Automated microfluidic cell culture of stem cell derived dopaminergic neurons

Elossaily G, Ansari MN, Ali N. An Insight on Microfluidic Organ-on-a-Chip Models for PM2.5-Induced Pulmonary Complications

Pulmonary diseases like asthma, chronic obstructive pulmonary disorder, lung fibrosis, and lung cancer pose a significant burden to global human health. Many of these complications arise as a result of exposure to particulate matter (PM), which has been examined in several preclinical and clinical trials for its effect on several respiratory diseases. Particulate matter of size less than 2.5 μm (PM2.5) has been known to inflict unforeseen repercussions, although data from epidemiological studies to back this are pending. Conventionally utilized two-dimensional (2D) cell culture and preclinical animal models have provided insufficient benefits in emulating the in vivo physiological and pathological pulmonary conditions. Three-dimensional (3D) structural models, including organ-on-a-chip models, have experienced a developmental upsurge in recent times. Lung-on-a-chip models have the potential to simulate the specific features of the lungs. With the advancement of technology, an emerging and advanced technique termed microfluidic organ-on-a-chip has been developed with the aim of identifying the complexity of the respiratory cellular microenvironment of the body. In the present Review, the role of lung-on-a-chip modeling in reproducing pulmonary complications has been explored, with a specific emphasis on PM2.5-induced pulmonary complications.

Microfluidic Brain-on-a-Chip: From Key Technology to System Integration and Application

As an ideal in vitro model, brain-on-chip (BoC) is an important tool to comprehensively elucidate brain characteristics. However, the in vitro model for the definition scope of BoC has not been universally recognized. In this review, BoC is divided into brain cells-on-a- chip, brain slices-on-a-chip, and brain organoids-on-a-chip according to the type of culture on the chip. Although these three microfluidic BoCs are constructed in different ways, they all use microfluidic chips as carrier tools. This method can better meet the needs of maintaining high culture activity on a chip for a long time. Moreover, BoC has successfully integrated cell biology, the biological material platform technology of microenvironment on a chip, manufacturing technology, online detection technology on a chip, and so on, enabling the chip to present structural diversity and high compatibility to meet different experimental needs and expand the scope of applications. Here, the relevant core technologies, challenges, and future development trends of BoC are summarized.

Scaling up stem cell production: harnessing the potential of microfluidic devices

Stem cells are specialised cells characterised by their unique ability to both self-renew and transform into a wide array of specialised cell types. The widespread interest in stem cells for regenerative medicine and cultivated meat has led to a significant demand for these cells in both research and practical applications. Despite the growing need for stem cell manufacturing, the industry faces significant obstacles, including high costs for equipment and maintenance, complicated operation, and low product quality and yield. Microfluidic technology presents a promising solution to the abovementioned challenges. As an innovative approach for manipulating liquids and cells within microchannels, microfluidics offers a plethora of advantages at an industrial scale. These benefits encompass low setup costs, ease of operation and multiplexing, minimal energy consumption, and the added advantage of being labour-free. This review presents a thorough examination of the prominent microfluidic technologies employed in stem cell research and explores their promising applications in the burgeoning stem cell industry. It thoroughly examines how microfluidics can enhance cell harvesting from tissue samples, facilitate mixing and cryopreservation, streamline microcarrier production, and efficiently conduct cell separation, purification, washing, and final cell formulation post-culture.

Corneal neuroepithelial compartmentalized microfluidic chip model for evaluation of toxicity-induced dry eye

Part of the lacrimal functional unit, the cornea protects the ocular surface from numerous environmental aggressions and xenobiotics. Toxicological evaluation of compounds remains a challenge due to complex interactions between corneal nerve endings and epithelial cells. To this day, models do not integrate the physiological specificity of corneal nerve endings and are insufficient for the detection of low toxic effects essential to anticipate Toxicity-Induced Dry Eye (TIDE). Using high-content imaging tool, we here characterize toxicity-induced cellular alterations using primary cultures of mouse trigeminal sensory neurons and corneal epithelial cells in a compartmentalized microfluidic chip. We validate this model through the analysis of benzalkonium chloride (BAC) toxicity, a well-known preservative in eyedrops, after a single (6h) or repeated (twice a day for 15 min over 5 days) topical 5.10-4% BAC applications on the corneal epithelial cells and nerve terminals. In combination with high-content image analysis, this advanced microfluidic protocol reveal specific and tiny changes in the epithelial cells and axonal network as well as in trigeminal cells, not directly exposed to BAC, with ATF3/6 stress markers and phospho-p44/42 cell activation marker. Altogether, this corneal neuroepithelial chip enables the evaluation of toxic effects of ocular xenobiotics, distinguishing the impact on corneal sensory innervation and epithelial cells. The combination of compartmentalized co-culture/high-content imaging/multiparameter analysis opens the way for the systematic analysis of toxicants but also neuroprotective compounds.

Role of three-dimensional cell culture in therapeutics and diagnostics: an updated review

Drug development and testing are a tedious and expensive process with a high degree of uncertainty in the clinical success and preclinical validation of manufactured therapeutic agents. Currently, to understand the drug action, disease mechanism, and drug testing, most therapeutic drug manufacturers use 2D cell culture models to validate the drug action. However, there are many uncertainties and limitations with the conventional use of 2D (monolayer) cell culture models for drug testing that are primarily attributed due to poor mimicking of cellular mechanisms, disturbance in environmental interaction, and changes in structural morphology. To overcome such odds and difficulties in the preclinical validation of therapeutic medications, newer in vivo drug testing cell culture models with higher screening efficiencies are required. One such promising and advanced cell culture model reported recently is the "three-dimensional cell culture model." The 3D cell culture models are reported to show evident benefits over conventional 2D cell models. This review article outlines and describes the current advancement in cell culture models, their types, significance in high-throughput screening, limitations, applications in drug toxicity screening, and preclinical testing methodologies to predict in vivo efficacy.

NGN2-based neuronal programming of hiPSCs in an automated microfluidic platform

The generation of induced pluripotent stem cells (iPSCs) via somatic cell reprogramming allowed to have an unlimited in vitro source of patient-specific cells. This achievement has introduced a new revolutionary way to create human in vitro models and to study human diseases starting from patient's own cells, especially important for inaccessible tissues like the brain. Recently, lab-on-a-chip technology has opened new reliable alternatives to conventional in vitro models able to replicate key aspects of human physiology, thanks to the intrinsic high surface-area-to-volume ratio, which allows fine control of the cellular microenvironment. The development of automated microfluidic platforms allowed the implementation of this technology to perform high-throughput, standardized and parallelized assays, suitable for drug screenings and developing new therapeutic approaches in a cost-effective way. However, the major challenges in the broad application of automated lab-on-a-chip in biological research are the lack of production robustness and ease of use of the devices. Here, we present an automated microfluidic platform able to host the rapid conversion of human iPSCs (hiPSCs) into neurons via viral-mediated overexpression of Neurogenin 2 (NGN2) in a user-friendly manner. The design of the platform, built with multilayer soft-lithography techniques, shows easiness in the fabrication and assembly thanks to the simple geometry and experimental reproducibility at the same time. All operations are managed automatically, from the cell seeding, medium change, doxycycline-mediated neuronal induction, selection of the genetically engineered cells, and analysis of the output of differentiation, including immunofluorescence assay. Our results show a high-throughput, efficient and homogenous conversion of hiPSCs into neurons in 10 days, characterized by the expression of the mature neuronal marker MAP2 and calcium signaling. The neurons-on-chip model here described represents a fully automated loop system able to address the challenges in the field of neurological diseases modelling in vitro and improve current preclinical models.

