotic Membrane for Dural Repair and Duraplasty: A Systematic Review of Safety and Efficacy

The use of human amniotic membrane (HAM) has recently gained attention as a promising alternative option for duraplasty due to its superior tensile strength, elasticity, and anti-inflammatory and anti-fibrotic properties, offering greater durability and reliability compared to autologous grafts like the muscle fascia and pericranium. This systematic review aimed to evaluate the complications associated with duraplasty using HAM. We comprehensively searched the PubMed, Scopus, and Web of Science databases for studies on duraplasty with HAM. The eligibility criteria included studies on patients who underwent dural repair with duraplasty using HAM, with or without a control group. Duraplasty involves opening the dura mater, the protective covering of the brain and spinal cord, and using a graft to enlarge the space around the cerebellum. Dual repair, on the other hand, involves repairing the dura mater without opening it and then using a patch to enlarge the space around the cerebellum. Randomized controlled trials, observational studies, case series, and case reports were included, and quality assessment was conducted. Our search yielded 191 articles. Ten studies were included, with a total of 560 participants. The overall incidence of cerebrospinal fluid (CSF) leakage was three (0.63%) out of 478 in the HAM group and three (4.76%) out of 63 in the other methods group (pericranium, temporalis fascia, and biological dural substitutes). Regarding the incidence of postoperative complications, the overall incidence was eight (1.92%) out of 417 in the HAM group and two (8%) out of 25 in the other methods group. The overall incidence of meningitis was one (0.67%) out of 150 in the HAM group and three (10%) out of 30 in the other methods group. In conclusion, duraplasty using HAM may be a safe and effective alternative to traditional methods, with a low incidence of CSF leakage and postoperative complications.

Multilayer amnion-PCL nanofibrous membrane loaded with celecoxib exerts a therapeutic effect against tendon adhesion by improving the inflammatory microenvironment

Tendon adhesion is a common complication after tendon surgery. The inflammatory phase of tendon healing is characterized by the release of a large number of inflammatory factors, whose mediated excessive inflammatory response is an important cause of tendon adhesion formation. Nonsteroidal anti-inflammatory drugs(NSAIDs) were used to prevent tendon adhesions by reducing the inflammatory response. However, recent studies have shown that the NSAIDs partially impairs tendon healing. Therefore, optimizing the anti-adhesive membrane loaded with NSAIDs to mitigate the effects on tendon healing requires further in-depth study. Amniotic membranes(AM) are natural polymeric semi-permeable membranes from living organisms that are rich in matrix, growth factors, and other active ingredients. In this study, we used electrostatic spinning technology to construct multifunctional nanofiber membranes of the PCL membrane loaded with celecoxib and AM. In vitro cellular assays revealed that celecoxib-loaded PCL membranes significantly inhibited the adhesion and proliferation of fibroblasts with increasing concentrations of celecoxib. In a rabbit tendon repair model, biomechanical tests further confirmed that the PCL membrane loaded with celecoxib had better anti-adhesion effects. Further experimental studies revealed that the PCL/AM membrane improved the inflammatory microenvironment by downregulating the expression of pro-inflammatory factors such as COX-2, IL-1β, and TNF-α proteins; and inhibiting the synthesis of COL I and COL Ⅲ. The PCL/AM membrane can continuously release celecoxib to reduce the inflammatory response and deliver growth factors to the damaged area to build a suitable microenvironment for tendon repair, which provides a new direction to improve the repair efficiency of tendon.

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.

