Bioprinting最新文献

Nanoparticles have been broadly investigated in 3D bioprinting (3DBP) for various purposes, including drug delivery, enhanced mechanical performance, biocompatibility, and bioactivity.

While polymeric nanoparticles have been widely studied for functionalization and drug delivery purposes, current reviews lack investigation of their application for 3DBP, where polymeric nanoparticles can also add unique properties in composition and application for 3DBP.

Both natural and synthetic polymeric nanoparticles have been employed in 3DBP, with natural polymers providing a strong advantage for biocompatibility and bioactivity and synthetic polymers enabling more control over nanomaterial properties. In 3D printed structures, the colloidal network between polymeric nanoparticles can enhance rheological and mechanical properties and printability. Additionally, these nanomaterials may introduce stimuli responsive elements and deliver key biomolecules, including growth factors or medications. This paper discusses the current application of polymeric nanoparticles and highlights their potential in 3DBP for tissue engineering and drug delivery specifically.

An estimated 750,000 arthroscopic knee operations are performed in the United States each year, and many are due to a torn meniscus. Transplantation with donor tissue is the gold standard of care in cases where the meniscus cannot be repaired. However, there is a limited supply of transplantable tissue, which may not be the ideal size or shape for the recipient. 3D printing and tissue engineering have been used to produce replacement tissue of specified shape and size, but none offer the compressive modulus or durability of adult-derived tissue. While biomechanical loading of engineered tissues is known to increase mechanical strength, no current paradigms provide sufficient strength. Instead, a combinatorial approach addressing both physiological form and function has emerged as a promising strategy. In this work, anisotropic menisci were bioprinted using ink composed of collagen types I & II, chondroitin sulfate, and mesenchymal stem cells. After printing, a custom bioreactor was used to apply cyclic compression within an incubator throughout the culture period. Compression cycled prints containing cells maintained viability for 3 weeks, while the mechanical strength of cellularized prints increased after 1 week. However, print dimensions and mass of cellular prints decreased over time independent of compression, while glycosaminoglycans were lost from the prints into the culture media. The expression of eight genes were significantly altered due to compression cycling. This work demonstrated that bioprinted menisci containing live cells can be successfully compressed over long time periods in culture without cell death, and despite changing print dimensions, cells under compression contributed to meniscal strengthening whereas acellular prints consistently weaken. By optimizing structure, culture conditions, and compression paradigms, the strength of bioprinted menisci may approach that of native tissue, and this combinatorial approach may reduce or eliminate the need for cadaveric tissues for allograft transplants.

Lithography 3D printing technologies such as stereolithography (SLA), two-photon polymerization (TPP), digital light processing (DLP), and other approaches based on vat photopolymerization effect, have been continuously dominating the 3D printing market creating tremendous impact on global economy and society over the past 30 years. The vibrant question is where lithography 3D printing research is heading now? In this study, we conduct a bibliometric analysis and literature review to identify the top 10 research directions that will drive the development of lithography 3D printing in the following decade. We analyzed metadata of nearly ten thousands articles to reveal the evolution of the hottest keywords, most appreciated articles, and other factors in field of lithography 3D printing over the past 30 years. Based on the mined data and literature review, we envision and discus 10 directions that are either emerging or shall emerge promptly, namely tissue engineering (1), DLP of ceramics (2) and metals (3), volumetric printing (4), microneedles printing (5) 4D printing and smart materials (6), metamaterials (7), hot lithography (8), diamond printing (9), and multimaterial printing (10). Recent advances and challenges of each direction were outlined delivering focal points for further research.

Respiratory tissue engineering offers a robust framework for studying cell-cell and host-pathogen interactions in a tissue-like environment and offers a platform for studying lung tissue regeneration and disease mechanisms. However, the challenge of replicating dynamic three-dimensional (3D) microenvironments is a huge obstacle with existing technology. Current animal models and two-dimensional cell culture models do not replicate in vivo conditions seen in human lungs, thus research utilizing these techniques often fails to help alleviate the global burden of respiratory diseases. Respiratory tissue engineering has been drawing significant attention over the past decade. Particularly with the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), many inspiring developments and advances have been reported. This review presents the recent advances of respiratory tissue engineering focusing on 3D bioprinting, organ-on-a-chip, and organoid technologies. It also provides an overview of recent attempts to integrate biomechanical stimulus with the aim of improving the integrity of 3D constructs and enhancing cellular propagation. This review addresses the challenges inherent in existing 3D respiratory models and discusses the future prospects of research in this field, urging continuing innovation and investment toward the success of respiratory tissue engineering and increasing clinical relevance.

