Supercritical Fluid-Based Decellularization Technologies for Regenerative Medicine Applications

Decellularized kidney capsule as a three-dimensional scaffold for tissue regeneration

Tissue regeneration is thought to have considerable promise with the use of scaffolds designed for tissue engineering. Although polymer-based scaffolds for tissue engineering have been used extensively and developed quickly, their ability to mimic the in-vivo milieu, overcome immunogenicity, and have comparable mechanical or biochemical properties has limited their capability for repair. Fortunately, there is a compelling method to get around these challenges thanks to the development of extracellular matrix (ECM) scaffolds made from decellularized tissues. We used ECM decellularized sheep kidney capsule tissue in our research. Using detergents such as Triton-X100 and sodium dodecyl sulfate (SDS), these scaffolds were decellularized. DNA content, histology, mechanical properties analysis, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), biocompatibility, hemocompatibility and scanning electron microscope (SEM) imaging were measured. The results showed that the three-dimensional (3D) structure of the ECM remained largely intact. The scaffolds mentioned above had several hydrophilic properties. The best biocompatibility and blood compatibility properties were reported in the SDS method of 0.5%. The best decellularization scaffold was introduced with 0.5% SDS. Therefore, it can be proposed as a scaffold that has ECM like natural tissue, for tissue engineering 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.

Molecular dynamics simulation of the interaction between palmitic acid and high pressure CO2

In this study, molecular dynamics simulation was used to explore the interaction characteristics of palmitic acid and CO2, and the effects of temperature and pressure on the solubility of palmitic acid in CO2 were investigated. In the range of 293-353 K and 5-30 MPa, the snapshot of palmitic acid distribution in CO2 shows that the molecular chain of palmitic acid in high-density CO2 system is more straight and more dispersed than that in low-density CO2 system. The radial distribution function further clearly shows that the solubility of palmitic acid in CO2 decreases with the increase of temperature and increases with the increase of pressure, which is consistent with the fatty acid solubility data reported in the literature and the setting rules of supercritical CO2 extraction process conditions. As the temperature decreases and the pressure increases, the interaction energy between palmitic acid and CO2 increases, which is conducive to overcoming the intermolecular force of palmitic acid and promoting dissolution. The solubility parameters of palmitic acid and CO2 can better reflect the trend of palmitic acid solubility changing with temperature and pressure, which can play a guiding role in the determination of process conditions and even the development of new processes.

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.

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.

Application of decellularized vascular matrix in small-diameter vascular grafts

Coronary artery bypass grafting (CABG) remains the most common procedure used in cardiovascular surgery for the treatment of severe coronary atherosclerotic heart disease. In coronary artery bypass grafting, small-diameter vascular grafts can potentially replace the vessels of the patient. The complete retention of the extracellular matrix, superior biocompatibility, and non-immunogenicity of the decellularized vascular matrix are unique advantages of small-diameter tissue-engineered vascular grafts. However, after vascular implantation, the decellularized vascular matrix is also subject to thrombosis and neoplastic endothelial hyperplasia, the two major problems that hinder its clinical application. The keys to improving the long-term patency of the decellularized matrix as vascular grafts include facilitating early endothelialization and avoiding intravascular thrombosis. This review article sequentially introduces six aspects of the decellularized vascular matrix as follows: design criteria of vascular grafts, components of the decellularized vascular matrix, the changing sources of the decellularized vascular matrix, the advantages and shortcomings of decellularization technologies, modification methods and the commercialization progress as well as the application prospects in small-diameter vascular grafts.

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

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

Contributions of supercritical fluid technology for advancing decellularization and postprocessing of viable biological materials

The demand for tissue and organ transplantation worldwide has led to an increased interest in the development of new therapies to restore normal tissue function through transplantation of injured tissue with biomedically engineered matrices. Among these developments is decellularization, a process that focuses on the removal of immunogenic cellular material from a tissue or organ. However, decellularization is a complex and often harsh process that frequently employs techniques that can negatively impact the properties of the materials subjected to it. The need for a more benign alternative has driven research on supercritical carbon dioxide (scCO₂) assisted decellularization. scCO₂ can achieve its critical point at relatively low temperature and pressure conditions, and for its high transfer rate and permeability. These properties make scCO₂ an appealing methodology that can replace or diminish the exposure of harsh chemicals to sensitive materials, which in turn could lead to better preservation of their biochemical and mechanical properties. The presented review covers relevant literature over the last years where scCO₂-assisted decellularization is employed, as well as discussing major topics such as the mechanism of action behind scCO₂-assisted decellularization, CO₂ and cosolvents' solvent properties, effect of the operational parameters on decellularization efficacy and on the material's properties.