Biological importance of human amniotic membrane in tissue engineering and regenerative medicine

The human amniotic membrane (hAM) is the innermost layer of the placenta. Its distinctive structure and the biological and physical characteristics make it a highly biocompatible material in a variety of regenerative medicine applications. It also acts as a supply of bioactive factors and cells, which indicate the advantages over other tissues. In this review, we firstly discussed the biological properties of hAM-derived cells in vivo or in vitro, along with their stemness of markers, pointing out a promising source of stem cells for regenerative medicine. Then, we systematically summarized current knowledge on the collection, preparation, preservation, and decellularization of hAM, as well as their characteristics helping to improve the understanding of applications in tissue engineering. Finally, we highlighted the recent advances in which hAM has undergone additional modifications to achieve an adequate perspective of regenerative medicine applications. More investigations are required in utilizing appropriate modifications to enhance the therapeutic effectiveness of hAM in the future.

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.

Placental-Derived Biomaterials and Their Application to Wound Healing: A Review

Chronic wounds are associated with considerable patient morbidity and present a significant economic burden to the healthcare system. Often, chronic wounds are in a state of persistent inflammation and unable to progress to the next phase of wound healing. Placental-derived biomaterials are recognized for their biocompatibility, biodegradability, angiogenic, anti-inflammatory, antimicrobial, antifibrotic, immunomodulatory, and immune privileged properties. As such, placental-derived biomaterials have been used in wound management for more than a century. Placental-derived scaffolds are composed of extracellular matrix (ECM) that can mimic the native tissue, creating a reparative environment to promote ECM remodeling, cell migration, proliferation, and differentiation. Reliable evidence exists throughout the literature to support the safety and effectiveness of placental-derived biomaterials in wound healing. However, differences in source (i.e., anatomical regions of the placenta), preservation techniques, decellularization status, design, and clinical application have not been fully evaluated. This review provides an overview of wound healing and placental-derived biomaterials, summarizes the clinical results of placental-derived scaffolds in wound healing, and suggests directions for future work.

Contemporary Review: The Use of Human Placental Tissues in Foot and Ankle Surgery

The use of fetal tissues in regenerative medicine has long been a source of both promise and controversy. Since the turn of the century, their utilization has expanded because of antiinflammatory and analgesic properties, which have been theorized to act as an avenue for treating various orthopaedic conditions. With increased recognition and use, it is essential to understand the potential risks, efficacy, and long-term effects of these materials. Given the substantial body of literature published since 2015 (the date of the most recent review of fetal tissues in foot and ankle surgery), this manuscript provides an updated reference on the topic. Specifically, we evaluate the recent literature regarding the role of fetal tissues in wound healing, hallux rigidus, total ankle arthroplasty, osteochondral defects of the talus, Achilles tendinopathy, and plantar fasciitis.

Nanofibrous polycaprolactone/amniotic membrane facilitates peripheral nerve regeneration by promoting macrophage polarization and regulating inflammatory microenvironment

Appropriate levels of inflammation are an important part of functional repair of nerve damage. However, excessive inflammation can cause the continuous activation of immune inflammatory cells and degeneration of nerve cells. Regulating the temporal and spatial changes in M1/M2 macrophages can regulate the local inflammatory immune environment of the tissue to promote its transformation to a direction conducive to tissue repair.In the present study, a multi-layer multifunctional nanofiber composite membrane of polycaprolactone(PCL) and amniotic membrane (AM) was constructed using electrospinning. In vitro studies have shown that the PCL/AM composite promoted the axon growth of SH-SY5Y cells and induced their differentiation into neurons. The PCL/AM composite wrapped the nerve stump to form a microenvironment that was conducive to nerve regeneration, blocked the invasion of scar tissue, promoted the recruitment of macrophages and moderate polarization to M2, enhanced the expression of anti-inflammatory factors IL-10 and IL-13, inhibited the expression of pro-inflammatory factors IL-6 and TNF-α, and induced myelin sheath and axon regeneration. By releasing various bioactive substances to regulate the polarization of M2 macrophages and formation of anti-inflammatory factors, the PCL/AM composite can enhance axonal regeneration and improve nerve repair.

