Organs-on-a-Chip

Microfluidics Based Particle and Droplet Generation for Gene and Drug Delivery Approaches

Microfluidics-based droplets have emerged as a powerful technology for biomedical research, offering precise control over droplet size and structure, optimal mixing of solutions, and prevention of cross-contamination. It is a major branch of microfluidic technology with applications in diagnostic testing, imaging, separation, and gene amplification. This review discusses the different aspects of microfluidic devices, droplet generation techniques, droplet types, and the production of micro/nano particles, along with their advantages and limitations. Passive and active methods for droplet formation are discussed, as well as the manipulation of droplet shape and content. This review also highlights the potential applications of droplet microfluidics in tissue engineering, cancer therapy, and drug delivery systems. The use of microfluidics in the production of lipid nanoparticles and polymeric microparticles is also presented, with emphasis on their potential in drug delivery and biomedical research. Finally, the contributions of microfluidics to vaccines, gene therapy, personalized medicine, and future perspectives are discussed, emphasizing the need for continuous innovation and integration with other technologies, such as AI and wearable devices, to further enhance its potential in personalized medicine and drug delivery. However, it is also noted that challenges in commercialization and widespread adoption still need to be addressed.

Progress in the Application of Organoids-On-A-Chip in Diseases

With the rapid development of the field of life sciences, traditional 2D cell culture and animal models have long been unable to meet the urgent needs of modern biomedical research and new drug development. Establishing a new generation of experimental models and research models is of great significance for deeply understanding human health and disease processes, and developing effective treatment measures. As is well known, long research and development cycles, high risks, and high costs are the "three mountains" facing the development of new drugs today. Organoids and organ-on-chips technology can highly simulate and reproduce the human physiological environment and complex reactions in vitro, greatly improving the accuracy of drug clinical efficacy prediction, reducing drug development costs, and avoiding the defects of drug testing animal models. Therefore, organ-on-chips have enormous potential in medical diagnosis and treatment.

Mapping the landscape of PSC-CM research through bibliometric analysis

Objectives

The discovery of pluripotent stem cell-derived cardiomyocytes (PSC-CMs) has not only deepened our understanding of the pathogenesis and progression of heart disease, but also advanced the development of engineered cardiac tissues, cardiac regenerative therapy, drug discovery and the cardiotoxicity assessment of drugs. This study aims to visualize the developmental trajectory of PSC-CM research over the past 18 years to identify the emerging research frontiers and challenges.

Methods

The literature on PSC-CMs from 2007 to 2024 was retrieved from the Web of Science and PubMed databases. Bibliometrix, VOSviewer and CiteSpace software were used for statistical analysis and visualization of scientific literature. Previous clinical trials were summarized using data from the ClinicalTrials.gov database.

Results

A total of 29,660 authors from 81 countries and regions published 6,406 papers on PSC-CMs over the past 18 years. The annual output of PSC-CM research experienced a general upward trend from 2007 to 2021, reaching its peak in 2021, followed by a notable decline in 2022 and 2023. The United States has emerged as the most influential nation in this field, with Stanford University being the most prolific institution and Joseph C. Wu standing out as the most productive and highly cited scholar. Circulation Research, Circulation, and Nature have been identified as the most co-cited journals. Organ-on-a-chip, 3D bio-printing, cardiac microtissue, extracellular vesicle, inflammation, energy metabolism, atrial fibrillation, personalized medicine etc., with a longer burst period, and maturation of PSC-CMs, with the highest burst strength of 27.19, are the major research focuses for rigorous investigation in recent years. Cardiac organoid is emerging as a promising key research frontier. While the clinical trials of stem-cell-mediated treatment for heart diseases shows promise, significant challenges remain. Further research is imperative to optimize protocols, enhance cell delivery methods, and establish standardized practices to improve clinical outcomes.

