Decellularized Scaffolds for Skin Repair and Regeneration

Comparative Postoperative Complications of Acellular Dermal Matrix and Mesh Use in Prepectoral and Subpectoral One-Stage Direct to Implant Reconstruction: A Retrospective Cohort Study

BACKGROUND

One-stage direct-to-implant (DTI) breast reconstruction is increasingly popular with the use of prepectoral reconstruction leading to increased demand for structural scaffolds. It is vital to determine if differences in safety profiles exist among scaffolds.

METHODS

We performed a retrospective cohort study of consecutive patients in our breast cancer center undergoing DTI reconstruction. Outcomes relating to postoperative infections, wound complications, and implant related complications were extracted. Outcomes were grouped into major, minor, and long-term complications. Univariate and multivariate analysis determined outcome differences and accounted for confounding variables.

RESULTS

Two hundred forty-two patients (404 breasts) underwent DTI reconstruction. One hundred ninety-two breasts were reconstructed with FlexHD Pliable Preformed (PP; MTF Biologics, Edison, NJ), 122 with AlloDerm Ready To Use (RTU; Allergan Aesthetics, Irvine, CA), 22 with DermACELL (LifeNet Health, Virginia Beach, VA), 21 with Galaflex (Galatea Surgical, Lexington, MA), 22 with Meso BioMatrix (MTF Biologics), and 25 with autologous dermal flaps alone. Univariate analysis demonstrated statistically significant differences among scaffolds in the incidence of cellulitis treated with oral antibiotics, capsular contracture, explantation for capsular contracture, seroma requiring operative drainage, minor complications, and long-term complications. On multivariate regression, FlexHD PP had reduced rates of capsular contracture, explantation for capsular contracture, minor complications, and long-term complications compared to AlloDerm RTU. Reconstruction with Galaflex had increased rates of capsular contracture when compared to FlexHD PP.

CONCLUSIONS

Certain structural scaffolds have differing safety profiles that should be considered when selecting, which product to use in DTI reconstruction.

Exploiting the Potential of Decellularized Extracellular Matrix (ECM) in Tissue Engineering: A Review Study

While significant progress has been made in creating polymeric structures for tissue engineering, the therapeutic application of these scaffolds remains challenging owing to the intricate nature of replicating the conditions of native organs and tissues. The use of human-derived biomaterials for therapeutic purposes closely imitates the properties of natural tissue, thereby assisting in tissue regeneration. Decellularized extracellular matrix (dECM) scaffolds derived from natural tissues have become popular because of their unique biomimetic properties. These dECM scaffolds can enhance the body's ability to heal itself or be used to generate new tissues for restoration, expanding beyond traditional tissue transfers and transplants. Enhanced knowledge of how ECM scaffold materials affect the microenvironment at the injury site is expected to improve clinical outcomes. In this review, recent advancements in dECM scaffolds are explored and relevant perspectives are offered, highlighting the development and application of these scaffolds in tissue engineering for various organs, such as the skin, nerve, bone, heart, liver, lung, and kidney.

A Comprehensive Literature Review on Advancements and Challenges in 3D Bioprinting of Human Organs: Ear, Skin, and Bone

The field of 3D bioprinting is rapidly emerging within the realm of regenerative medicine, offering significant potential in dealing with the issue of organ shortages. Despite being in its early stages, it has the potential to replicate tissue structures accurately, providing new potential solutions for reconstructive surgery. This review explores the diverse applications of 3D bioprinting in regenerative medicine, pharmaceuticals, and the food industry, specifically focusing on ear, skin, and bone tissues due to their unique challenges and implications in the field. Significant progress has been made in cartilage and bone scaffold fabrication in ear reconstruction, yet challenges in functional maturation persist. Recent advancements highlight the potential for patient-specific ear substitutes, emphasizing the need for extensive clinical trials. In skin regeneration, 3D bioprinting addresses limitations in existing models, offering opportunities for improved wound healing and realistic skin models. While challenges exist, progress in biomaterials and in-situ bioprinting holds promise. In bone regeneration, 3D bioprinting presents personalized solutions for defects, but scaffold design refinement and addressing regulatory and ethical considerations are crucial. The transformative potential of 3D bioprinting in the field of medicine holds the promise of redefining therapeutic approaches and delivering personalized treatments and functional tissues. Interdisciplinary collaboration is essential for fully realizing the capabilities of 3D bioprinting. This review provides a detailed analysis of current methodologies, challenges, and prospects in 3D bioprinting for ear, skin, and bone tissue regeneration.

Human keratinocytes grown at a gas-permeable interface in vitro stratify correctly to generate engineered human epidermis

BACKGROUND

One of the key functions of human skin is to provide a barrier, protecting the body from the surrounding environment and maintaining homeostasis of the internal environment. A mature, stratified epidermis is critical to achieve skin barrier function and is particularly important when producing skin grafts in vitro for wound treatment. For decades epidermal stratification has been achieved in vitro by culturing keratinocytes at an air-liquid interface, triggering proliferating basal keratinocytes to differentiate and form all epidermal layers.

RESULTS

We show here that culturing keratinocytes at a gas-permeable interface can induce epidermal stratification equivalent to an air-liquid interface.

CONCLUSIONS

Culturing skin grafts at a gas-permeable interface has a number of advantages over the traditional air-liquid interface method including: less time input from highly skilled personnel, with consequent cost savings; fewer manipulations, with concomitant reduced risk of cell culture contamination; increased scalability of skin graft size; and improved potential for automation. These advantages confer significant benefits to the use of cell culture devices with gas-permeable interfaces to grow human skin for the treatment of major burns and other skin injuries.

The role of histology in tissue engineering: Significance of complex morphological characterization of decellularized foreskin scaffolds

Decellularization is a technique of cell removal that prepares vacant extracellular matrices (ECMs), which can be reseeded with patient-specific cells and used in regenerative medicine. Histological methods are vital for protocol standardization and efficacy assessment, which are necessary for preparing such bioscaffolds. Foreskins from male subjects (n=20) aged three to fifteen years were harvested and decellularized using detergent-based and enzyme-based protocols. To acquire a standardized protocol that would provide the optimal balance between effective cell removal and ECM preservation, a total of seven protocols were evaluated using the most basic formalin-fixed paraffin-embedded (FFPE) tissue blocks, which were sectioned and stained with HE, Masson's blue trichrome and orcein. After achieving the optimal result, we further morphologically characterized the scaffolds using scanning electron microscopy (SEM) and immunohistochemical (IHC) detection of fibronectin and collagen IV. Histology proved to be a quick, relatively easy, and cheap method to achieve protocol standardization and assess decellularization efficacy and ECM preservation. Morphological analysis via normal histology, SEM, and IHC showed that both definitive protocols are effective in cell removal but, at the same time, don't compromise the structural integrity of the ECM. Morphological characterization of foreskin-derived bioscaffolds via normal histology, IHC, and SEM is irreplaceable for standardizing decellularization protocols, assessing the efficacy of cell removal, and evaluating ECM preservation.

Decellularization of various tissues and organs through chemical methods

Due to the increase in demand for donor organs and tissues during the past 20 years, new approaches have been created. These methods include, for example, tissue engineering in vitro and the production of regenerative biomaterials for transplantation. Applying the natural extracellular matrix (ECM) as a bioactive biomaterial for clinical applications is a unique approach known as decellularization technology. Decellularization is the process of eliminating cells from an extracellular matrix while preserving its natural components including its structural and functional proteins and glycosaminoglycan. This can be achieved by physical, chemical, or biological processes. A naturally formed three-dimensional structure with a biocompatible and regenerative structure is the result of the decellularization process. Decreasing the biological factors and antigens at the transplant site reduces the risk of adverse effects including inflammatory responses and immunological rejection. Regenerative medicine and tissue engineering applications can benefit from the use of decellularization, a promising approach that provides a biomaterial that preserves its extracellular matrix.

