Decellularization of Aorta Tissue Using Sonication Treatment as Potential Scaffold for Vascular Tissue Engineering

Physico-chemical characterization of the tumour microenvironment of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive lethal malignancy that accounts for more than 90% of pancreatic cancer diagnoses. Our research is focused on the physico-chemical properties of the tumour microenvironment (TME), including its tumoural extracellular matrix (tECM), as they may have an important impact on the success of cancer therapies. PDAC xenografts and their decellularized tECM offer a great material source for research in terms of biomimicry with the original human tumour. Our aim was to evaluate and quantify the physico-chemical properties of the PDAC TME. Both cellularized (native TME) and decellularized (tECM) patient-derived PDAC xenografts were analyzed. A factorial design of experiments identified an optimal combination of factors for effective xenograft decellularization. Our results provide a complete advance in our understanding of the PDAC TME and its corresponding stroma, showing that it presents an interconnected porous architecture with very low permeability and small pores due to the contractility of the cellular components. This fact provides a potential therapeutic strategy based on the therapeutic agent size.

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.

Decellularized Extracellular Matrix Scaffolds for Cardiovascular Tissue Engineering: Current Techniques and Challenges

Cardiovascular diseases are the leading cause of global mortality. Over the past two decades, researchers have tried to provide novel solutions for end-stage heart failure to address cardiac transplantation hurdles such as donor organ shortage, chronic rejection, and life-long immunosuppression. Cardiac decellularized extracellular matrix (dECM) has been widely explored as a promising approach in tissue-regenerative medicine because of its remarkable similarity to the original tissue. Optimized decellularization protocols combining physical, chemical, and enzymatic agents have been developed to obtain the perfect balance between cell removal, ECM composition, and function maintenance. However, proper assessment of decellularized tissue composition is still needed before clinical translation. Recellularizing the acellular scaffold with organ-specific cells and evaluating the extent of cardiomyocyte repopulation is also challenging. This review aims to discuss the existing literature on decellularized cardiac scaffolds, especially on the advantages and methods of preparation, pointing out areas for improvement. Finally, an overview of the state of research regarding the application of cardiac dECM and future challenges in bioengineering a human heart suitable for transplantation is provided.

Decellularization for the retention of tissue niches

Decellularization of natural tissues to produce extracellular matrix is a promising method for three-dimensional scaffolding and for understanding microenvironment of the tissue of interest. Due to the lack of a universal standard protocol for tissue decellularization, recent investigations seek to develop novel methods for whole or partial organ decellularization capable of supporting cell differentiation and implantation towards appropriate tissue regeneration. This review provides a comprehensive and updated perspective on the most recent advances in decellularization strategies for a variety of organs and tissues, highlighting techniques of chemical, physical, biological, enzymatic, or combinative-based methods to remove cellular contents from tissues. In addition, the review presents modernized approaches for improving standard decellularization protocols for numerous organ types.

Preconditioning process for dermal tissue decellularization using electroporation with sonication

Decellularization to produce bioscaffolds composed of the extracellular matrix (ECM) uses enzymatic, chemical and physical methods to remove antigens and cellular components from tissues. Effective decellularization methods depend on the characteristics of tissues, and in particular, tissues with dense, complex structure and abundant lipid content are difficult to completely decellularize. Our study enables future research on the development of methods and treatments for fabricating bioscaffolds via decellularization of complex and rigid skin tissues, which are not commonly considered for decellularization to date as their structural and functional characteristics could not be preserved after severe decellularization. In this study, decellularization of human dermal tissue was done by a combination of both chemical (0.05% trypsin-EDTA, 2% SDS and 1% Triton X-100) and physical methods (electroporation and sonication). After decellularization, the content of DNA remaining in the tissue was quantitatively confirmed, and the structural change of the tissue and the retention and distribution of ECM components were evaluated through histological and histochemical analysis, respectively. Conditions of the chemical pretreatment that increase the efficiency of physical stimulation as well as decellularization, and conditions for electroporation and sonication without the use of detergents, unlike the methods performed in previous studies, were established to enable the complete decellularization of the skin tissue. The combinatorial decellularization treatment formed micropores in the lipid bilayers of the skin tissues while removing all cell and cellular residues without affecting the ECM properties. Therefore, this procedure can be widely used to fabricate bioscaffolds by decellularizing biological tissues with dense and complex structures.

