Replacing Animal Testing with Stem Cell-Organoids : Advantages and Limitations

Various groups including animal protection organizations, medical organizations, research centers, and even federal agencies such as the U.S. Food and Drug Administration, are working to minimize animal use in scientific experiments. This movement primarily stems from animal welfare and ethical concerns. However, recent advances in technology and new studies in medicine have contributed to an increase in animal experiments throughout the years. With the rapid increase in animal testing, concerns arise including ethical issues, high cost, complex procedures, and potential inaccuracies.Alternative solutions have recently been investigated to address the problems of animal testing. Some of these technologies are related to stem cell technologies, such as organ-on-a-chip, organoids, and induced pluripotent stem cell models. The aim of the review is to focus on stem cell related methodologies, such as organoids, that can serve as an alternative to animal testing and discuss its advantages and limitations, alongside regulatory considerations.Although stem cell related methodologies has shortcomings, it has potential to replace animal testing. Achieving this requires further research on stem cells, with potential societal and technological benefits.

Emerging trends in the methodology of environmental toxicology: 3D cell culture and its applications

Human diseases and health concerns caused by environmental pollutants are globally emerging. Therefore, rapid and efficient evaluation of the effects of environmental pollutants on human health is essential. Due to the significant differences between humans and animals and the lack of physiologically related environments, animal models and two-dimensional (2D) culture cannot accurately describe toxicological effects and predict actual in vivo responses. To make up for the limitations of traditional environmental toxicology screening, three-dimensional (3D) culture has been developed. The 3D culture could provide a good organizational structure comparable to the complex internal environment of humans and produce a more realistic response to environmental pollutants, which has been used in drug development, toxicity evaluation, personalized therapy and biological mechanism research. The goal of environmental toxicology is to provide clues and support for the risk assessment and management of environmental pollutants. With the development of 3D culture that can reproduce specific physiological aspects loaded with specific cells that reflect human biology, interactions between pollutants and target tissues and organs can be explored to assess the acute and chronic adverse health effects of exposure to various environmental toxins. The 3D culture with great potential shows broad prospects in toxicology research and is expected to bridge the gap between 2D culture and animal models eventually. In this sense, we strongly recommend that 3D culture be used to identify and understand environmental toxins, which will greatly facilitate the public's comprehensive understanding of environmental toxins.

Construction of a Multitubular Perfusable Kidney-on-Chip for the Study of Renal Diseases

The organ-on-chip model offers versatility and modularity of in vitro models while approaching the biological fidelity of in vivo models. We propose a method to build a perfusable kidney-on-chip aiming at reproducing key features of the densely packed segments of nephrons in vitro; such as their geometry, their extracellular matrix, and their mechanical properties. The core of the chip is made of parallel tubular channels molded into collagen I that are as small as 80 μm in diameter and as close as 100 μm apart. These channels can further be coated with basement membrane components and seeded by perfusion of a suspension of cells originating from a given segment of the nephron. We optimized the design of our microfluidic device to achieve high reproducibility regarding the seeding density of the channels and high fluidic control of the channels. This chip was designed as a versatile tool to study nephropathies in general, contributing to building ever better in vitro models. It could be particularly interesting for pathologies such as polycystic kidney diseases where mechanotransduction of the cells and their interaction with adjacent extracellular matrix and nephrons may play a key role.

Technology-based approaches toward a better understanding of neuro-coagulation in brain homeostasis

Blood coagulation factors can enter the brain under pathological conditions that affect the blood–brain interface. Besides their contribution to pathological brain states, such as neural hyperexcitability, neurodegeneration, and scar formation, coagulation factors have been linked to several physiological brain functions. It is for example well established that the coagulation factor thrombin modulates synaptic plasticity; it affects neural excitability and induces epileptic seizures via activation of protease-activated receptors in the brain. However, major limitations of current experimental and clinical approaches have prevented us from obtaining a profound mechanistic understanding of “neuro-coagulation” in health and disease. Here, we present how novel human relevant models, i.e., Organ-on-Chips equipped with advanced sensors, can help overcoming some of the limitations in the field, thus providing a perspective toward a better understanding of neuro-coagulation in brain homeostasis.

Multicellular Systems to Translate Somatic Cell Genome Editors to Humans

As genome editors move into clinical trials, there is a need to establish ex vivo multicellular systems to rapidly assess and predict toxic effects of genome editors in physiologically relevant human models. Advancements in organoid and organs-on-chip technologies offer the possibility to create multicellular systems that replicate the cellular composition and metabolic function of native tissues. Some multicellular systems have been validated in multiple applications for drug discovery and could be easily adapted to test genome editors; other models, especially those of the adaptive immune system, will require validation before being used as benchmarks for testing genome editors. Likewise, protocols to assess immunogenicity, to detect off-target effects, and to predict ex vivo to in vivo translation will need to be established and validated. This review will discuss key aspects to consider when designing, building, and/or adopting in vitro human multicellular systems for testing genome editors.