Microfluidic Liver-on-a-Chip for Preclinical Drug Discovery

Drug discovery is an expensive, long, and complex process, usually with a high degree of uncertainty. In order to improve the efficiency of drug development, effective methods are demanded to screen lead molecules and eliminate toxic compounds in the preclinical pipeline. Drug metabolism is crucial in determining the efficacy and potential side effects, mainly in the liver. Recently, the liver-on-a-chip (LoC) platform based on microfluidic technology has attracted widespread attention. LoC systems can be applied to predict drug metabolism and hepatotoxicity or to investigate PK/PD (pharmacokinetics/pharmacodynamics) performance when combined with other artificial organ-on-chips. This review discusses the liver physiological microenvironment simulated by LoC, especially the cell compositions and roles. We summarize the current methods of constructing LoC and the pharmacological and toxicological application of LoC in preclinical research. In conclusion, we also discussed the limitations of LoC in drug discovery and proposed a direction for improvement, which may provide an agenda for further research.

Challenges in the clinical advancement of cell therapies for Parkinson's disease

Cell therapies as potential treatments for Parkinson's disease first gained traction in the 1980s, owing to the clinical success of trials that used transplants of foetal midbrain dopaminergic tissue. However, the poor standardization of the tissue for grafting, and constraints on its availability and ethical use, have hindered this treatment strategy. Recent advances in stem-cell technologies and in the understanding of the development of dopaminergic neurons have enabled preclinical advancements of promising stem-cell therapies. To move these therapies to the clinic, appropriate levels of safety screening, as well as optimization of the cell products and the scalability of their manufacturing, will be required. In this Review, we discuss how challenges pertaining to cell sources, functional and safety testing, manufacturing and storage, and clinical-trial design are being addressed to advance the translational and clinical development of cell therapies for Parkinson's disease.

Short chain fatty acids: key regulators of the local and systemic immune response in inflammatory diseases and infections

The human intestinal microbiome substantially affects human health and resistance to infections in its dynamic composition and varying release of microbial-derived metabolites. Short-chain fatty acids (SCFA) produced by commensal bacteria through fermentation of indigestible fibres are considered key regulators in orchestrating the host immune response to microbial colonization by regulating phagocytosis, chemokine and central signalling pathways of cell growth and apoptosis, thereby shaping the composition and functionality of the intestinal epithelial barrier. Although research of the last decades provided valuable insight into the pleiotropic functions of SCFAs and their capability to maintain human health, mechanistic details on how SCFAs act across different cell types and other organs are not fully understood. In this review, we provide an overview of the various functions of SCFAs in regulating cellular metabolism, emphasizing the orchestration of the immune response along the gut-brain, the gut-lung and the gut-liver axes. We discuss their potential pharmacological use in inflammatory diseases and infections and highlight new options of relevant human three-dimensional organ models to investigate and validate their biological functions in more detail.

In Vitro 3D Modeling of Neurodegenerative Diseases

The study of neurodegenerative diseases (such as Alzheimer's disease, Parkinson's disease, Huntington's disease, or amyotrophic lateral sclerosis) is very complex due to the difficulty in investigating the cellular dynamics within nervous tissue. Despite numerous advances in the in vivo study of these diseases, the use of in vitro analyses is proving to be a valuable tool to better understand the mechanisms implicated in these diseases. Although neural cells remain difficult to obtain from patient tissues, access to induced multipotent stem cell production now makes it possible to generate virtually all neural cells involved in these diseases (from neurons to glial cells). Many original 3D culture model approaches are currently being developed (using these different cell types together) to closely mimic degenerative nervous tissue environments. The aim of these approaches is to allow an interaction between glial cells and neurons, which reproduces pathophysiological reality by co-culturing them in structures that recapitulate embryonic development or facilitate axonal migration, local molecule exchange, and myelination (to name a few). This review details the advantages and disadvantages of techniques using scaffolds, spheroids, organoids, 3D bioprinting, microfluidic systems, and organ-on-a-chip strategies to model neurodegenerative diseases.

Viral and non-viral gene therapy using 3D (bio)printing

The overall success in launching discovered drugs is tightly restricted to the high rate of late-stage failures, which ultimately inhibits the distribution of medicines in markets. As a result, it is imperative that methods reliably predict the effectiveness and, more critically, the toxicity of medicine early in the drug development process before clinical trials be continuously innovated. We must stay up to date with the fast appearance of new infections and diseases by rapidly developing the requisite vaccinations and medicines. Modern in vitro models of disease may be used as an alternative to traditional disease models, and advanced technology can be used for the creation of pharmaceuticals as well as cells, drugs, and gene delivery systems to expedite the drug discovery procedure. Furthermore, in vitro models that mimic the spatial and chemical characteristics of native tissues, such as a 3D bioprinting system or other technologies, have proven to be more effective for drug screening than traditional 2D models. Viral and non-viral gene delivery vectors are a hopeful tool for combinatorial gene therapy, suggesting a quick way of simultaneously deliver multiple genes. A 3D bioprinting system embraces an excellent potential for gene delivery into the different cells or tissues for different diseases, in tissue engineering and regeneration medicine, in which the precise nucleic acid is located in the 3D printed tissues and scaffolds. Non-viral nanocarriers, in combination with 3D printed scaffolds, are applied to their delivery of genes and controlled release properties. There remains, however, a big obstacle in reaching the full potential of 3D models because of a lack of in vitro manufacturing of live tissues. Bioprinting advancements have made it possible to create biomimetic constructions that may be used in various drug discovery research applications. 3D bioprinting also benefits vaccinations, medicines, and relevant delivery methods because of its flexibility and adaptability. This review discusses the potential of 3D bioprinting technologies for pharmaceutical studies.

Organs-on-Chips Platforms Are Everywhere: A Zoom on Biomedical Investigation

Over the decades, conventional in vitro culture systems and animal models have been used to study physiology, nutrient or drug metabolisms including mechanical and physiopathological aspects. However, there is an urgent need for Integrated Testing Strategies (ITS) and more sophisticated platforms and devices to approach the real complexity of human physiology and provide reliable extrapolations for clinical investigations and personalized medicine. Organ-on-a-chip (OOC), also known as a microphysiological system, is a state-of-the-art microfluidic cell culture technology that sums up cells or tissue-to-tissue interfaces, fluid flows, mechanical cues, and organ-level physiology, and it has been developed to fill the gap between in vitro experimental models and human pathophysiology. The wide range of OOC platforms involves the miniaturization of cell culture systems and enables a variety of novel experimental techniques. These range from modeling the independent effects of biophysical forces on cells to screening novel drugs in multi-organ microphysiological systems, all within microscale devices. As in living biosystems, the development of vascular structure is the salient feature common to almost all organ-on-a-chip platforms. Herein, we provide a snapshot of this fast-evolving sophisticated technology. We will review cutting-edge developments and advances in the OOC realm, discussing current applications in the biomedical field with a detailed description of how this technology has enabled the reconstruction of complex multi-scale and multifunctional matrices and platforms (at the cellular and tissular levels) leading to an acute understanding of the physiopathological features of human ailments and infections in vitro.