Emerging Technological Advancement for Chronic Wound Treatment and Their Role in Accelerating Wound Healing

Chronic wounds are a major healthcare burden and may severely affect the social, mental, and economic status of the patients. Any impairment in wound healing stages due to underlying factors leads to a prolonged healing time and subsequently to chronic wounds. Traditional approaches for the treatment of chronic wounds include dressing free local therapy, dressing therapy, and tissue engineering based scaffold therapies. However, traditional therapies need improvisation and have been advanced through breakthrough technologies. The present review spans traditional therapies and further gives an extensive account of advancements in the treatment of chronic wounds. Cutting edge technologies, such as 3D printing, which includes inkjet printing, fused deposition modeling, digital light processing, extrusion-based printing, microneedle array-based therapies, gene therapy, which includes microRNAs (miRNAs) therapy, and smart wound dressings for real time monitoring of wound conditions through assessment of pH, temperature, oxygen, moisture, metabolites, and their use for planning of better treatment strategies have been discussed in detail. The review further gives the future direction of treatments that will aid in lowering the healthcare burden caused due to chronic wounds.

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.

Therapeutic Effect of Decellularized Extracellular Matrix from Fish Skin for Accelerating Skin Regeneration

A cellular matrix derived from natural tissue functions as a highly biocompatible and versatile material for wound healing application. It provides a complex and highly organized environment with biological molecules and physical stimuli. Recently, various kinds of tissue/organ decellularized extracellular matrixes (dECMs) from bovine and porcine have been used as biomedical applications to support tissue regeneration but inherit religious restrictions and the risk of disease transmission to humans. Marine fish-derived dECMs are seen as attractive alternatives due to their similarity to mammalian physiology, reduced biological risks, and fewer religious restrictions. The aim of this study was to derive a decellularized matrix from the olive flounder (Paralichthys olivaceus) skin and evaluate its suitability as a wound healing application. Olive flounder skin was treated with a series of chemical treatments to remove cellular components. Decellularized fish skin (dFS) was confirmed to be successful in decellularization by evaluating the DNA content (2.84%). The dFS was characterized and evaluated in vivo to assess its biological activities. The mouse wound defect model was used to evaluate the in vivo performance of the dFS compared with that of the decellularized porcine skin (dPS). The resultant dFS was shown to enhance wound healing compared with the no-treatment group and dPS. This study suggests that dFS has potential for skin regeneration application.

Extracellular matrix-inspired biomaterials for wound healing

Diabetic foot ulcers (DFU) are a debilitating and life-threatening complication of Diabetes Mellitus. Ulceration develops from a combination of associated diabetic complications, including neuropathy, circulatory dysfunction, and repetitive trauma, and they affect approximately 19-34% of patients as a result. The severity and chronic nature of diabetic foot ulcers stems from the disruption to normal wound healing, as a result of the molecular mechanisms which underly diabetic pathophysiology. The current standard-of-care is clinically insufficient to promote healing for many DFU patients, resulting in a high frequency of recurrence and limb amputations. Biomaterial dressings, and in particular those derived from the extracellular matrix (ECM), have emerged as a promising approach for the treatment of DFU. By providing a template for cell infiltration and skin regeneration, ECM-derived biomaterials offer great hope as a treatment for DFU. A range of approaches exist for the development of ECM-derived biomaterials, including the use of purified ECM components, decellularisation and processing of donor/ animal tissues, or the use of in vitro-deposited ECM. This review discusses the development and assessment of ECM-derived biomaterials for the treatment of chronic wounds, as well as the mechanisms of action through which ECM-derived biomaterials stimulate wound healing.

Assessment of inflammatory suppression and fibroblast infiltration in tissue remodelling by supercritical CO2 acellular dermal matrix (scADM) utilizing Sprague Dawley models

Human skin-derived ECM aids cell functions but can trigger immune reactions; therefore it is addressed through decellularization. Acellular dermal matrices (ADMs), known for their regenerative properties, are used in tissue and organ regeneration. ADMs now play a key role in plastic and reconstructive surgery, enhancing aesthetics and reducing capsular contracture risk. Innovative decellularization with supercritical carbon dioxide preserves ECM quality for clinical use. The study investigated the cytotoxicity, biocompatibility, and anti-inflammatory properties of supercritical CO2 acellular dermal matrix (scADM) in vivo based on Sprague Dawley rat models. Initial experiments in vitro with fibroblast cells confirmed the non-toxic nature of scADM and demonstrated cell infiltration into scADMs after incubation. Subsequent tests in vitro revealed the ability of scADM to suppress inflammation induced by lipopolysaccharides (LPS) presenting by the reduction of pro-inflammatory cytokines TNF-α, IL-6, IL-1β, and MCP-1. In the in vivo model, histological assessment of implanted scADMs in 6 months revealed a decrease in inflammatory cells, confirmed further by the biomarkers of inflammation in immunofluorescence staining. Besides, an increase in fibroblast infiltration and collagen formation was observed in histological staining, which was supported by various biomarkers of fibroblasts. Moreover, the study demonstrated vascularization and macrophage polarization, depicting increased endothelial cell formation. Alteration of matrix metalloproteinases (MMPs) was analyzed by RT-PCR, indicating the reduction of MMP2, MMP3, and MMP9 levels over time. Simultaneously, an increase in collagen deposition of collagen I and collagen III was observed, verified in immunofluorescent staining, RT-PCR, and western blotting. Overall, the findings suggested that scADMs offer significant benefits in improving outcomes in implant-based procedures as well as soft tissue substitution.

The application of small intestinal submucosa in tissue regeneration

The distinctive three-dimensional architecture, biological functionality, minimal immunogenicity, and inherent biodegradability of small intestinal submucosa extracellular matrix materials have attracted considerable interest and found wide-ranging applications in the domain of tissue regeneration engineering. This article presents a comprehensive examination of the structure and role of small intestinal submucosa, delving into diverse preparation techniques and classifications. Additionally, it proposes approaches for evaluating and modifying SIS scaffolds. Moreover, the advancements of SIS in the regeneration of skin, bone, heart valves, blood vessels, bladder, uterus, and urethra are thoroughly explored, accompanied by their respective future prospects. Consequently, this review enhances our understanding of the applications of SIS in tissue and organ repair and keeps researchers up-to-date with the latest research advancements in this area.

Treatment of hard-to-heal wounds in ischaemic lower extremities with a novel fish skin-derived matrix

OBJECTIVE

To evaluate the efficacy of treatment of hard-to-heal wounds of patients with ischaemia of the lower extremities, and compare an omega-3 wound matrix product (Kerecis, Iceland) with a standard dressing.

METHOD

A single-centre, prospective, randomised, controlled clinical trial of patients with hard-to-heal wounds following three weeks of standard care was undertaken. The ischaemic condition of the wound was confirmed as a decreased transcutaneous oxygen pressure (TcPO2) of <40mmHg. After randomising patients into either a case (omega-3 dressing) or a control group (standard dressing), the weekly decrease in wound area over 12 weeks and the number of patients that achieved complete wound closure were compared between the two groups. Patients with a TcPO2 of ≤32mmHg were taken for further analysis of their wound in a severe ischaemic context.

RESULTS

A total of 28 patients were assigned to the case group and 22 patients to the control group. Over the course of 12 weeks, the wound area decreased more rapidly in the case group than the control group. Complete wound healing occurred in 82% of patients in the case group and 45% in the control group. Even in patients with a severe ischaemic wound with a TcPO2 value of <32 mmHg, wound area decreased more rapidly in the case group than the control group. The proportions of re-epithelialised area in the case and control groups were 80.24% and 57.44%, respectively.

CONCLUSION

Considering the more rapid decrease in wound area and complete healing ratio in the case group, application of a fish skin-derived matrix for treating lower-extremity hard-to-heal wounds, especially with impaired vascularity, would appear to be a good treatment option.

Exosome-loaded decellularized tissue: Opening a new window for regenerative medicine

Mesenchymal stem cell-derived exosomes (MSCs-EXO) have received a lot of interest recently as a potential therapeutic tool in regenerative medicine. Extracellular vesicles (EVs) known as exosomes (EXOs) are crucial for cell-cell communication throughout a variety of activities including stress response, aging, angiogenesis, and cell differentiation. Exploration of the potential use of EXOs as essential therapeutic effectors of MSCs to encourage tissue regeneration was motivated by success in the field of regenerative medicine. EXOs have been administered to target tissues using a variety of methods, including direct, intravenous, intraperitoneal injection, oral delivery, and hydrogel-based encapsulation, in various disease models. Despite the significant advances in EXO therapy, various methods are still being researched to optimize the therapeutic applications of these nanoparticles, and it is not completely clear which approach to EXO administration will have the greatest effects. Here, we will review emerging developments in the applications of EXOs loaded into decellularized tissues as therapeutic agents for use in regenerative medicine in various tissues.