Conclusions

In conclusion, several major research hotspots, including engineered cardiac tissue and maturation, exosome-based regenerative therapy, inflammation response, energy metabolism, atrial fibrillation, and personalized medicine etc. will continue to attract substantial interest from investigators worldwide. Cardiac organoids to in vitro recapitulate the intricate human heart is emerging as a promising key research frontier. Significant challenges persist in the clinical trials of stem-cell-mediated therapies for heart diseases.

Digitalization of toxicology: improving preclinical to clinical translation

Though the portfolio of medicines that are extending and improving the lives of patients continues to grow, drug discovery and development remains a challenging business on its best day. Safety liabilities are a significant contributor to development attrition where the costliest liabilities to both drug developers and patients emerge in late development or post-marketing. Animal studies are an important and influential contributor to the current drug discovery and development paradigm intending to provide evidence that a novel drug candidate can be used safely and effectively in human volunteers and patients. However, translational gaps-such as toxicity in patients not predicted by animal studies-have prompted efforts to improve their effectiveness, especially in safety assessment. More holistic monitoring and "digitalization" of animal studies has the potential to enrich study outcomes leading to datasets that are more computationally accessible, translationally relevant, replicable, and technically efficient. Continuous monitoring of animal behavior and physiology enables longitudinal assessment of drug effects, detection of effects during the animal's sleep and wake cycles and the opportunity to detect health or welfare events earlier. Automated measures can also mitigate human biases and reduce subjectivity. Reinventing a conservative, standardized, and traditional paradigm like drug safety assessment requires the collaboration and contributions of a broad and multi-disciplinary stakeholder group. In this perspective, we review the current state of the field and discuss opportunities to improve current approaches by more fully leveraging the power of sensor technologies, artificial intelligence (AI), and animal behavior in a home cage environment.

Controlling bead and cell mobility in a recirculating hanging-drop network

Integrating flowing cells, such as immune cells or circulating tumour cells, within a microphysiological system is crucial for body-on-a-chip applications. However, ensuring unimpeded recirculation of cells is a significant challenge. Closed microfluidic devices have a no-slip boundary condition along channel walls and a defined chip geometry (laminar flow) that hinders the ability to freely control cell flow. Open microfluidic devices, where the bottom device boundary is an air-liquid interface (ALI), e.g., hanging drop networks (HDNs), offer the advantage of an easily-actuatable fluid-phase geometry, where cells can either flow or stagnate. In this paper, we optimized a hanging-drop-integrated pneumatic-pump system for closed-loop recirculation of particles (i.e., beads or cells). Experiments with both beads and cells in cell culture medium initially resulted in particle stagnation, which was suggestive of a pseudo-no-slip boundary condition at the ALI. Transmission electron microscopy and dynamic light scattering measurements of the ALI suggested that aggregation of submicron-scale cell-culture-medium components is the cause of the pseudo-no-slip boundary condition. We used the finite element method to study the forces on particles at the ALI and to optimize HDN design (drop aperture) and operation (drop height) parameters. Based on this analysis, we report a phase diagram delineating the conditions for free flow or stagnation of particles at the ALI of hanging drops. Using our experimental setup with 3.5 mm drop apertures, we conducted particle flow experiments while actuating drop heights. We confirmed the ability to control the flow or stagnation of particles by actuating the height of hanging drops: a drop height over 300 μm led to particle stagnation and a drop height under 300 μm allowed for particle flow. This particle-flow control, combined with the ease of integrating scaffold-free organ models (microtissues or organoids) in HDNs, constitutes the basis for an experimental setup enabling the control of the residence time of single cells around 3D organ models.

