Deployable extrusion bioprinting of compartmental tumoroids with cancer associated fibroblasts for immune cell interactions

Three-dimensional bioprinted in vitro glioma tumor constructs for synchrotron microbeam radiotherapy dosimetry and biological study using gelatin methacryloyl hydrogel

Synchrotron microbeam radiotherapy (MRT) is an innovative cancer treatment that uses micron-sized of ultra-high dose rate spatially fractionated X-rays to effectively control cancer growth while reducing the damage to surrounding healthy tissue. However, the current pre-clinical experiments are commonly limited with the use of conventional two-dimensional cell cultures which cannot accurately model in vivo tissue environment. This study aims to propose a three-dimensional (3D) bioprinting gelatin methacryloyl (GelMA) hydrogel protocol and to characterize 3D bioprinted glioma relative to cell monolayer and spheroid models for experimental MRT using 9L rat gliosarcoma and U87 human glioma. Synchrotron broad-beam (SBB) and MRT beams were delivered to all cell models using 5, 10, and 20 Gy. 3D bioprinting enables the creation of 3D cell models that mimic in vivo conditions using bioinks, biomaterials, and cells. Synchrotron dosimetry, Monte Carlo simulation, in vitro cell viability, and fluorescence microscopy were performed to understand the relationship of the radiation dosimetry with the radiobiological response of different cancer models. Encapsulated gliomas were placed inside 3D printed human and rat phantoms to mimic scattering conditions. Results showed that MRT kills more gliomas relative to SBB for all cell models. The 3D bioprinted culture detected the spatial clustering of dead cells due to MRT high peak doses as seen in fluorescence imaging. The result of this study progresses MRT research by integrating 3D bioprinting techniques in radiobiological experiments. The study's bioprinting protocol and results will help in reducing the use of animal experiments and possibly in clinical translation of MRT.

Establishing a Bioink Assessment Protocol: GelMA and Collagen in the Bioprinting of a Potential In Vitro Intestinal Model

Collagen and gelatin methacryloyl (GelMA) are widely studied biomaterials for extrusion-based bioprinting (EBB) due to their excellent biological properties and ability to mimic the extracellular matrix of native tissues. This study aims to establish a preliminary workflow for approaching EBB by assessing collagen and GelMA printability and biological performance. GelMA was selected for its cost-effectiveness and ease of synthesis, while our collagen formulation was specifically optimized for printability, which is a challenging aspect of bioprinting. A parallel evaluation of their printability and biological performance is provided to develop a preliminary 3D intestinal model replicating the submucosa, lamina propria, and epithelial layer. Rheological analyses demonstrated that both materials exhibit a shear-thinning behavior. Collagen (u-CI) displayed a shear-thinning parameter p = 0.1 and a consistency index C = 80.62 Pa·s, while GelMA (u-GI) exhibited a more pronounced shear-thinning effect and enhanced shape retention (p = 0.06, C = 286.6 Pa·s). Post-extrusion recovery was higher for collagen (85%), compared to GelMA (45%), indicating its greater mechanical resilience. Photo-crosslinking improved hydrogel stability, with an increase in storage modulus G' for both materials. Printing tests confirmed the suitability of both hydrogels for bioprinting, with GelMA demonstrating higher print fidelity than collagen. Dimensional stability assessments under incubating conditions revealed that collagen constructs maintained their shape for 14 days before degradation, whereas GelMA constructs exhibited a gradual decrease in diameter over 21 days. Cell culture studies showed that human skin fibroblasts (HSFs) and human colon adenocarcinoma cells (HCT-8) could be successfully cocultured in an optimized RPMI 1640-based medium. AlamarBlue assays and Live/Dead staining confirmed high cell viability and proliferation within both hydrogel matrices. Notably, HSFs in GelMA exhibited more elongated morphologies, likely due to the material's lower stiffness (380 Pa) compared to collagen (585 Pa). HCT-8 cells adhered more rapidly to GelMA constructs, forming colonies within 7 days, whereas on collagen, colony formation was delayed to 14 days. Finally, a layered intestinal model was fabricated, and immunostaining confirmed the expression of tight junction (ZO-1) and adhesion (E-cadherin) proteins, validating the epithelial monolayer integrity. These findings highlight the potential of collagen and GelMA in 3D bioprinting applications for gut tissue engineering and pave the way for future developments of in vitro intestinal models.