Dynamical properties of solid and hydrated collagen: Insight from nuclear magnetic resonance relaxometry

1H spin-lattice Nuclear Magnetic Resonance relaxometry experiments have been performed for collagen and collagen-based artificial tissues in the frequency range of 10 kHz-20 MHz. The studies were performed for non-hydrated and hydrated materials. The relaxation data have been interpreted as including relaxation contributions originating from 1H-1H and 1H-14N dipole-dipole interactions, the latter leading to Quadrupole Relaxation Enhancement effects. The 1H-1H relaxation contributions have been decomposed into terms associated with dynamical processes on different time scales. A comparison of the parameters for the non-hydrated and hydrated systems has shown that hydration leads to a decrease in the dipolar relaxation constants without significantly affecting the dynamical processes. In the next step, the relaxation data for the hydrated systems were interpreted in terms of a model assuming two-dimensional translational diffusion of water molecules in the vicinity of the macromolecular surfaces and a sub-diffusive motion leading to a power law of the frequency dependencies of the relaxation rates. It was found that the water diffusion process is slowed down by at least two orders of magnitude compared to bulk water diffusion. The frequency dependencies of the relaxation rates in hydrated tissues and hydrated collagen are characterized by different power laws (ωH-β, where ωH denotes the 1H resonance frequency): the first of about 0.4 and the second close to unity.

Swim bladder-derived biomaterials: structures, compositions, properties, modifications, and biomedical applications

Animal-derived biomaterials have been extensively employed in clinical practice owing to their compositional and structural similarities with those of human tissues and organs, exhibiting good mechanical properties and biocompatibility, and extensive sources. However, there is an associated risk of infection with pathogenic microorganisms after the implantation of tissues from pigs, cattle, and other mammals in humans. Therefore, researchers have begun to explore the development of non-mammalian regenerative biomaterials. Among these is the swim bladder, a fish-derived biomaterial that is rapidly used in various fields of biomedicine because of its high collagen, elastin, and polysaccharide content. However, relevant reviews on the biomedical applications of swim bladders as effective biomaterials are lacking. Therefore, based on our previous research and in-depth understanding of this field, this review describes the structures and compositions, properties, and modifications of the swim bladder, with their direct (including soft tissue repair, dural repair, cardiovascular repair, and edible and pharmaceutical fish maw) and indirect applications (including extracted collagen peptides with smaller molecular weights, and collagen or gelatin with higher molecular weights used for hydrogels, and biological adhesives or glues) in the field of biomedicine in recent years. This review provides insights into the use of swim bladders as source of biomaterial; hence, it can aid biomedicine scholars by providing directions for advancements in this field.

Decellularized Bovine Skeletal Muscle Scaffolds: Structural Characterization and Preliminary Cytocompatibility Evaluation

Skeletal muscle degeneration is responsible for major mobility complications, and this muscle type has little regenerative capacity. Several biomaterials have been proposed to induce muscle regeneration and function restoration. Decellularized scaffolds present biological properties that allow efficient cell culture, providing a suitable microenvironment for artificial construct development and being an alternative for in vitro muscle culture. For translational purposes, biomaterials derived from large animals are an interesting and unexplored source for muscle scaffold production. Therefore, this study aimed to produce and characterize bovine muscle scaffolds to be applied to muscle cell 3D cultures. Bovine muscle fragments were immersed in decellularizing solutions for 7 days. Decellularization efficiency, structure, composition, and three-dimensionality were evaluated. Bovine fetal myoblasts were cultured on the scaffolds for 10 days to attest cytocompatibility. Decellularization was confirmed by DAPI staining and DNA quantification. Histological and immunohistochemical analysis attested to the preservation of main ECM components. SEM analysis demonstrated that the 3D structure was maintained. In addition, after 10 days, fetal myoblasts were able to adhere and proliferate on the scaffolds, attesting to their cytocompatibility. These data, even preliminary, infer that generated bovine muscular scaffolds were well structured, with preserved composition and allowed cell culture. This study demonstrated that biomaterials derived from bovine muscle could be used in tissue engineering.

Application of pulsed electric field technology to skin engineering

Tissue engineering encompasses a range of techniques that direct the growth of cells into a living tissue construct for regenerative medicine applications, disease models, drug discovery, and safety testing. These techniques have been implemented to alleviate the clinical burdens of impaired healing of skin, bone, and other tissues. Construct development requires the integration of tissue-specific cells and/or an extracellular matrix-mimicking biomaterial for structural support. Production of such constructs is generally expensive and environmentally costly, thus eco-sustainable approaches should be explored. Pulsed electric field (PEF) technology is a nonthermal physical processing method commonly used in food production and biomedical applications. In this review, the key principles of PEF and the application of PEF technology for skin engineering will be discussed, with an emphasis on how PEF can be applied to skin cells to modify their behaviour, and to biomaterials to assist in their isolation or sterilisation, or to modify their physical properties. The findings indicate that the success of PEF in tissue engineering will be reliant on systematic evaluation of key parameters, such as electric field strength, and their impact on different skin cell and biomaterial types. Linking tangible input parameters to biological responses critical to healing will assist with the development of PEF as a sustainable tool for skin repair and other tissue engineering applications.

Improvement in Biocompatibility and Biointegration of Human Acellular Dermal Matrix through Vacuum Plasma Surface Treatment

Efforts are ongoing to enhance the functionality of human acellular dermal matrices (hADMs), which are extensively utilized in reconstructive surgeries. Among these efforts, plasma treatments, particularly vacuum plasma treatments, have recently emerged in the medical field. This study aims to investigate the efficacy of a vacuum plasma treatment in enhancing the biocompatibility and biointegration of hADMs. Utilizing a plasma activator (ACTILINK reborn, Plasmapp Co., Ltd., Daejeon, Republic of Korea), hADMs were treated and evaluated through in vitro and in vivo analyses. Hydrophilicity changes were gauged by the blood absorption times, while SEM imaging was used to analyze physical surface deformation. Protein adsorption was measured with fluorescently labeled bovine serum albumin and fibronectin. For the in vivo study, mice were implanted with plasma-treated and untreated hADMs, and the post-implantation effects were analyzed through histological and immunofluorescence microscopy. The plasma-treated hADMs demonstrated a significantly enhanced hydrophilicity compared to the untreated samples. SEM imaging confirmed the maintenance of the microroughness after the treatment. The treated hADMs showed a significant reduction in fibronectin adsorption, a critical factor for cellular adhesion. In vivo, the plasma-treated hADMs exhibited reduced capsule formation and enhanced fibroblast infiltration, indicating improved biocompatibility and integration. These findings highlight the potential of a plasma treatment to enhance the performance of hADMs in clinical settings, offering a promising avenue for improving reconstructive surgery outcomes.

Application of Decellularized Adipose Matrix as a Bioscaffold in Different Tissue Engineering

With the development of tissue engineering, the application of decellularized adipose matrix as scaffold material in tissue engineering has been intensively explored due to its wide source and excellent potential in tissue regeneration. Decellularized adipose matrix is a promising candidate for adipose tissue regeneration, while modification of decellularized adipose matrix scaffold can also allow it to transcend the limitations of adipose tissue source properties and applied to other tissue engineering fields, including cartilage and bone tissue engineering, neural tissue engineering, and skin tissue engineering. In this review, we summarized the development of the applications of decellularized adipose matrix in different tissue engineering and present future perspectives.Level of Evidence III This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

An overview of the production of tissue extracellular matrix and decellularization process

Thousands of patients need an organ transplant yearly, while only a tiny percentage have this chance to receive a tissue/organ transplant. Nowadays, decellularized animal tissue is one of the most widely used methods to produce engineered scaffolds for transplantation. Decellularization is defined as physically or chemically removing cellular components from tissues while retaining structural and functional extracellular matrix (ECM) components and creating an ECM-derived scaffold. Then, decellularized scaffolds could be reseeded with different cells to fabricate an autologous graft. Effective decellularization methods preserve ECM structure and bioactivity through the application of the agents and techniques used throughout the process. The most valuable agents for the decellularization process depend on biological properties, cellular density, and the thickness of the desired tissue. ECM-derived scaffolds from various mammalian tissues have been recently used in research and preclinical applications in tissue engineering. Many studies have shown that decellularized ECM-derived scaffolds could be obtained from tissues and organs such as the liver, cartilage, bone, kidney, lung, and skin. This review addresses the significance of ECM in organisms and various decellularization agents utilized to prepare the ECM. Also, we describe the current knowledge of the decellularization of different tissues and their applications.