Engineering Organ-on-a-Chip to Accelerate Translational Research

We guide the use of organ-on-chip technology in tissue engineering applications. Organ-on-chip technology is a form of microengineered cell culture platform that elaborates the in-vivo like organ or tissue microenvironments. The organ-on-chip platform consists of microfluidic channels, cell culture chambers, and stimulus sources that emulate the in-vivo microenvironment. These platforms are typically engraved into an oxygen-permeable transparent material. Fabrication of these materials requires the use of microfabrication strategies, including soft lithography, 3D printing, and injection molding. Here we provide an overview of what is an organ-on-chip platform, where it can be used, what it is composed of, how it can be fabricated, and how it can be operated. In connection with this topic, we also introduce an overview of the recent applications, where different organs are modeled on the microscale using this technology.

Automatic differentiation of human induced pluripotent stem cells toward synchronous neural networks on an arrayed monolayer of nanofiber membrane

Automatic differentiation of human-induced pluripotent stem cells (hiPSCs) facilitates the generation of cortical neural networks and studies of brain functions. Here, we present a method of directed differentiation of hiPSCs with a substrate made of a honeycomb microframe and a monolayer of crosslinked gelatin nanofibers in the form of an array of nanofiber membranes. Neural precursor cells (NPCs) were firstly derived from hiPSCs and then placed on the nanofiber membranes for automatically controlled neural differentiation over a long period. Due to the strong modulation of the substrate stiffness and permeability, most cells were found in the center area of the honeycomb compartments, giving rise to regular and inter-connected cortical neural clusters. More importantly, the neural activities of the clusters were synchronized proving the reliability of the method. Our results showed that the self-organization, as well as the neural activities of differentiating neural cells, were more efficient in the nanofiber membrane compared to the types of the substrate such as glass and nanofiber-covered glass. In addition to the inherent advantages such as manpower saving and fewer risks of contamination and human error, automatic differentiation avoided undesired shaking which might have critical effects on the formation of synchronous neural clusters. STATEMENT OF SIGNIFICANCE: : Synchronization of cortical neural activities is essential for information processing and human cognition. By automated differentiation of human induced pluripotent stem cells on arrayed monolayer of nanofiber membrane, synchronous neural clusters could be formed. Such an approach would allow creating a variety of neural networks with regular and interconnected clusters for systematic studies of human cortical functions.

Recapitulating Tumor Hypoxia in a Cleanroom-Free, Liquid-Pinning-Based Microfluidic Tumor Model

In tumors, the metabolic demand of cancer cells often outpaces oxygen supply, resulting in a gradient of tumor hypoxia accompanied with heterogeneous resistance to cancer therapeutics. Models recapitulating tumor hypoxia are therefore essential for developing more effective cancer therapeutics. Existing in vitro models often fail to capture the spatial heterogeneity of tumor hypoxia or involve high-cost, complex fabrication/handling techniques. Here, we designed a highly tunable microfluidic device that induces hypoxia through natural cell metabolism and oxygen diffusion barriers. We adopted a cleanroom-free, micromilling-replica-molding strategy and a microfluidic liquid-pinning approach to streamline the fabrication and tumor model establishment. We also implemented a thin-film oxygen diffusion barrier design, which was optimized through COMSOL simulation, to support both two-dimensional (2-D) and three-dimensional (3-D) hypoxic models. We demonstrated that liquid-pinning enables an easy, injection-based micropatterning of cancer cells of a wide range of parameters, showing the high tunability of our design. Human breast cancer and prostate cancer cells were seeded and stained after 24 h of 2-D and 3-D culture to validate the natural induction of hypoxia. We further demonstrated the feasibility of the parallel microfluidic channel design to evaluate dual therapeutic conditions in the same device. Overall, our new microfluidic tumor model serves as a user-friendly, cost-effective, and highly scalable platform that provides spatiotemporal analysis of the hypoxic tumor microenvironments suitable for high-content biological studies and therapeutic discoveries.

Microfluidics for 3D Cell and Tissue Cultures: Microfabricative and Ethical Aspects Updates

The necessity to improve in vitro cell screening assays is becoming ever more important. Pharmaceutical companies, research laboratories and hospitals require technologies that help to speed up conventional screening and therapeutic procedures to produce more data in a short time in a realistic and reliable manner. The design of new solutions for test biomaterials and active molecules is one of the urgent problems of preclinical screening and the limited correlation between in vitro and in vivo data remains one of the major issues. The establishment of the most suitable in vitro model provides reduction in times, costs and, last but not least, in the number of animal experiments as recommended by the 3Rs (replace, reduce, refine) ethical guiding principles for testing involving animals. Although two-dimensional (2D) traditional cell screening assays are generally cheap and practical to manage, they have strong limitations, as cells, within the transition from the three-dimensional (3D) in vivo to the 2D in vitro growth conditions, do not properly mimic the real morphologies and physiology of their native tissues. In the study of human pathologies, especially, animal experiments provide data closer to what happens in the target organ or apparatus, but they imply slow and costly procedures and they generally do not fully accomplish the 3Rs recommendations, i.e., the amount of laboratory animals and the stress that they undergo must be minimized. Microfluidic devices seem to offer different advantages in relation to the mentioned issues. This review aims to describe the critical issues connected with the conventional cells culture and screening procedures, showing what happens in the in vivo physiological micro and nano environment also from a physical point of view. During the discussion, some microfluidic tools and their components are described to explain how these devices can circumvent the actual limitations described in the introduction.

Human Brain-Based Models Provide a Powerful Tool for the Advancement of Parkinson’s Disease Research and Therapeutic Development

Parkinson’s disease (PD) is the second most common neurodegenerative disease and affects approximately 2–3% of the population over the age of 65. PD is characterised by the loss of dopaminergic neurons from the substantia nigra, leading to debilitating motor symptoms including bradykinesia, tremor, rigidity, and postural instability. PD also results in a host of non-motor symptoms such as cognitive decline, sleep disturbances and depression. Although existing therapies can successfully manage some motor symptoms for several years, there is still no means to halt progression of this severely debilitating disorder. Animal models used to replicate aspects of PD have contributed greatly to our current understanding but do not fully replicate pathological mechanisms as they occur in patients. Because of this, there is now great interest in the use of human brain-based models to help further our understanding of disease processes. Human brain-based models include those derived from embryonic stem cells, patient-derived induced neurons, induced pluripotent stem cells and brain organoids, as well as post-mortem tissue. These models facilitate in vitro analysis of disease mechanisms and it is hoped they will help bridge the existing gap between bench and bedside. This review will discuss the various human brain-based models utilised in PD research today and highlight some of the key breakthroughs they have facilitated. Furthermore, the potential caveats associated with the use of human brain-based models will be detailed.