Macroporous hydrogel scaffolds are widely used in tissue engineering to promote cell growth and proliferation. Aiming to enhance cell seeding efficiency and facilitate the osteodifferentiation of mesenchymal stem cells, this study demonstrates the fabrication of pore gradient biodegradable hydrogel scaffolds inspired by natural bone structure for bone tissue engineering applications. The scaffolds were fabricated via extrusion-based 3D printing, using sequential deposition of three customized Gelatin/Oxidized Alginate - based inks with subsequent cryogenic crosslinking for permanent structure fixation. The resulting constructs were characterized and featured a continuous gradient morphology with pore sizes ranging from 10 to 300 μm. The gradient scaffolds exhibited improved mechanical stability, with a compression resistance of 149 kPa, as opposed to the non-gradient scaffold's 116 kPa at 70 % strain, and a sustained degradation rate with only a 10 % loss of its initial weight within three weeks. Gradient scaffolds demonstrated a doubling of cell seeding efficiency to 47 % with dense and homogeneously distributed cellular layers, as evidenced by confocal and electron microscopy. Furthermore, the gradient scaffolds demonstrated superior osteodifferentiation, with significantly higher ALP and DMP1 production and enhanced extracellular matrix mineralization compared to gradientless macroporous scaffolds. This study provides insights into the design of macroporous scaffolds and emphasizes the advantages of pore gradient over homogeneous gradientless morphologies.

Various 3D bioprinting techniques have been introduced and developed to fabricate biomimetic constructs based on biomaterials or cell-laden bioinks to create functionally engineered tissues or organs for tissue engineering applications. However, single-biomaterial printing techniques often fail to replicate the intricate compositions and diversity found in native tissues. Multi-bioinks or multi-biomaterials in bioprinting can be utilized through either a single printhead or multiple separate printheads. However, the cost of commercially available multi-heads for bioprinting is prohibitively high, hindering their application in tissue engineering endeavors. Additionally, each bioink or biomaterial possesses unique printing characteristics that are best suited for specific printing techniques. The current study presents the development of a modular and cost-effective dual-head position bioprinter based on an open-source approach using Marlin firmware. The highlighted features of the 3D bioprinter include the use of various power sources such as compressed air and electricity for the printheads, the integration of a movable printhead mechanism with a wiper arm to prevent collisions with large printed samples during printing, a printhead adapter, as well as nozzle kits designed in a modular form for easy replacement for specific bio-applications. Therefore, despite the presence of two positions to mount the printheads, the custom-designed bioprinter exhibits the capability to flexibly accommodate four distinct printhead modules and three modular nozzle kits to print various biomaterials, such as polycaprolactone (PCL) and its composites with sodium alginate (SA), tricalcium phosphate (TCP) and hydrogel mixtures including SA, gelatin (GL), and k-carrageenan (κ-Carr). Complex tissue scaffolds were successfully fabricated using multi-biomaterials to showcase the versatility of the bioprinter, thereby demonstrating its potential for a wide range of tissue engineering applications.

