Tissue-Specific Decellularization Methods: Rationale and Strategies to Achieve Regenerative Compounds

Decellularized porcine peripheral nerve based injectable hydrogels as a Schwann cell carrier for injured spinal cord regeneration

Objective.To develop a clinically relevant injectable hydrogel derived from decellularized porcine peripheral nerves and with mechanical properties comparable to native central nervous system (CNS) tissue to be used as a delivery vehicle for Schwann cell transplantation to treat spinal cord injury (SCI).Approach.Porcine peripheral nerves (sciatic and peroneal) were decellularized by chemical decellularization using a sodium deoxycholate and DNase (SDD) method previously developed by our group. The decellularized nerves were delipidated using dichloromethane and ethanol solvent and then digested using pepsin enzyme to form injectable hydrogel formulations. Genipin was used as a crosslinker to enhance mechanical properties. The injectability, mechanical properties, and gelation kinetics of the hydrogels were further analyzed using rheology. Schwann cells encapsulated within the injectable hydrogel formulations were passed through a 25-gauge needle and cell viability was assessed using live/dead staining. The ability of the hydrogel to maintain Schwann cell viability against an inflammatory milieu was assessedin vitrousing inflamed astrocytes co-cultured with Schwann cells.Mainresults. The SDD method effectively removes cells and retains extracellular matrix in decellularized tissues. Using rheological studies, we found that delipidation of decellularized porcine peripheral nerves using dichloromethane and ethanol solvent improves gelation kinetics and mechanical strength of hydrogels. The delipidated and decellularized hydrogels crosslinked using genipin mimicked the mechanical strength of CNS tissue. The hydrogels were found to have shear thinning properties desirable for injectable formulations and they also maintained higher Schwann cell viability during injection compared to saline controls. Usingin vitroco-culture experiments, we found that the genipin-crosslinked hydrogels also protected Schwann cells from astrocyte-mediated inflammation.Significance. Injectable hydrogels developed using delipidated and decellularized porcine peripheral nerves are a potential clinically relevant solution to deliver Schwann cells, and possibly other therapeutic cells, at the SCI site by maintaining higher cellular viability and increasing therapeutic efficacy for SCI treatment.

Optimizing decellularization protocols for human thyroid tissues: a step towards tissue engineering and transplantation

Hypothyroidism is caused by insufficient stimulation or disruption of the thyroid. However, the drawbacks of thyroid transplantation have led to the search for new treatments. Decellularization allows tissue transplants to maintain their biomimetic structures while preserving cell adhesion, proliferation, and differentiation. This study aimed to decellularize human thyroid tissues using a structure-preserving optimization strategy and present preliminary data on recellularization. Nine methods were used for physical and chemical decellularization. Quantitative and immunohistochemical analyses were performed to investigate the DNA and extracellular matrix components of the tissues. Biomechanical properties were determined by compression test, and cell viability was examined after seeding MDA-T32 papillary thyroid cancer (PTC) cells onto the decellularized tissues. Decellularized tissues exhibited a notable decrease (<50 ng mg-1DNA, except for Groups 2 and 7) compared to the native thyroid tissue. Nonetheless, collagen and glycosaminoglycans were shown to be conserved in all decellularized tissues. Laminin and fibronectin were preserved at comparatively higher levels, and Young's modulus was elevated when decellularization included SDS. It was observed that the strain value in Group 1 (1.63 ± 0.14 MPa) was significantly greater than that in the decellularized tissues between Groups 2-9, ranging from 0.13 ± 0.03-0.72 ± 0.29 MPa. Finally, viability assessment demonstrated that PTC cells within the recellularized tissue groups successfully attached to the 3D scaffolds and sustained metabolic activity throughout the incubation period. We successfully established a decellularization optimization for human thyroid tissues, which has potential applications in tissue engineering and transplantation research. Our next goal is to conduct recellularization using the methods utilized in Group 1 and transplant the primary thyroid follicular cell-seeded tissues into anin vivoanimal model, particularly due to their remarkable 3D structural preservation and cell adhesion-promoting properties.

Paintable Decellularized-ECM Hydrogel for Preventing Cardiac Tissue Damage

The tissue-specific heart decellularized extracellular matrix (hdECM) demonstrates a variety of therapeutic advantages, including fibrosis reduction and angiogenesis. Consequently, recent research for myocardial infarction (MI) therapy has utilized hdECM with various delivery techniques, such as injection or patch implantation. In this study, a novel approach for hdECM delivery using a wet adhesive paintable hydrogel is proposed. The hdECM-containing paintable hydrogel (pdHA_t) is simply applied, with no theoretical limit to the size or shape, making it highly beneficial for scale-up. Additionally, pdHA_t exhibits robust adhesion to the epicardium, with a minimal swelling ratio and sufficient adhesion strength for MI treatment when applied to the rat MI model. Moreover, the adhesiveness of pdHA_t can be easily washed off to prevent undesired adhesion with nearby organs, such as the rib cages and lungs, which can result in stenosis. During the 28 days of in vivo analysis, the pdHA_t not only facilitates functional regeneration by reducing ventricular wall thinning but also promotes neo-vascularization in the MI region. In conclusion, the pdHA_t presents a promising strategy for MI treatment and cardiac tissue regeneration, offering the potential for improved patient outcomes and enhanced cardiac function post-MI.

Evaluation of Different Decellularization Protocols for Obtaining and Characterizing Canine Cardiac Extracellular Matrix

Cardiovascular diseases are considered the leading cause of mortality globally; even with low mortality in dogs, such diseases are described in the same way in companion animals and humans. This study aimed to devise an effective decellularization protocol for the canine myocardium through the association of physical, chemical, and enzymatic methods, assessing resultant alterations in the myocardial extracellular matrix to obtain a suitable scaffold. Two canine hearts were collected; the samples were sectioned into ±1 cm2 fragments, washed in distilled water and 1× PBS solution, and followed by treatment under four distinct decellularization protocols. Sodium Dodecyl Sulfate (SDS) 1% 7 days + Triton X-100 1% for 48 h (Protocol I); Sodium Dodecyl Sulfate (SDS) 1% 5 days + Triton X-100 1% for 48 h (Protocol II); Trypsin 0.05% for 1 h at 36 °C + freezing -80 °C overnight + Sodium Dodecyl Sulfate (SDS) 1% for 3 days, Triton-X-100 for 48 h hours (Protocol III); 0.05% trypsin for 1 h at 36 °C + freezing at -80 °C overnight + 1% Sodium Dodecyl Sulfate (SDS) for 2 days + 1% Triton-X-100 for 24 h (Protocol IV). After analysis, Protocols I and II showed the removal of cellular content and preservation of extracellular matrix (ECM) contents, unlike Protocols III and IV, which retracted the ECM and removed essential elements of the matrix. In theory, although Protocols I and II have similar results, Protocol II stands out for the preservation of the architecture and components of the extracellular matrix, along with reduced exposure time to reagents, making it the recommended protocol for the development of a canine myocardial scaffold.

Development of porcine skeletal muscle extracellular matrix-derived hydrogels with improved properties and low immunogenicity

Hydrogels derived from decellularized extracellular matrices (ECM) of animal origin show immense potential for regenerative applications due to their excellent cytocompatibility and biomimetic properties. Despite these benefits, the impact of decellularization protocols on the properties and immunogenicity of these hydrogels remains relatively unexplored. In this study, porcine skeletal muscle ECM (smECM) underwent decellularization using mechanical disruption (MD) and two commonly employed decellularization detergents, sodium deoxycholate (SDC) or Triton X-100. To mitigate immunogenicity associated with animal-derived ECM, all decellularized tissues were enzymatically treated with α-galactosidase to cleave the primary xenoantigen-the α-Gal antigen. Subsequently, the impact of the different decellularization protocols on the resultant hydrogels was thoroughly investigated. All methods significantly reduced total DNA content in hydrogels. Moreover, α-galactosidase treatment was crucial for cleaving α-Gal antigens, suggesting that conventional decellularization methods alone are insufficient. MD preserved total protein, collagen, sulfated glycosaminoglycan, laminin, fibronectin, and growth factors more efficiently than other protocols. The decellularization method impacted hydrogel gelation kinetics and ultrastructure, as confirmed by turbidimetric and scanning electron microscopy analyses. MD hydrogels demonstrated high cytocompatibility, supporting satellite stem cell recruitment, growth, and differentiation into multinucleated myofibers. In contrast, the SDC and Triton X-100 protocols exhibited cytotoxicity. Comprehensive in vivo immunogenicity assessments in a subcutaneous xenotransplantation model revealed MD hydrogels' biocompatibility and low immunogenicity. These findings highlight the significant influence of the decellularization protocol on hydrogel properties. Our results suggest that combining MD with α-galactosidase treatment is an efficient method for preparing low-immunogenic smECM-derived hydrogels with enhanced properties for skeletal muscle regenerative engineering and clinical applications.