Induced pluripotent stem cell-based organ-on-a-chip as personalized drug screening tools: A focus on neurodegenerative disorders

The Organ-on-a-Chip (OoC) technology shows great potential to revolutionize the drugs development pipeline by mimicking the physiological environment and functions of human organs. The translational value of OoC is further enhanced when combined with patient-specific induced pluripotent stem cells (iPSCs) to develop more realistic disease models, paving the way for the development of a new generation of patient-on-a-chip devices. iPSCs differentiation capacity leads to invaluable improvements in personalized medicine. Moreover, the connection of single-OoC into multi-OoC or body-on-a-chip allows to investigate drug pharmacodynamic and pharmacokinetics through the study of multi-organs cross-talks. The need of a breakthrough thanks to this technology is particularly relevant within the field of neurodegenerative diseases, where the number of patients is increasing and the successful rate in drug discovery is worryingly low. In this review we discuss current iPSC-based OoC as drug screening models and their implication in development of new therapies for neurodegenerative disorders.

The impact of microfluidics in high-throughput drug-screening applications

Drug discovery is an expensive and lengthy process. Among the different phases, drug discovery and preclinical trials play an important role as only 5-10 of all drugs that begin preclinical tests proceed to clinical trials. Indeed, current high-throughput screening technologies are very expensive, as they are unable to dispense small liquid volumes in an accurate and quick way. Moreover, despite being simple and fast, drug screening assays are usually performed under static conditions, thus failing to recapitulate tissue-specific architecture and biomechanical cues present in vivo even in the case of 3D models. On the contrary, microfluidics might offer a more rapid and cost-effective alternative. Although considered incompatible with high-throughput systems for years, technological advancements have demonstrated how this gap is rapidly reducing. In this Review, we want to further outline the role of microfluidics in high-throughput drug screening applications by looking at the multiple strategies for cell seeding, compartmentalization, continuous flow, stimuli administration (e.g., drug gradients or shear stresses), and single-cell analyses.

Organoid Models for Precision Cancer Immunotherapy

Cancer immunotherapy is exploited for the treatment of disease by modulating the immune system. Since the conventional in vivo animal and 2D in vitro models insufficiently recapitulate the complex tumor immune microenvironment (TIME) of the original tumor. In addition, due to the involvement of the immune system in cancer immunotherapy, more physiomimetic cancer models, such as patient-derived organoids (PDOs), are required to evaluate the efficacy of immunotherapy agents. On the other hand, the dynamic interactions between the neoplastic cells and non-neoplastic host components in the TIME can promote carcinogenesis, tumor metastasis, cancer progression, and drug resistance of cancer cells. Indeed, tumor organoid models can properly recapitulate the TIME by preserving endogenous stromal components including various immune cells, or by adding exogenous immune cells, cancer-associated fibroblasts (CAFs), vasculature, and other components. Therefore, organoid culture platforms could model immunotherapy responses and facilitate the immunotherapy preclinical testing. Here, we discuss the various organoid culture approaches for the modeling of TIME and the applications of complex tumor organoids in testing cancer immunotherapeutics and personalized cancer immunotherapy.

Organ-on-Chip platforms to study tumor evolution and chemosensitivity

Despite tremendous advancements in oncology research and therapeutics, cancer remains a primary cause of death worldwide. One of the significant factors in this critical challenge is a precise diagnosis and limited knowledge on how the tumor microenvironment (TME) behaves to the treatment and its role in chemo-resistance. Therefore, it is critical to understand the contribution of a heterogeneous TME in cancer drug response in individual patients for effective therapy management. Micro-physiological systems along with tissue engineering have facilitated the development of more physiologically relevant platforms, known as Organ-on-Chips (OoC). OoC platforms recapitulate the critical hallmarks of the TME in vitro and subsequently abet in sensitivity and efficacy testing of anti-cancer drugs before clinical trials. The OoC platforms incorporating conventional in vitro models enable researchers to control the cellular, molecular, chemical, and biophysical parameters of the TME in precise combinations while analyzing how they contribute to tumor progression and therapy response. This review discusses the application of OoC platforms integrated with conventional 2D cell lines, 3D organoids and spheroid models, and the organotypic tissue slices, including patient-derived and xenograft tumor slice cultures in cancer treatment responses. We summarize the relevance and drawbacks of conventional in vitro models in assessing cancer treatment response, challenges and limitations associated with OoC models, and future opportunities enabled by the OoC technologies towards developing personalized cancer diagnostics and therapeutics.

Artificial Intelligence-Controlled Microfluidic Device for Fluid Automation and Bubble Removal of Immunoassay Operated by a Smartphone

There have been tremendous innovations in microfluidic clinical diagnostics to facilitate novel point-of-care testing (POCT) over the past decades. However, the automatic operation of microfluidic devices that minimize user intervention still lacks reliability and repeatability because microfluidic errors such as bubbles and incomplete filling pose a major bottleneck in commercializing the microfluidic devices for clinical testing. In this work, for the first time, various states of microfluid were recognized to control immunodiagnostics by artificial intelligence (AI) technology. The developed AI-controlled microfluidic platform was operated via an Android smartphone, along with a low-cost polymer device to effectuate enzyme-linked immunosorbent assay (ELISA). To overcome the limited machine-learning capability of smartphones, the region-of-interest (ROI) cascading and conditional activation algorithms were utilized herein. The developed microfluidic chip was incorporated with a bubble trap to remove any bubbles detected by AI, which helps in preventing false signals during immunoassay, as well as controlling the reagents' movement with an on-chip micropump and valve. Subsequently, the developed immunosensing platform was tested for conducting real ELISA using a single microplate from the 96-well to detect the Human Cardiac Troponin I (cTnI) biomarker, with a detection limit as low as 0.98 pg/mL. As a result, the developed platform can be envisaged as an AI-based revolution in microfluidics for point-of-care clinical diagnosis.

From organ-on-chip to body-on-chip: The next generation of microfluidics platforms for in vitro drug efficacy and toxicity testing

The high failure rate in drug development is often attributed to the lack of accurate pre-clinical models that may lead to false discoveries and inconclusive data when the compounds are eventually tested in clinical phase. With the evolution of cell culture technologies, drug testing systems have widely improved, and today, with the emergence of microfluidics devices, drug screening seems to be at the dawn of an important revolution. An organ-on-chip allows the culture of living cells in continuously perfused microchambers to reproduce physiological functions of a particular tissue or organ. The advantages of such systems are not only their ability to recapitulate the complex biochemical interactions between different human cell types but also to incorporate physical forces, including shear stress and mechanical stretching or compression. To improve this model, and to reproduce the absorption, distribution, metabolism, and elimination process of an exogenous compound, organ-on-chips can even be linked fluidically to mimic physiological interactions between different organs, leading to the development of body-on-chips. Although these technologies are still at a young age and need to address a certain number of limitations, they already demonstrated their relevance to study the effect of drugs or toxins on organs, displaying a similar response to what is observed in vivo. The purpose of this review is to present the evolution from organ-on-chip to body-on-chip, examine their current use for drug testing and discuss their advantages and future challenges they will face in order to become an essential pillar of pharmaceutical research.

