Research and Development of Microphysiological Systems in Japan Supported by the AMED-MPS Project

The Current Status and Use of Microphysiological Systems by the Pharmaceutical Industry: The International Consortium for Innovation and Quality Microphysiological Systems Affiliate Survey and Commentary

Microphysiological systems (MPS) are comprised of one or multiple cell types of human or animal origins that mimic the biochemical/electrical/mechanical responses and blood-tissue barrier properties of the cells observed within a complex organ. The goal of incorporating these in vitro systems is to expedite and advance the drug discovery and development paradigm with improved predictive and translational capabilities. Considering the industry need for improved efficiency and the broad challenges of model qualification and acceptance, the International Consortium for Innovation and Quality (IQ) founded an IQ MPS working group in 2014 and Affiliate in 2018. This group connects thought leaders and end users, provides a forum for crosspharma collaboration, and engages with regulators to qualify translationally relevant MPS models. To understand how pharmaceutical companies are using MPS, the IQ MPS Affiliate conducted two surveys in 2019, survey 1, and 2021, survey 2, which differed slightly in the scope of definition of the complex in vitro models under question. The surveys captured demographics, resourcing, rank order for organs of interest, compound modalities tested, and MPS organ-specific questions, including nonclinical species needs and cell types. The major focus of this manuscript is on results from survey 2, where we specifically highlight the context of use for MPS within safety, pharmacology, or absorption, disposition, metabolism, and excretion and discuss considerations for including MPS data in regulatory submissions. In summary, these data provide valuable insights for developers, regulators, and pharma, offering a view into current industry practices and future considerations while highlighting key challenges impacting MPS adoption. SIGNIFICANCE STATEMENT: The application of microphysiological systems (MPS) represents a growing area of interest in the drug discovery and development framework. This study surveyed 20+ pharma companies to understand resourcing, current areas of application, and the key challenges and barriers to internal MPS adoption. These results will provide regulators, tech providers, and pharma industry leaders a starting point to assess the current state of MPS applications along with key learnings to effectively realize the potential of MPS as an emerging technology.

Standalone cell culture microfluidic device-based microphysiological system for automated cell observation and application in nephrotoxicity tests

Microphysiological systems (MPS) offer an alternative method for culturing cells on microfluidic platforms to model organ functions in pharmaceutical and medical sciences. Although MPS hardware has been proposed to maintain physiological organ function through perfusion culture, no existing MPS can automatically assess cell morphology and conditions online to observe cellular dynamics in detail. Thus, with this study, we aimed to establish a practical strategy for automating cell observation and improving cell evaluation functions with low temporal resolution and throughput in MPS experiments. We developed a versatile standalone cell culture microfluidic device (SCCMD) that integrates microfluidic chips and their peripherals. This device is compliant with the ANSI/SLAS standards and has been seamlessly integrated into an existing automatic cell imaging system. This integration enables automatic cell observation with high temporal resolution in MPS experiments. Perfusion culture of human kidney proximal tubule epithelial cells using the SCCMD improves cell function. By combining the proximal tubule MPS with an existing cell imaging system, nephrotoxicity studies were successfully performed to automate morphological and material permeability evaluation. We believe that the concept of building the ANSI/SLAS-compliant-sized MPS device proposed herein and integrating it into an existing automatic cell imaging system for the online measurement of detailed cell dynamics information and improvement of throughput by automating observation operations is a novel potential research direction for MPS research.