Reconstruction of the human nipple-areolar complex: a tissue engineering approach

Introduction: Nipple-areolar complex (NAC) reconstruction after breast cancer surgery is challenging and does not always provide optimal long-term esthetic results. Therefore, generating a NAC using tissue engineering techniques, such as a decellularization-recellularization process, is an alternative option to recreate a specific 3D NAC morphological unit, which is then covered with an in vitro regenerated epidermis and, thereafter, skin-grafted on the reconstructed breast. Materials and methods: Human NACs were harvested from cadaveric donors and decellularized using sequential detergent baths. Cellular clearance and extracellular matrix (ECM) preservation were analyzed by histology, as well as by DNA, ECM proteins, growth factors, and residual sodium dodecyl sulfate (SDS) quantification. In vivo biocompatibility was evaluated 30 days after the subcutaneous implantation of native and decellularized human NACs in rats. In vitro scaffold cytocompatibility was assessed by static seeding of human fibroblasts on their hypodermal side for 7 days, while human keratinocytes were seeded on the scaffold epidermal side for 10 days by using the reconstructed human epidermis (RHE) technique to investigate the regeneration of a new epidermis. Results: The decellularized NAC showed a preserved 3D morphology and appeared white. After decellularization, a DNA reduction of 98.3% and the absence of nuclear and HLA staining in histological sections confirmed complete cellular clearance. The ECM architecture and main ECM proteins were preserved, associated with the detection and decrease in growth factors, while a very low amount of residual SDS was detected after decellularization. The decellularized scaffolds were in vivo biocompatible, fully revascularized, and did not induce the production of rat anti-human antibodies after 30 days of subcutaneous implantation. Scaffold in vitro cytocompatibility was confirmed by the increasing proliferation of seeded human fibroblasts during 7 days of culture, associated with a high number of living cells and a similar viability compared to the control cells after 7 days of static culture. Moreover, the RHE technique allowed us to recreate a keratinized pluristratified epithelium after 10 days of culture. Conclusion: Tissue engineering allowed us to create an acellular and biocompatible NAC with a preserved morphology, microarchitecture, and matrix proteins while maintaining their cell growth potential and ability to regenerate the skin epidermis. Thus, tissue engineering could provide a novel alternative to personalized and natural NAC reconstruction.

A High-biocompatibility Interface for the Breast Implant: First Report of a Novel Biological Matrix-assisted Technique in Aesthetic Revision Surgery

Development of human-compatible tissues is an active field of research that is leading to the production of optimized biological scaffolds to support regenerative medicine. Xenogenic acellular matrices are known to have strongly influenced the field of breast surgery, playing an integral role in wound healing and in preventing the foreign body reaction to silicone implants. Here, we present our experience in using a biological matrix for aesthetic revision surgery with malposition and severe capsular contracture. Revisions were performed using the new MASQUE equine acellular-pericardium-matrix (APM) as an anterior cover for the synthetic prosthesis. Acting as an internal support, the thin APM layer provides a biological and biocompatible interface between the synthetic implant and living tissues, exerting a protective function against fibrotic responses and capsular contracture. The role of an APM in matrix-assisted mammoplasty has yet to be fully established. Our early experience of APM-assisted aesthetic revision surgery shows promising results, laying the foundations for equine biological matrices as a valid tool for the management of capsular contracture-susceptible patients.

A TA/Cu2+ Nanoparticle Enhanced Carboxymethyl Chitosan-Based Hydrogel Dressing with Antioxidant Properties and Promoting Wound Healing

Background

As the first line of immune defense and the largest organ of body, skin is vulnerable to damage caused by surgery, burns, collisions and other factors. Wound healing in the skin is a long and complex physiological process that is influenced by a number of different factors. Proper wound care can greatly improve the speed of wound healing and reduce the generation of scars. However, traditional wound dressings (bandages, gauze, etc.) often used in clinical practice have a single function, lack of active ingredients and are limited in use. Hydrogels with three-dimensional network structure are a potential biomedical material because of their physical and chemical environment similar to extracellular matrix. In particular, hydrogel dressings with low price, good biocompatibility, degradability, antibacterial and angiogenic activity are favored by the public.

Methods

Here, a carboxymethyl chitosan-based hydrogel dressing (CMCS-TA/Cu2+) reinforced by copper ion crosslinked tannic acid (TA/Cu2+) nanoparticles was developed. This study investigated the physical and chemical characteristics, cytotoxicity, and angiogenesis of TA/Cu2+ nanoparticles and CMCS-TA/Cu2+ hydrogels. Furthermore, a full-thickness skin defect wound model was employed to assess the in vivo wound healing capacity of hydrogel dressings.

Results

The introduction of TA/Cu2+ nanoparticles not only could increase the mechanical properties of the hydrogel but also continuously releases copper ions to promote cell migration (the cell migration could reach 92% at 48 h) and tubule formation, remove free radicals and promote wound healing (repair rate could reach 90% at 9 days).

Conclusion

Experiments have proved that CMCS-TA/Cu2+ hydrogel has good cytocompatibility, antioxidant and wound healing ability, providing an advantageous solution for skin repair.

In Vivo Efficacy of an Injectable Human Acellular Dermal Matrix

BACKGROUND

Human acellular dermal matrix (hADM) has found applications in a variety of settings, particularly in breast surgery. The most common hADM is a sheet. Recently, an injectable hADM has been introduced; we compared the biocompatibility and long-term structural integrity of, an injectable hADM and a sheet-type hADM in mice.

METHODS

An injectable hADM (experimental group) and a sheet-type hADM (control group) were implanted into sub-panniculus pockets on the backs of 50 mice. The animals were sacrificed 2, 4, 8, 12, or 24 weeks later and the hADMs and surrounding tissues were recovered and stained for histopathological analyses. The microscopic endpoints included the thickness of the hADM and capsule around the hADM, and the extents of fibroblast proliferation and neovascularization.

RESULTS

No animal developed a complication or infection. The capsule was significantly thinner in the experimental than the control group. There were no significant differences between groups in the hADM thickness. Microscopically, the fibroblast density inside the hADM was significantly higher in the experimental group. The fibroblasts inside of the hADM lay significantly deeper in the experimental group. Similarly, the experimental group exhibited significantly deeper microvessels inside the hADM.

CONCLUSIONS

The injectable hADM had a thinner capsule thickness (more biocompatible), than the sheet-type hADM. It maintained its thickness as well as the sheet-type hADM and had a more fibroblast proliferation and neovascularization. This means the tissue incorporation and long-term structural integrity of the injectable hADM may be as good as or better than that of the sheet-type hADM.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Bioengineered skin constructs based on mesenchymal stromal cells and acellular dermal matrix exposed to inflammatory microenvironment releasing growth factors involved in skin repair

BACKGROUND

Skin tissue engineering is a rapidly evolving field of research that effectively combines stem cells and biological scaffolds to replace damaged tissues. Human Wharton's jelly mesenchymal stromal cells (hWJ-MSCs) are essential to generate tissue constructs, due to their potent immunomodulatory effects and release of paracrine factors for tissue repair. Here, we investigated whether hWJ-MSC grown on human acellular dermal matrix (hADM) scaffolds and exposed to a proinflammatory environment maintain their ability to produce in vitro growth factors involved in skin injury repair and promote in vivo wound healing.

