Lactobionic acid-functionalized polyethersulfone hollow fiber membranes promote HepG2 attachment and function

Stem Cell-Based Strategies: The Future Direction of Bioartificial Liver Development

Acute liver failure (ALF) results from severe liver damage or end-stage liver disease. It is extremely fatal and causes serious health and economic burdens worldwide. Once ALF occurs, liver transplantation (LT) is the only definitive and recommended treatment; however, LT is limited by the scarcity of liver grafts. Consequently, the clinical use of bioartificial liver (BAL) has been proposed as a treatment strategy for ALF. Human primary hepatocytes are an ideal cell source for these methods. However, their high demand and superior viability prevent their widespread use. Hence, finding alternatives that meet the seed cell quality and quantity requirements is imperative. Stem cells with self-renewing, immunogenic, and differentiative capacities are potential cell sources. MSCs and its secretomes encompass a spectrum of beneficial properties, such as anti-inflammatory, immunomodulatory, anti-ROS (reactive oxygen species), anti-apoptotic, pro-metabolomic, anti-fibrogenesis, and pro-regenerative attributes. This review focused on the recent status and future directions of stem cell-based strategies in BAL for ALF. Additionally, we discussed the opportunities and challenges associated with promoting such strategies for clinical applications.

Bioartificial livers: a review of their design and manufacture

Acute liver failure (ALF) is a rapidly progressive disease with high morbidity and mortality rates. Liver transplantation and artificial liver support systems, such as artificial livers (ALs) and bioartificial livers (BALs), are the two major therapies for ALF. Compared to ALs, BALs are composed of functional hepatocytes that provide essential liver functions, including detoxification, metabolite synthesis, and biotransformation. Furthermore, BALs can potentially provide effective support as a form of bridging therapy to liver transplantation or spontaneous recovery for patients with ALF. In this review, we systematically discussed the currently available state-of-the-art designs and manufacturing processes for BAL support systems. Specifically, we classified the cell sources and bioreactors that are applied in BALs, highlighted the advanced technologies of hepatocyte culturing and bioreactor fabrication, and discussed the current challenges and future trends in developing next generation BALs for large scale clinical applications.

Multiscale Porosity in Compressible Cryogenically 3D Printed Gels for Bone Tissue Engineering

Three-dimensional (3D) printing technology has seen several refinements when introduced in the field of medical devices and regenerative medicines. However, it is still a challenge to 3D print gels for building complex constructs as per the desired shape and size. Here, we present a novel method to 3D print gelatin/carboxymethylchitin/hydroxyapatite composite gel constructs of a complex shape. The objective of this study is to fabricate a bioactive gel scaffold with a controlled hierarchical structure. The hierarchy ranges from 3D outer shape to macroporosity to microporosity and rough surface. The fabrication process developed here uses 3D printing in a local cryogenic atmosphere, followed by lyophilization and cross-linking. The gel instantly freezes after extrusion on the cold plate. The cooling action is not limited to the build plate, but the entire gel scaffold is cooled during the 3D printing process. This enables the construction of a stable self-sustaining large-sized 3D complex geometry. Further, lyophilization introduces bulk microporosity into the scaffolds. The outer shape and macroporosity were controlled with the 3D printer, whereas the microporous structure and desirable rough surface morphology were obtained through lyophilization. With cryogenic 3D printing, up to 90% microporosity could be incorporated into the scaffolds. The microporosity and pore size distribution were controlled by changing the cross-linker and total polymer concentration, which resulted in six times increase in surface open pores of size <20 μm on increasing the cross-linker concentration from 25 to 100 mg/mL. The introduction of bulk microporosity was shown to increase swelling by 1.8 times along with a significant increase in human umbilical cord mesenchymal stem cells and Saos-2 cell attachment (2×), proliferation (2.4×), Saos-2 cell alkaline phosphatase level (2×), and mineralization (3×). The scaffolds are spongy in nature in a wet state, thus making them potential implants for bone cavities with a small opening. The application of these cryogenically 3D printed compressible gel scaffolds with multiscale porosity extends to a small- as well as a large-sized open/partially open patient-specific bone defect.