Early three-month report of amniotic bladder therapy in patients with interstitial cystitis/bladder pain syndrome

BACKGROUND

Interstitial cystitis/bladder pain syndrome (IC/BPS) is characterized by symptomatic frequency and urgency, as well as chronic pelvic pain. Disruption of the urothelial barrier is closely associated with IC/BPS. As amniotic membranes (AM) offer capabilities of wound healing in many other fields of medicine, likewise amniotic bladder therapy (ABT) may offer capability of urothelial healing in IC/BPS.

METHODS

Under general anesthesia, 10 consecutive IC/BPS patients received intra-detrusor injections of 100 mg micronized AM (Clarix Flo) diluted in 10 ml 0.9% preservative-free sodium chloride. Clinical evaluation and questionnaires (Interstitial Cystitis Symptom Index (ICSI), Interstitial Cystitis Problem Index (ICPI), Bladder Pain/ Interstitial Cystitis Symptom Score (BPIC-SS), Overactive Bladder Assessment Tool, and SF-12 Health Survey) were repeated at pre-op and 2, 4, 8 and 12 weeks post-op.

RESULTS

Ten females (47.4 ± 14.4 years) who had recalcitrant IC/BPS for 7.8 years (5.2-12.1 years) received injection of micronized AM uneventful in all cases. After treatment, voiding symptoms and bladder pain significantly improved from pre-injection to 3 months. BPIC-SS significantly decreased from 37.4 ± 0.70 at baseline to 12.2 ± 2.90 at 3 months (p < 0.001). This corresponded to a significant improvement in their overall physical and mental quality of life. No adverse events occurred related to micronized AM injections, such as UTIs or acute urinary retention.

CONCLUSION

ABT could be an innovative treatment option for IC/BPS patients in terms of improving clinical symptoms based on preliminary outcomes at 3 months. Further studies are warranted to confirm the usefulness of ABT in patients with IC/BPS and to determine the duration of the effect.

Preparation of human amniotic membrane for transplantation in different application areas

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

Human Mesenchymal Stromal Cells Derived from Perinatal Tissues: Sources, Characteristics and Isolation Methods

Mesenchymal stromal/stem cells (MSCs) derived from perinatal tissues have become indispensable sources for clinical applications due to their superior properties, ease of accessibility and minimal ethical concerns. MSCs isolated from different placenta (PL) and umbilical cord (UC) compartments exhibit great potential for stem cell-based therapies. However, their biological activities could vary due to tissue origins and differences in differentiation potentials. This review provides an overview of MSCs derived from various compartments of perinatal tissues, their characteristics and current isolation methods. Factors affecting the yield and purity of MSCs are also discussed as they are important to ensure consistent and unlimited supply for regenerative medicine and tissue engineering.

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.

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.

Developing small-diameter vascular grafts with human amniotic membrane: long-term evaluation of transplantation outcomes in a small animal model

While current clinical utilization of large vascular grafts for vascular transplantation is encouraging, tissue engineering of small grafts still faces numerous challenges. This study aims to investigate the feasibility of constructing a small vascular graft from decellularized amniotic membranes (DAMs). DAMs were rolled around a catheter and each of the resulting grafts was crosslinked with (a) 0.1% glutaraldehyde; (b) 1-ethyl-3-(3-dimethylaminopropyl) crbodiimidehydro-chloride (20 mM)-N-hydroxy-succinimide (10 mM); (c) 0.5% genipin; and (d) no-crosslinking, respectively. Our results demonstrated the feasibility of using a rolling technique followed by lyophilization to transform DAM into a vessel-like structure. The genipin-crosslinked DAM graft showed an improved integrated structure, prolonged stability, proper mechanical property, and superior biocompatibility. After transplantation in rat abdominal aorta, the genipin-crosslinked DAM graft remained patent up to 16 months, with both endothelial and smooth muscle cell regeneration, which suggests that the genipin-crosslinked DAM graft has great potential to beimplementedas a small tissue engineered graft for futurevasculartransplantation.