Recent Advances in Hydrogel-Based 3D Disease Modeling and Drug Screening Platforms

Three-dimensional (3D) disease modeling and drug screening systems have become important in tissue engineering, drug screening, and development. The newly developed systems support cell and extracellular matrix (ECM) interactions, which are necessary for the formation of the tissue or an accurate model of a disease. Hydrogels are favorable biomaterials due to their properties: biocompatibility, high swelling capacity, tunable viscosity, mechanical properties, and their ability to biomimic the structure and function of ECM. They have been used to model various diseases such as tumors, cancer diseases, neurodegenerative diseases, cardiac diseases, and cardiovascular diseases. Additive manufacturing approaches, such as 3D printing/bioprinting, stereolithography (SLA), selective laser sintering (SLS), and fused deposition modeling (FDM), enable the design of scaffolds with high precision; thus, increasing the accuracy of the disease models. In addition, the aforementioned methodologies improve the design of the hydrogel-based scaffolds, which resemble the complicated structure and intricate microenvironment of tissues or tumors, further advancing the development of therapeutic agents and strategies. Thus, 3D hydrogel-based disease models fabricated through additive manufacturing approaches provide an enhanced 3D microenvironment that empowers personalized medicine toward targeted therapeutics, in accordance with 3D drug screening platforms.

Recent advances in 3D bioprinted neural models: A systematic review on the applications to drug discovery

The design of neural tissue models with architectural and biochemical relevance to native tissues opens the way for the fundamental study and development of therapies for many disorders with limited treatment options. Here, we systematically review the most recent literature on 3D bioprinted neural models, including their potential for use in drug screening. Neural tissues that model the central nervous system (CNS) from the relevant literature are reviewed with comprehensive summaries of each study, and discussion of the model types, bioinks and additives, cell types used, bioprinted construct shapes and culture time, and the characterization methods used. In this review, we accentuate the lack of standardization among characterization methods to analyze the functionality (including chemical, metabolic and other pathways) and mechanical relevance of the 3D bioprinted constructs, and discuss this as a critical area for future exploration. These gaps must be addressed for this technology to be applied for effective drug screening applications, despite its enormous potential for rapid and efficient drug screening. The future of biomimetic, 3D printed neural tissues is promising and evaluation of the in vivo relevance on multiple levels should be sought to adequately compare model performance and develop viable treatment options for neurodegenerative diseases, or other conditions that affect the CNS.

A Low-Cost, Open-Source 3D Printer for Multimaterial and High-Throughput Direct Ink Writing of Soft and Living Materials

Direct ink writing is a 3D printing method that is compatible with a wide range of structural, elastomeric, electronic, and living materials, and it continues to expand its uses into physics, engineering, and biology laboratories. However, the large footprint, closed hardware and software ecosystems, and expense of commercial systems often hamper widespread adoption. This work introduces a compact, low-cost, multimaterial, and high-throughput direct ink writing 3D printer platform with detailed assembly files and instructions provided freely online. In contrast to existing low-cost 3D printers and bioprinters, which typically modify off-the-shelf plastic 3D printers, this system is built from scratch, offering a lower cost and full customizability. Active mixing of cell-laden bioinks, high-throughput production of auxetic lattices using multimaterial multinozzle 3D (MM3D) printing methods, and a high-toughness, photocurable hydrogel for fabrication of heart valves are introduced. Finally, hardware for embedded multinozzle and 3D gradient nozzle printing is developed for producing high-throughput and graded 3D parts. This powerful, simple-to-build, and customizable printing platform can help stimulate a vibrant biomaker community of engineers, biologists, and educators.