METHODS

We developed a novel method involving physicochemical and enzymatic treatment of cadaveric human skin to obtain hADM scaffold. Subsequently, skin bioengineered constructs were generated by seeding hWJ-MSCs on the hADM scaffold (construct 1) and coating it with human platelet lysate clot (hPL) (construct 2). Either construct 1 or 2 were then incubated with proinflammatory cytokines (IL-1α, IL-1β, IL-6, TNF-α) for 12, 24, 48, 72 and 96 h. Supernatants from treated and untreated constructs and hWJ-MSCs on tissue culture plate (TCP) were collected, and concentration of the following growth factors, bFGF, EGF, HGF, PDGF, VEGF and Angiopoietin-I, was determined by immunoassay. We also asked whether hWJ-MSCs in the construct 1 have potential toward epithelial differentiation after being cultured in an epithelial induction stimulus using an air-liquid system. Immunostaining was used to analyze the synthesis of epithelial markers such as filaggrin, involucrin, plakoglobin and the mesenchymal marker vimentin. Finally, we evaluated the in vivo potential of hADM and construct 1 in a porcine full-thickness excisional wound model.

RESULTS

We obtained and characterized the hADM and confirmed the viability of hWJ-MSCs on the scaffold. In both constructs without proinflammatory treatment, we reported high bFGF production. In contrast, the levels of other growth factors were similar to the control (hWJ-MSC/TCP) with or without proinflammatory treatment. Except for PDGF in the stimulated group. These results indicated that the hADM scaffold maintained or enhanced the production of these bioactive molecules by hWJ-MSCs. On the other hand, increased expression of filaggrin, involucrin, and plakoglobin and decreased expression of vimentin were observed in constructs cultured in an air-liquid system. In vivo experiments demonstrated the potential of both hADM and hADM/hWJ-MSCs constructs to repair skin wounds with the formation of stratified epithelium, basement membrane and dermal papillae, improving the appearance of the repaired tissue.

CONCLUSIONS

hADM is viable to fabricate a tissue construct with hWJ-MSCs able to promote the in vitro synthesis of growth factors and differentiation of these cells toward epithelial lineage, as well as, promote in a full-thickness skin injury the new tissue formation. These results indicate that hADM 3D architecture and its natural composition improved or maintained the cell function supporting the potential therapeutic use of this matrix or the construct for wound repair and providing an effective tissue engineering strategy for skin repair.

Decellularization Techniques for Tissue Engineering: Towards Replicating Native Extracellular Matrix Architecture in Liver Regeneration

The process of tissue regeneration requires the utilization of a scaffold, which serves as a structural framework facilitating cellular adhesion, proliferation, and migration within a physical environment. The primary aim of scaffolds in tissue engineering is to mimic the structural and functional properties of the extracellular matrix (ECM) in the target tissue. The construction of scaffolds that accurately mimic the architecture of the extracellular matrix (ECM) is a challenging task, primarily due to the intricate structural nature and complex composition of the ECM. The technique of decellularization has gained significant attention in the field of tissue regeneration because of its ability to produce natural scaffolds by removing cellular and genetic components from the extracellular matrix (ECM) while preserving its structural integrity. The present study aims to investigate the various decellularization techniques employed for the purpose of isolating the extracellular matrix (ECM) from its native tissue. Additionally, a comprehensive comparison of these methods will be presented, highlighting their respective advantages and disadvantages. The primary objective of this study is to gain a comprehensive understanding of the anatomical and functional features of the native liver, as well as the prevalence and impact of liver diseases. Additionally, this study aims to identify the limitations and difficulties associated with existing therapeutic methods for liver diseases. Furthermore, the study explores the potential of tissue engineering techniques in addressing these challenges and enhancing liver performance. By investigating these aspects, this research field aims to contribute to the advancement of liver disease treatment and management.

Biostimulation effect of platelet-rich fibrin augmented with decellularized bovine pericardium on full-thickness cutaneous wound healing in Donkeys (Equus asinus)

AIM

The current research aimed to evaluate the potential effect of adding platelet-rich fibrin (PRF) to the decellularized bovine pericardium (DBP) on the distal limb of donkeys' full-thickness cutaneous wounds healing (Equus asinus).

MATERIALS AND METHODS

Healthy male donkeys (n = 12) were used in this study. Under general anesthesia, 6 cm2 full-thickness incisions were made on the middle dorsolateral surface of both forelimbs' metacarpi. The left forelimbs were control wounds, while the right wounds were treated with PRF/DBP. Control wounds were bandaged with a standard dressing after saline irrigation and were evaluated at days 4, 7, 10, 13, 16, 19, 22, 25, and 28 post-wounding. PRF/DBP-treated wounds were dressed with a combination of PRF/DBP at the first, second, and third weeks post-wounding. Clinical and histopathological examinations of the wounds were performed to assess the healing process. Additionally, the immunohistochemical evaluation and gene expression profiles of myofibroblastic and angiogenic genes (transforming growth factor-β1, vascular endothelial growth factor-A, fibroblast growth factor 7 (FGF-7), and collagen type 3α1) were analyzed.

RESULTS

PRF/DBP wounds had a significantly faster healing process (61.3 ± 2.6 days) than control wounds (90.3 ± 1.4 days) (p < 0.05). The immunohistochemical examination and gene expression profile revealed significant enrichment in PRF/DBP wounds compared to control wounds.

CONCLUSION

PRF/DBP dressing can be considered a natural and cost-effective biomaterial for enhancing the recovery of donkeys' distal limb injuries.

Acellular fish skin for wound healing

Fish skin grafting as a new skin substitute is currently being used in clinical applications. Acceleration of the wound healing, lack of disease transmission, and low cost of the production process can introduce fish skin as a potential alternative to other grafts. An appropriate decellularization process allows the design of 3D acellular scaffolds for skin regeneration without damaging the morphology and extracellular matrix content. Therefore, the role of decellularization processes is very important to maintain the properties of fish skin. In this review article, recent studies on various decellularization processes as well as biological, physical, and mechanical properties of fish skin and its applications with therapeutic effects in wound healing were investigated.

Construction of cardiac fibrosis for biomedical research

Cardiac remodeling is critical for effective tissue recuperation, nevertheless, excessive formation and deposition of extracellular matrix components can result in the onset of cardiac fibrosis. Despite the emergence of novel therapies, there are still no lifelong therapeutic solutions for this issue. Understanding the detrimental cardiac remodeling may aid in the development of innovative treatment strategies to prevent or reverse fibrotic alterations in the heart. Further combining the latest understanding of disease pathogenesis with cardiac tissue engineering has provided the conversion of basic laboratory studies into the therapy of cardiac fibrosis patients as an increasingly viable prospect. This review presents the current main mechanisms and the potential tissue engineering of cardiac fibrosis. Approaches using biomedical materials-based cardiac constructions are reviewed to consider key issues for simulating in vitro cardiac fibrosis, outlining a future perspective for preclinical applications.

Comprehensive Care of Lower-Extremity Wounds

There are 5 common types of chronic nonhealing lower-extremity wounds: arterial, venous, diabetic foot ulcer, pressure, and mixed or atypical. Each chronic wound type has distinct features, and understanding the underlying cause will dictate the wound treatment plan. Here, the authors review the distinguishing wound properties for these 5 common chronic nonhealing lower-extremity wounds and outline a comprehensive treatment plan that addresses wound perfusion, debridement, infection control, moisture balance, and use of complementary advanced wound care products.

3D-printed placental-derived bioinks for skin tissue regeneration with improved angiogenesis and wound healing properties

Extracellular matrix (ECM)-based bioinks has attracted much attention in recent years for 3D printing of native-like tissue constructs. Due to organ unavailability, human placental ECM can be an alternative source for the construction of 3D print composite scaffolds for the treatment of deep wounds. In this study, we use different concentrations (1.5%, 3% and 5%w/v) of ECM derived from the placenta, sodium-alginate and gelatin to prepare a printable bioink biomimicking natural skin. The printed hydrogels' morphology, physical structure, mechanical behavior, biocompatibility, and angiogenic property are investigated. The optimized ECM (5%w/v) 3D printed scaffold is applied on full-thickness wounds created in a mouse model. Due to their unique native-like structure, the ECM-based scaffolds provide a non-cytotoxic microenvironment for cell adhesion, infiltration, angiogenesis, and proliferation. In contrast, they do not show any sign of immune response to the host. Notably, the biodegradation, swelling rate, mechanical property, cell adhesion and angiogenesis properties increase with the increase of ECM concentrations in the construct. The ECM 3D printed scaffold implanted into deep wounds increases granulation tissue formation, angiogenesis, and re-epithelialization due to the presence of ECM components in the construct, when compared with printed scaffold with no ECM and no treatment wound. Overall, our findings demonstrate that the 5% ECM 3D scaffold supports the best deep wound regeneration in vivo, produces a skin replacement with a cellular structure comparable to native skin.