The Long and Winding Road to Cardiac Regeneration

Cardiac regeneration is a critical endeavor in the treatment of heart diseases, aimed at repairing and enhancing the structure and function of damaged myocardium. This review offers a comprehensive overview of current advancements and strategies in cardiac regeneration, with a specific focus on regenerative medicine and tissue engineering-based approaches. Stem cell-based therapies, which involve the utilization of adult stem cells and pluripotent stem cells hold immense potential for replenishing lost cardiomyocytes and facilitating cardiac tissue repair and regeneration. Tissue engineering also plays a prominent role employing synthetic or natural biomaterials, engineering cardiac patches and grafts with suitable properties, and fabricating upscale bioreactors to create functional constructs for cardiac recovery. These constructs can be transplanted into the heart to provide mechanical support and facilitate tissue healing. Additionally, the production of organoids and chips that accurately replicate the structure and function of the whole organ is an area of extensive research. Despite significant progress, several challenges persist in the field of cardiac regeneration. These include enhancing cell survival and engraftment, achieving proper vascularization, and ensuring the long-term functionality of engineered constructs. Overcoming these obstacles and offering effective therapies to restore cardiac function could improve the quality of life for individuals with heart diseases.

Development of a human malaria-on-a-chip disease model for drug efficacy and off-target toxicity evaluation

A functional, multi-organ, serum-free system was developed for the culture of P. falciparum in an attempt to establish innovative platforms for therapeutic drug development. It contains 4 human organ constructs including hepatocytes, splenocytes, endothelial cells, as well as recirculating red blood cells which allow for infection with the parasite. Two strains of P. falciparum were used: the 3D7 strain, which is sensitive to chloroquine; and the W2 strain, which is resistant to chloroquine. The maintenance of functional cells was successfully demonstrated both in healthy and diseased conditions for 7 days in the recirculating microfluidic model. To demonstrate an effective platform for therapeutic development, systems infected with the 3D7 strain were treated with chloroquine which significantly decreased parasitemia, with recrudescence observed after 5 days. Conversely, when the W2 systems were dosed with chloroquine, parasitemia levels were moderately decreased when compared to the 3D7 model. The system also allows for the concurrent evaluation of off-target toxicity for the anti-malarial treatment in a dose dependent manner which indicates this model could be utilized for therapeutic index determination. The work described here establishes a new approach to the evaluation of anti-malarial therapeutics in a realistic human model with recirculating blood cells for 7 days.

Uses and Challenges of Antiviral Polyclonal and Monoclonal Antibody Therapies

Viral diseases represent a major public health concerns and ever-present risks for developing into future pandemics. Antiviral antibody therapeutics, either alone or in combination with other therapies, emerged as valuable preventative and treatment options, including during global emergencies. Here we will discuss polyclonal and monoclonal antiviral antibody therapies, focusing on the unique biochemical and physiological properties that make them well-suited as therapeutic agents. We will describe the methods of antibody characterization and potency assessment throughout development, highlighting similarities and differences between polyclonal and monoclonal products as appropriate. In addition, we will consider the benefits and challenges of antiviral antibodies when used in combination with other antibodies or other types of antiviral therapeutics. Lastly, we will discuss novel approaches to the characterization and development of antiviral antibodies and identify areas that would benefit from additional research.

A Poly-(ethylene glycol)-diacrylate 3D-Printed Micro-Bioreactor for Direct Cell Biological Implant-Testing on the Developing Chicken Chorioallantois Membrane

Advancements in biomaterial manufacturing technologies calls for improved standards of fabrication and testing. Currently 3D-printable resins are being formulated which exhibit the potential to rapidly prototype biocompatible devices. For validation purposes, 3D-printed materials were subjected to a hierarchical validation onto the chorioallantoic membrane of the developing chicken, better known as the HET CAM assay. Working along these lines, prints made from poly-(ethylene glycol)-diacrylate (PEGDA), which had undergone appropriate post-print processing, outperformed other commercial resins. This material passed all tests without displaying adverse effects, as experienced with other resin types. Based on this finding, the micro bioreactors (MBR) design, first made of PDMS and that also passed with cell tests on the HET-CAM, was finally printed in PEGDA, and applied in vivo. Following this workflow shows the applicability of 3D-printable resins for biomedical device manufacturing, consents to adherence to the present standards of the 3R criteria in material research and development, and provides flexibility and fast iteration of design and test cycles for MBR adaptation and optimization.