Advancing tumor microenvironment and lymphoid tissue research through 3D bioprinting and biofabrication

Cancer progression is significantly influenced by the complex interactions within the tumor microenvironment (TME). Immune cells, in particular, play a critical role by infiltrating tumors from the circulation and surrounding lymphoid tissues in an attempt to control their spread. However, they often fail in this task. Current in vivo and in vitro preclinical models struggle to fully capture these intricate interactions affecting our ability to understand immune evasion and predict drugs behaviour in the clinic. To address this challenge, biofabrication and particularly 3D bioprinting has emerged as a promising tool for modeling both tumors and the immune system. Its ability to incorporate multiple cell types into 3D matrices, enable tissue compartmentalization with high spatial accuracy, and integrate vasculature makes it a valuable approach. Nevertheless, limited research has focused on capturing the complex tumor-immune interplay in vitro. This review highlights the composition and significance of the TME, the architecture and function of lymphoid tissues, and innovative approaches to modeling their interactions in vitro, while proposing the concept of an extended TME.

In Situ Bioprinting: Process, Bioinks, and Applications

Traditional tissue engineering methods face challenges, such as fabrication, implantation of irregularly shaped scaffolds, and limited accessibility for immediate healthcare providers. In situ bioprinting, an alternate strategy, involves direct deposition of biomaterials, cells, and bioactive factors at the site, facilitating on-site fabrication of intricate tissue, which can offer a patient-specific personalized approach and align with the principles of precision medicine. It can be applied using a handled device and robotic arms to various tissues, including skin, bone, cartilage, muscle, and composite tissues. Bioinks, the critical components of bioprinting that support cell viability and tissue development, play a crucial role in the success of in situ bioprinting. This review discusses in situ bioprinting techniques, the materials used for bioinks, and their critical properties for successful applications. Finally, we discuss the challenges and future trends in accelerating in situ printing to translate this technology in a clinical settings for personalized regenerative medicine.

Fibrosis-Encapsulated Tumoroid, A Solid Cancer Assembloid Model for Cancer Research and Drug Screening

Peritumoral fibrosis is known to promote cancer progression and confer treatment resistance in various solid tumors. Consequently, developing accurate cancer research and drug screening models that replicate the structure and function of a fibrosis-surrounded tumor mass is imperative. Previous studies have shown that self-assembly three-dimensional (3D) co-cultures primarily produce cancer-encapsulated fibrosis or maintain a fibrosis-encapsulated tumor mass for a short period, which is inadequate to replicate the function of fibrosis, particularly as a physical barrier. To address this limitation, a multi-layer spheroid formation method is developed to create a fibrosis-encapsulated tumoroid (FET) structure that maintains structural stability for up to 14 days. FETs exhibited faster tumor growth, higher expression of immunosuppressive cytokines, and equal or greater resistance to anticancer drugs compared to their parental tumoroids. Additionally, FETs serve as a versatile model for traditional cancer research, enabling the study of exosomal miRNA and gene functions, as well as for mechanobiology research when combined with alginate hydrogel. Our findings suggest that the FET represents an advanced model that more accurately mimics solid cancer tissue with peritumoral fibrosis. It may show potential superiority over self-assembly-based 3D co-cultures for cancer research and drug screening, and holds promise for personalized drug selection in cancer treatment.

Recent applications of three-dimensional bioprinting in drug discovery and development

The ability of three-dimensional (3D) bioprinting to fabricate biomimetic organ and disease models has been recognised to be promising for drug discovery and development as 3D bioprinted models can better mimic human physiology compared to two-dimensional (2D) cultures and animal models. This is useful for target selection where disease models can be studied to understand disease pathophysiology and identify disease-linked compounds. Lead identification and preclinical studies also benefit from 3D bioprinting as 3D bioprinted models can be utilised in high-throughput screening (HTS) systems and to produce efficacy and safety data that closely resembles clinical observations. Although no published applications of 3D bioprinting in clinical trials were found, there are two clinical trials planning to evaluate the predictive ability of 3D bioprinted models by comparing human and model responses to the same chemotherapy. Overall, this review provides a comprehensive summary of the latest applications of 3D bioprinting in drug discovery and development.