Exploring the properties and potential of the neural extracellular matrix for next-generation regenerative therapies

The extracellular matrix (ECM) is a dynamic and complex network of proteins and molecules that surrounds cells and tissues in the nervous system and orchestrates a myriad of biological functions. This review carefully examines the diverse interactions between cells and the ECM, as well as the transformative chemical and physical changes that the ECM undergoes during neural development, aging, and disease. These transformations play a pivotal role in shaping tissue morphogenesis and neural activity, thereby influencing the functionality of the central nervous system (CNS). In our comprehensive review, we describe the diverse behaviors of the CNS ECM in different physiological and pathological scenarios and explore the unique properties that make ECM-based strategies attractive for CNS repair and regeneration. Addressing the challenges of scalability, variability, and integration with host tissues, we review how advanced natural, synthetic, and combinatorial matrix approaches enhance biocompatibility, mechanical properties, and functional recovery. Overall, this review highlights the potential of decellularized ECM as a powerful tool for CNS modeling and regenerative purposes and sets the stage for future research in this exciting field. This article is categorized under: Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement Therapeutic Approaches and Drug Discovery > Nanomedicine for Neurological Disease Implantable Materials and Surgical Technologies > Nanomaterials and Implants.

Application of extracellular matrix cross-linked by microbial transglutaminase to promote wound healing

One primary focus of skin tissue engineering has been the creation of innovative biomaterials to facilitate rapid wound healing. Extracellular matrix (ECM), an essential biofunctional substance, has recently been discovered to play a crucial role in wound healing. Consequently, we endeavored to decellularize ECM from pig achilles tendon and refine its mechanical and biological properties through modification by utilizing cross-linking agents. Glutaraldehyde (GA), 1-ethyl-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS), double aldol starch (DAS), and microbial transglutaminase (MTG) were utilized to produce crosslinked ECM variants (GA-ECM, EDC/NHS-ECM, DAS-ECM, and MTG-ECM). Comprehensive assessments were conducted to evaluate the physical properties, biocompatibility, and wound healing efficacy of each material. The results indicated that MTG-ECM exhibited superior tensile strength, excellent hydrophilicity, minimal cytotoxicity, and the best pro-healing impact among the four modified scaffolds. Staining analysis of tissue sections further revealed that MTG-ECM impeded the transition from type III collagen to type I collagen in the wound area, potentially reducing the development of wound scar. Therefore, MTG-ECM is expected to be a potential pro-skin repair scaffold material to prevent scar formation.

Preparation of Decellularized Tissue as Dual Cell Carrier Systems: A Step Towards Facilitating Re-epithelization and Cell Encapsulation for Tracheal Reconstruction

Surgical treatment of tracheal diseases, trauma, and congenital stenosis has shown success through tracheal reconstruction coupled with palliative care. However, challenges in surgical-based tracheal repairs have prompted the exploration of alternative approaches for tracheal replacement. Tissue-based treatments, involving the cultivation of patient cells on a network of extracellular matrix (ECM) from donor tissue, hold promise for restoring tracheal structure and function without eliciting an immune reaction. In this study, we utilized decellularized canine tracheas as tissue models to develop two types of cell carriers: a decellularized scaffold and a hydrogel. Our hypothesis posits that both carriers, containing essential biochemical niches provided by ECM components, facilitate cell attachment without inducing cytotoxicity. Canine tracheas underwent vacuum-assisted decellularization (VAD), and the ECM-rich hydrogel was prepared through peptic digestion of the decellularized trachea. The decellularized canine trachea exhibited a significant reduction in DNA content and major histocompatibility complex class II, while preserving crucial ECM components such as collagen, glycosaminoglycan, laminin, and fibronectin. Scanning electron microscope and fluorescent microscope images revealed a fibrous ECM network on the luminal side of the cell-free trachea, supporting epithelial cell attachment. Moreover, the ECM-rich hydrogel exhibited excellent viability for human mesenchymal stem cells encapsulated for 3 days, indicating the potential of cell-laden hydrogel in promoting the development of cartilage rings of the trachea. This study underscores the versatility of the trachea in producing two distinct cell carriers-decellularized scaffold and hydrogel-both containing the native biochemical niche essential for tracheal tissue engineering applications.

Decellularized brain extracellular matrix based NGF-releasing cryogel for brain tissue engineering in traumatic brain injury

Traumatic brain injuries(TBI) pose significant challenges to human health, specifically neurological disorders and related motor activities. After TBI, the injured neuronal tissue is known for hardly regenerated and recovered to their normal neuron physiology and tissue compositions. For this reason, tissue engineering strategies that promote neuronal regeneration have gained increasing attention. This study explored the development of a novel neural tissue regeneration cryogel by combining brain-derived decellularized extracellular matrix (ECM) with heparin sulfate crosslinking that can perform nerve growth factor (NGF) release ability. Morphological and mechanical characterizations of the cryogels were performed to assess their suitability as a neural regeneration platform. After that, the heparin concnentration dependent effects of varying NGF concentrations on cryogel were investigated for their controlled release and impact on neuronal cell differentiation. The results revealed a direct correlation between the concentration of released NGF and the heparin sulfate ratio in cryogel, indicating that the cryogel can be tailored to carry higher loads of NGF with heparin concentration in cryogel that induced higher neuronal cell differentiation ratio. Furthermore, the study evaluated the NGF loaded cryogels on neuronal cell proliferation and brain tissue regeneration in vivo. The in vivo results suggested that the NGF loaded brain ECM derived cryogel significantly affects the regeneration of brain tissue. Overall, this research contributes to the development of advanced neural tissue engineering strategies and provides valuable insights into the design of regenerative cryogels that can be customized for specific therapeutic applications.

Comparative analysis of supercritical fluid-based and chemical-based decellularization techniques for nerve tissue regeneration

Axon regeneration and Schwann cell proliferation are critical processes in the repair and functional recovery of damaged neural tissues. Biomaterials can play a crucial role in facilitating cell proliferative processes that can significantly impact the target tissue repair. Chemical decellularization and supercritical fluid-based decellularization methods are similar approaches that eliminate DNA from native tissues for tissue-mimetic biomaterial production by using different solvents and procedures to achieve the final products. In this study, we conducted a comparative analysis of these two methods in the context of nerve regeneration and neuron cell differentiation efficiency. We evaluated the efficacy of each method in terms of biomaterial quality, preservation of extracellular matrix components, promotion of neuronal cell differentiation and nerve tissue repair ability in vivo. Our results indicate that while both methods produce high-quality biomaterials, supercritical fluid-based methods have several advantages over conventional chemical decellularization, including better preservation of extracellular matrix components and mechanical properties and superior promotion of cellular responses. We conclude that supercritical fluid-based methods show great promise for biomaterial production for nerve regeneration and neuron cell differentiation applications.

Chemical, Physical, and Biological Corneal Decellularization Methods: A Review of Literature

The cornea is one of the most commonly transplanted tissues worldwide. It is used to restore vision when severe visual impairment or blindness occurs in patients with corneal diseases or after trauma. Due to the global shortage of healthy donor corneas, decellularized corneal tissue has significant potential as an alternative to corneal transplantation. It preserves the native and biological ultrastructure of the cornea and, therefore, represents the most promising scaffold. This article discusses different methods of corneal decellularization based on the current literature. We searched PubMed.gov for articles from January 2009 to December 2023 using the following keywords: corneal decellularization, decellularization methods, and corneal transplantation. Although several methods of decellularization of corneal tissue have been reported, a universal standardised protocol of corneal decellularization has not yet been introduced. In general, a combination of decellularization methods has been used for efficient decellularization while preserving the optimal properties of the corneal tissue.