Dramatic improvement in the mechanical properties of polydopamine/polyacrylamide hydrogel mediated human amniotic membrane

Human amniotic membrane (hAM) is a promising material for tissue engineering due to several benefits, including desirable biocompatibility, stem cell source, antibacterial activity, etc. However, because of its low elasticity, the clinical application of hAM is severely restricted. To solve this issue, we employed polydopamine/polyacrylamide (PDA/PAM) hydrogels to toughen hAM. The test results indicated that the PDA/PAM hydrogel can enhance the toughness of hAM dramatically due to the formation of abundant chemical bonds and the strong mechanical properties of the hydrogel itself. Compared to pure hAM, the break elongation and tensile strength of PDA/PAM-toughened hAM rose by 154.15 and 492.31%, respectively. And most importantly, the fracture toughness was almost 15 times higher than untreated hAM. In addition, the cytotoxicity of the PDA/PAM-coated hAM was not detected due to the superior biocompatibility of the chemicals used in the study. Treating hAM with adhesive hydrogels to increase its mechanical characteristics will further promote the application of hAM as a tissue engineering material.

Effects of the Application of Decellularized Amniotic Membrane Solubilized with Hyaluronic Acid on Wound Healing

A perfect graft for wound care must be readily available without affecting the immune response, covering and protecting the wound bed. Considering previous studies have already established the use of hyaluronic acid (HA) for the treatment of wounds but the data presented on the amniotic membrane (AM) and its promising effects on healing still requires further investigation, this study aimed to evaluate the effects of the application of a decellularized amniotic membrane solubilized with hyaluronic acid on the healing process of cutaneous wounds on the 7th and 14th day, to evaluate the evolution of the wound and the inflammatory phases in these two times. Cutaneous lesions were excised from the dorsal region and 96 Wistar rats were divided into four groups: I-Excisional wound (EW); II-EW + AM; III-EW + HA; IV-EW + AM + HA. The present study demonstrated that the proposed combined therapy favors the tissue repair process of the epithelial lesion. Results showed a reduction in pro-inflammatory cytokines, an increase in anti-inflammatory cytokines, an increase in TGF-β, and attenuation of oxidative stress, reducing the acute inflammatory response and promoting the beginning of tissue repair. We concluded that the proposed therapies accelerated the inflammatory process with anticipation of the repair phase.

Perinatal derivatives application: Identifying possibilities for clinical use

Perinatal derivatives are drawing growing interest among the scientific community as an unrestricted source of multipotent stromal cells, stem cells, cellular soluble mediators, and biological matrices. They are useful for the treatment of diseases that currently have limited or no effective therapeutic options by means of developing regenerative approaches. In this paper, to generate a complete view of the state of the art, a comprehensive 10-years compilation of clinical-trial data with the common denominator of PnD usage has been discussed, including commercialized products. A set of criteria was delineated to challenge the 10-years compilation of clinical trials data. We focused our attention on several aspects including, but not limited to, treated disorders, minimal or substantial manipulation, route of administration, dosage, and frequency of application. Interestingly, a clear correlation of PnD products was observed within conditions, way of administration or dosage, suggesting there is a consolidated clinical practice approach for the use of PnD in medicine. No regulatory aspects could be read from the database since this information is not mandatory for registration. The database will be publicly available for consultation. In summary, the main aims of this position paper are to show possibilities for clinical application of PnD and propose an approach for clinical trial preparation and registration in a uniform and standardized way. For this purpose, a questionnaire was created compiling different sections that are relevant when starting a new clinical trial using PnD. More importantly, we want to bring the attention of the medical community to the perinatal products as a consolidated and efficient alternative for their use as a new standard of care in the clinical practice.

