Recent Advances in Organ-on-Chips Integrated with Bioprinting Technologies for Drug Screening

Recent advances in 3D models of the nervous system for neural regeneration research and drug development

The development of drugs for nervous diseases poses distinctive difficulties owing to the incomplete understanding of the physiology and complex pathogenesis of the multifaceted central (CNS) and peripheral (PNS) nervous systems. Conventional animal tests and in vitro two-dimensional (2D) cell cultures fail to reproduce the sophisticated structure of natural human tissues, hindering the new drug discovery process. The emerging three-dimensional (3D) neural tissue models, including organoids, organ-on-chips and 3D-printed neural scaffolds, can provide an improved reproduction of the critical features, structural complexity, biological functions, dynamic circulation micro-environment and cell-matrix/cell interactions of the nervous systems. This review examines state-of-the-art 3D models for neural physiology/pathology, emphasizing their drug development applications. Fundamental advantages of various in vitro 3D neural models for investigating the mechanisms of nerve regeneration and disorders in both the CNS and PNS are compared in terms of the different modeling techniques. In addition, the applications of 3D neural models in drug development are summarized covering a range of areas such as disease modeling for basic research, pharmacokinetic and pharmacodynamic testing for drug screening and drug safety evaluation. Furthermore, current challenges and future outlook of biomimetic models and the existing bottlenecks hindering their successful translation into clinical use are discussed. STATEMENT OF SIGNIFICANCE: This review highlights the groundbreaking potential of 3D neural models-organoids, organ-on-chips, and 3D-printed scaffolds-to revolutionize neurological research and drug development. Unlike conventional methods, these models replicate the intricate structure and function of human nervous systems, enabling precise study of diseases like Alzheimer's, spinal injuries, and brain tumors. By synthesizing recent advancements, the review compares techniques, their applications in drug screening and personalized medicine, and addresses challenges in model accuracy and scalability. Bridging neuroscience, engineering, and pharmacology, this work provides a roadmap for researchers to innovate therapies. Its insights are critical for accelerating drug discovery and improving treatment outcomes, making it essential for scientists and clinicians tackling neurological disorders.

Sex-stratified osteochondral organ-on-chip model reveals sex-specific responses to inflammatory stimulation

Osteoarthritis (OA) is a musculoskeletal degenerative disease characterized by alterations in cartilage and subchondral bone leading to impaired joint function. OA disproportionally affects females more than males, yet the molecular mechanisms underlying these biological sex differences remain elusive. Current therapeutic strategies to halt the progression of OA are still lacking, in part due to the limited predictive potential of standard models which often do not account for sex disparities. Herein, an organ-on-chip microfluidic platform was developed to model the osteochondral unit, composed of adjacent bone and cartilage culture chambers, and capture sex-specific hallmarks of OA. Sex-stratified human primary chondrocytes and osteoblasts were compartmentalized within biomimetic hydrogels emulating the bone-cartilage interface, which were subjected to inflammatory triggers to mimic the onset of OA. We confirmed that interleukin-1β and Tumor Necrosis Factor-α stimulation triggered upregulation of pro-inflammatory cytokines and matrix metalloproteinases related genes in all donors, with marginal trends for increased expression in female cells. In addition, metabolic labeling coupled with confocal imaging revealed that inflammatory stimulation modulated extracellular matrix deposition by human chondrocytes in a sex-specific fashion. Not only matrix deposition but also matrix remodeling was altered upon inflammation, leading to a significant reduction in matrix stiffness in both cartilage and bone compartments. Overall, sex-stratified osteochondral unit on-chips offer novel insights into sex-specific cellular responses to inflammatory insults, demonstrating the importance of incorporating sex stratification in emergent organ-on-chip models. Thus, this platform provides a physiologically relevant 3D microenvironment to further investigate sex-specific drivers of OA, paving the way for targeted therapies.