Characterization and biocompatibility evaluation of acellular rat skin scaffolds for skin tissue engineering applications

Utilization of acellular scaffolds, extracellular matrix (ECM) without cell content, is growing in tissue engineering, due to their high biocompatibility, bioactivity ad mechanical support. Hence, the purpose of this research was to study the characteristics and biocompatibility of decellularized rat skin scaffolds using the osmotic shock method. First, the skin of male Wistar rats was harvested and cut into 1 × 1 cm2 pieces. Then, some of the harvested parts were subjected to the decellularization process by applying osmotic shock. Comparison of control and scaffold samples was conducted in order to assure cell elimination and ECM conservation by means of histological evaluations, quantification of biochemical factors, measurement of DNA amount, and photographing the ultrastructure of the samples by scanning electron microscopy (SEM). In order to evaluate stem cell viability and adhesion to the scaffold, adipose-derived mesenchymal stem cells (AD-MSCs) were seeded on the acellular scaffolds. Subsequently, MTT test and SEM imaging of the scaffolds containing cultured cells were applied. The findings indicated that in the decellularized scaffolds prepared by osmotic shock method, not only the cell content was removed, but also the ECM components and its ultrastructure were preserved. Also, the 99% viability and adhesion of AD-MSCs cultured on the scaffolds indicate the biocompatibility of the decellularized skin scaffold. In conclusion, decellularized rat skin scaffolds are biocompatible and appropriate scaffolds for future investigations of tissue engineering applications.

Molecular analysis of the extracellular microenvironment: from form to function

The extracellular matrix (ECM) proteome represents an important component of the tissue microenvironment that controls chemical flux and induces cell signaling through encoded structure. The analysis of the ECM represents an analytical challenge through high levels of post-translational modifications, protease-resistant structures, and crosslinked, insoluble proteins. This review provides a comprehensive overview of the analytical challenges involved in addressing the complexities of spatially profiling the extracellular matrix proteome. A synopsis of the process of synthesizing the ECM structure, detailing inherent chemical complexity, is included to present the scope of the analytical challenge. Current chromatographic and spatial techniques addressing these challenges are detailed. Capabilities for multimodal multiplexing with cellular populations are discussed with a perspective on developing a holistic view of disease processes that includes both the cellular and extracellular microenvironment.

Enhancement of Wound Healing and Angiogenesis Using Mouse Embryo Fibroblasts Loaded in Decellularized Skin Scaffold

Background

Synthetic and natural polymer scaffolds can be used to design wound dressing for repairing the damaged skin tissue. This study investigated acute wound healing process using a decellularized skin scaffold and mouse embryo fibroblast (MEF).

Methods

Mouse skin fragments were decellularized and evaluated by DNA content, toxicity, H&E staining, Raman confocal microscopy, Masson’s trichrome staining, SEM, and biodegradation assays. The fragments were recellularized by the MEFs, and cell attachment and penetration were studied. De- and decellularized scaffolds were used wound dressings in mouse acute wound models as two experimental groups. Using morphological and immunohistochemical assessments, wound healing was evaluated and compared among the experimental and control groups.

Results

DNA content of the decellularized tissue significantly reduced compared to the native control group (7% vs. 100%; p < 0.05). extracellular matrix components, e.g. collagen types I, III, and IV, elastin, and glycosaminoglycan, were well preserved in the decellularized group. The porosity and fiber arrangement in the stroma had a structure similar to normal skin tissue. A significant reduction in healing time was observed in the group treated with a decellularized scaffold. A thicker epidermis layer was observed in the recovered tissue in both experimental groups compared to the control group. Immunostaining showed a positive reaction for CD31 as an endothelial marker in both experimental groups, confirming new vascularization in these groups.

Conclusion

Using MEFs with decellularized skin as a wound dressing increases the rate of wound healing and also the formation of new capillaries. This system could be beneficial for clinical applications in the field of tissue engineering.

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.

Proteomic analysis of decellularized mice liver and kidney extracellular matrices

BACKGROUND

The extracellular matrix (ECM) is a three-dimensional network of proteins that encases and supports cells within a tissue and promotes physiological and pathological cellular differentiation and functionality. Understanding the complex composition of the ECM is essential to decrypt physiological processes as well as pathogenesis. In this context, the method of decellularization is a useful technique to eliminate cellular components from tissues while preserving the majority of the structural and functional integrity of the ECM.

RESULTS

In this study, we employed a bottom-up proteomic approach to elucidate the intricate network of proteins in the decellularized extracellular matrices of murine liver and kidney tissues. This approach involved the use of a novel, perfusion-based decellularization protocol to generate acellular whole organ scaffolds. Proteomic analysis of decellularized mice liver and kidney ECM scaffolds revealed tissue-specific differences in matrisome composition, while we found a predominantly stable composition of the core matrisome, consisting of collagens, glycoproteins, and proteoglycans. Liver matrisome analysis revealed unique proteins such as collagen type VI alpha-6, fibrillin-2 or biglycan. In the kidney, specific ECM-regulators such as cathepsin z were detected.

CONCLUSION

The identification of distinct proteomic signatures provides insights into how different matrisome compositions might influence the biological properties of distinct tissues. This experimental workflow will help to further elucidate the proteomic landscape of decellularized extracellular matrix scaffolds of mice in order to decipher complex cell-matrix interactions and their contribution to a tissue-specific microenvironment.

Decellularization and Their Significance for Tissue Regeneration in the Era of 3D Bioprinting

Three-dimensional bioprinting is an emerging technology that has high potential application in tissue engineering and regenerative medicine. Increasing advancement and improvement in the decellularization process have led to an increase in the demand for using a decellularized extracellular matrix (dECM) to fabricate tissue engineered products. Decellularization is the process of retaining the extracellular matrix (ECM) while the cellular components are completely removed to harvest the ECM for the regeneration of various tissues and across different sources. Post decellularization of tissues and organs, they act as natural biomaterials to provide the biochemical and structural support to establish cell communication. Selection of an effective method for decellularization is crucial, and various factors like tissue density, geometric organization, and ECM composition affect the regenerative potential which has an impact on the end product. The dECM is a versatile material which is added as an important ingredient to formulate the bioink component for constructing tissue and organs for various significant studies. Bioink consisting of dECM from various sources is used to generate tissue-specific bioink that is unique and to mimic different biometric microenvironments. At present, there are many different techniques applied for decellularization, and the process is not standardized and regulated due to broad application. This review aims to provide an overview of different decellularization procedures, and we also emphasize the different dECM-derived bioinks present in the current global market and the major clinical outcomes. We have also highlighted an overview of benefits and limitations of different decellularization methods and various characteristic validations of decellularization and dECM-derived bioinks.

Omentum Extracellular Matrix-Silk Fibroin Hydroscaffold Promotes Wound Healing through Vascularization and Tissue Remodeling in the Diabetic Rat Model

Nonhealing diabetic wounds are often associated with significant mortality and cause economic and clinical burdens to the healthcare system. Herein, a biomimetic hydroscaffold is developed using omentum tissue-derived decellularized-extracellular matrix (dECM) and silk fibroin (SF) proteins that associate the behavior of a collagenous fibrous scaffold and a hydrogel to reproduce all aspects of the provisional skin tissue matrix. The chemical cross-linker-free in situ gelation property of the two types of SF proteins from Bombyx mori and Antheraea assamensis ensures the adherence of dECM with surrounding tissue on the wound bed, circumventing further suturing. The physicochemical and mechanical properties of the composite hydroscaffold (SF-dECM) were thoroughly evaluated. The hydroscaffolds were found to support the growth and proliferation of human dermal fibroblasts and influence the angiogenic potential of endothelial cells under in vitro conditions. Furthermore, the healing efficacy of the composites was evaluated by generating full-thickness wounds on a streptozotocin-induced diabetic rat model. The presence of dECM components in the composite facilitated the rate of wound closure, granulation tissue formation, and re-epithelialization by providing intrinsic cues to advance the inflammatory stage and stimulating angiogenesis. Collectively, as an off-the-shelf wound dressing requiring only a single topical administration, the SF-dECM hydroscaffold is a promising, cost-effective dressing for the management of chronic diabetic wounds.