Layer-by-Layer Fabrication of PAH/PAMAM/Nano-CaCO3 Composite Films and Characterization for Enhanced Biocompatibility

Nanoparticle production and functionalization for various biomedical uses are still challenging. Polymer composites constituted of poly(amidoamine) (PAMAM), polyallylamine hydrochloride (PAH), and calcium carbonate (CaCO₃) nanoparticles have good biocompatibility with physiological tissue and fluids, making them excellent candidates for biomedical applications. This study investigated the characteristics of polymeric/nano-CaCO₃ composite films based on a PAH/PAMAM matrix, which were fabricated through layer-by-layer synthesis on quartz glass substrates. It was found that the as-prepared elastic moduli of the resultant (PAH/PAMAM)_n-CaCO₃ (where n represents the number of bilayers) composite films varied from 1.40 to 23.70 GPa for different degrees of cross-linking when 0.1 M nano-CaCO₃ particles were incorporated into the polymer matrix. The highly cross-linked (PAH/PAMAM)₁₅-CaCO₃ composite film had the highest recorded elastic modulus of 23.70 GPa, while it was observed that for all the composite films fabricated for the present study, the addition of the nano-CaCO₃ particles approximately doubled the elastic modulus regardless of the degree of polymerization. Live/Dead assays were used to determine whether the produced composite films were compatible with human lung fibroblast cells. The findings indicate that the (PAH/PAMAM)_7.5-CaCO₃ composite film had the most positive effect on cell growth and proliferation, with the (PAH/PAMAM)₁₅-CaCO₃ composite film demonstrating significant ion transport behavior with low impedance, which was considered good for in vivo rapid cell-to-cell communication. Therefore, the (PAH/PAMAM)_7.5-CaCO₃ and (PAH/PAMAM)₁₅-CaCO₃ composite films are potential tissue engineering biomaterials, but further studies are essential to generate more data to evaluate the suitability of these composites for this and other biomedical functions.

Mimicking the Natural Basement Membrane for Advanced Tissue Engineering

Advancements in the field of tissue engineering have led to the elucidation of physical and chemical characteristics of physiological basement membranes (BM) as specialized forms of the extracellular matrix. Efforts to recapitulate the intricate structure and biological composition of the BM have encountered various advancements due to its impact on cell fate, function, and regulation. More attention has been paid to synthesizing biocompatible and biofunctional fibrillar scaffolds that closely mimic the natural BM. Specific modifications in biomimetic BM have paved the way for the development of in vitro models like alveolar-capillary barrier, airway models, skin, blood-brain barrier, kidney barrier, and metastatic models, which can be used for personalized drug screening, understanding physiological and pathological pathways, and tissue implants. In this Review, we focus on the structure, composition, and functions of in vivo BM and the ongoing efforts to mimic it synthetically. Light has been shed on the advantages and limitations of various forms of biomimetic BM scaffolds including porous polymeric membranes, hydrogels, and electrospun membranes This Review further elaborates and justifies the significance of BM mimics in tissue engineering, in particular in the development of in vitro organ model systems.

Controlled Thin Polydimethylsiloxane Membrane with Small and Large Micropores for Enhanced Attachment and Detachment of the Cell Sheet

Polydimethylsiloxane (PDMS) membranes can allow the precise control of well-defined micropore generation. A PDMS solution was mixed with a Rushton impeller to generate a large number of microbubbles. The mixed solution was spin-coated on silicon wafer to control the membrane thickness. The microbubbles caused the generation of a large number of small and large micropores in the PDMS membranes with decreased membrane thickness. The morphology of the thinner porous PDMS membrane induced higher values of roughness, Young’s modulus, contact angle, and air permeability. At day 7, the viability of cells on the porous PDMS membranes fabricated at the spin-coating speed of 5000 rpm was the highest (more than 98%) due to their internal networking structure and surface properties. These characteristics closely correlated with the increased formation of actin stress fibers and migration of keratinocyte cells, resulting in enhanced physical connection of actin stress fibers of neighboring cells throughout the discontinuous adherent junctions. The intact detachment of a cell sheet attached to a porous PDMS membrane was demonstrated. Therefore, PDMS has a great potential for enhancing the formation of cell sheets in regenerative medicine.