Bone Marrow Microenvironment-On-Chip for Culture of Functional Hematopoietic Stem Cells

Hematopoiesis takes place in the bone marrow and is supported by a complex cellular and molecular network in the bone marrow microenvironment. Commonly used models of the human bone marrow microenvironment include murine models and two-dimensional and three-dimensional tissue cultures. While these model systems have led to critical advances in the field, they fail to recapitulate many aspects of the human bone marrow. This has limited our understanding of human bone marrow pathophysiology and has led to deficiencies in therapy for many bone marrow pathologies such as bone marrow failure syndromes and leukemias. Therefore, we have developed a modular murine bone marrow microenvironment-on-chip using a commercially available microfluidic platform. This model includes a vascular channel separated from the bone marrow channel by a semi-porous membrane and incorporates critical components of the bone marrow microenvironment, including osteoblasts, endothelial cells, mesenchymal stem cells, and hematopoietic stem and progenitor cells. This system is capable of maintaining functional hematopoietic stem cells in vitro for at least 14 days at frequencies similar to what is found in the primary bone marrow. The modular nature of this system and its accessibility will allow for acceleration of our understanding of the bone marrow.

Microfluidic Tissue Engineering and Bio-Actuation

Bio-hybrid technologies aim to replicate the unique capabilities of biological systems that could surpass advanced artificial technologies. Soft bio-hybrid robots consist of synthetic and living materials and have the potential to self-assemble, regenerate, work autonomously, and interact safely with other species and the environment. Cells require a sufficient exchange of nutrients and gases, which is guaranteed by convection and diffusive transport through liquid media. The functional development and long-term survival of biological tissues in vitro can be improved by dynamic flow culture, but only microfluidic flow control can develop tissue with fine structuring and regulation at the microscale. Full control of tissue growth at the microscale will eventually lead to functional macroscale constructs, which are needed as the biological component of soft bio-hybrid technologies. This review summarizes recent progress in microfluidic techniques to engineer biological tissues, focusing on the use of muscle cells for robotic bio-actuation. Moreover, the instances in which bio-actuation technologies greatly benefit from fusion with microfluidics are highlighted, which include: the microfabrication of matrices, biomimicry of cell microenvironments, tissue maturation, perfusion, and vascularization.

Bioengineering Strategies to Create 3D Cardiac Constructs from Human Induced Pluripotent Stem Cells

Human induced pluripotent stem cells (hiPSCs) can be used to generate various cell types in the human body. Hence, hiPSC-derived cardiomyocytes (hiPSC-CMs) represent a significant cell source for disease modeling, drug testing, and regenerative medicine. The immaturity of hiPSC-CMs in two-dimensional (2D) culture limit their applications. Cardiac tissue engineering provides a new promise for both basic and clinical research. Advanced bioengineered cardiac in vitro models can create contractile structures that serve as exquisite in vitro heart microtissues for drug testing and disease modeling, thereby promoting the identification of better treatments for cardiovascular disorders. In this review, we will introduce recent advances of bioengineering technologies to produce in vitro cardiac tissues derived from hiPSCs.

W. Emerging technologies and their impact on regulatory science

There is an evolution and increasing need for the utilization of emerging cellular, molecular and in silico technologies and novel approaches for safety assessment of food, drugs, and personal care products. Convergence of these emerging technologies is also enabling rapid advances and approaches that may impact regulatory decisions and approvals. Although the development of emerging technologies may allow rapid advances in regulatory decision making, there is concern that these new technologies have not been thoroughly evaluated to determine if they are ready for regulatory application, singularly or in combinations. The magnitude of these combined technical advances may outpace the ability to assess fit for purpose and to allow routine application of these new methods for regulatory purposes. There is a need to develop strategies to evaluate the new technologies to determine which ones are ready for regulatory use. The opportunity to apply these potentially faster, more accurate, and cost-effective approaches remains an important goal to facilitate their incorporation into regulatory use. However, without a clear strategy to evaluate emerging technologies rapidly and appropriately, the value of these efforts may go unrecognized or may take longer. It is important for the regulatory science field to keep up with the research in these technically advanced areas and to understand the science behind these new approaches. The regulatory field must understand the critical quality attributes of these novel approaches and learn from each other's experience so that workforces can be trained to prepare for emerging global regulatory challenges. Moreover, it is essential that the regulatory community must work with the technology developers to harness collective capabilities towards developing a strategy for evaluation of these new and novel assessment tools.