Cultivated Meat from Aligned Muscle Layers and Adipose Layers Formed from Glutenin Films

Cultivated meat production is a promising technology to generate meat while reducing the reliance on traditional animal farming. Biomaterial scaffolds are critical components in cultivated meat production, enabling cell adhesion, proliferation, differentiation, and orientation. In the present work, naturally derived glutenin was fabricated into films with and without surface patterning and in the absence of toxic cross-linking or stabilizing agents for cell culture related to cultivated meat goals. The films were stable in culture media for at least 28 days, and the surface patterns induced cell alignment and guided myoblast organization (C2C12s) and served as a substrate for 3T3-L1 adipose cells. The films supported adhesion, proliferation, and differentiation with mass balance considerations (films, cells, and matrix production). Freeze-thaw cycles were applied to remove cells from glutenin films and monitor changes in glutenin mass with respect to culture duration. Extracellular matrix (ECM) extraction was utilized to quantify matrix deposition and changes in the original biomaterial mass over time during cell cultivation. Glutenin films with C2C12s showed mass increases with time due to cell growth and new collagen-based ECM expression during proliferation and differentiation. All mass balances were compared among cell and noncell systems as controls, along with gelatin control films, with time-dependent changes in the relative content of film, matrix deposition, and cell biomass. These data provide a foundation for cell/biomaterial/matrix ratios related to time in culture as well as nutritional and textural features.

Characterisation of Matrix-Bound Nanovesicles (MBVs) Isolated from Decellularised Bovine Pericardium: New Frontiers in Regenerative Medicine

Matrix-bound nanovesicles (MBVs) are a recently discovered type of extracellular vesicles (EVs), and they are characterised by a strong adhesion to extracellular matrix structural proteins (ECM) and ECM-derived biomaterials. MBVs contain a highly bioactive and tissue-specific cargo that recapitulates the biological activity of the source ECM. The rich content of MBVs has shown to be capable of potent cell signalling and of modulating the immune system, thus the raising interest for their application in regenerative medicine. Given the tissue-specificity and the youthfulness of research on MBVs, until now they have only been isolated from a few ECM sources. Therefore, the objective of this research was to isolate and identify the presence of MBVs in decellularised bovine pericardium ECM and to characterise their protein content, which is expected to play a major role in their biological potential. The results showed that nanovesicles, corresponding to the definition of recently described MBVs, could be isolated from decellularised bovine pericardium ECM. Moreover, these MBVs were composed of numerous proteins and cytokines, thus preserving a highly potential biological effect. Overall, this research shows that bovine pericardium MBVs show a rich and tissue-specific biological potential.

Exploring polysaccharide and protein-enriched decellularized matrix scaffolds for tendon and ligament repair: A review

Tissue engineering (TE) has become a primary research topic for the treatment of diseased or damaged tendon/ligament (T/L) tissue. T/L injuries pose a severe clinical burden worldwide, necessitating the development of effective strategies for T/L repair and tissue regeneration. TE has emerged as a promising strategy for restoring T/L function using decellularized extracellular matrix (dECM)-based scaffolds. dECM scaffolds have gained significant prominence because of their native structure, relatively high bioactivity, low immunogenicity, and ability to function as scaffolds for cell attachment, proliferation, and differentiation, which are difficult to imitate using synthetic materials. Here, we review the recent advances and possible future prospects for the advancement of dECM scaffolds for T/L tissue regeneration. We focus on crucial scaffold properties and functions, as well as various engineering strategies employed for biomaterial design in T/L regeneration. dECM provides both the physical and mechanical microenvironments required by cells to survive and proliferate. Various decellularization methods and sources of allogeneic and xenogeneic dECM in T/L repair and regeneration are critically discussed. Additionally, dECM hydrogels, bio-inks in 3D bioprinting, and nanofibers are briefly explored. Understanding the opportunities and challenges associated with dECM-based scaffold development is crucial for advancing T/L repairs in tissue engineering and regenerative medicine.

Decellularized Extracellular Matrix for Modeling Cardiac Extracellular Microenvironment

The extracellular matrix (ECM) forms most of the tissue microenvironment and is in a constant and dynamic equilibrium with cells. The decellularization process employs physical or chemical methods, or a combination of them, to remove the cellular components of tissues and organs while preserving the architecture and composition of the ECM. Depending on the methodology used, the decellularized ECM (dECM) is then suitable for research or clinical applications. Here, we describe an optimized protocol for the efficient decellularization of the human myocardium to generate 3D scaffolds of well-preserved cardiac extracellular matrix that can be used for in vitro or in vivo studies.

Decellularized extracellular matrix and silk fibroin-based hybrid biomaterials: A comprehensive review on fabrication techniques and tissue-specific applications

Biomaterials play a fundamental role in tissue engineering by providing biochemical and physical cues that influence cellular fate and matrix development. Decellularized extracellular matrix (dECM) as a biomaterial is distinguished by its abundant composition of matrix proteins, such as collagen, elastin, fibronectin, and laminin, as well as glycosaminoglycans and proteoglycans. However, the mechanical properties of only dECM-based constructs may not always meet tissue-specific requirements. Recent advancements address this challenge by utilizing hybrid biomaterials that harness the strengths of silk fibroin (SF), which contributes the necessary mechanical properties, while dECM provides essential cellular cues for in vitro studies and tissue regeneration. This review discusses emerging trends in developing such biopolymer blends, aiming to synergistically combine the advantages of SF and dECM through optimal concentrations and desired cross-linking density. We focus on different fabrication techniques and cross-linking methods that have been utilized to fabricate various tissue-engineered hybrid constructs. Furthermore, we survey recent applications of such biomaterials for the regeneration of various tissues, including bone, cartilage, trachea, bladder, vascular graft, heart, skin, liver, and other soft tissues. Finally, the trajectory and prospects of the constructs derived from this blend in the tissue engineering field have been summarized, highlighting their potential for clinical translation.

Injectable Xenogeneic Dental Pulp Decellularized Extracellular Matrix Hydrogel Promotes Functional Dental Pulp Regeneration

The present challenge in dental pulp tissue engineering scaffold materials lies in the development of tissue-specific scaffolds that are conducive to an optimal regenerative microenvironment and capable of accommodating intricate root canal systems. This study utilized porcine dental pulp to derive the decellularized extracellular matrix (dECM) via appropriate decellularization protocols. The resultant dECM was dissolved in an acid pepsin solution to form dECM hydrogels. The analysis encompassed evaluating the microstructure and rheological properties of dECM hydrogels and evaluated their biological properties, including in vitro cell viability, proliferation, migration, tube formation, odontogenic, and neurogenic differentiation. Gelatin methacrylate (GelMA) hydrogel served as the control. Subsequently, hydrogels were injected into treated dentin matrix tubes and transplanted subcutaneously into nude mice to regenerate dental pulp tissue in vivo. The results showed that dECM hydrogels exhibited exceptional injectability and responsiveness to physiological temperature. It supported the survival, odontogenic, and neurogenic differentiation of dental pulp stem cells in a 3D culture setting. Moreover, it exhibited a superior ability to promote cell migration and angiogenesis compared to GelMA hydrogel in vitro. Additionally, the dECM hydrogel demonstrated the capability to regenerate pulp-like tissue with abundant blood vessels and a fully formed odontoblast-like cell layer in vivo. These findings highlight the potential of porcine dental pulp dECM hydrogel as a specialized scaffold material for dental pulp regeneration.

Enhanced recellularization by using albumin coating with roller bottle cell culture

Introduction

The decellularization and recellularization is a promising approach for tissue engineering and regenerative medicine. However, the decellularization process depletes important components like glycosaminoglycans (GAGs), affecting cell attachment and causing immunogenicity. Studies have explored various surface modification strategies to enhance recellularization.