Combining a microphysiological system of three organ equivalents and transcriptomics to assess toxicological endpoints for cosmetic ingredients

Animal testing for cosmetic ingredients and final products has been banned in Europe and is gaining legal force worldwide. However, the need for reliable testing methodologies remains for safety assessment of cosmetic ingredients. While new approach methodologies exist for many toxicological endpoints, some complex ones lack appropriate testing methods. Microphysiological systems (MPSs) have emerged as a promising tool to address this gap in pre-clinical testing, offering higher predictivity compared to animal models due to the phylogenetic distance between humans and animals. Moreover, they provide a more physiological approach than traditional in vitro testing by mimicking interconnections between different culture compartments as seen in complex organisms. This study presents a three-organ microfluidic MPS comprising skin, liver, and intestine equivalents. Combining this model with gene expression analysis, we evaluated toxicological endpoints of chemicals, demonstrating its potential for diverse applications. Our findings highlight the MPS model as a reliable and ethical method to be applied in an integrated approach for safety assessment in the cosmetic industry. It offers a promising strategy to evaluate toxicological endpoints for cosmetic ingredients and other chemicals, supporting the elimination of animal testing while ensuring consumer safety.

Usefulness of a humanized tricellular static transwell blood-brain barrier model as a microphysiological system for drug development applications. - A case study based on the benchmark evaluations of blood-brain barrier microphysiological system

Microphysiological system (MPS), a new technology for in vitro testing platforms, have been acknowledged as a strong tool for drug development. In the central nervous system (CNS), the blood‒brain barrier (BBB) limits the permeation of circulating substances from the blood vessels to the brain, thereby protecting the CNS from circulating xenobiotic compounds. At the same time, the BBB hinders drug development by introducing challenges at various stages, such as pharmacokinetics/pharmacodynamics (PK/PD), safety assessment, and efficacy assessment. To solve these problems, efforts are being made to develop a BBB MPS, particularly of a humanized type. In this study, we suggested minimal essential benchmark items to establish the BBB-likeness of a BBB MPS; these criteria support end users in determining the appropriate range of applications for a candidate BBB MPS. Furthermore, we examined these benchmark items in a two-dimensional (2D) humanized tricellular static transwell BBB MPS, the most conventional design of BBB MPS with human cell lines. Among the benchmark items, the efflux ratios of P-gp and BCRP showed high reproducibility in two independent facilities, while the directional transports meditated through Glut1 or TfR were not confirmed. We have organized the protocols of the experiments described above as standard operating procedures (SOPs). We here provide the SOPs with the flow chart including entire procedure and how to apply each SOP. Our study is important developmental step of BBB MPS towards the social acceptance, which enable end users to check and compare the performance the BBB MPSs.

[Development of Microphysiological Systems (MPSs) Based on Microfluidic Technology for Drug Discovery in Japan]

Microphysiological systems (MPSs) based on microfluidic devices are attracting attention as an alternative cell assay platform to animal experiments in drug discovery. When we use microfluidic devices for cell culture, it is possible to experiment with various culture conditions that are difficult with conventional cell culture methods, such as fabrication of microstructures for cell placement, temporal and spatial control of liquid factors and adhesive conditions, and physical stimulation by flow and expansion/contraction. MPSs, which use microfluidic technology to construct the structure and function of physiological biological tissues and organs, are being commercialized and put to practical use worldwide with the entry of venture companies and pharmaceutical companies. Although research on the practical application of MPS in Japan has lagged far behind the efforts of Western countries, the Japan Agency for Medical Research and Development (AMED) launched the MPS Development and Research Project in FY2017 and established a system for MPS commercialization through industry-government-academia collaboration. The project is characterized by the formation of a consortium involving many researchers not only from academia but also from manufacturing and pharmaceutical companies with the aim of commercializing MPS devices. By FY2021, the final year of this project, several MPSs were successfully positioned in various stages of commercialization. This paper introduces two MPSs that the author was involved in commercializing in collaboration with domestic companies within the project.