Microphysiological Systems: Stakeholder Challenges to Adoption in Drug Development

Microphysiological systems (MPS) or tissue chips/organs-on-chips are novel in vitro models that emulate human physiology at the most basic functional level. In this review, we discuss various hurdles to widespread adoption of MPS technology focusing on issues from multiple stakeholder sectors, e.g., academic MPS developers, commercial suppliers of platforms, the pharmaceutical and biotechnology industries, and regulatory organizations. Broad adoption of MPS technology has thus far been limited by a gap in translation between platform developers, end-users, regulatory agencies, and the pharmaceutical industry. In this brief review, we offer a perspective on the existing barriers and how end-users may help surmount these obstacles to achieve broader adoption of MPS technology.

Stem/Proliferative and Differentiated Cells within Primary Murine Colonic Epithelium Display Distinct Intracellular Free Ca2+ Signal Codes

The second messenger, intracellular free calcium (Ca2+ ), acts to transduce mitogenic and differentiation signals incoming to the colonic epithelium. A self-renewing monolayer of primary murine colonic epithelial cells is formed over a soft, transparent hydrogel matrix for the scalable analysis of intracellular Ca2+ transients. Cultures that are enriched for stem/proliferative cells exhibit repetitive, high frequency (≈25 peaks h-1 ), and short pulse width (≈25 s) Ca2+ transients. Upon cell differentiation the transient frequency declines by 50% and pulse width widens by 200%. Metabolites and growth factors that are known to modulate stem cell proliferation and differentiation through Wnt and Notch signaling pathways, including CHIR-99021, N-[(3,5-Difluorophenyl)acetyl]-L-alanyl-2-phenylglycine-1,1-dimethylethyl ester (DAPT), bone morphogenetic proteins (BMPs), and butyrate, also modulate Ca2+ oscillation patterns in a consistent manner. Increasing the stiffness of the supportive matrix from 200 Pa to 3 GPa shifts Ca2+ transient patterns toward those resembling differentiated cells. The ability to monitor Ca2+ oscillations with the spatial and temporal resolution offered by this platform, combined with its amenability to high-content screens, provides a powerful tool for investigating real-time communication within a wide range of primary tissues in addition to the colonic epithelium.

Organs-on-a-chip models for biological research

We explore the utility of bioengineered human tissues-individually or connected into physiological units-for biological research. While much smaller and simpler than their native counterparts, these tissues are complex enough to approximate distinct tissue phenotypes: molecular, structural, and functional. Unlike organoids, which form spontaneously and recapitulate development, "organs-on-a-chip" are engineered to display some specific functions of whole organs. Looking back, we discuss the key developments of this emerging technology. Thinking forward, we focus on the challenges faced to fully establish, validate, and utilize the fidelity of these models for biological research.

New Endeavors of (Micro)Tissue Engineering: Cells Tissues Organs on-Chip and Communication Thereof