Methods

To optimize the decellularization method, we employed whole kidney perfusion and slice kidney immersion/agitation techniques. The decellularized extracellular matrix (dECM) was then analyzed using hematoxylin and eosin (H&E) staining, scanning electron microscope (SEM), and DNA quantification. To enhance cell proliferation efficiency, albumin coating and rotating culture were applied. Also, we evaluated in vitro blood clot formation on the albumin-coated dECM by immersing it in blood.

Results

After decellularization, the unique structures of the kidney were preserved whether cellular components were removed. Subsequently, we utilized albumin coating and rotating culture for recellularization, and observed that albumin-coated dECM not only promoted high cell proliferation rates but also prevented blood clot formation.

Conclusion

The albumin-coated dECM promoted cell proliferation and reduced blood clot formation in vitro. Also, dynamic culture condition using rotating culture allowed for improved cellular penetration into the dECM, leading to a conductive environment for enhanced tissue infiltration. This new approach suggests that the combined utilization of albumin coating and rotating culture conditions can improve the efficiency of recellularization.

Detergent-Based Decellularization for Anisotropic Cardiac-Specific Extracellular Matrix Scaffold Generation

Cell-derived extracellular matrix (ECM) has become increasingly popular in tissue engineering applications due to its ability to provide tailored signals for desirable cellular responses. Anisotropic cardiac-specific ECM scaffold decellularized from human induced pluripotent stem cell (hiPSC)-derived cardiac fibroblasts (hiPSC-CFs) mimics the native cardiac microenvironment and provides essential biochemical and signaling cues to hiPSC-derived cardiomyocytes (hiPSC-CMs). The objective of this study was to assess the efficacy of two detergent-based decellularization methods: (1) a combination of ethylenediaminetetraacetic acid and sodium dodecyl sulfate (EDTA + SDS) and (2) a combination of sodium deoxycholate and deoxyribonuclease (SD + DNase), in preserving the composition and bioactive substances within the aligned ECM scaffold while maximumly removing cellular components. The decellularization effects were evaluated by characterizing the ECM morphology, quantifying key structural biomacromolecules, and measuring preserved growth factors. Results showed that both treatments met the standard of cell removal (less than 50 ng/mg ECM dry weight) and substantially preserved major ECM biomacromolecules and growth factors. The EDTA + SDS treatment was more time-efficient and has been determined to be a more efficient method for generating an anisotropic ECM scaffold from aligned hiPSC-CFs. Moreover, this cardiac-specific ECM has demonstrated effectiveness in supporting the alignment of hiPSC-CMs and their expression of mature structural and functional proteins in in vitro cultures, which is crucial for cardiac tissue engineering.

Evaluation of Vascular Endothelial Growth Factor Gene Expression in Recellularized Liver Tissue by Mouse Embryo Fibroblast

Background

The aim of the present study was to evaluate alterations in the vegf gene expression as an angiogenic factor in mouse embryo fibroblasts seeded on the decellularized liver fragments.

Methods

Liver tissue samples (n = 10) collected from adult male mice were randomly divided into decellularized and native control groups. Tissues were decellularized by treating with 1% Triton X-100 and 0.1% SDS for 24 hours and assessed by H&E staining and SEM. Then DNA content analysis and toxicity tests were performed. By centrifugation, DiI-labeled mouse embryo fibroblasts were seeded on each scaffold and cultured for one week. The recellularized scaffolds were studied by H&E staining, SEM, and LSCM. After RNA extraction and cDNA synthesis, the expression of the vegf gene in these samples was investigated using real-time RT-PCR.

Results

Our observations showed that the decellularized tissues had morphology and porous structure similar to the control group, and their DNA content significantly reduced (p < 0.05) and reached to 4.12% of the control group. The MTT test indicated no significant cellular toxicity for the decellularized scaffolds. Light microscopy, SEM, and LSCM observations confirmed the attachment and penetration of embryonic fibroblast cells on the surface and into different depths of the scaffolds. There was no statistically significant difference in terms of vegf gene expression in the cultured cells in the presence and absence of a scaffold.

Conclusion

The reconstructed scaffold had no effect on vegf gene expression. Decellularized mouse liver tissue recellularized by embryonic fibroblasts could have an application in regenerative medicine.

Nerve regeneration using decellularized tissues: challenges and opportunities

In tissue engineering, the decellularization of organs and tissues as a biological scaffold plays a critical role in the repair of neurodegenerative diseases. Various protocols for cell removal can distinguish the effects of treatment ability, tissue structure, and extracellular matrix (ECM) ability. Despite considerable progress in nerve regeneration and functional recovery, the slow regeneration and recovery potential of the central nervous system (CNS) remains a challenge. The success of neural tissue engineering is primarily influenced by composition, microstructure, and mechanical properties. The primary objective of restorative techniques is to guide existing axons properly toward the distal end of the damaged nerve and the target organs. However, due to the limitations of nerve autografts, researchers are seeking alternative methods with high therapeutic efficiency and without the limitations of autograft transplantation. Decellularization scaffolds, due to their lack of immunogenicity and the preservation of essential factors in the ECM and high angiogenic ability, provide a suitable three-dimensional (3D) substrate for the adhesion and growth of axons being repaired toward the target organs. This study focuses on mentioning the types of scaffolds used in nerve regeneration, and the methods of tissue decellularization, and specifically explores the use of decellularized nerve tissues (DNT) for nerve transplantation.

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.

Developing Bovine Brain-Derived Extracellular Matrix Hydrogels: a Screen of Decellularization Methods for Their Impact on Biochemical and Mechanical Properties

Tissue models that recapitulate the key biochemical and physical aspects of the brain have been highly pursued in neural tissue engineering. Decellularization of native organs offers the advantage of preserving the composition of native extracellular matrix (ECM). Brain ECM has distinct features which play a major role in neural cell behavior. Cell instructive ligands and mechanical properties take part in the regulation of cellular processes in homeostasis and diseases. One of the main challenges in decellularization is maintaining mechanical integrity in reconstituted hydrogels and achieving physiologically relevant stiffness. The effect of the decellularization process on different mechanical aspects, particularly the viscoelasticity of brain-derived hydrogels, has not been addressed. In this study, we developed bovine brain-derived hydrogels for the first time. We pursued seven protocols for decellularization and screened their effect on biochemical content, hydrogel formation, and mechanical characteristics. We show that bovine brain offers an easily accessible alternative for in vitro brain tissue modeling. Our data demonstrate that the choice of decellularization method strongly alters gelation as well as the stiffness and viscoelasticity of the resulting hydrogels. Lastly, we investigated the cytocompatibility of brain ECM hydrogels and the effect of modulated mechanical properties on the growth and morphological features of neuroblastoma cells.

Decellularized extracellular matrix in the treatment of spinal cord injury

Functional limitation caused by spinal cord injury (SCI) has the problem of significant clinical and economic burden. Damaged spinal axonal connections and an inhibitory environment severely hamper neuronal function. Regenerative biomaterials can fill the cavity and produce an optimal microenvironment at the site of SCI, inhibiting apoptosis, inflammation, and glial scar formation while promoting neurogenesis, axonal development, and angiogenesis. Decellularization aims to eliminate cells from the ultrastructure of tissues while keeping tissue-specific components that are similar to the structure of real tissues, making decellularized extracellular matrix (dECM) a suitable scaffold for tissue engineering. dECM has good biocompatibility, it can be widely obtained from natural organs of different species, and can be co-cultured with cells for 3D printing to obtain the target scaffold. In this paper, we reviewed the pathophysiology of SCI, the characteristics of dECM and its preparation method, and the application of dECM in the treatment of SCI. Although dECM has shown its therapeutic effect at present, there are still many indicators that need to be taken into account, such as the difficulty in obtaining materials and standardized production mode for large-scale use, the effect of decellularization on the physical and chemical properties of dECM, and the study on the synergistic effect of dECM and cells.