Biofabrication and biomanufacturing in Ireland and the UK

As we navigate the transition from the Fourth to the Fifth Industrial Revolution, the emerging fields of biomanufacturing and biofabrication are transforming life sciences and healthcare. These sectors are benefiting from a synergy of synthetic and engineering biology, sustainable manufacturing, and integrated design principles. Advanced techniques such as 3D bioprinting, tissue engineering, directed assembly, and self-assembly are instrumental in creating biomimetic scaffolds, tissues, organoids, medical devices, and biohybrid systems. The field of biofabrication in the United Kingdom and Ireland is emerging as a pivotal force in bioscience and healthcare, propelled by cutting-edge research and development. Concentrating on the production of biologically functional products for use in drug delivery, in vitro models, and tissue engineering, research institutions across these regions are dedicated to innovating healthcare solutions that adhere to ethical standards while prioritising sustainability, affordability, and healthcare system benefits.

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The cutting-edge progress in bioprinting for biomedicine: principles, applications, and future perspectives

Bioprinting is a highly promising application area of additive manufacturing technology that has been widely used in various fields, including tissue engineering, drug screening, organ regeneration, and biosensing. Its primary goal is to produce biomedical products such as artificial implant scaffolds, tissues and organs, and medical assistive devices through software-layered discrete and numerical control molding. Despite its immense potential, bioprinting technology still faces several challenges. It requires concerted efforts from researchers, engineers, regulatory bodies, and industry stakeholders are principal to overcome these challenges and unlock the full potential of bioprinting. This review systematically discusses bioprinting principles, applications, and future perspectives while also providing a topical overview of research progress in bioprinting over the past two decades. The most recent advancements in bioprinting are comprehensively reviewed here. First, printing techniques and methods are summarized along with advancements related to bioinks and supporting structures. Second, interesting and representative cases regarding the applications of bioprinting in tissue engineering, drug screening, organ regeneration, and biosensing are introduced in detail. Finally, the remaining challenges and suggestions for future directions of bioprinting technology are proposed and discussed. Bioprinting is one of the most promising application areas of additive manufacturing technology that has been widely used in various fields. It aims to produce biomedical products such as artificial implant scaffolds, tissues and organs, and medical assistive devices. This review systematically discusses bioprinting principles, applications, and future perspectives, which provides a topical description of the research progress of bioprinting.

Bioprinting of Cells, Organoids and Organs-on-a-Chip Together with Hydrogels Improves Structural and Mechanical Cues

The 3D bioprinting technique has made enormous progress in tissue engineering, regenerative medicine and research into diseases such as cancer. Apart from individual cells, a collection of cells, such as organoids, can be printed in combination with various hydrogels. It can be hypothesized that 3D bioprinting will even become a promising tool for mechanobiological analyses of cells, organoids and their matrix environments in highly defined and precisely structured 3D environments, in which the mechanical properties of the cell environment can be individually adjusted. Mechanical obstacles or bead markers can be integrated into bioprinted samples to analyze mechanical deformations and forces within these bioprinted constructs, such as 3D organoids, and to perform biophysical analysis in complex 3D systems, which are still not standard techniques. The review highlights the advances of 3D and 4D printing technologies in integrating mechanobiological cues so that the next step will be a detailed analysis of key future biophysical research directions in organoid generation for the development of disease model systems, tissue regeneration and drug testing from a biophysical perspective. Finally, the review highlights the combination of bioprinted hydrogels, such as pure natural or synthetic hydrogels and mixtures, with organoids, organoid-cell co-cultures, organ-on-a-chip systems and organoid-organ-on-a chip combinations and introduces the use of assembloids to determine the mutual interactions of different cell types and cell-matrix interferences in specific biological and mechanical environments.

3D bioprinted tumor model: a prompt and convenient platform for overcoming immunotherapy resistance by recapitulating the tumor microenvironment

BACKGROUND

Cancer immunotherapy is receiving worldwide attention for its induction of an anti-tumor response. However, it has had limited efficacy in some patients who acquired resistance. The dynamic and sophisticated complexity of the tumor microenvironment (TME) is the leading contributor to this clinical dilemma. Through recapitulating the physiological features of the TME, 3D bioprinting is a promising research tool for cancer immunotherapy, which preserves in vivo malignant aggressiveness, heterogeneity, and the cell-cell/matrix interactions. It has been reported that application of 3D bioprinting holds potential to address the challenges of immunotherapy resistance and facilitate personalized medication.