The development of new therapies is tremendously hampered by the insufficient availability of human model systems suitable for preclinical research on disease target identification, drug efficacy, and toxicity. Thus, drug failures in clinical trials are too common and too costly. Animal models or standard 2D in vitro tissue cultures, regardless of whether they are human based, are regularly not representative of specific human responses. Approaching near human tissues and organs test systems is the key goal of organs-on-chips (OoC) technology. This technology is currently showing its potential to reduce both drug development costs and time-to-market, while critically lessening animal testing. OoC are based on human (stem) cells, potentially derived from healthy or disease-affected patients, thereby amenable to personalized therapy development. It is noteworthy that the OoC market potential goes beyond pharma, with the possibility to test cosmetics, food additives, or environmental contaminants. This (micro)tissue engineering-based technology is highly multidisciplinary, combining fields such as (developmental) biology, (bio)materials, microfluidics, sensors, and imaging. The enormous potential of OoC is currently facing an exciting new challenge: emulating cross-communication between tissues and organs, to simulate more complex systemic responses, such as in cancer, or restricted to confined environments, as occurs in osteoarthritis. This review describes key examples of multiorgan/tissue-on-chip approaches, or linked organs/tissues-on-chip, focusing on challenges and promising new avenues of this advanced model system. Additionally, major emphasis is given to the translation of established tissue engineering approaches, bottom up and top down, towards the development of more complex, robust, and representative (multi)organ/tissue-on-chip approaches.

Microphysiological systems: What it takes for community adoption

Microphysiological systems (MPS) are promising in vitro tools which could substantially improve the drug development process, particularly for underserved patient populations such as those with rare diseases, neural disorders, and diseases impacting pediatric populations. Currently, one of the major goals of the National Institutes of Health MPS program, led by the National Center for Advancing Translational Sciences (NCATS), is to demonstrate the utility of this emerging technology and help support the path to community adoption. However, community adoption of MPS technology has been hindered by a variety of factors including biological and technological challenges in device creation, issues with validation and standardization of MPS technology, and potential complications related to commercialization. In this brief Minireview, we offer an NCATS perspective on what current barriers exist to MPS adoption and provide an outlook on the future path to adoption of these in vitro tools.

Environmental toxicology wars: Organ-on-a-chip for assessing the toxicity of environmental pollutants

Environmental pollution is a widespread problem, which has seriously threatened human health and led to an increase of human diseases. Therefore, it is critical to evaluate environmental pollutants quickly and efficiently. Because of obvious inter-species differences between animals and humans, and lack of physiologically-relevant microenvironment, animal models and in vitro two-dimensional (2D) models can not accurately describe toxicological effects and predicting actual in vivo responses. To make up the limitations of conventional environmental toxicology screening, organ-on-a-chip (OOC) systems are increasingly developing. OOC systems can provide a well-organized architecture with comparable to the complex microenvironment in vivo and generate realistic responses to environmental pollutants. The feasibility, adjustability and reliability of OCC systems make it possible to offer new opportunities for environmental pollutants screening, which can study their metabolism, collective response, and fate in vivo. Further progress can address the challenges to make OCC systems better investigate and evaluate environmental pollutants with high predictive power.

The scientific basis of rational prescribing. A guide to precision clinical pharmacology based on the WHO 6-step method

Background and methods

This opinion paper expanded on the WHO “six-step approach to optimal pharmacotherapy,” by detailed exploration of the underlying pharmacological and pathophysiological principles. This exercise led to the identification of a large number of domains of research that should be addressed to make clinical pharmacology progress toward “precision clinical pharmacology,” as a prerequisite for precision medicine.