A proposed model of xeno-keratoplasty using 3D printing and decellularization

Corneal opacity is a leading cause of vision impairment and suffering worldwide. Transplantation can effectively restore vision and reduce chronic discomfort. However, there is a considerable shortage of viable corneal graft tissues. Tissue engineering may address this issue by advancing xeno-keratoplasty as a viable alternative to conventional keratoplasty. In particular, livestock decellularization strategies offer the potential to generate bioartificial ocular prosthetics in sufficient supply to match existing and projected needs. To this end, we have examined the best practices and characterizations that have supported the current state-of-the-art driving preclinical and clinical applications. Identifying the challenges that delimit activities to supplement the donor corneal pool derived from acellular scaffolds allowed us to hypothesize a model for keratoprosthesis applications derived from livestock combining 3D printing and decellularization.

Soft Biomimetic Approach for the Development of Calcinosis-Resistant Glutaraldehyde-Fixed Biomaterials for Cardiovascular Surgery

Pathological aseptic calcification is the most common form of structural valvular degeneration (SVD), leading to premature failure of heart valve bioprostheses (BHVs). The processing methods used to obtain GA-fixed pericardium-based biomaterials determine the hemodynamic characteristics and durability of BHVs. This article presents a comparative study of the effects of several processing methods on the degree of damage to the ECM of GA-fixed pericardium-based biomaterials as well as on their biostability, biocompatibility, and resistance to calcification. Based on the assumption that preservation of the native ECM structure will enable the creation of calcinosis-resistant materials, this study provides a soft biomimetic approach for the manufacture of GA-fixed biomaterials using gentle decellularization and washing methods. It has been shown that the use of soft methods for preimplantation processing of materials, ensuring maximum preservation of the intactness of the pericardial ECM, radically increases the resistance of biomaterials to calcification. These obtained data are of interest for the development of new calcinosis-resistant biomaterials for the manufacture of BHVs.

Co-Culture of Mouse Blastocysts on A Human Recellularized Endometrial Scaffold: An In Vitro Model for Future Implantation Studies

OBJECTIVE

This study evaluates the interaction of mouse blastocysts as a surrogate embryo on a recellularized endometrial scaffold by seeding human endometrial mesenchymal cells (hEMCs).

MATERIALS AND METHODS

In this experimental study, prepared decellularized human endometrial tissues were characterized by morphological staining, DNA content analysis, and scanning electron microscopic (SEM) analysis. The scaffolds were subsequently recellularized by hEMCs. After seven days of cultivation, the mouse blastocysts were co-cultured on the recellularized scaffolds for 48 hours. Embryo attachment and implantation within these scaffolds were evaluated at the morphological, ultrastructural, molecular, and hormonal levels.

RESULTS

There was no morphological evidence of cells and nuclei in the decellularized scaffold. DNA content significantly decreased by 89.92% compared to the control group (P<0.05). Both decellularized and native tissues had similar patterns of collagen bundles and elastin fibers, and glycosaminoglycan (GAGs) distribution in the stroma. After recellularization, the hEMCs attached to the scaffold surface and penetrated different parts of these scaffolds. In the co-cultured group, the embryo attached to the surface of the scaffold after 24 hours and penetrated the recellularized endometrial tissue after 48 hours. We observed multi-layered organoid-like structures formed by hEMC proliferation. The relative expressions of epithelial-related genes, ZO-1 and COL4A1, and SSP1, MMP2, and PRL, as decidualizationrelated genes, were significantly higher in the recellularized group on day 9 in the presence of the embryo compared to the other groups (P<0.05). Beta human chorionic gonadotropin (β-hCG) and prolactin were statistically increased in the recellularized group on day 9 group (P<0.05).

CONCLUSION

hEMCs and mouse embryo co-cultured on a decellularized endometrial scaffold provides an alternative model to study embryo implantation and the earlier stage of embryo development.

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.

Extracellular Matrix Proteomics: The mdx-4cv Mouse Diaphragm as a Surrogate for Studying Myofibrosis in Dystrophinopathy

The progressive degeneration of the skeletal musculature in Duchenne muscular dystrophy is accompanied by reactive myofibrosis, fat substitution, and chronic inflammation. Fibrotic changes and reduced tissue elasticity correlate with the loss in motor function in this X-chromosomal disorder. Thus, although dystrophinopathies are due to primary abnormalities in the DMD gene causing the almost-complete absence of the cytoskeletal Dp427-M isoform of dystrophin in voluntary muscles, the excessive accumulation of extracellular matrix proteins presents a key histopathological hallmark of muscular dystrophy. Animal model research has been instrumental in the characterization of dystrophic muscles and has contributed to a better understanding of the complex pathogenesis of dystrophinopathies, the discovery of new disease biomarkers, and the testing of novel therapeutic strategies. In this article, we review how mass-spectrometry-based proteomics can be used to study changes in key components of the endomysium, perimysium, and epimysium, such as collagens, proteoglycans, matricellular proteins, and adhesion receptors. The mdx-4cv mouse diaphragm displays severe myofibrosis, making it an ideal model system for large-scale surveys of systematic alterations in the matrisome of dystrophic fibers. Novel biomarkers of myofibrosis can now be tested for their appropriateness in the preclinical and clinical setting as diagnostic, pharmacodynamic, prognostic, and/or therapeutic monitoring indicators.

Comparison of Bovine- and Porcine-Derived Decellularized Biomaterials: Promising Platforms for Tissue Engineering Applications

Animal-derived xenogeneic biomaterials utilized in different surgeries are promising for various applications in tissue engineering. However, tissue decellularization is necessary to attain a bioactive extracellular matrix (ECM) that can be safely transplanted. The main objective of the present study is to assess the structural integrity, biocompatibility, and potential use of various acellular biomaterials for tissue engineering applications. Hence, a bovine pericardium (BP), porcine pericardium (PP), and porcine tunica vaginalis (PTV) were decellularized using a Trypsin, Triton X (TX), and sodium dodecyl sulfate (SDS) (Trypsin + TX + SDS) protocol. The results reveal effective elimination of the cellular antigens with preservation of the ECM integrity confirmed via staining and electron microscopy. The elasticity of the decellularized PP (DPP) was markedly (p < 0.0001) increased. The tensile strength of DBP, and DPP was not affected after decellularization. All decellularized tissues were biocompatible with persistent growth of the adipose stem cells over 30 days. The staining confirmed cell adherence either to the peripheries of the materials or within their matrices. Moreover, the in vivo investigation confirmed the biocompatibility and degradability of the decellularized scaffolds. Conclusively, Trypsin + TX + SDS is a successful new protocol for tissue decellularization. Moreover, decellularized pericardia and tunica vaginalis are promising scaffolds for the engineering of different tissues with higher potential for the use of DPP in cardiovascular applications and DBP and DPTV in the reconstruction of higher-stress-bearing abdominal walls.

Extracellular Matrix-Based and Electrospun Scaffolding Systems for Vaginal Reconstruction

Congenital vaginal anomalies and pelvic organ prolapse affect different age groups of women and both have significant negative impacts on patients' psychological well-being and quality of life. While surgical and non-surgical treatments are available for vaginal defects, their efficacy is limited, and they often result in long-term complications. Therefore, alternative treatment options are urgently needed. Fortunately, tissue-engineered scaffolds are promising new treatment modalities that provide an extracellular matrix (ECM)-like environment for vaginal cells to adhere, secrete ECM, and be remodeled by host cells. To this end, ECM-based scaffolds or the constructs that resemble ECM, generated by self-assembly, decellularization, or electrospinning techniques, have gained attention from both clinicians and researchers. These biomimetic scaffolds are highly similar to the native vaginal ECM and have great potential for clinical translation. This review article aims to discuss recent applications, challenges, and future perspectives of these scaffolds in vaginal reconstruction or repair strategies.