Automated liquid handling robot for rapid lateral flow assay development

The lateral flow assay (LFA) is one of the most popular technologies on the point-of-care diagnostics market due to its low cost and ease of use, with applications ranging from pregnancy to environmental toxins to infectious disease. While the use of these tests is relatively straightforward, significant development time and effort are required to create tests that are both sensitive and specific. Workflows to guide the LFA development process exist but moving from target selection to an LFA that is ready for field testing can be labor intensive, resource heavy, and time consuming. To reduce the cost and the duration of the LFA development process, we introduce a novel development platform centered on the flexibility, speed, and throughput of an automated robotic liquid handling system. The system comprises LFA-specific hardware and software that enable large optimization experiments with discrete and continuous variables such as antibody pair selection or reagent concentration. Initial validation of the platform was demonstrated during development of a malaria LFA but was readily expanded to encompass development of SARS-CoV-2 and Mycobacterium tuberculosis LFAs. The validity of the platform, where optimization experiments are run directly on LFAs rather than in solution, was based on a direct comparison between the robotic system and a more traditional ELISA-like method. By minimizing hands-on time, maximizing experiment size, and enabling improved reproducibility, the robotic system improved the quality and quantity of LFA assay development efforts.

Graphical abstract

Bioengineered models of Parkinson's disease using patient-derived dopaminergic neurons exhibit distinct biological profiles in a 3D microenvironment

Three-dimensional (3D) in vitro culture systems using human induced pluripotent stem cells (hiPSCs) are useful tools to model neurodegenerative disease biology in physiologically relevant microenvironments. Though many successful biomaterials-based 3D model systems have been established for other neurogenerative diseases, such as Alzheimer's disease, relatively few exist for Parkinson's disease (PD) research. We employed tissue engineering approaches to construct a 3D silk scaffold-based platform for the culture of hiPSC-dopaminergic (DA) neurons derived from healthy individuals and PD patients harboring LRRK2 G2019S or GBA N370S mutations. We then compared results from protein, gene expression, and metabolic analyses obtained from two-dimensional (2D) and 3D culture systems. The 3D platform enabled the formation of dense dopamine neuronal network architectures and developed biological profiles both similar and distinct from 2D culture systems in healthy and PD disease lines. PD cultures developed in 3D platforms showed elevated levels of α-synuclein and alterations in purine metabolite profiles. Furthermore, computational network analysis of transcriptomic networks nominated several novel molecular interactions occurring in neurons from patients with mutations in LRRK2 and GBA. We conclude that the brain-like 3D system presented here is a realistic platform to interrogate molecular mechanisms underlying PD biology.

Biomaterial-based strategies for in vitro neural models

In vitro models have been used as a complementary tool to animal studies in understanding the nervous system's physiological mechanisms and pathological disorders, while also serving as platforms to evaluate the safety and efficiency of therapeutic candidates. Following recent advances in materials science, micro- and nanofabrication techniques and cell culture systems, in vitro technologies have been rapidly gaining the potential to bridge the gap between animal and clinical studies by providing more sophisticated models that recapitulate key aspects of the structure, biochemistry, biomechanics, and functions of human tissues. This was made possible, in large part, by the development of biomaterials that provide cells with physicochemical features that closely mimic the cellular microenvironment of native tissues. Due to the well-known material-driven cellular response and the importance of mimicking the environment of the target tissue, the selection of optimal biomaterials represents an important early step in the design of biomimetic systems to investigate brain structures and functions. This review provides a comprehensive compendium of commonly used biomaterials as well as the different fabrication techniques employed for the design of neural tissue models. Furthermore, the authors discuss the main parameters that need to be considered to develop functional platforms not only for the study of brain physiological functions and pathological processes but also for drug discovery/development and the optimization of biomaterials for neural tissue engineering.

Advances in microfluidic 3D cell culture for preclinical drug development

Drug development is often a very long, costly, and risky process due to the lack of reliability in the preclinical studies. Traditional current preclinical models, mostly based on 2D cell culture and animal testing, are not full representatives of the complex in vivo microenvironments and often fail. In order to reduce the enormous costs, both financial and general well-being, a more predictive preclinical model is needed. In this chapter, we review recent advances in microfluidic 3D cell culture showing how its development has allowed the introduction of in vitro microphysiological systems, laying the foundation for organ-on-a-chip technology. These findings provide the basis for numerous preclinical drug discovery assays, which raise the possibility of using micro-engineered systems as emerging alternatives to traditional models, based on 2D cell culture and animals.

Modelling and Prevention of Acute Kidney Injury through Ischemia and Reperfusion in a Combined Human Renal Proximal Tubule/Blood Vessel-on-a-Chip

Background

Renal ischemia/reperfusion injury (rIRI) is one of the major causes of AKI. Although animal models are suitable for investigating systemic symptoms of AKI, they are limited in translatability. Human in vitro models are crucial in giving mechanistic insights into rIRI; however, they miss out on crucial aspects such as reperfusion injury and the multitissue aspect of AKI.

Methods

We advanced the current renal proximal tubule-on-a-chip model to a coculture model with a perfused endothelial vessel separated by an extracellular matrix. The coculture was characterized for its three-dimensional structure, protein expression, and response to nephrotoxins. Then, rIRI was captured through control of oxygen levels, nutrient availability, and perfusion flow settings. Injury was quantified through morphologic assessment, caspase-3/7 activation, and cell viability.

Results

The combination of low oxygen, reduced glucose, and interrupted flow was potent to disturb the proximal tubules. This effect was strongly amplified upon reperfusion. Endothelial vessels were less sensitive to the ischemia-reperfusion parameters. Adenosine treatment showed a protective effect on the disruption of the epithelium and on the caspase-3/7 activation.

Conclusions

A human in vitro rIRI model was developed using a coculture of a proximal tubule and blood vessel on-a-chip, which was used to characterize the renoprotective effect of adenosine. The robustness of the model and assays in combination with the throughput of the platform make it ideal to advance pathophysiological research and enable the development of novel therapeutic modalities.

Modelling the central nervous system: tissue engineering of the cellular microenvironment

With the increasing prevalence of neurodegenerative diseases, improved models of the central nervous system (CNS) will improve our understanding of neurophysiology and pathogenesis, whilst enabling exploration of novel therapeutics. Studies of brain physiology have largely been carried out using in vivo models, ex vivo brain slices or primary cell culture from rodents. Whilst these models have provided great insight into complex interactions between brain cell types, key differences remain between human and rodent brains, such as degree of cortical complexity. Unfortunately, comparative models of human brain tissue are lacking. The development of induced Pluripotent Stem Cells (iPSCs) has accelerated advancement within the field of in vitro tissue modelling. However, despite generating accurate cellular representations of cortical development and disease, two-dimensional (2D) iPSC-derived cultures lack an entire dimension of environmental information on structure, migration, polarity, neuronal circuitry and spatiotemporal organisation of cells. As such, researchers look to tissue engineering in order to develop advanced biomaterials and culture systems capable of providing necessary cues for guiding cell fates, to construct in vitro model systems with increased biological relevance. This review highlights experimental methods for engineering of in vitro culture systems to recapitulate the complexity of the CNS with consideration given to previously unexploited biophysical cues within the cellular microenvironment.