Sodium alginate (SA) hydrogels are widely used in 3D extrusion bioprinting, but their isolated use does not meet all the requirements for this application. To overcome this problem, crosslinking with divalent cations and combinations with other polymers, such as gelatin (Gel), are employed to improve their mechanical performance and bioactivity. In this study, we proposed a new concept of pre-crosslinking SA and SA/Gel inks with divalent cations Ca²⁺, Co²⁺, and Zn²⁺ and their binary mixtures. These inks were successfully formulated and characterized, and it was observed that different ion ratios can impart essential characteristics and properties for 3D extrusion bioprinting. To evaluate the thermosensitive response of these inks, it was included gelatin in a dispersed phase, giving the 3D-printed system a 4D character. The hydrogel with the best mechanical and biological performance was the pre-crosslinked composition with mixtures of divalent Ca²⁺/Co²⁺ ions, whereas it was observed through the live/dead assay that the presence of Zn²⁺ ions in the hydrogels on day 3 reduced the cell viability. This composition was used to develop a bioink for 4D printing using cell spheroid or single cells, with spheroids presenting better viability after 7 days than single cells. These results emphasize the importance of obtaining a pre-crosslinked bioink with modulated properties by employing divalent ions for 4D biofabrication and that 3D cell culture ensures superior resistance to 3D extrusion bioprinting when compared to single cells. Those characteristics give us an interesting bioink with high potential to be used in regenerative medicine of soft tissues.

The generation of kidney organoids derived from human induced pluripotent stem cells offers various applications such as tissue regeneration, drug screening, and disease modeling. The traditional methodology for generating organoids presents challenges, including labor-intensive procedures, limited scalability, and batch-to-batch variability in organoid quality. To address these obstacles, we have developed a low-cost and readily accessible automated three-dimensional bioprinting platform capable of printing nephron progenitor cells derived from induced pluripotent stem cells to form kidney organoids. Bioprinted organoids expressed markers for major cell types of the kidney including podocytes, proximal tubules, distal tubules, and endothelial cells. Quantification of nephron-like structures in varying sizes of the organoids was also conducted. This study demonstrates the ability to efficiently generate kidney organoids with as few as 8000 cells. Our low-cost, high-throughput bioprinter holds the potential for fabricating various other organoids and tissue.

Thermosensitive inks are considered an attractive option for the 3D bioprinting of different tissue types, yet comprehensive information on their reliability, preparation, and properties remains lacking.

This paper addresses this gap by presenting a twofold aim: firstly, characterizing the preparation, rheology, and printing aspects of two inks that have demonstrated success in skeletal muscle tissue engineering both in vitro and in vivo. The first ink is composed of fibrinogen, gelatin, hyaluronic acid, and glycerol, while the second is a sacrificial ink made of gelatin, hyaluronic acid, and glycerol. Secondly, from this analysis, we demonstrate how thermosensitive and multicomponent inks can exhibit high variability and unpredictability. Thus, we emphasize the importance of thorough ink characterization to ensure the reproducibility and reliability of scientific outcomes.

We quantified the inherent variability in ink manufacturing and we proposed specific quality assessment criteria. We found storing the fibroink at 4 °C for one day did not alter fibroink properties, while significant changes were produced if the storage time was seven days. Cell viability within the fibroink was evaluated at different temperatures, identifying 9 °C as the optimal trade-off between cell viability and printability. Rheological analyses confirmed the shear-thinning behavior of both inks and identified their respective sol-gel transition temperatures. A systematic assessment of printing fidelity was performed, by varying pressure, speed, and needle offset. The methodology proposed in this study may be useful for the management of other thermosensitive bioinks, thus properly considering their inherent variability.

Three-dimensional (3D) extrusion bioprinting, an additive manufacturing process that hybridizes traditional thermoplastic 3D printing technology with the latest developments in tissue engineering, is a promising tool for engineering lab-scale tissues and organs for drug screening, pathological modeling, and transplantation. The technology has been proven to be reliable, high-throughput, and capable of printing complex physiological structures at relevant scales. Commercially available 3D extrusion bioprinters can manipulate a broad range of soft materials with sub-millimeter resolution. However, these bioprinters are expensive and typically contain proprietary software, impeding the customization of bioprinters to lab-specific applications. In response, researchers have recently manufactured and published open-source 3D extrusion bioprinters converted from thermoplastic printers. This review compares and evaluates currently available open-source 3D extrusion bioprinters, including their total cost, features, and necessary technical experience to fabricate in most academic labs. Current open-source slicing software is detailed, and guidelines are offered to ensure this technology continues contributing to the democratization of additive manufacturing technology. These comparisons and recommendations will allow researchers to choose an open-source printer that best suits their laboratory's 3D bioprinting needs and will highlight the need to iterate and improve published designs.