Engineered Myoblast-Laden Collagen Filaments Fabricated Using a Submerged Bioprinting Process to Obtain Efficient Myogenic Activities

Fibrillar Hydrogel Inducing Cell Mechanotransduction for Tissue Engineering

One of the key strategies for tissue engineering is to design multifunctional bioinks that balance printability with cytocompatibility. Here, we describe fibrillar hydrogels produced by Schiff base formation between B-type gelatin and oxidized sodium alginate, followed by the incorporation of type I collagen, yielding a new gel (MyoColl). The resulting hydrogel exhibits a temperature- and mass-ratio-dependent sol-gel transition, showing variability of hydrogel properties depending on the component ratio. MyoColl composition provides a convenient platform for biofabrication in terms of shear thinning, yielding, Young's modulus, and shape accuracy. Metabolic activity tests and fluorescent microscopy of 2D hydrogel-based mouse C2C12 myoblast cell culture show significant cytocompatibility of the developed carriers. In addition, primary signs of cell mechanotransduction and myofilament formation of 3D printed MyoColl-based cell cultures were detected and described. Due to these promising results, the described hydrogel composition has shown itself as a convenient platform for muscle tissue engineering.

Towards more realistic cultivated meat by rethinking bioengineering approaches

Cultivated meat (CM) refers to edible lab-grown meat that incorporates cultivated animal cells. It has the potential to address some issues associated with real meat (RM) production, including the ethical and environmental impact of animal farming, and health concerns. Recently, various biomanufacturing methods have been developed to attempt to recreate realistic meat in the laboratory. We therefore overview recent achievements and challenges in the production of CM. We also discuss the issues that need to be addressed and suggest additional recommendations and potential criteria to help to bridge the gap between CM and RM from an engineering standpoint.

Synergistic coupling between 3D bioprinting and vascularization strategies

Three-dimensional (3D) bioprinting offers promising solutions to the complex challenge of vascularization in biofabrication, thereby enhancing the prospects for clinical translation of engineered tissues and organs. While existing reviews have touched upon 3D bioprinting in vascularized tissue contexts, the current review offers a more holistic perspective, encompassing recent technical advancements and spanning the entire multistage bioprinting process, with a particular emphasis on vascularization. The synergy between 3D bioprinting and vascularization strategies is crucial, as 3D bioprinting can enable the creation of personalized, tissue-specific vascular network while the vascularization enhances tissue viability and function. The review starts by providing a comprehensive overview of the entire bioprinting process, spanning from pre-bioprinting stages to post-printing processing, including perfusion and maturation. Next, recent advancements in vascularization strategies that can be seamlessly integrated with bioprinting are discussed. Further, tissue-specific examples illustrating how these vascularization approaches are customized for diverse anatomical tissues towards enhancing clinical relevance are discussed. Finally, the underexplored intraoperative bioprinting (IOB) was highlighted, which enables the direct reconstruction of tissues within defect sites, stressing on the possible synergy shaped by combining IOB with vascularization strategies for improved regeneration.

Bioprinted hASC-laden cell constructs with mechanically stable and cell alignment cue for tenogenic differentiation

3D bioprinting is a technology that enables the precise and controlled deposition of cells and an artificial extracellular matrix (ECM) to create functional tissue constructs. However, current 3D bioprinting methods still struggle to obtain mechanically stable and unique cell-morphological structures, such as fully aligned cells. In this study, we propose a new 3D bioprinting approach that utilizes a high concentration of bioink without cells to support mechanical properties and drag flow to fully align cells in a thin bath filled with cell-laden bioink, resulting in a hybrid cell-laden construct with a mechanical stable and fully aligned cell structure. To demonstrate the feasibility of this approach, we used it to fabricate a cell-laden construct using human adipose stem cells (hASCs) for tendon tissue engineering. To achieve appropriate processing conditions, various factors such as the bioink concentration, nozzle moving speed, and volume flow rate were considered. To enhance the biocompatibility of the cell-laden construct, we used porcine decellularized tendon ECM.In vitrocellular responses, including tenogenic differentiation of the fabricated hybrid cell structures with aligned or randomly distributed cells, were evaluated using hASCs. In addition, the mechanical properties of the hybrid cell-laden construct could be adjusted by controlling the concentration of the mechanically reinforcing strut using methacrylated tendon-decellularized extracellular matrix. Based on these results, the hybrid cell-laden structure has the potential to be a highly effective platform for the alignment of musculoskeletal tissues.

3D bioprinted liver tissue and disease models: Current advances and future perspectives

Three-dimensional (3D) bioprinting is a promising technology for fabricating complex tissue constructs with biomimetic biological functions and stable mechanical properties. In this review, the characteristics of different bioprinting technologies and materials are compared, and development in strategies for bioprinting normal and diseased hepatic tissue are summarized. In particular, features of bioprinting and other bio-fabrication strategies, such as organoids and spheroids are compared to demonstrate the strengths and weaknesses of 3D printing technology. Directions and suggestions, such as vascularization and primary human hepatocyte culture, are provided for the future development of 3D bioprinting.

Regulable Supporting Baths for Embedded Printing of Soft Biomaterials with Variable Stiffness

Three-dimensional (3D) embedded printing is emerging as a potential solution for the fabrication of complex biological structures and with ultrasoft biomaterials. For the supporting medium, bulk gels can support a wide range of bioinks with higher printing resolution as well as better finishing surfaces than granular microgel baths. However, the difficulties of regulating the physical properties of existing bulk gel supporting baths limit the further development of this method. This work has developed a bulk gel supporting bath with easily regulable physical properties to facilitate soft-material fabrication. The proposed bath is composed based on the hydrophobic association between a hydrophobically modified hydroxypropylmethyl cellulose (H-HPMC) and Pluronic F-127 (PF-127). Its rheological properties can be easily regulated; in the preprinting stage by varying the relative concentration of components, during printing by changing the temperature, and postprinting by adding additives with strong hydrophobicity or hydrophilicity. This has made the supporting bath not only available for various bioinks with a range of printing windows but also easy to be removed. Also, the removal strategy is independent of printing conditions like temperature and ions, which empowers the bath to hold great potential for the embedded printing of commonly used biomaterials. The adjustable rheological properties of the bath were leveraged to characterize the embedded printing quantitatively, involving the disturbance during the printing, filament cross-sectional shape, printing resolution, continuity, and the coalescence between adjacent filaments. The match between the bioink and the bath was also explored. Furthermore, low-viscosity bioinks (with 0.008-2.4 Pa s viscosity) were patterned into various 3D complex delicate soft structures (with a 0.5-5 kPa compressive modulus). It is believed that such an easily regulable assembled bath could serve as an available tool to support the complex biological structure fabrication and open unique prospects for personalized medicine.