Tissue Engineering-Based Strategies for Diabetic Foot Ulcer Management

Significance: Diabetic foot ulcers (DFU) are a mounting problem with the increasingly frail population. Injuries that would otherwise heal are kept open by risk factors such as diabetes, obesity, and age-related conditions, which interferes with the natural wound healing processes. Recent Advances: This review summarizes recent advancements in the field of tissue engineering for the treatment of DFUs. FDA-approved approaches, including signaling-based therapies, stem cell therapies, and skin substitutes are summarized and cutting-edge experimental technologies that have the potential to manage chronic wounds, such as skin printing, skin organogenesis, skin self-assembly, and prevascularization, are discussed. Critical Issues: The standard of care for chronic wounds involves wound debridement, wound dressings, and resolving the underlying cause such as lowering the glycemic index and reducing wound pressure. Current DFU treatments are limited by low wound closure rates and poor regrown skin quality. New adjuvant therapies that facilitate wound closure in place of or in conjunction with standard care are critically needed. Future Directions: Tissue engineering strategies are limited by the plasticity of adult human cells. In addition to traditional techniques, genetic modification, although currently an emerging technology, has the potential to unlock human regeneration and can be incorporated in future therapeutics.

Study on the preparation and properties of acellular matrix from the skin of silver carp (Hypophthalmichthys molitrix)

Acellular matrices are mainly composed of mammalian tissues, and aquatic tissues with lower biological risks and less religious restrictions are considered alternatives to mammalian tissues. The acellular fish skin matrix (AFSM) has been commercially available. Silver carp has the advantages of farmability, high yield and low price, but there are few studies on the silver carp acellular fish skin matrix (SC-AFSM). In this study, an acellular matrix with low DNA and endotoxin was prepared from the skin of silver carp. After treatment with trypsin/sodium dodecyl sulfate and Triton X-100 solutions, the DNA content in SC-AFSM reached 11.03 ± 0.85 ng/mg, and the endotoxin removal rate was 96.8%. The porosity of SC-AFSM was 79.64% ± 0.17%, which is favorable for cell infiltration and proliferation. The relative cell proliferation rate of SC-AFSM extract was 117.79% ± 15.26%. The wound healing experiment showed that SC-AFSM had no adverse acute pro-inflammatory response, which had a similar effect as commercial products in promoting tissue repair. Therefore, SC-AFSM has great application potential in biomaterials.

The effect of source animal age, decellularization protocol, and sterilization method on bovine acellular dermal matrix as a scaffold for wound healing and skin regeneration

BACKGROUND

Healing the full-thickness skin wounds has remained a challenge. One of the most frequently used grafts for skin regeneration is xenogeneic acellular dermal matrices (ADMs), including bovine ADMs. This study investigated the effect of the source animal age, enzymatic versus non-enzymatic decellularization protocols, and gamma irradiation versus ethylene oxide (EO) sterilization on the scaffold.

METHODS

ADMs were prepared using the dermises of fetal bovine or calf skins. All groups were decellularized through chemical and mechanical methods, unless T-FADM samples, in which an enzymatic step was added to the decellularization protocol. All groups were sterilized with ethylene oxide (EO), except G-FADM which was sterilized using gamma irradiation. The scaffolds were characterized through scanning electron microscopy, differential scanning calorimetry, tensile test, MTT assay, DNA quantification, and real-time PCR. The performance of the ADMs in wound treatment was also evaluated macroscopically and histologically.

RESULTS

All ADMs were effectively decellularized. In comparison to FADM (EO-sterilized fetal ADM), morphological, and mechanical properties of G-FADM, T-FADM, and CADM (EOsterilized calf ADM) were changed to different extents. In addition, the CADM and G-FADM were thermally more stable than the FADM and T-FADM. Although all ADMs were noncytotoxic, the wounds of the FADM, T-FADM, and G-FADM groups were contracted to almost 30.0% of the original area on day 7, significantly faster than the CADM (17.5% ± 1.7) and control (12.2% ± 1.59) groups. However, by day 21, all ADMs were mostly closed except for the untreated group (60.1 ± 1.8).

CONCLUSION

Altogether, fetal source and EO-sterilized samples performed better than calf source and gamma-sterilized samples unless in some mechanical properties. There was no added value in using enzymatic treatment during the decellularization process. Our results suggest that the age, decellularization, and sterilization methods of animal source should be selected based on the clinical requirements.

The basement membrane in epidermal polarity, stemness, and regeneration

The epidermis is a specialized epithelium that constitutes the outermost layer of the skin, and it provides a protective barrier against environmental assaults. Primarily consisting of multilayered keratinocytes, the epidermis is continuously renewed by proliferation of stem cells and the differentiation of their progeny, which undergo terminal differentiation as they leave the basal layer and move upward toward the surface, where they die and slough off. Basal keratinocytes rest on a basement membrane at the dermal-epidermal junction that is composed of specific extracellular matrix proteins organized into interactive and mechanically supportive networks. Firm attachment of basal keratinocytes, and their dynamic regulation via focal adhesions and hemidesmosomes, is essential for maintaining major skin processes, such as self-renewal, barrier function, and resistance to physical and chemical stresses. The adhesive integrin receptors expressed by epidermal cells serve structural, signaling, and mechanosensory roles that are critical for epidermal cell anchorage and tissue homeostasis. More specifically, the basement membrane components play key roles in preserving the stem cell pool, and establishing cell polarity cues enabling asymmetric cell divisions, which result in the transition from a proliferative basal cell layer to suprabasal cells committed to terminal differentiation. Finally, through a well-regulated sequence of synthesis and remodeling, the components of the dermal-epidermal junction play an essential role in regeneration of the epidermis during skin healing. Here too, they provide biological and mechanical signals that are essential to the restoration of barrier function.

Effective decellularization of human skin tissue for regenerative medicine by supercritical carbon dioxide technique

Allotransplantation, performed using an acellular dermal matrix (ADM), plays a significant role in the cultivation of constituted and damaged organs in clinical. Herein, we fabricated an innovative ADM for allografting derived from decellularized human skin by utilizing the supercritical fluid of carbon dioxide to eliminate immunogenic components. By using histological staining, the ADM product demonstrated the successful removal of cellular constituents without exerting any harmful influence on the extracellular matrix. The results from DNA electrophoresis also supported this phenomenon by showing the complete DNA removal in the product, accompanied by the absence of Major Histocompatibility Complex 1, which suggested the supercritical fluid is an effective method for cellular withdrawal. Moreover, the mechanical property of the ADM products, which showed similarity to that of native skin, displayed great compatibility for using our human-derived ADM as an allograft in clinical treatment. Specifically, the cell viability demonstrated the remarkable biocompatibility of the product to human bio-cellular environment which was noticeably higher than that of other products. Additionally, the significant increase in the level of growth factors such as vascular endothelial growth factor, urokinase-type plasminogen activator receptor, granulocyte-macrophage colony-stimulating factor suggested the ability to stimulate cellular processes, proving the products to be innovative in the field of regeneration when applied to clinical in the future. This study provides a thoroughly extensive analysis of the new ADM products, enabling them to be applied in industrial and clinical treatment.