Parkinson's disease and the gut: Models of an emerging relationship

Parkinson's disease (PD) is a common neurodegenerative disease characterized by a progressive loss of fine motor function that impacts 1-2 out of 1,000 people. PD occurs predominately late in life and lacks a definitive biomarker for early detection. Recent cross-disciplinary progress has implicated the gut as a potential origin of PD pathogenesis. The gut-origin hypothesis has motivated research on gut PD pathology and transmission to the brain, especially during the prodromal stage (10-20 years before motor symptom onset). Early findings have revealed several possible triggers for Lewy pathology - the pathological hallmark of PD - in the gut, suggesting that microbiome and epithelial interactions may play a greater than appreciated role. But the mechanisms driving Lewy pathology and gut-brain transmission in PD remain unknown. Development of artificial α-Synuclein aggregates (α-Syn preformed fibrils) and animal disease models have recapitulated features of PD progression, enabling for the first time, controlled investigation of the gut-origin hypothesis. However, the role of specific cells in PD transmission, such as neurons, remains limited and requires in vitro models for controlled evaluation and perturbation. Human cell populations, three-dimensional organoids, and microfluidics as discovery platforms inch us closer to improving existing treatment for patients by providing platforms for discovery and screening. This review includes a discussion of PD pathology, conventional treatments, in vivo and in vitro models, and future directions. STATEMENT OF SIGNIFICANCE: Parkinson's Disease remains a common neurodegenerative disease with palliative versus causal treatments. Recently, the gut-origin hypothesis, where Parkinson's disease is thought to originate and spread from the gut to the brain, has gained traction as a field of investigation. However, despite the wealth of studies and innovative approaches to accelerate the field, there remains a need for in vitro tools to enable fundamental biological understanding of disease progression, and compound screening and efficacy. In this review, we present a historical perspective of Parkinson's Disease pathogenesis, detection, and conventional therapy, animal and human models investigating the gut-origin hypothesis, in vitro models to enable controlled discovery, and future outlooks for this blossoming field.

Engineered neural circuits for modeling brain physiology and neuropathology

The neural circuits of the central nervous system are the regulatory pathways for feeling, motion control, learning, and memory, and their dysfunction is closely related to various neurodegenerative diseases. Despite the growing demand for the unraveling of the physiology and functional connectivity of the neural circuits, their fundamental investigation is hampered because of the inability to access the components of neural circuits and the complex microenvironment. As an alternative approach, in vitro human neural circuits show principles of in vivo human neuronal circuit function. They allow access to the cellular compartment and permit real-time monitoring of neural circuits. In this review, we summarize recent advances in reconstituted in vitro neural circuits using engineering techniques. To this end, we provide an overview of the fabrication techniques and methods for stimulation and measurement of in vitro neural circuits. Subsequently, representative examples of in vitro neural circuits are reviewed with a particular focus on the recapitulation of structures and functions observed in vivo, and we summarize their application in the study of various brain diseases. We believe that the in vitro neural circuits can help neuroscience and the neuropharmacology. STATEMENT OF SIGNIFICANCE: Despite the growing demand to unravel the physiology and functional connectivity of the neural circuits, the studies on the in vivo neural circuits are frequently limited due to the poor accessibility. Furthermore, single neuron-based analysis has an inherent limitation in that it does not reflect the full spectrum of the neural circuit physiology. As an alternative approach, in vitro engineered neural circuit models have arisen because they can recapitulate the structural and functional characteristics of in vivo neural circuits. These in vitro neural circuits allow the mimicking of dysregulation of the neural circuits, including neurodegenerative diseases and traumatic brain injury. Emerging in vitro engineered neural circuits will provide a better understanding of the (patho-)physiology of neural circuits.

Microfluidic Devices as Process Development Tools for Cellular Therapy Manufacturing

Cellular therapies are creating a paradigm shift in the biomanufacturing industry. Particularly for autologous therapies, small-scale processing methods are better suited than the large-scale approaches that are traditionally employed in the industry. Current small-scale methods for manufacturing personalized cell therapies, however, are labour-intensive and involve a number of 'open events'. To overcome these challenges, new cell manufacturing platforms following a GMP-in-a-box concept have recently come on the market (GMP: Good Manufacturing Practice). These are closed automated systems with built-in pumps for fluid handling and sensors for in-process monitoring. At a much smaller scale, microfluidic devices exhibit many of the same features as current GMP-in-a-box systems. They are closed systems, fluids can be processed and manipulated, and sensors integrated for real-time detection of process variables. Fabricated from polymers, they can be made disposable, i.e. single-use. Furthermore, microfluidics offers exquisite spatiotemporal control over the cellular microenvironment, promising both reproducibility and control of outcomes. In this chapter, we consider the challenges in cell manufacturing, highlight recent advances of microfluidic devices for each of the main process steps, and summarize our findings on the current state of the art. As microfluidic cell culture devices have been reported for both adherent and suspension cell cultures, we report on devices for the key process steps, or unit operations, of both stem cell therapies and cell-based immunotherapies.

Micro-Droplet Platform for Exploring the Mechanism of Mixed Field Agglutination in B3 Subtype

B3 is the most common subtype of blood group B in the Taiwanese population, and most of the B3 individuals in the Taiwanese population have the IVS3 + 5 G > A (rs55852701) gene variation. Additionally, a typical mixed field agglutination is observed when the B3 subtype is tested with anti-B antibody or anti-AB antibody. The molecular biology of the gene variation in the B3 subtype has been identified, however, the mechanism of the mixed field agglutination caused by the type B3 blood samples is still unclear. Therefore, the purpose of this study was to understand the reason for the mixed field agglutination caused by B3. A micro-droplet platform was used to observe the agglutination of type B and type B3 blood samples in different blood sample concentrations, antibody concentrations, and at reaction times. We found that the agglutination reaction in every droplet slowed down with an increase in the dilution ratio of blood sample and antibody, whether type B blood or type B3 blood was used. However, as the reaction time increased, the complete agglutination in the droplet was seen in type B blood, while the mixed field agglutination still occurred in B3 within 1 min. In addition, the degree of agglutination was similar in each droplet, which showed high reproducibility. As a result, we inferred that there are two types of cells in the B3 subtype that simultaneously create a mixed field agglutination, rather than each red blood cell carrying a small amount of antigen, resulting in less agglutination.