CONCLUSIONS AND PERSPECTIVES

In this review, we briefly summarize the contributions of cellular and noncellular components of the TME in the development of immunotherapy resistance, and introduce recent advances in 3D bioprinted tumor models that served as platforms to study the interactions between tumor cells and the TME. By constructing multicellular 3D bioprinted tumor models, cellular and noncellular crosstalk is reproduced between tumor cells, immune cells, fibroblasts, adipocytes, and the extracellular matrix (ECM) within the TME. In the future, by quickly preparing 3D bioprinted tumor models with patient-derived components, information on tumor immunotherapy resistance can be obtained timely for clinical reference. The combined application with tumoroid or other 3D culture technologies will also help to better simulate the complexity and dynamics of tumor microenvironment in vitro. We aim to provide new perspectives for overcoming cancer immunotherapy resistance and inspire multidisciplinary research to improve the clinical application of 3D bioprinting technology.

Epithelial-Mesenchymal Transition of Cancer Cells on Micropillar Arrays

Epithelial-mesenchymal transition (EMT) is critical for tumor invasion and many other cell-relevant processes. While much progress has been made about EMT, no report concerns the EMT of cells on topological biomaterial interfaces with significant nuclear deformation. Herein, we prepared a poly(lactide-co-glycolide) micropillar array with an appropriate dimension to enable significant deformation of cell nuclei and examined EMT of a human lung cancer epithelial cell (A549). We show that A549 cells undergo serious nuclear deformation on the micropillar array. The cells express more E-cadherin and less vimentin on the micropillar array than on the smooth surface. After transforming growth factor-β1 (TGF-β1) treatment, the expression of E-cadherin as an indicator of the epithelial phenotype is decreased and the expression of vimentin as an indicator of the mesenchymal phenotype is increased for the cells both on smooth surfaces and on micropillar arrays, indicating that EMT occurs even when the cell nuclei are deformed and the culture on the micropillar array more enhances the expression of vimentin. Expression of myosin phosphatase targeting subunit 1 is reduced in the cells on the micropillar array, possibly affecting the turnover of myosin light chain phosphorylation and actin assembly; this makes cells on the micropillar array prefer the epithelial-like phenotype and more sensitive to TGF-β1. Overall, the micropillar array exhibits a promoting effect on the EMT.

Engineering Biomaterials to Model Immune-Tumor Interactions In Vitro

Engineered biomaterial scaffolds are becoming more prominent in research laboratories to study drug efficacy for oncological applications in vitro, but do they have a place in pharmaceutical drug screening pipelines? The low efficacy of cancer drugs in phase II/III clinical trials suggests that there are critical mechanisms not properly accounted for in the pre-clinical evaluation of drug candidates. Immune cells associated with the tumor may account for some of these failures given recent successes with cancer immunotherapies; however, there are few representative platforms to study immune cells in the context of cancer as traditional 2D culture is typically monocultures and humanized animal models have a weakened immune composition. Biomaterials that replicate tumor microenvironmental cues may provide a more relevant model with greater in vitro complexity. In this review, the authors explore the pertinent microenvironmental cues that drive tumor progression in the context of the immune system, discuss how these cues can be incorporated into hydrogel design to culture immune cells, and describe progress toward precision oncological drug screening with engineered tissues.

Artificial tumor matrices and bioengineered tools for tumoroid generation

The tumor microenvironment (TME) is critical for tumor growth and metastasis. The TME contains cancer-associated cells, tumor matrix, and tumor secretory factors. The fabrication of artificial tumors, so-called tumoroids, is of great significance for the understanding of tumorigenesis and clinical cancer therapy. The assembly of multiple tumor cells and matrix components through interdisciplinary techniques is necessary for the preparation of various tumoroids. This article discusses current methods for constructing tumoroids (tumor tissue slices and tumor cell co-culture) for pre-clinical use. This article focuses on the artificial matrix materials (natural and synthetic materials) and biofabrication techniques (cell assembly, bioengineered tools, bioprinting, and microfluidic devices) used in tumoroids. This article also points out the shortcomings of current tumoroids and potential solutions. This article aims to promotes the next-generation tumoroids and the potential of them in basic research and clinical application.

