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

Development and in vitro evaluation of biomimetic injectable hydrogels from decellularized human nerves for central nervous system regeneration

Injuries to the central nervous system (CNS) often lead to persistent inflammation and limited regeneration. This study developed a clinically relevant injectable hydrogel derived from decellularized human peripheral nerves, with mechanical properties biomimicking native CNS tissue. Using a modified Hudson method, human sciatic nerves were decellularized, effectively removing immunogenic cellular debris while retaining the extracellular matrix. Two delipidation solvents, dichloromethane: ethanol (2:1 v/v) and n-hexane: isopropanol (3:1 v/v), were evaluated, with the former achieving optimal lipid removal and better digestion. The resulting solution was crosslinked with genipin, forming an injectable hydrogel (iHPN) that gelled within 12 min at 37 °C and exhibited mechanical stiffness of approximately 400 Pa. Human astrocytes, human microglial cell clone 3 (HMC3), and mouse RAW 264.7 macrophages were cultured individually within iHPN, with lipopolysaccharide (LPS) added to mimic CNS inflammation following injury. Compared to LPS-activated cells on tissue culture plates (TCP), astrocytes within iHPN maintained a quiescent state, as evidenced by reduced GFAP expression and IL-1β secretion. RAW 264.7 and HMC3 cells in iHPN displayed an anti-inflammatory phenotype, as shown by increased CD206 and decreased CD86/CD68 expression, along with higher IL-4 and lower TNF-α/IL-1β secretion. Human SH-SY5Y neuroblastoma cells exhibited higher viability and improved neuronal differentiation in iHPN compared to TCP. Human brain neurons had higher neuronal differentiation within iHPN compared to TCP or collagen hydrogels. Overall, iHPN is a novel injectable hydrogel that has potential for minimally invasive CNS applications, such as a carrier for cell or drug delivery and/or a biomaterial to support axonal growth.

Innovative approaches to tissue engineering: Utilizing decellularized extracellular matrix hydrogels for mesenchymal stem cell transport

In recent years, the realm of tissue regeneration experienced significant advancements, leading to the development of innovative therapeutic agents. The systemic delivery of mesenchymal stem cells (MSCs) emerged as a promising strategy for promoting tissue regeneration. However, this approach is hindered by hurdles such as poor cell survival, limited cell propagation, and inadequate cell integration. Decellularized extracellular matrix (dECM) hydrogel serves as an innovative carrier that protects MSCs from the detrimental effects of the hostile microenvironment, facilitates their localization and retention at the injection site, and preserves their viability. Regarding its low immunogenicity, low cytotoxicity, high biocompatibility, and its ability to mimic natural extracellular matrix (ECM), this natural hydrogel offers a new avenue for systemic delivery of MSCs. This review digs into the properties of dECM hydrogels (dECMHs), the methods employed for decellularization and the utilization of dECMH as carriers for various types of MSCs for tissue regeneration purposes. This review also sheds light on the benefits of hybrid hydrogels composed of dECMH and other components such as proteins and polysaccharides. By addressing the limitations of conventional hydrogels and enhancing efficacy of cell therapy, dECMH opens new pathways for the future of tissue regeneration.

Supercritical CO2-Mediated Decellularization of Bovine Spinal Cord Meninges: A Comparative Study for Decellularization Performance

The extracellular matrix (ECM) of spinal meninge tissue closely resembles the wealthy ECM content of the brain and spinal cord. The ECM is typically acquired through the process of decellularizing tissues. Nevertheless, the decellularization process of the brain and spinal cord is challenging due to their high-fat content, in contrast to the spinal meninges. Hence, bovine spinal cord meninges offer a promising source to produce ECM-based scaffolds, thanks to their abundance, accessibility, and ease of decellularization for neural tissue engineering. However, most decellularization techniques involve disruptive chemicals and repetitive rinsing processes, which could lead to drastic modifications in the tissue ultrastructure and a loss of mechanical stability. Over the past decade, supercritical fluid technology has experienced considerable advancements in fabricating biomaterials with its applications spreading out to tissue engineering to tackle the complications mentioned above. Supercritical carbon-dioxide (scCO2)-based decellularization procedures especially offer a significant advantage over classical decellularization techniques, enabling the preservation of extracellular matrix components and structures. In this study, we decellularized the bovine spinal cord meninges by seven different methods. To identify the most effective approach, the decellularized matrices were characterized by dsDNA, collagen, and glycosaminoglycan contents and histological analyses. Moreover, the mechanical properties of the hydrogels produced from the decellularized matrices were evaluated. The novel scCO2-based treatment was completed in a shorter time than the conventional method (3 versus 7 days) while maintaining the structural and mechanical integrity of the tissue. Additionally, all hydrogels derived from scCO2-decellularized matrices demonstrated high cell viability and biocompatibility in a cell culture. The current study suggests a rapid, effective, and detergent-free scCO2-assisting decellularization protocol for clinical tissue engineering applications.

Decellularized extracellular matrix for organoid and engineered organ culture

The repair and regeneration of tissues and organs using engineered biomaterials has attracted great interest in tissue engineering and regenerative medicine. Recent advances in organoids and engineered organs technologies have enabled scientists to generate 3D tissue that recapitulate the structural and functional characteristics of native organs, opening up new avenues in regenerative medicine. The matrix is one of the most important aspects for improving organoids and engineered organs construction. However, the clinical application of these techniques remained a big challenge because current commercial matrix does not represent the complexity of native microenvironment, thereby limiting the optimal regenerative capacity. Decellularized extracellular matrix (dECM) is expected to maintain key native matrix biomolecules and is believed to hold enormous potential for regenerative medicine applications. Thus, it is worth investigating whether the dECM can be used as matrix for improving organoid and engineered organs construction. In this review, the characteristics of dECM and its preparation method were summarized. In addition, the present review highlights the applications of dECM in the fabrication of organoids and engineered organs.