Comprehensive Development in Organ-On-A-Chip Technology

The expeditious advancement in the organ on chip technology provided a phase change to the conventional in vitro tests used to evaluate absorption, distribution, metabolism, excretion (ADME) studies and toxicity assessments. The demand for an accurate predictive model for assessing toxicity and reducing the potential risk factors became the prime area of any drug delivery process. Researchers around the globe are welcoming the incorporation of organ-on-a-chips for ADME and toxicity evaluation. Organ-on-a-chip (OOC) is an interdisciplinary technology that evolved as a contemporary in vitro model for the pharmacokinetics and pharmacodynamics (PK-PD) studies of a proposed drug candidate in the pre-clinical phases of drug development. The OOC provides a platform that mimics the physiological functions occurring in the human body. The precise flow control systems and the rapid sample processing makes OOC more advanced than the conventional two-dimensional (2D) culture systems. The integration of various organs as in the multi organs-on-a-chip provides more significant ideas about the time and dose dependant effects occurring in the body when a new drug molecule is administered as part of the pre-clinical times. This review outlines the comprehensive development in the organ-on-a-chip technology, various OOC models and its drug development applications, toxicity evaluation and efficacy studies.

Microfluidic technologies for immunotherapy studies on solid tumours

Immunotherapy is a powerful and targeted cancer treatment that exploits the body's immune system to attack and eliminate cancerous cells. This form of therapy presents the possibility of long-term control and prevention of recurrence due to the memory capabilities of the immune system. Various immunotherapies are successful in treating haematological malignancies and have dramatically improved outcomes in melanoma. However, tackling other solid tumours is more challenging, mostly because of the immunosuppressive tumour microenvironment (TME). Current in vitro models based on traditional 2D cell monolayers and animal models, such as patient-derived xenografts, have limitations in their ability to mimic the complexity of the human TME. As a result, they have inadequate translational value and can be poorly predictive of clinical outcome. Thus, there is a need for robust in vitro preclinical tools that more faithfully recapitulate human solid tumours to test novel immunotherapies. Microfluidics and lab-on-a-chip technologies offer opportunities, especially when performing mechanistic studies, to understand the role of the TME in immunotherapy, and to expand the experimental throughput when using patient-derived tissue through its miniaturization capabilities. This review first introduces the basic concepts of immunotherapy, presents the current preclinical approaches used in immuno-oncology for solid tumours and then discusses the underlying challenges. We provide a rationale for using microfluidic-based approaches, highlighting the most recent microfluidic technologies and methodologies that have been used for studying cancer-immune cell interactions and testing the efficacy of immunotherapies in solid tumours. Ultimately, we discuss achievements and limitations of the technology, commenting on potential directions for incorporating microfluidic technologies in future immunotherapy studies.

Emerging Brain-Pathophysiology-Mimetic Platforms for Studying Neurodegenerative Diseases: Brain Organoids and Brains-on-a-Chip

Neurodegenerative diseases are a group of disorders characterized by progressive degeneration of the structural and functional integrity of the central and peripheral nervous systems. Millions of people suffer from degenerative brain diseases worldwide, and the mortality continues to increase every year, causing a growing demand for knowledge of the underlying mechanisms and development of therapeutic targets. Conventional 2D-based cell culture platforms and animal models cannot fully recapitulate the pathophysiology, and this has limited the capability for estimating drug efficacy. Recently, engineered platforms, including brain organoids and brain-on-a-chip, have emerged. They mimic the physiology of brain tissue and reflect the fundamental pathophysiological signatures of neurodegenerative diseases, such as the accumulation of neurotoxic proteins, structural abnormalities, and functional loss. In this paper, recent advances in brain-mimetic platforms and their potential for modeling features of neurodegenerative diseases in vitro are reviewed. The development of a physiologically relevant model should help overcome unresolved neurodegenerative diseases.

Electrophysiology Read-Out Tools for Brain-on-Chip Biotechnology

Brain-on-Chip (BoC) biotechnology is emerging as a promising tool for biomedical and pharmaceutical research applied to the neurosciences. At the convergence between lab-on-chip and cell biology, BoC couples in vitro three-dimensional brain-like systems to an engineered microfluidics platform designed to provide an in vivo-like extrinsic microenvironment with the aim of replicating tissue- or organ-level physiological functions. BoC therefore offers the advantage of an in vitro reproduction of brain structures that is more faithful to the native correlate than what is obtained with conventional cell culture techniques. As brain function ultimately results in the generation of electrical signals, electrophysiology techniques are paramount for studying brain activity in health and disease. However, as BoC is still in its infancy, the availability of combined BoC-electrophysiology platforms is still limited. Here, we summarize the available biological substrates for BoC, starting with a historical perspective. We then describe the available tools enabling BoC electrophysiology studies, detailing their fabrication process and technical features, along with their advantages and limitations. We discuss the current and future applications of BoC electrophysiology, also expanding to complementary approaches. We conclude with an evaluation of the potential translational applications and prospective technology developments.

A directional 3D neurite outgrowth model for studying motor axon biology and disease

We report a method to generate a 3D motor neuron model with segregated and directed axonal outgrowth. iPSC-derived motor neurons are cultured in extracellular matrix gel in a microfluidic platform. Neurons extend their axons into an adjacent layer of gel, whereas dendrites and soma remain predominantly in the somal compartment, as verified by immunofluorescent staining. Axonal outgrowth could be precisely quantified and was shown to respond to the chemotherapeutic drug vincristine in a highly reproducible dose-dependent manner. The model was shown susceptible to excitotoxicity upon exposure with excess glutamate and showed formation of stress granules upon excess glutamate or sodium arsenite exposure, mimicking processes common in motor neuron diseases. Importantly, outgrowing axons could be attracted and repelled through a gradient of axonal guidance cues, such as semaphorins. The platform comprises 40 chips arranged underneath a microtiter plate providing both throughput and compatibility to standard laboratory equipment. The model will thus prove ideal for studying axonal biology and disease, drug discovery and regenerative medicine.

Integrated, automated maintenance, expansion and differentiation of 2D and 3D patient-derived cellular models for high throughput drug screening

Patient-derived cellular models become an increasingly powerful tool to model human diseases for precision medicine approaches. The identification of robust cellular disease phenotypes in these models paved the way towards high throughput screenings (HTS) including the implementation of laboratory advanced automation. However, maintenance and expansion of cells for HTS remains largely manual work. Here, we describe an integrated, complex automated platform for HTS in a translational research setting also designed for maintenance and expansion of different cell types. The comprehensive design allows automation of all cultivation steps and is flexible for development of methods for variable cell types. We demonstrate protocols for controlled cell seeding, splitting and expansion of human fibroblasts, induced pluripotent stem cells (iPSC), and neural progenitor cells (NPC) that allow for subsequent differentiation into different cell types and image-based multiparametric screening. Furthermore, we provide automated protocols for neuronal differentiation of NPC in 2D culture and 3D midbrain organoids for HTS. The flexibility of this multitask platform makes it an ideal solution for translational research settings involving experiments on different patient-derived cellular models for precision medicine.