Biofabrication methods for reconstructing extracellular matrix mimetics

In the human body, almost all cells interact with extracellular matrices (ECMs), which have tissue and organ-specific compositions and architectures. These ECMs not only function as cellular scaffolds, providing structural support, but also play a crucial role in dynamically regulating various cellular functions. This comprehensive review delves into the examination of biofabrication strategies used to develop bioactive materials that accurately mimic one or more biophysical and biochemical properties of ECMs. We discuss the potential integration of these ECM-mimics into a range of physiological and pathological in vitro models, enhancing our understanding of cellular behavior and tissue organization. Lastly, we propose future research directions for ECM-mimics in the context of tissue engineering and organ-on-a-chip applications, offering potential advancements in therapeutic approaches and improved patient outcomes.

Biomarkers and experimental models for cancer immunology investigation

The rapid advancement of tumor immunotherapies poses challenges for the tools used in cancer immunology research, highlighting the need for highly effective biomarkers and reproducible experimental models. Current immunotherapy biomarkers encompass surface protein markers such as PD-L1, genetic features such as microsatellite instability, tumor-infiltrating lymphocytes, and biomarkers in liquid biopsy such as circulating tumor DNAs. Experimental models, ranging from 3D in vitro cultures (spheroids, submerged models, air-liquid interface models, organ-on-a-chips) to advanced 3D bioprinting techniques, have emerged as valuable platforms for cancer immunology investigations and immunotherapy biomarker research. By preserving native immune components or coculturing with exogenous immune cells, these models replicate the tumor microenvironment in vitro. Animal models like syngeneic models, genetically engineered models, and patient-derived xenografts provide opportunities to study in vivo tumor-immune interactions. Humanized animal models further enable the simulation of the human-specific tumor microenvironment. Here, we provide a comprehensive overview of the advantages, limitations, and prospects of different biomarkers and experimental models, specifically focusing on the role of biomarkers in predicting immunotherapy outcomes and the ability of experimental models to replicate the tumor microenvironment. By integrating cutting-edge biomarkers and experimental models, this review serves as a valuable resource for accessing the forefront of cancer immunology investigation.

Advancements in robotic arm-based 3D bioprinting for biomedical applications

3D bioprinting emerges as a critical tool in biofabricating functional 3D tissue or organ equivalents for regenerative medicine. Bioprinting techniques have been making strides in integrating automation, customization, and digitalization in coping with diverse tissue engineering scenarios. The convergence of robotic arm-based 3D bioprinting techniques, especially in situ 3D bioprinting, is a versatile toolbox in the industrial field, promising for biomedical application and clinical research. In this review, we first introduce conceptualized modalities of robotic arm-based bioprinting from a mechanical perspective, which involves configurative categories of current robot arms regarding conventional bioprinting strategies. Recent advances in robotic arm-based bioprinting in tissue engineering have been summarized in distinct tissues and organs. Ultimately, we systematically discuss relative advantages, disadvantages, challenges, and future perspectives from bench to bedside for biomedical application.

Recent advances of three-dimensional bioprinting technology in hepato-pancreato-biliary cancer models

Hepato-pancreato-biliary (HPB) cancer is a serious category of cancer including tumors originating in the liver, pancreas, gallbladder and biliary ducts. It is limited by two-dimensional (2D) cell culture models for studying its complicated tumor microenvironment including diverse contents and dynamic nature. Recently developed three-dimensional (3D) bioprinting is a state-of-the-art technology for fabrication of biological constructs through layer-by-layer deposition of bioinks in a spatially defined manner, which is computer-aided and designed to generate viable 3D constructs. 3D bioprinting has the potential to more closely recapitulate the tumor microenvironment, dynamic and complex cell-cell and cell-matrix interactions compared to the current methods, which benefits from its precise definition of positioning of various cell types and perfusing network in a high-throughput manner. In this review, we introduce and compare multiple types of 3D bioprinting methodologies for HPB cancer and other digestive tumors. We discuss the progress and application of 3D bioprinting in HPB and gastrointestinal cancers, focusing on tumor model manufacturing. We also highlight the current challenges regarding clinical translation of 3D bioprinting and bioinks in the field of digestive tumor research. Finally, we suggest valuable perspectives for this advanced technology, including combination of 3D bioprinting with microfluidics and application of 3D bioprinting in the field of tumor immunology.