3D Bioprinting Models for Glioblastoma: From Scaffold Design to Therapeutic Application

Conventional in vitro models fail to accurately mimic the tumor in vivo characteristics, being appointed as one of the causes of clinical attrition rate. Recent advances in 3D culture techniques, replicating essential physical and biochemical cues such as cell-cell and cell-extracellular matrix interactions, have led to the development of more realistic tumor models. Bioprinting has emerged to advance the creation of 3D in vitro models, providing enhanced flexibility, scalability, and reproducibility. This is crucial for the development of more effective drug treatments, and glioblastoma (GBM) is no exception. GBM, the most common and deadly brain cancer, remains a major challenge, with a median survival of only 15 months post-diagnosis. This review highlights the key components needed for 3D bioprinted GBM models. It encompasses an analysis of natural and synthetic biomaterials, along with crosslinking methods to improve structural integrity. Also, it critically evaluates current 3D bioprinted GBM models and their integration into GBM-on-a-chip platforms, which hold noteworthy potential for drug screening and personalized therapies. A versatile development framework grounded on Quality-by-Design principles is proposed to guide the design of bioprinting models. Future perspectives, including 4D bioprinting and machine learning approaches, are discussed, along with the current gaps to advance the field further.

Integrating microfluidic and bioprinting technologies: advanced strategies for tissue vascularization

Tissue engineering offers immense potential for addressing the unmet needs in repairing tissue damage and organ failure. Vascularization, the development of intricate blood vessel networks, is crucial for the survival and functions of engineered tissues. Nevertheless, the persistent challenge of ensuring an ample nutrient supply within implanted tissues remains, primarily due to the inadequate formation of blood vessels. This issue underscores the vital role of the human vascular system in sustaining cellular functions, facilitating nutrient exchange, and removing metabolic waste products. In response to this challenge, new approaches have been explored. Microfluidic devices, emulating natural blood vessels, serve as valuable tools for investigating angiogenesis and allowing the formation of microvascular networks. In parallel, bioprinting technologies enable precise placement of cells and biomaterials, culminating in vascular structures that closely resemble the native vessels. To this end, the synergy of microfluidics and bioprinting has further opened up exciting possibilities in vascularization, encompassing innovations such as microfluidic bioprinting. These advancements hold great promise in regenerative medicine, facilitating the creation of functional tissues for applications ranging from transplantation to disease modeling and drug testing. This review explores the potentially transformative impact of microfluidic and bioprinting technologies on vascularization strategies within the scope of tissue engineering.

Droplet-based 3D bioprinting for drug delivery and screening

Recently, the conventional criterion of "one-size-fits-all" is not qualified for each individual patient, requiring precision medicine for enhanced therapeutic effects. Besides, drug screening is a high-cost and time-consuming process which requires innovative approaches to facilitate drug development rate. Benefiting from consistent technical advances in 3D bioprinting techniques, droplet-based 3D bioprinting techniques have been broadly utilized in pharmaceutics due to the noncontact printing mechanism and precise control on the deposition position of droplets. More specifically, cell-free/cell-laden bioinks which are deposited for the fabrication of drug carriers/3D tissue constructs have been broadly utilized for precise drug delivery and high throughput drug screening, respectively. This review summarizes the mechanism of various droplet-based 3D bioprinting techniques and the most up-to-date applications in drug delivery and screening and discusses the potential improvements of droplet-based 3D bioprinting techniques from both technical and material aspects. Through technical innovations, materials development, and the assistance from artificial intelligence, the formation process of drug carriers will be more stable and accurately controlled guaranteeing precise drug delivery. Meanwhile, the shape fidelity and uniformity of the printed tissue models will be significantly improved ensuring drug screening efficiency and efficacy.

Biological Scaffolds in 3D Cell Models: Driving Innovation in Drug Discovery

The discipline of 3D cell modeling is currently undergoing a surge of captivating developments that are enhancing the realism and utility of tissue simulations. Using bioinks which represent cells, scaffolds, and growth factors scientists can construct intricate tissue architectures layer by layer using innovations like 3D bioprinting. Drug testing can be accelerated and organ functions more precisely replicated owing to the precise control that microfluidic technologies and organ-on-chip devices offer over the cellular environment. Tissue engineering is becoming more dynamic with materials that can modify their surroundings with the advent of hydrogels and smart biomaterials. Advances in spheroids and organoids are not only bringing us towards more effective and customized therapies, but they are also improving their ability to resemble actual human tissues. Confocal and two-photon microscopy are examples of advanced imaging methods that provide precise images of the functioning and interaction of cells. Artificial Intelligence models have applications for enhanced scaffold designs and for predicting the response of tissues to medications. Furthermore, via strengthening predictive models, optimizing data analysis, and simplifying 3D cell culture design, artificial intelligence is revolutionizing this field. When combined, these technologies are improving our ability to conduct research and moving us toward more individualized and effective medical interventions.