Pipeline for precise insoluble matrisome coverage in tissue extracellular matrices

The extracellular matrix (ECM) is assembled by hundreds of proteins orchestrating tissue patterning and surrounding cell fates via the mechanical-biochemical feedback loop. Aberrant ECM protein production or assembly usually creates pathological niches eliciting lesions that mainly involve fibrogenesis and carcinogenesis. Yet, our current knowledge about the pathophysiological ECM compositions and alterations in healthy or diseased tissues is limited since the methodology for precise insoluble matrisome coverage in the ECM is a "bottleneck." Our current study proposes an enhanced sodium dodecyl sulfonate (E-SDS) workflow for thorough tissue decellularization and an intact pipeline for the accurate identification and quantification of highly insoluble ECM matrisome proteins. We tested this pipeline in nine mouse organs and highlighted the full landscape of insoluble matrisome proteins in the decellularized ECM (dECM) scaffolds. Typical experimental validations and mass spectrometry (MS) analysis confirmed very little contamination of cellular debris remaining in the dECM scaffolds. Our current study will provide a low-cost, simple, reliable, and effective pipeline for tissue insoluble matrisome analysis in the quest to comprehend ECM discovery proteomic studies.

The effect of decellularization protocols on characterizations of thermoresponsive and light-curable corneal extracellular matrix hydrogels

To compare the effects of two decellularization protocols on the characteristics of fabricated COrnea Matrix (COMatrix) hydrogels. Porcine corneas were decellularized with Detergent (De) or Freeze-Thaw (FT)-based protocols. DNA remnant, tissue composition and α-Gal epitope content were measured. The effect of α-galactosidase on α-Gal epitope residue was assessed. Thermoresponsive and light-curable (LC) hydrogels were fabricated from decellularized corneas and characterized with turbidimetric, light-transmission and rheological experiments. The cytocompatibility and cell-mediated contraction of the fabricated COMatrices were assessed. Both protocols reduced the DNA content to < 0.1 µg/mg (native, > 0.5 µg/mg), and preserved the collagens and glycosaminoglycans. The α-Gal epitope remnant decreased by > 50% following both decellularization methods. We observed more than 90% attenuation in α-Gal epitope after treatment with α-galactosidase. The thermogelation half-time of thermoresponsive COMatrices derived from De-Based protocol (De-COMatrix) was 18 min, similar to that of FT-COMatrix (21 min). The rheological characterizations revealed significantly higher shear moduli of thermoresponsive FT-COMatrix (300.8 ± 22.5 Pa) versus De-COMatrix 178.7 ± 31.3 Pa, p < 0.01); while, this significant difference in shear moduli was preserved after fabrication of FT-LC-COMatrix and De-LC-COMatrix (18.3 ± 1.7 vs 2.8 ± 2.6 kPa, respectively, p < 0.0001). All thermoresponsive and light-curable hydrogels have similar light-transmission to human corneas. Lastly, the obtained products from both decellularization methods showed excellent in vitro cytocompatibility. We found that FT-LC-COMatrix was the only fabricated hydrogel with no significant cell-mediated contraction while seeded with corneal mesenchymal stem cells (p < 0.0001). The significant effect of decellularization protocols on biomechanical properties of hydrogels derived from porcine corneal ECM should be considered for further applications.

Extracellular matrix composition analysis of human articular cartilage for the development of organ-on-a-chip

INTRODUCTION

Articular cartilage has a complex extracellular matrix (ECM) that provides it a defined architecture for its load-bearing properties. The complete understanding of ECM components is imperative for developing biomimetic organ-on-a-chip tissue construct.

OBJECTIVE

This study aimed to decellularize and characterize the ECM for its protein profiling to generate a niche for enhanced chondrocyte proliferation.

METHODS

Articular cartilage scrapings were subjected to mechanical and collagenase digestion, followed by sodium dodecyl sulfate (SDS) treatment for 8 h and 16 h. The de-cellularization efficiency was confirmed by hematoxylin & eosin, alcian blue, masson's trichrome staining, and scanning electron microscopy (SEM). The ECM protein profile was quantified by liquid chromatography tandem mass spectrometry (LC-MS/MS) using a bottom-up approach.

RESULTS

Histological characterization revealed void lacunae that lacked staining for cellular components. The ECM, sulfated glycosaminoglycan content, and collagen fibers were preserved after 8 h and 16 h of de-cellularization. The SEM ultrastructure images showed that few chondrocytes adhered to the ECM after 8 h and cell-free ECM after 16 h of de-cellularization. LC-MS/MS analysis identified 66 proteins with heterotypic collagen types COL1A1-COL6A1, COL14A1, COL22A1 and COL25A1 showed moderate fold change and expression levels, while COL18A1, COL26A1, chondroitin sulfate, matrix metalloproteinase-9 (MMP9), fibronectin, platelet glycoprotein 1 beta alpha (GP1BA), vimentin, bone morphogenetic protein 6 (BMP6), fibroblast growth factor 4 (FGF4) and growth hormone receptor (GHR) showed maximum fold change and expression levels.

CONCLUSIONS

The standardized de-cellularization process could preserve majority of ECM components, providing structural integrity and architecture to the ECM. The Identified proteins quantified for their expression levels provided insight into engineering the ECM composition for developing cartilage-on-a-chip.

Recent Advances in Decellularized Extracellular Matrix-Based Bioinks for 3D Bioprinting in Tissue Engineering

In recent years, three-dimensional (3D) bioprinting has been widely utilized as a novel manufacturing technique by more and more researchers to construct various tissue substitutes with complex architectures and geometries. Different biomaterials, including natural and synthetic materials, have been manufactured into bioinks for tissue regeneration using 3D bioprinting. Among the natural biomaterials derived from various natural tissues or organs, the decellularized extracellular matrix (dECM) has a complex internal structure and a variety of bioactive factors that provide mechanistic, biophysical, and biochemical signals for tissue regeneration and remodeling. In recent years, more and more researchers have been developing the dECM as a novel bioink for the construction of tissue substitutes. Compared with other bioinks, the various ECM components in dECM-based bioink can regulate cellular functions, modulate the tissue regeneration process, and adjust tissue remodeling. Therefore, we conducted this review to discuss the current status of and perspectives on dECM-based bioinks for bioprinting in tissue engineering. In addition, the various bioprinting techniques and decellularization methods were also discussed in this study.

Patient Derived Organoids (PDOs), Extracellular Matrix (ECM), Tumor Microenvironment (TME) and Drug Screening: State of the Art and Clinical Implications of Ovarian Cancer Organoids in the Era of Precision Medicine

Ovarian cancer (OC) has the highest mortality rate of all gynecological malignancies due to the high prevalence of advanced stages of diagnosis and the high rate of recurrence. Furthermore, the heterogeneity of OC tumors contributes to the rapid development of resistance to conventional chemotherapy. In recent years, in order to overcome these problems, targeted therapies have been introduced in various types of tumors, including gynecological cancer. However, the lack of predictive biomarkers showing different clinical benefits limits the effectiveness of these therapies. This requires the development of preclinical models that can replicate the histological and molecular characteristics of OC subtypes. In this scenario, organoids become an important preclinical model for personalized medicine. In fact, patient-derived organoids (PDO) recapture tumor heterogeneity with the possibility of performing drug screening. However, to best reproduce the patient’s characteristics, it is necessary to develop a specific extracellular matrix (ECM) and introduce a tumor microenvironment (TME), which both represent an actual object of study to improve drug screening, particularly when used in targeted therapy and immunotherapy to guide therapeutic decisions. In this review, we summarize the current state of the art for the screening of PDOs, ECM, TME, and drugs in the setting of OC, as well as discussing the clinical implications and future perspectives for the research of OC organoids.

Nuclei on the Rise: When Nuclei-Based Methods Meet Next-Generation Sequencing

In the last decade, we have witnessed an upsurge in nuclei-based studies, particularly coupled with next-generation sequencing. Such studies aim at understanding the molecular states that exist in heterogeneous cell populations by applying increasingly more affordable sequencing approaches, in addition to optimized methodologies developed to isolate and select nuclei. Although these powerful new methods promise unprecedented insights, it is important to understand and critically consider the associated challenges. Here, we provide a comprehensive overview of the rise of nuclei-based studies and elaborate on their advantages and disadvantages, with a specific focus on their utility for transcriptomic sequencing analyses. Improved designs and appropriate use of the various experimental strategies will result in acquiring biologically accurate and meaningful information.