Development of decellularized aortic scaffold for regenerative medicine using Sapindus mukorossi fruit pericarp extract

The aim of this study is to develop a novel decellularization method using aqueous extract of soap nut pericarp (SPE) and its evaluation using hematoxylin-eosin staining, scanning electron microscopy, diamidino-2-phenylindol (DAPI) staining, mechanical testing, sodium dodecyl sulfate polyacrylamide gel electrophoresis and DNA quantification. The presently available decellularization agent raises some concerns due to the potential for presence of residual cytotoxic agents in the extracellular matrix. Histological analysis of hematoxylin and eosin and masson's trichrome stained processed aortic samples shows complete decellularization with preservation of extracellular matrix microarchitecture at 120 h. Further, staining of tissue samples with DAPI demonstrates complete removal of DNA fragments. Quantitative evaluation of DNA in the decellularized aorta tissues demonstrated a significant (P < 0.01) decrease in DNA content as compared to native tissues. Collagen quantification assay indicate no significant (P> 0.05) difference in its content between native and decellularized caprine aorta. Tensile strength of the decellularized scaffolds decreased non-significantly (P > 0.05) when compared to native tissues. There was no significant (P > 0.05) difference in young's modulus of elasticity, stiffness and stretch ratio between native aortic tissues and decellularized aortic scaffolds. Histological and scanning electron microscopic examination of in vitro cultured scaffold demonstrated the cell viability and proliferation of primary chicken embryo fibroblasts. SPE treatment is thus capable of producing cytocompatible decellularized caprine aorta scaffold with preservation of extracellular matrix architecture for vascular tissue engineering and could be applied widely as one of the decellularization agent.

Combined Use of Detergents and Ultrasonication for Generation of an Acellular Pig Larynx

The larynx is a fairly complex organ comprised of different muscles, cartilages, mucosal membrane, and nerves. Larynx cancer is generally the most common type of head and neck cancer. Treatment options are limited in patients with total or partial laryngectomy. Tissue-engineered organs have shown to be a promising alternative treatment for patients with laryngectomy. In this report we present an alternative and simple procedure to construct a whole pig larynx scaffold consisting of complete acellular structures of integrated muscle and cartilage. Larynges were decellularized (DC) using perfusion-agitation with detergents coupled with ultrasonication. DC larynges were then characterized to investigate the extracellular matrix (ECM) proteins, residual DNA, angiogenic growth factors, and morphological and ultrastructural changes to ECM fibers. After 17 decellularization cycles, no cells were observed in all areas of the larynx as confirmed by hematoxylin and eosin and DAPI (4',6-diamidino-2-phenylindole) staining. However, DC structures of dense thyroid and cricoid cartilage showed remnants of cells. All structures of DC larynges (epiglottis [p < 0.0001], muscle [p < 0.0001], trachea [p = 0.0045], and esophagus [p = 0.0008]) showed DNA <50 ng/mg compared with native larynx. Immunohistochemistry, Masson's trichrome staining, and Luminex analyses showed preservation of important ECM proteins and angiogenic growth factors in DC larynges. Compared with other growth factors, mostly retained growth factors in DC epiglottis, thyroid muscle, and trachea include granulocyte colony-stimulating factor, Leptin, fibroblast growth factor-1, Follistatin, hepatocyte growth factor, and vascular endothelial growth factor-A. Scanning electron microscopy and transmission electron microscopy analysis confirmed the structural arrangements of ECM fibers in larynges to be well preserved after DC. Our findings suggest that larynges can be effectively DC using detergent ultrasonication. ECM proteins and angiogenic growth factors appear to be better preserved using this method when compared with the native structures of larynges. This alternative DC method could be helpful in building scaffolds from dense tissue structures such as cartilage, tendon, larynx, or trachea for future in vitro recellularization studies or in vivo implantation studies in the clinic.

A versatile perfusion bioreactor and endothelializable photo cross-linked tubes of gelatin methacryloyl as promising tools in tissue engineering

Size and function of bioartificial tissue models are still limited due to the lack of blood vessels and dynamic perfusion for nutrient supply. In this study, we evaluated the use of cytocompatible methacryl-modified gelatin for the fabrication of a hydrogel-based tube by dip-coating and subsequent photo-initiated cross-linking. The wall thickness of the tubes and the diameter were tuned by the degree of gelatin methacryl-modification and the number of dipping cycles. The dipping temperature of the gelatin solution was adjusted to achieve low viscous fluids of approximately 0.1 Pa s and was different for gelatin derivatives with different modification degrees. A versatile perfusion bioreactor for the supply of surrounding tissue models was developed, which can be adapted to several geometries and sizes of blood-vessel mimicking tubes. The manufactured bendable gelatin tubes were permeable for water and dissolved substances, like Nile Blue and serum albumin. As a proof of concept, human fibroblasts in a three-dimensional collagen tissue model were successfully supplied with nutrients via the central gelatin tube under dynamic conditions for 2 days. Moreover, the tubes could be used as scaffolds to build-up a functional and viable endothelial layer. Hence, the presented tools can contribute to solving current challenges in tissue engineering.