Braxon®-assisted prepectoral breast reconstruction: A decade later

We are sitting on the cusp of the bioengineered breast era, in which implant-based breast reconstruction is seeing a growing trend and biotechnology research progressively empowers clinical practice. As never before, the choice of biomaterials has acquired great importance for achieving reconstructive outcomes, and the increase in the use of acellular dermal matrices (ADMs) in the field of senology tells us a story of profound upheaval and progress. With the advent of prepectoral breast reconstruction (PPBR), plenty of devices have been proposed to wrap the silicone prosthesis, either completely or partially. However, this has caused a great deal of confusion and dissent with regard to the adoption of feasible reconstructive strategies as well as the original scientific rationale underlying the prepectoral approach. Braxon^® is the very first device that made prepectoral implant positioning possible, wrapping around the prosthesis and exerting the proven ADM regenerative potential at the implant–tissue interface, taking advantage of the body's physiological healing mechanisms. To date, the Braxon^® method is among the most studied and practiced worldwide, and more than 50 publications confirm the superior performance of the device in the most varied clinical scenarios. However, a comprehensive record of the working of this pioneering device is still missing. Therefore, our aim with this review is to lay a structured knowledge of surgery with BRAXON^® and to provide a decision-making tool in the field of PPBR through a complete understanding on the very first device for prepectoral, one decade after its introduction.

Perfusion decellularization for vascularized composite allotransplantation

Vascularized composite allotransplantation is becoming the emerging standard for reconstructive surgery treatment for patients with limb trauma and facial injuries involving soft tissue loss. Due to the complex immunogenicity of composite grafts, patients who undergo vascularized composite allotransplantation are reliant on lifelong immunosuppressive therapy. Decellularization of donor grafts to create an extracellular matrix bio-scaffold provides an immunomodulatory graft that preserves the structural and bioactive function of the extracellular matrix. Retention of extracellular matrix proteins, growth factors, and signaling cascades allow for cell adhesion, migration, proliferation, and tissue regeneration. Perfusion decellularization of detergents through the graft vasculature allows for increased regent access to all tissue layers, and removal of cellular debris through the venous system. Grafts can subsequently be repopulated with appropriate cells through the vasculature to facilitate tissue regeneration. The present work reviews methods of decellularization, process parameters, evaluation of adequate cellular and nuclear removal, successful applications of perfusion decellularization for use in vascularized composite allotransplantation, and current limitations.

Advancements in Extracellular Matrix-Based Biomaterials and Biofabrication of 3D Organotypic Skin Models

Over the last decades, three-dimensional (3D) organotypic skin models have received enormous attention as alternative models to in vivo animal models and in vitro two-dimensional assays. To date, most organotypic skin models have an epidermal layer of keratinocytes and a dermal layer of fibroblasts embedded in an extracellular matrix (ECM)-based biomaterial. The ECM provides mechanical support and biochemical signals to the cells. Without advancements in ECM-based biomaterials and biofabrication technologies, it would have been impossible to create organotypic skin models that mimic native human skin. In this review, the use of ECM-based biomaterials in the reconstruction of skin models, as well as the study of complete ECM-based biomaterials, such as fibroblasts-derived ECM and decellularized ECM as a better biomaterial, will be highlighted. We also discuss the benefits and drawbacks of several biofabrication processes used in the fabrication of ECM-based biomaterials, such as conventional static culture, electrospinning, 3D bioprinting, and skin-on-a-chip. Advancements and future possibilities in modifying ECM-based biomaterials to recreate disease-like skin models will also be highlighted, given the importance of organotypic skin models in disease modeling. Overall, this review provides an overview of the present variety of ECM-based biomaterials and biofabrication technologies available. An enhanced organotypic skin model is expected to be produced in the near future by combining knowledge from previous experiences and current research.

Recent Advances in Bioengineered Scaffolds for Cutaneous Wound Healing

Wound healing is an evolved dynamic biological process. Though many research and clinical approaches have been explored to restore damaged or diseased skin, the current treatment for deep cutaneous injuries is far from being perfect, and the ideal regenerative therapy remains a significant challenge. Of all treatments, bioengineered scaffolds play a key role and represent great progress in wound repair and skin regeneration. In this review, we focus on the latest advancement in biomaterial scaffolds for wound healing. We discuss the emerging philosophy of designing biomaterial scaffolds, followed by precursor development. We pay particular attention to the therapeutic interventions of bioengineered scaffolds for cutaneous wound healing, and their dual effects while conjugating with bioactive molecules, stem cells, and even immunomodulation. As we review the advancement and the challenges of the current strategies, we also discuss the prospects of scaffold development for wound healing.

Decellularized Tissues for Wound Healing: Towards Closing the Gap Between Scaffold Design and Effective Extracellular Matrix Remodeling

The absence or damage of a tissue is the main cause of most acute or chronic diseases and are one of the appealing challenges that novel therapeutic alternatives have, in order to recover lost functions through tissue regeneration. Chronic cutaneous lesions are the most frequent cause of wounds, being a massive area of regenerative medicine and tissue engineering to have efforts to develop new bioactive medical products that not only allow an appropriate and rapid healing, but also avoid severe complications such as bacterial infections. In tissue repair and regeneration processes, there are several overlapping stages that involve the synergy of cells, the extracellular matrix (ECM) and biomolecules, which coordinate processes of ECM remodeling as well as cell proliferation and differentiation. Although these three components play a crucial role in the wound healing process, the ECM has the function of acting as a biological platform to permit the correct interaction between them. In particular, ECM is a mixture of crosslinked proteins that contain bioactive domains that cells recognize in order to promote migration, proliferation and differentiation. Currently, tissue engineering has employed several synthetic polymers to design bioactive scaffolds to mimic the native ECM, by combining biopolymers with growth factors including collagen and fibrinogen. Among these, decellularized tissues have been proposed as an alternative for reconstructing cutaneous lesions since they maintain the complex protein conformation, providing the required functional domains for cell differentiation. In this review, we present an in-depth discussion of different natural matrixes recently employed for designing novel therapeutic alternatives for treating cutaneous injuries, and overview some future perspectives in this area.

Decellularized human amniotic membrane reinforced by MoS2-Polycaprolactone nanofibers, a novel conductive scaffold for cardiac tissue engineering

In order to regenerate myocardial tissues with functional characteristics, we need to copy some properties of the myocardium, such as its extracellular matrix and electrical conductivity. In this study, we synthesized nanosheets of Molybdenum disulfide (MoS2), and integrated them into polycaprolactone (PCL) and electrospun on the surface of decellularized human amniotic membrane (DHAM) with the purpose of improving the scaffolds mechanical properties and electrical conductivity. For in vitro studies, we seeded the mouse embryonic cardiac cells, mouse Embryonic Cardiac Cells (mECCs), on the scaffolds and then studied the MoS2 nanocomposites by scanning electron microscopy and Raman spectroscopy. In addition, we characterized the DHAM/PCL and DHAM/PCL-MoS2 by SEM, transmission electron microscopy, water contact angle measurement, electrical conductivity, and tensile test. Besides, we confirmed the scaffolds are biocompatible by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide, MTT assay. Furthermore, by means of SEM images, it was shown that mECCs attached to the DHAM/PCL-MoS2 scaffold have more cell aggregations and elongated morphology. Furthermore, through the Real-Time PCR and immunostaining studies, we found out cardiac genes were maturated and upregulated, and they also included GATA-4, c-TnT, NKX 2.5, and alpha-myosin heavy chain in cells cultured on DHAM/PCL-MoS2 scaffold in comparison to DHAM/PCL and DHAM. Therefore, in terms of cardiac tissue engineering, DHAM nanofibrous scaffolds reinforced by PCL-MoS2 can be suggested as a proper candidate.

Comparison of extracellular matrix enrichment protocols for the improved characterization of the skin matrisome by mass spectrometry

A striking feature of skin organization is that the extracellular matrix (ECM) occupies a larger volume than the cells. Skin ECM also directly contributes to aging and most cutaneous diseases. In recent years, specific ECM enrichment protocols combined with in silico approaches allowed the proteomic description of the matrisome of various organs and tumor samples. Nevertheless, the skin matrisome remains under-studied and protocols allowing the efficient recovery of the diverse ECM found in skin are still to be described. Here, we compared four protocols allowing the enrichment of ECM proteins from adult mouse back skin and found that all protocols led to a significant enrichment (up to 65%) of matrisome proteins when compared to total skin lysates. The protocols based on decellularization and solubility profiling gave the best results in terms of numbers of proteins identified and confirmed that skin matrisome proteins exhibit very diverse solubility and abundance profiles. We also report the first description of the skin matrisome of healthy adult mice that includes 236 proteins comprising 95 core matrisome proteins and 141 associated matrisome proteins. These results provide a reliable basis for future characterizations of skin ECM proteins and their dysregulations in disease-specific contexts. SIGNIFICANCE: Extracellular matrix proteins are key players in skin physiopathology and have been involved in several diseases such as genetic disorders, wound healing defects, scleroderma and skin carcinoma. However, skin ECM proteins are numerous, diverse and challenging to analyze by mass spectrometry due to the multiplicity of their post-translational modifications and to the heterogeneity of their solubility profiles. Here, we performed the thorough evaluation of four ECM enrichment protocols compatible with the proteomic analysis of mouse back skin and provide the first description of the adult mouse skin matrisome in homeostasis conditions. Our work will greatly facilitate the future characterization of skin ECM alterations in preclinical mouse models and will inspire new optimizations to analyze the skin matrisome of other species and of human clinical samples.