[Toward Regulatory Acceptance of MPS-Cardiac Safety Assessment as an Example]

Microphysiological system (MPS) are "Cell/tissue culture systems that reproduce in vivo organ functions in vitro by placing organ compartments that mimic the physiological environment of various organs such as the liver, small intestine, and lungs in micro-spaces." The MPS are attracting attention around the world as tools to improve human predictability in drug discovery research. In the U.S., in 2012, the NIH (National Institutes of Health) allocated a large budget to academia for research development of MPS. In Japan, the National Institute of Advanced Industrial Science and Technology and the NIHS (National Institute of Health Sciences) have been playing a central role in commercialization, performance evaluation, and standardization of MPS devices developed by academia for the liver, small intestine, kidney, and BBB as target organs/tissues in the AMED-MPS project that started in 2017. Pharmaceutical companies are beginning to utilize MPS in drug discovery research. However, MPS have only just been raised as a topic of discussion between regulatory authorities and pharmaceutical companies, and it will be necessary to overcome many barriers before data obtained by MPS can be included in drug approval documents and be widely accepted administratively. In this review, I would like to introduce cardiac safety evaluation as a concrete example to show what paths MPS should take to gain regulatory approval. In addition, I would like also to introduce human 3D heart tissue, which was developed in NIHS, as a cardiac MPS.

Consideration of Commercially Available Hepatocytes as Cell Sources for Liver-Microphysiological Systems by Comparing Liver Characteristics

In recent years, microphysiological systems (MPS) have been developed to shorten the test period and reduce animal experiments for drug development. We examined cell sources for the liver-MPS, i.e., MPS mimicking liver function. For liver-MPS, liver-like cells with high liver functions are required. Cryo-preserved hepatocytes (cryoheps), the gold standard hepatocytes for in vitro drug development, present several disadvantages, including differences between lots due to individual donor variations or a limited cell supply from the same donor. As such, alternatives for cryoheps are sought. Hepatocyte-like cells derived from human induced pluripotent stem cells (hiPSC-Heps), hepatocytes derived from liver-humanized mice (PXB-cells), and human liver cancer cells (HepG2 cells) were examined as source candidates for liver-MPS. Gene expression levels of the major cytochrome P450 of hiPSC-Heps, PXB cells, and HepG2 cells were compared with 22 lots of cryoheps, and the activities of hiPSC-Heps were compared with 8 lots of cryopreserved hepatocytes. A focused DNA microarray was used for the global gene analysis of the liver-like characteristics of hiPSC-Heps, PXB-cells, cryoheps, and HepG2 cells. Gene expression data from the focused microarray were analyzed by principal component analysis, hierarchical clustering, and enrichment analysis. The results indicated the characteristics of individual hepatocyte cell source and raised their consideration points as an alternative cell source candidate for liver-MPS. The study contributes to the repetitive utilization of a robust in vitro hepatic assay system over long periods with stable functionality.

Microphysiological Systems Evaluation: Experience of TEX-VAL Tissue Chip Testing Consortium

Much has been written and said about the promise and excitement of microphysiological systems, miniature devices that aim to recreate aspects of human physiology on a chip. The rapid explosion of the offerings and persistent publicity placed high expectations on both product manufacturers and regulatory agencies to adopt the data. Inevitably, discussions of where this technology fits in chemical testing paradigms are ongoing. Some end-users became early adopters, while others have taken a more cautious approach because of the high cost and uncertainties of their utility. Here, we detail the experience of a public-private collaboration established for testing of diverse microphysiological systems. Collectively, we present a number of considerations on practical aspects of using microphysiological systems in the context of their applications in decision-making. Specifically, future end-users need to be prepared for extensive on-site optimization and have access to a wide range of imaging and other equipment. We reason that cells, related reagents and the technical skills of the research staff, not the devices themselves, are the most critical determinants of success. Extrapolation from concentration-response effects in microphysiological systems to human blood or oral exposures, difficulties with replicating the whole organ, and long-term functionality remain as critical challenges. Overall, we conclude that it is unlikely that a rodent- or human-equivalent model is achievable through a finite number of microphysiological systems in the near future; therefore, building consensus and promoting the gradual incorporation of these models into tiered approaches for safety assessment and decision-making is the sensible path to wide adoption.