Result

In order to improve clinical efficacy and safety in patient groups (to guide drug development) as well as in individuals (to guide therapeutic options and optimize clinical outcome), developments in clinical pharmacology should at least tackle the following: (1) molecular diagnostic assays to guide drug design and development and allow physicians to identify the optimal targets for therapy in the individual patient in a quick and precise manner (to guide selection of the right drug for the right patient); (2) the setting up and validation of biomarkers of target engagement and modification as predictors of clinical efficacy and safety; (3) integration of physiological PK/PD models and intermediate markers of pharmacological effects with the natural evolution of the disease to predict the drug dose that most effectively improves clinical outcome in patient groups and individuals, making use of advanced modeling technologies (building on deterministic models, machine-learning, and deep learning algorithms); (4) methodology to validate human or humanized in vitro, ex vivo, and in vivo models for their ability to predict clinical outcome with investigational therapies, including nucleic acids or recombinant genes together with vectors (including viruses or nanoparticles), cell therapy, or therapeutic vaccines; (5) methodological complements to the gold-standard, large Phase 3 randomized clinical trial to provide clinically relevant and reliable data on the efficacy and safety of all treatment options at the population level (pragmatic clinical trials), as well as in small groups of patients (as low as n = 1); (6) regulatory science, so as to optimize the ethical review process, documentation, and monitoring of clinical trials, improve efficiency, and reduce costs of clinical drug development; (7) interventions to effectively improve patient compliance and to rationalize polypharmacy for the reduction of adverse effects and the enhancement of therapeutic interactions; and (8) appraisal of the ecological and societal impact of drug use to safeguard against environmental hazards (following the “One Health” concept) and to reduce drug resistance.

Discussion and conclusion

As can be seen, precision clinical pharmacology aims at being highly translational, which will require very large panels of complementary skills. Interdisciplinary collaborations, including non-clinical pharmacologists, will be key to achieve such an ambitious program.

CNS-Targeting Therapies for Lysosomal Storage Diseases: Current Advances and Challenges

During the past decades, several therapeutic approaches have been developed and made rapidly available for many patients afflicted with lysosomal storage disorders (LSDs), inborn organelle disorders with broad clinical manifestations secondary to the progressive accumulation of undegraded macromolecules within lysosomes. These conditions are individually rare, but, collectively, their incidence ranges from 1 in 2,315 to 7,700 live-births. Most LSDs are manifested by neurological symptoms or signs, including developmental delay, seizures, acroparesthesia, motor weakness, and extrapyramidal signs. The chronic and later-onset clinical forms are at one end of the continuum spectrum and are characterized by a subtle and slow progression of neurological symptoms. Due to its inherent physiological properties, unfortunately, the blood-brain barrier (BBB) constitutes a significant obstacle for current and upcoming therapies to achieve the central nervous system (CNS) and treat neurological problems so prevalent in these conditions. To circumvent this limitation, several strategies have been developed to make the therapeutic agent achieve the CNS. This narrative will provide an overview of current therapeutic strategies under development to permeate the BBB, and address and unmet need for treatment of the progressive neurological manifestations, which are so prevalent in these inherited lysosomal disorders.

A 3D Cell Culture Organ-on-a-Chip Platform With a Breathable Hemoglobin Analogue Augments and Extends Primary Human Hepatocyte Functions in vitro

Remarkable advances in three-dimensional (3D) cell cultures and organ-on-a-chip technologies have opened the door to recapitulate complex aspects of human physiology, pathology, and drug responses in vitro. The challenges regarding oxygen delivery, throughput, assay multiplexing, and experimental complexity are addressed to ensure that perfused 3D cell culture organ-on-a-chip models become a routine research tool adopted by academic and industrial stakeholders. To move the field forward, we present a throughput-scalable organ-on-a-chip insert system that requires a single tube to operate 48 statistically independent 3D cell culture organ models. Then, we introduce in-well perfusion to circumvent the loss of cell signaling and drug metabolites in otherwise one-way flow of perfusate. Further, to augment the relevancy of 3D cell culture models in vitro, we tackle the problem of oxygen transport by blood using, for the first time, a breathable hemoglobin analog to improve delivery of respiratory gases to cells, because in vivo approximately 98% of oxygen delivery to cells takes place via reversible binding to hemoglobin. Next, we show that improved oxygenation shifts cellular metabolic pathways toward oxidative phosphorylation that contributes to the maintenance of differentiated liver phenotypes in vitro. Lastly, we demonstrate that the activity of cytochrome P450 family of drug metabolizing enzymes is increased and prolonged in primary human hepatocytes cultured in 3D compared to two-dimensional (2D) cell culture gold standard with important ramifications for drug metabolism, drug-drug interactions and pharmacokinetic studies in vitro.