Clinical applications of acellular dermal matrices: A review

INTRODUCTION

The extracellular matrix (ECM) plays an integral role in wound healing. It provides both structure and growth factors that allow for the organised cell proliferation. Large or complex tissue defects may compromise host ECM, creating an environment that is unfavourable for the recovery of anatomical function and appearance. Acellular dermal matrices (ADMs) have been developed from a variety of sources, including human (HADM), porcine (PADM) and bovine (BADM), with multiple different processing protocols. The objective of this report is to provide an overview of current literature assessing the clinical utility of ADMs across a broad spectrum of applications.

METHODS

PubMed, MEDLINE, EMBASE, Scopus, Cochrane and Web of Science were searched using keywords 'acellular dermal matrix', 'acellular dermal matrices' and brand names for commercially available ADMs. Our search was limited to English language articles published from 1999 to 2020 and focused on clinical data.

RESULTS

A total of 2443 records underwent screening. After removing non-clinical studies and correspondence, 222 were assessed for eligibility. Of these, 170 were included in our synthesis of the literature. While the earliest ADMs were used in severe burn injuries, usage has expanded to a number of surgical subspecialties and procedures, including orthopaedic surgery (e.g. tendon and ligament reconstructions), otolaryngology, oral surgery (e.g. treating gingival recession), abdominal wall surgery (e.g. hernia repair), plastic surgery (e.g. breast reconstruction and penile augmentation), and chronic wounds (e.g. diabetic ulcers).

CONCLUSION

Our understanding of ADM's clinical utility continues to evolve. More research is needed to determine which ADM has the best outcomes for each clinical scenario.

LAY SUMMARY

Large or complex wounds present unique reconstructive and healing challenges. In normal healing, the extracellular matrix (ECM) provides both structural and growth factors that allow tissue to regenerate in an organised fashion to close the wound. In difficult or large soft-tissue defects, however, the ECM is often compromised. Acellular dermal matrix (ADM) products have been developed to mimic the benefits of host ECM, allowing for improved outcomes in a variety of clinical scenarios. This review summarises the current clinical evidence regarding commercially available ADMs in a wide variety of clinical contexts.

Benefit of coupling heparin to crosslinked collagen I/III scaffolds for human dermal fibroblast subpopulations' tissue growth

Currently, there is a lack of models representing the skin dermal heterogeneity for relevant research and skin engineering applications. This is the first study reporting production of dermal equivalents reproducing features of papillary and reticular dermal compartments. Inspired from our current knowledge on the architecture and composition differences between the papillary and reticular dermis, we evaluated different collagen-based porous materials to serve as scaffolds for the three-dimensional expansion of freshly isolated papillary and/or reticular fibroblasts. The scaffolds, composed of either collagen I or collagen I and III mixtures, were prepared by lyophilization. Pore size and hydrolytic stability were controlled by crosslinking with 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) or EDC/NHS with covalently bound heparin. The evaluation of the resultant "papillary" and "reticular" dermal equivalents was based on the analysis of characteristic features of each dermal compartment, such as cell density and deposition of newly synthetized extracellular matrix components in histological sections. Crosslinking supported cell growth during dermal tissue formation independent on the fibroblast subpopulation. The presence of collagen III seemed to have some positive but non-specific effect only on the maintenance of the mechanical strength of the scaffolds during dermal formation. Histological analyses demonstrated a significant and specific effect of heparin on generating dermal equivalents reproducing the respective higher papillary than reticular cell densities and supporting distinct extracellular matrix components deposition (three to five times more carbohydrate material deposited by papillary fibroblasts in all scaffolds containing heparin, while higher collagen production was observed only in the presence of heparin).

3D-Printed Products for Topical Skin Applications: From Personalized Dressings to Drug Delivery

3D printing has been widely used for the personalization of therapies and on-demand production of complex pharmaceutical forms. Recently, 3D printing has been explored as a tool for the development of topical dosage forms and wound dressings. Thus, this review aims to present advances related to the use of 3D printing for the development of pharmaceutical and biomedical products for topical skin applications, covering plain dressing and products for the delivery of active ingredients to the skin. Based on the data acquired, the important growth in the number of publications over the last years confirms its interest. The semisolid extrusion technique has been the most reported one, probably because it allows the use of a broad range of polymers, creating the most diverse therapeutic approaches. 3D printing has been an excellent field for customizing dressings, according to individual needs. Studies discussed here imply the use of metals, nanoparticles, drugs, natural compounds and proteins and peptides for the treatment of wound healing, acne, pain relief, and anti-wrinkle, among others. The confluence of 3D printing and topical applications has undeniable advantages, and we would like to encourage the research groups to explore this field to improve the patient's life quality, adherence and treatment efficacy.

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.

Optimization of Novel Human Acellular Dermal Dressing Sterilization for Routine Use in Clinical Practice

Gamma rays and electrons with kinetic energy up to 10 MeV are routinely used to sterilize biomaterials. To date, the effects of irradiation upon human acellular dermal matrices (hADMs) remain to be fully elucidated. The optimal irradiation dosage remains a critical parameter affecting the final product structure and, by extension, its therapeutic potential. ADM slides were prepared by various digestion methods. The influence of various doses of radiation sterilization using a high-energy electron beam on the structure of collagen, the formation of free radicals and immune responses to non-irradiated (native) and irradiated hADM was investigated. The study of the structure changes was carried out using the following methods: immunohistology, immunoblotting, and electron paramagnetic resonance (EPR) spectroscopy. It was shown that radiation sterilization did not change the architecture and three-dimensional structure of hADM; however, it significantly influenced the degradation of collagen fibers and induced the production of free radicals in a dose-dependent manner. More importantly, the observed effects did not disrupt the therapeutic potential of the new transplants. Therefore, radiation sterilization at a dose of 35kGy can ensure high sterility of the dressing while maintaining its therapeutic potential.

Ready-to-Use Micronized Human Acellular Dermal Matrix to Accelerate Wound Healing in Diabetic Foot Ulcers: A Prospective Randomized Pilot Study

OBJECTIVE

To examine and report clinical outcomes of a ready-to-use micronized dermal matrix for diabetic foot ulcers (DFUs) and compare it to treatment with conventional negative-pressure wound therapy (NPWT) only.

METHODS

The researchers randomly allocated 30 DFUs Wagner grade 2 or higher from 30 adult patients into two groups. The control group (n = 15) was treated with conventional NPWT, and the experimental group (n = 15) was treated with micronized dermal matrix and NPWT. The researchers evaluated the following outcomes: granulation tissue formation, proportion of patients with closed or granulated wounds at 42 and 120 days, achievement of complete wound healing in the 6 months of follow-up, and intervals from enrollment to final surgical procedures.

RESULTS

All 15 wounds treated with the micronized matrix showed healthy granulation tissue without noticeable complications during follow-up. At 42 days, 46.7% of wounds in the experimental group had closed compared with 28.6% in the conventional NPWT group (P = .007). At 120 days, 86.7% of the experimental group had completely closed wounds, compared with 57.1% in the conventional therapy group (P = .040). During the 6-month follow-up period, 93.3% of the experimental group achieved complete wound healing compared with 85.7% of the conventional therapy group (P = .468).

CONCLUSIONS

The healing outcomes for DFUs in the experimental group were superior when micronized matrix treatment was combined with NPWT.