Musculoskeletal Organs-on-Chips: An Emerging Platform for Studying the Nanotechnology-Biology Interface

Nanotechnology-based approaches are promising for the treatment of musculoskeletal (MSK) disorders, which present significant clinical burdens and challenges, but their clinical translation requires a deep understanding of the complex interplay between nanotechnology and MSK biology. Organ-on-a-chip (OoC) systems have emerged as an innovative and versatile microphysiological platform to replicate the dynamics of tissue microenvironment for studying nanotechnology-biology interactions. This review first covers recent advances and applications of MSK OoCs and their ability to mimic the biophysical and biochemical stimuli encountered by MSK tissues. Next, by integrating nanotechnology into MSK OoCs, cellular responses and tissue behaviors may be investigated by precisely controlling and manipulating the nanoscale environment. Analysis of MSK disease mechanisms, particularly bone, joint, and muscle tissue degeneration, and drug screening and development of personalized medicine may be greatly facilitated using MSK OoCs. Finally, future challenges and directions are outlined for the field, including advanced sensing technologies, integration of immune-active components, and enhancement of biomimetic functionality. By highlighting the emerging applications of MSK OoCs, this review aims to advance the understanding of the intricate nanotechnology-MSK biology interface and its significance in MSK disease management, and the development of innovative and personalized therapeutic and interventional strategies.

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.

From Organ-on-a-Chip to Human-on-a-Chip: A Review of Research Progress and Latest Applications

Organ-on-a-Chip (OOC) technology, which emulates the physiological environment and functionality of human organs on a microfluidic chip, is undergoing significant technological advancements. Despite its rapid evolution, this technology is also facing notable challenges, such as the lack of vascularization, the development of multiorgan-on-a-chip systems, and the replication of the human body on a single chip. The progress of microfluidic technology has played a crucial role in steering OOC toward mimicking the human microenvironment, including vascularization, microenvironment replication, and the development of multiorgan microphysiological systems. Additionally, advancements in detection, analysis, and organoid imaging technologies have enhanced the functionality and efficiency of Organs-on-Chips (OOCs). In particular, the integration of artificial intelligence has revolutionized organoid imaging, significantly enhancing high-throughput drug screening. Consequently, this review covers the research progress of OOC toward Human-on-a-chip, the integration of sensors in OOCs, and the latest applications of organoid imaging technologies in the biomedical field.

Research and development of microenvironment's influence on stem cells from the apical papilla - construction of novel research microdevices: tooth-on-a-chip

Stem cells are crucial in tissue engineering, and their microenvironment greatly influences their behavior. Among the various dental stem cell types, stem cells from the apical papilla (SCAPs) have shown great potential for regenerating the pulp-dentin complex. Microenvironmental cues that affect SCAPs include physical and biochemical factors. To research optimal pulp-dentin complex regeneration, researchers have developed several models of controlled biomimetic microenvironments, ranging from in vivo animal models to in vitro models, including two-dimensional cultures and three-dimensional devices. Among these models, the most powerful tool is a microfluidic microdevice, a tooth-on-a-chip with high spatial resolution of microstructures and precise microenvironment control. In this review, we start with the SCAP microenvironment in the regeneration of pulp-dentin complexes and discuss research models and studies related to the biological process.

Prototyping in Polymethylpentene to Enable Oxygen-Permeable On-a-Chip Cell Culture and Organ-on-a-Chip Devices Suitable for Microscopy

With the rapid development and commercial interest in the organ-on-a-chip (OoC) field, there is a need for materials addressing key experimental demands and enabling both prototyping and large-scale production. Here, we utilized the gas-permeable, thermoplastic material polymethylpentene (PMP). Three methods were tested to prototype transparent PMP films suitable for transmission light microscopy: hot-press molding, extrusion, and polishing of a commercial, hazy extruded film. The transparent films (thickness 20, 125, 133, 356, and 653 µm) were assembled as the cell-adhering layer in sealed culture chamber devices, to assess resulting oxygen concentration after 4 days of A549 cell culture (cancerous lung epithelial cells). Oxygen concentrations stabilized between 15.6% and 11.6%, where the thicker the film, the lower the oxygen concentration. Cell adherence, proliferation, and viability were comparable to glass for all PMP films (coated with poly-L-lysine), and transparency was adequate for transmission light microscopy of adherent cells. Hot-press molding was concluded as the preferred film prototyping method, due to excellent and reproducible film transparency, the possibility to easily vary film thickness, and the equipment being commonly available. The molecular orientation in the PMP films was characterized by IR dichroism. As expected, the extruded films showed clear orientation, but a novel result was that hot-press molding may also induce some orientation. It has been reported that orientation affects the permeability, but with the films in this study, we conclude that the orientation is not a critical factor. With the obtained results, we find it likely that OoC models with relevant in vivo oxygen concentrations may be facilitated by PMP. Combined with established large-scale production methods for thermoplastics, we foresee a useful role for PMP within the OoC field.