Mechanical Stimulation: A Crucial Element of Organ-on-Chip Models

Organ-on-chip (OOC) systems recapitulate key biological processes and responses in vitro exhibited by cells, tissues, and organs in vivo. Accordingly, these models of both health and disease hold great promise for improving fundamental research, drug development, personalized medicine, and testing of pharmaceuticals, food substances, pollutants etc. Cells within the body are exposed to biomechanical stimuli, the nature of which is tissue specific and may change with disease or injury. These biomechanical stimuli regulate cell behavior and can amplify, annul, or even reverse the response to a given biochemical cue or drug candidate. As such, the application of an appropriate physiological or pathological biomechanical environment is essential for the successful recapitulation of in vivo behavior in OOC models. Here we review the current range of commercially available OOC platforms which incorporate active biomechanical stimulation. We highlight recent findings demonstrating the importance of including mechanical stimuli in models used for drug development and outline emerging factors which regulate the cellular response to the biomechanical environment. We explore the incorporation of mechanical stimuli in different organ models and identify areas where further research and development is required. Challenges associated with the integration of mechanics alongside other OOC requirements including scaling to increase throughput and diagnostic imaging are discussed. In summary, compelling evidence demonstrates that the incorporation of biomechanical stimuli in these OOC or microphysiological systems is key to fully replicating in vivo physiology in health and disease.

Recent progress in translational engineered in vitro models of the central nervous system

The complexity of the human brain poses a substantial challenge for the development of models of the CNS. Current animal models lack many essential human characteristics (in addition to raising operational challenges and ethical concerns), and conventional in vitro models, in turn, are limited in their capacity to provide information regarding many functional and systemic responses. Indeed, these challenges may underlie the notoriously low success rates of CNS drug development efforts. During the past 5 years, there has been a leap in the complexity and functionality of in vitro systems of the CNS, which have the potential to overcome many of the limitations of traditional model systems. The availability of human-derived induced pluripotent stem cell technology has further increased the translational potential of these systems. Yet, the adoption of state-of-the-art in vitro platforms within the CNS research community is limited. This may be attributable to the high costs or the immaturity of the systems. Nevertheless, the costs of fabrication have decreased, and there are tremendous ongoing efforts to improve the quality of cell differentiation. Herein, we aim to raise awareness of the capabilities and accessibility of advanced in vitro CNS technologies. We provide an overview of some of the main recent developments (since 2015) in in vitro CNS models. In particular, we focus on engineered in vitro models based on cell culture systems combined with microfluidic platforms (e.g. 'organ-on-a-chip' systems). We delve into the fundamental principles underlying these systems and review several applications of these platforms for the study of the CNS in health and disease. Our discussion further addresses the challenges that hinder the implementation of advanced in vitro platforms in personalized medicine or in large-scale industrial settings, and outlines the existing differentiation protocols and industrial cell sources. We conclude by providing practical guidelines for laboratories that are considering adopting organ-on-a-chip technologies.

A Tissue Engineering Approach to Metastatic Colon Cancer

Colon cancer remains the third most common cause of cancer in the US, and the third most common cause of cancer death. Worldwide, colon cancer is the second most common cause of cancer and cancer deaths. At least 25% of patients still present with metastatic disease, and at least 25-30% will develop metastatic colon cancer in the course of their disease. While chemotherapy and surgery remain the mainstay of treatment, understanding the fundamental cellular niche and mechanical properties that result in metastases would facilitate both prevention and cure. Advances in biomaterials, novel 3D primary human cells, modelling using microfluidics and the ability to alter the physical environment, now offers a unique opportunity to develop and test impactful treatment.

Automation in the Life Science Research Laboratory

Protocols in the academic life science laboratory are heavily reliant on the manual manipulation of tools, reagents and instruments by a host of research staff and students. In contrast to industrial and clinical laboratory environments, the usage of automation to augment or replace manual tasks is limited. Causes of this 'automation gap' are unique to academic research, with rigid short-term funding structures, high levels of protocol variability and a benevolent culture of investment in people over equipment. Automation, however, can bestow multiple benefits through improvements in reproducibility, researcher efficiency, clinical translation, and safety. Less immediately obvious are the accompanying limitations, including obsolescence and an inhibitory effect on the freedom to innovate. Growing the range of automation options suitable for research laboratories will require more flexible, modular and cheaper designs. Academic and commercial developers of automation will increasingly need to design with an environmental awareness and an understanding that large high-tech robotic solutions may not be appropriate for laboratories with constrained financial and spatial resources. To fully exploit the potential of laboratory automation, future generations of scientists will require both engineering and biology skills. Automation in the research laboratory is likely to be an increasingly critical component of future research programs and will continue the trend of combining engineering and science expertise together to answer novel research questions.

Microfluidics for Biotechnology: Bridging Gaps to Foster Microfluidic Applications

Microfluidics and novel lab-on-a-chip applications have the potential to boost biotechnological research in ways that are not possible using traditional methods. Although microfluidic tools were increasingly used for different applications within biotechnology in recent years, a systematic and routine use in academic and industrial labs is still not established. For many years, absent innovative, ground-breaking and “out-of-the-box” applications have been made responsible for the missing drive to integrate microfluidic technologies into fundamental and applied biotechnological research. In this review, we highlight microfluidics’ offers and compare them to the most important demands of the biotechnologists. Furthermore, a detailed analysis in the state-of-the-art use of microfluidics within biotechnology was conducted exemplarily for four emerging biotechnological fields that can substantially benefit from the application of microfluidic systems, namely the phenotypic screening of cells, the analysis of microbial population heterogeneity, organ-on-a-chip approaches and the characterisation of synthetic co-cultures. The analysis resulted in a discussion of potential “gaps” that can be responsible for the rare integration of microfluidics into biotechnological studies. Our analysis revealed six major gaps, concerning the lack of interdisciplinary communication, mutual knowledge and motivation, methodological compatibility, technological readiness and missing commercialisation, which need to be bridged in the future. We conclude that connecting microfluidics and biotechnology is not an impossible challenge and made seven suggestions to bridge the gaps between those disciplines. This lays the foundation for routine integration of microfluidic systems into biotechnology research procedures.

Innovations in 3-Dimensional Tissue Models of Human Brain Physiology and Diseases

3-dimensional (3D) laboratory tissue cultures have emerged as an alternative to traditional 2-dimensional (2D) culture systems that do not recapitulate native cell behavior. The discrepancy between in vivo and in vitro tissue-cell-molecular responses impedes understanding of human physiology in general and creates roadblocks for the discovery of therapeutic solutions. Two parallel approaches have emerged for the design of 3D culture systems. The first is biomedical engineering methodology, including bioengineered materials, bioprinting, microfluidics and bioreactors, used alone or in combination, to mimic the microenvironments of native tissues. The second approach is organoid technology, in which stem cells are exposed to chemical and/or biological cues to activate differentiation programs that are reminiscent of human (prenatal) development. This review article describes recent technological advances in engineering 3D cultures that more closely resemble the human brain. The contributions of in vitro 3D tissue culture systems to new insights in neurophysiology, neurological diseases and regenerative medicine are highlighted. Perspectives on designing improved tissue models of the human brain are offered, focusing on an integrative approach merging biomedical engineering tools with organoid biology.