Research progress in decellularized extracellular matrix hydrogels for intervertebral disc degeneration

As one of the most common clinical disorders, low back pain (LBP) influences patient quality of life and causes substantial social and economic burdens. Many factors can result in LBP, the most common of which is intervertebral disc degeneration (IDD). The progression of IDD cannot be alleviated by conservative or surgical treatments, and gene therapy, growth factor therapy, and cell therapy have their own limitations. Recently, research on the use of hydrogel biomaterials for the treatment of IDD has garnered great interest, and satisfactory treatment results have been achieved. This article describes the classification of hydrogels, the methods of decellularized extracellular matrix (dECM) production and the various types of gel formation. The current research on dECM hydrogels for the treatment of IDD is described in detail in this article. First, an overview of the material sources, decellularization methods, and gel formation methods is given. The focus is on research performed over the last three years, which mainly consists of bovine and porcine NP tissues, while for decellularization methods, combinations of several approaches are primarily used. dECM hydrogels have significantly improved mechanical properties after the polymers are cross-linked. The main effects of these gels include induction of stem cell differentiation to intervertebral disc (IVD) cells, good mechanical properties to restore IVD height after polymer cross-linking, and slow release of exosomes. Finally, the challenges and problems still faced by dECM hydrogels for the treatment of IDD are summarised, and potential solutions are proposed. This paper is the first to summarise the research on dECM hydrogels for the treatment of IDD and aims to provide a theoretical reference for subsequent studies.

Current Trends on Bioengineering Approaches for Ovarian Microenvironment Reconstruction

Ovarian tissue has a unique microarchitecture and a complex cellular and molecular dynamics that are essential for follicular survival and development. Due to this great complexity, several factors may lead to ovarian insufficiency, and therefore to systemic metabolic disorders and female infertility. Techniques currently used in the reproductive clinic such as oocyte cryopreservation or even ovarian tissue transplant, although effective, have several limitations, which impair their wide application. In this scenario, mimetic ovarian tissue reconstruction comes as an innovative alternative to develop new methodologies for germ cells preservation and ovarian functions restoration. The ovarian extracellular matrix (ECM) is crucial for oocyte viability maintenance, once it acts actively in folliculogenesis. One of the key components of ovarian bioengineering is biomaterials application that mimics ECM and provides conditions for cell anchorage, proliferation, and differentiation. Therefore, this review aims at describing ovarian tissue engineering approaches and listing the main limitations of current methods for preservation and reestablishment of ovarian fertility. In addition, we describe the main elements that structure this study field, highlighting the main advances and the challenges to overcome to develop innovative methodologies to be applied in reproductive medicine. Impact Statement This review presents the main advances in the application of tissue bioengineering in the ovarian tissue reconstruction to develop innovative solutions for ovarian fertility reestablishment.

Different Decellularization Methods in Bovine Lung Tissue Reveals Distinct Biochemical Composition, Stiffness, and Viscoelasticity in Reconstituted Hydrogels

Extracellular matrix (ECM)-derived hydrogels are in demand for use in lung tissue engineering to mimic the native microenvironment of cells in vitro. Decellularization of native tissues has been pursued for preserving organotypic ECM while eliminating cellular content and reconstitution into scaffolds which allows re-cellularization for modeling homeostasis, regeneration, or diseases. Achieving mechanical stability and understanding the effects of the decellularization process on mechanical parameters of the reconstituted ECM hydrogels present a challenge in the field. Stiffness and viscoelasticity are important characteristics of tissue mechanics that regulate crucial cellular processes and their in vitro representation in engineered models is a current aspiration. The effect of decellularization on viscoelastic properties of resulting ECM hydrogels has not yet been addressed. The aim of this study was to establish bovine lung tissue decellularization for the first time via pursuing four different protocols and characterization of reconstituted decellularized lung ECM hydrogels for biochemical and mechanical properties. Our data reveal that bovine lungs provide a reproducible alternative to human lungs for disease modeling with optimal retention of ECM components upon decellularization. We demonstrate that the decellularization method significantly affects ECM content, stiffness, and viscoelastic properties of resulting hydrogels. Lastly, we examined the impact of these aspects on viability, morphology, and growth of lung cancer cells, healthy bronchial epithelial cells, and patient-derived lung organoids.

Supercritical carbon dioxide-decellularized arteries exhibit physiologic-like vessel regeneration following xenotransplantation in rats

Currently, many techniques are used for decellularization of grafts, including physical, enzymatic, and chemical treatments. Indeed, decellularized xenogenic grafts provide superior outcomes than alternative synthetic conduits. However, vascular grafts produced by these methods are not perfect; their defects include defective vessel wall structures, detergent residues, and the development of aneurysms after grafting. Therefore, it is essential to develop a more appropriate process to produce decellularized vascular grafts. Supercritical carbon dioxide (ScCO₂) has been used in decellularization technologies in recent years. It is beneficial for the long-term preservation of tissues and regeneration of new vessels. We have previously reported that ScCO₂-produced acellular porcine corneas show excellent biocompatibility following lamellar corneal transplantation in rabbits. In this study, we wanted to use this method to fabricate vascular grafts (ScCO₂-decellularized rabbit femoral artery (DFA)) and analyze their efficacy, parameters regarding rejection by the recipient's (ACI/NKyo rats) immune system and biocompatibility, structural regeneration, and functionality in vivo. The results indicated that the ScCO₂-DFA showed higher biocompatibility, enhanced chemotactic migration of endothelial progenitor cells, lower risk of vasculopathy, lower inflammatory and splenic immune responses, and better physiological-like tension responses after xenotransplantation (XTP) in ACI/NKyo rats compared with the results obtained after XTP using detergent decellularized vascular grafts (SDS-DFA). In conclusion, ScCO₂ is an excellent decellularization technique in the fabrication of biocompatible vascular grafts and has tremendous application in vascular regenerative medicine.

Constructing 3D In Vitro Models of Heterocellular Solid Tumors and Stromal Tissues Using Extrusion-Based Bioprinting

Malignant tumor tissues exhibit inter- and intratumoral heterogeneities, aberrant development, dynamic stromal composition, diverse tissue phenotypes, and cell populations growing within localized mechanical stresses in hypoxic conditions. Experimental tumor models employing engineered systems that isolate and study these complex variables using in vitro techniques are under development as complementary methods to preclinical in vivo models. Here, advances in extrusion bioprinting as an enabling technology to recreate the three-dimensional tumor milieu and its complex heterogeneous characteristics are reviewed. Extrusion bioprinting allows for the deposition of multiple materials, or selected cell types and concentrations, into models based upon physiological features of the tumor. This affords the creation of complex samples with representative extracellular or stromal compositions that replicate the biology of patient tissue. Biomaterial engineering of printable materials that replicate specific features of the tumor microenvironment offer experimental reproducibility, throughput, and physiological relevance compared to animal models. In this review, we describe the potential of extrusion-based bioprinting to recreate the tumor microenvironment within in vitro models.

Current approaches for the recreation of cardiac ischaemic environment in vitro

Myocardial ischaemia is one of the leading dead causes worldwide. Although animal experiments have historically provided a wealth of information, animal models are time and money consuming, and they usually miss typical human patient's characteristics associated with ischemia prevalence, including aging and comorbidities. Generating reliable in vitro models that recapitulate the human cardiac microenvironment during an ischaemic event can boost the development of new drugs and therapeutic strategies, as well as our understanding of the underlying cellular and molecular events, helping the optimization of therapeutic approaches prior to animal and clinical testing. Although several culture systems have emerged for the recreation of cardiac physiology, mimicking the features of an ischaemic heart tissue in vitro is challenging and certain aspects of the disease process remain poorly addressed. Here, current in vitro cardiac culture systems used for modelling cardiac ischaemia, from self-aggregated organoids to scaffold-based constructs and heart-on-chip platforms are described. The advantages of these models to recreate ischaemic hallmarks such as oxygen gradients, pathological alterations of mechanical strength or fibrotic responses are highlighted. The new models represent a step forward to be considered, but unfortunately, we are far away from recapitulating all complexity of the clinical situations.