Vessel graft fabricated by the on-site differentiation of human mesenchymal stem cells towards vascular cells on vascular extracellular matrix scaffold under mechanical stimulation in a rotary bioreactor

Although a significant number of studies on vascular tissue engineering have been reported, the current availability of vessel substitutes in the clinic remains limited mainly due to the mismatch of their mechanical properties and biological functions with native vessels. In this study, a novel approach to fabricating a vessel graft for vascular tissue engineering was developed by promoting differentiation of human bone marrow mesenchymal stem cells (MSCs) into endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) on a native vascular extracellular matrix (ECM) scaffold in a rotary bioreactor. The expression levels of CD31 and vWF, and the LDL uptake capacity as well as the angiogenesis capability of the EC-like cells in the dynamic culture system were significantly enhanced compared to the static system. In addition, α-actin and smoothelin expression, and contractility of VSMC-like cells harvested from the dynamic model were much higher than those in a static culture system. The combination of on-site differentiation of stem cells towards vascular cells in the natural vessel ECM scaffold and maturation of the resulting vessel construct in a dynamic cell culture environment provides a promising approach to fabricating a clinically applicable vessel graft with similar mechanical properties and physiological functions to those of native blood vessels.

The use of heparin, bFGF, and VEGF 145 grafted acellular vascular scaffold in small diameter vascular graft

We aim to test the application of heparin, bFGF, and VEGF 145 grafted acellular vascular scaffold in small diameter vascular graft. The amount of bFGF and VEGF 145 were determined by ELISA. Femoral artery transplantation was performed. Mechanical strength of acellular vascular scaffolds was determined. Angiography was performed for blood vessel patency. Factor VIII and α2-actin expression was detected by immunohistochemistry. bFGF and VEGF 145 had stable release at 60 and 70 days in vitro, and the release rate of VEGF 145 was slightly slower than that of bFGF. After transplantation, 9 months of the vascular patency rate was 100% at 1, 3, and 9 months, and, was up to 90% at 18 months, while the patency rate in group with grafted heparin only at 1-month was 60%, at 3-month was 40%, at 9-month was 15%, and at 18-month was 10%. The blood vessels taken after 18 months had no significant difference in the mechanical properties between the transplanted and the natural vessels. Positive expression of factor VIII and α2-actin was observed. The heparinized and bFGF and VEGF 145 grafted allogeneic vascular acellular scaffolds are preliminarily obtained, which show good biocompatibility and patency and are of great importance for small diameter vascular graft. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 00B: 000-000, 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 672-679, 2019.

Evaluation of recellularization on decellularized aorta scaffolds engineered by ultrasonication treatment

Aortic scaffolds prepared using sonication decellularization treatment has provided a successful medium for repopulation with vascular smooth muscle cells (VSMCs). The objective of this study is to explore the potential of tissue decellularization using ultrasonication treatment and its recellularization before implantation of the cell-seeded scaffolds into host. Aorta tissue samples are decellularized in 2% SDS with sonication for 10 hours and compared with the native tissues. The 4',6-diamidino-2-phenylindole (DAPI) staining was used to evaluate the decellularization and Hematoxylin-Eosin (H-E) staining was used to compare the VSMCs infiltrations onto the decellularized tissues at day-0 and day-6 after cell-seeding. The results histologically showed complete DNA removal from scaffolds after decellularization and subsequent recellularization resulted in successful VSMCs infiltration. Accordingly, the decellularized tissues treated with 2% SDS in sonication demonstrated successful VSMCs repopulation afterward and is speculated to have less toxicity and able to be effectively implanted into host.

Evaluation of histological and biomechanical properties on engineered meniscus tissues using sonication decellularization

Sonication decellularization treatment requires proper evaluations on its ability to decellularize meniscus tissue efficiently. This study was done to evaluate the histological and biomechanical properties within meniscus scaffolds. Van Gieson staining was done to evaluate the efficiency of cell removal in meniscus tissues. The consequences of treatment on viscoelastic properties are vital for scaffolds quality and were properly investigated. Picrosirius red and Safranin-O/Fast green staining was carried out to detect extracellular matrix materials (ECM). Sonication decellularization treatment has the ability to demonstrated complete nuclei removal compare to control samples as well as maintaining viscoelastic properties, namely stiffness, compression and residual force. Thus, sonication decellularization treatment had successfully produced and prepared a meniscus bioscaffold candidate in which its biomechanical strength is sustained through protection of ECM properties.

Cell-free vascular grafts: Recent developments and clinical potential

Recent advances in vascular tissue engineering have led to the development of cell-free grafts that are available off-the-shelf for on demand surgery. Challenges associated with cell-based technologies including cell sourcing, cell expansion and long-term bioreactor culture motivated the development of completely cell-free vascular grafts. These are based on decellularized arteries, decellularized cultured cell-based tissue engineered grafts or biomaterials functionalized with biological signals that promote in situ tissue regeneration. Clinical trials undertaken to demonstrate the applicability of these grafts are also discussed. This comprehensive review summarizes recent developments in vascular graft technologies, with potential applications in coronary artery bypass procedures, lower extremity bypass, vascular injury and trauma, congenital heart diseases and dialysis access shunts, to name a few.