New approach methods on the bench side to accelerate clinical trials during pregnancy

INTRODUCTION

Pregnant women are therapeutic orphans as they are excluded from clinical drug development and therapeutic trials. We identify limitations in conducting clinical trials and propose two 'New Approach Methods'(NAMs) to overcome them.

AREAS COVERED

NAMs have proven invaluable tools in basic and clinical research to understand human health and disease better, elucidate mechanisms, and study the efficacy and toxicity of therapeutics that have not been possible through animal-based methodologies. The lack of humanized experimental models of FMi and drugs that can safely and effectively cross FMi to reduce the risk of adverse pregnancy has hindered progress in the field of reproductive pharmacology. This report discusses two technological advancements in perinatal research and medicine to accelerate clinical trials during pregnancy. (1) We have developed a humanized microphysiologic system, an Organ-on-a-chip (OOC) platform, to study FMi and their utility in pharmacological studies, and (2) use of extracellular vesicles (EVs) as drug delivery vehicles that are immunologically inert and can cross the fetomaternal barriers.

EXPERT OPINION

We provide an overview of NAMs that can accelerate preclinical trials and develop drugs to cross the feto-maternal barriers to reduce the risk of adverse pregnancy outcomes like preterm birth.

The Material World of 3D-Bioprinted and Microfluidic-Chip Models of Human Liver Fibrosis

Biomaterials are extensively used to mimic cell-matrix interactions, which are essential for cell growth, function, and differentiation. This is particularly relevant when developing in vitro disease models of organs rich in extracellular matrix, like the liver. Liver disease involves a chronic wound-healing response with formation of scar tissue known as fibrosis. At early stages, liver disease can be reverted, but as disease progresses, reversion is no longer possible, and there is no cure. Research for new therapies is hampered by the lack of adequate models that replicate the mechanical properties and biochemical stimuli present in the fibrotic liver. Fibrosis is associated with changes in the composition of the extracellular matrix that directly influence cell behavior. Biomaterials could play an essential role in better emulating the disease microenvironment. In this paper, the recent and cutting-edge biomaterials used for creating in vitro models of human liver fibrosis are revised, in combination with cells, bioprinting, and/or microfluidics. These technologies have been instrumental to replicate the intricate structure of the unhealthy tissue and promote medium perfusion that improves cell growth and function, respectively. A comprehensive analysis of the impact of material hints and cell-material interactions in a tridimensional context is provided.

Nanotechnology-Based Drug Delivery Systems to Control Bacterial-Biofilm-Associated Lung Infections

Airway mucus dysfunction and impaired immunological defenses are hallmarks of several lung diseases, including asthma, cystic fibrosis, and chronic obstructive pulmonary diseases, and are mostly causative factors in bacterial-biofilm-associated respiratory tract infections. Bacteria residing within the biofilm architecture pose a complex challenge in clinical settings due to their increased tolerance to currently available antibiotics and host immune responses, resulting in chronic infections with high recalcitrance and high rates of morbidity and mortality. To address these unmet clinical needs, potential anti-biofilm therapeutic strategies are being developed to effectively control bacterial biofilm. This review focuses on recent advances in the development and application of nanoparticulate drug delivery systems for the treatment of biofilm-associated respiratory tract infections, especially addressing the respiratory barriers of concern for biofilm accessibility and the various types of nanoparticles used to combat biofilms. Understanding the obstacles facing pulmonary drug delivery to bacterial biofilms and nanoparticle-based approaches to combatting biofilm may encourage researchers to explore promising treatment modalities for bacterial-biofilm-associated chronic lung infections.