Deciphering potential vascularization factors of on-chip co-cultured hiPSC-derived cerebral organoids

Emerging brain organoids: 3D models to decipher, identify and revolutionize brain

Brain organoids are an emerging in vitro 3D brain model that is integrated from pluripotent stem cells. This model mimics the human brain's developmental process and disease-related phenotypes to a certain extent while advancing the development of human brain-based biological intelligence. However, many limitations of brain organoid culture (e.g., lacking a functional vascular system, etc.) prevent in vitro-cultured organoids from truly replicating the human brain in terms of cell type and structure. To improve brain organoids' scalability, efficiency, and stability, this paper discusses important contributions of material biology and microprocessing technology in solving the related limitations of brain organoids and applying the latest imaging technology to make real-time imaging of brain organoids possible. In addition, the related applications of brain organoids, especially the development of organoid intelligence combined with artificial intelligence, are analyzed, which will help accelerate the rational design and guidance of brain organoids.

The promise of cerebral organoids for neonatology

PURPOSE OF REVIEW

Applying discoveries from basic research to patients in the neonatal intensive care unit (NICU) is challenging given the difficulty of modeling this population in animal models, lack of translational relevance from animal models to humans, and scarcity of primary human tissue. Human cell-derived cerebral organoid models are an appealing way to address some of these gaps. In this review, we will touch on previous work to model neonatal conditions in cerebral organoids, some limitations of this approach, and recent strategies that have attempted to address these limitations.

RECENT FINDINGS

While modeling of neurodevelopmental disorders has been an application of cerebral organoids since their initial description, recent studies have dramatically expanded the types of brain regions and disease models available. Additionally, work to increase the complexity of organoid models by including immune and vascular cells, as well as modeling human heterogeneity with mixed donor organoids will provide new opportunities to model neonatal pathologies.

SUMMARY

Organoids are an attractive model to study human neurodevelopmental pathologies relevant to patients in the neonatal ICU. New technologies will broaden the applicability of these models to neonatal research and their usefulness as a drug screening platform.

Organoids meet microfluidics: recent advancements, challenges, and future of organoids-on-chip

Organoids are three-dimensional, miniaturized tissue-like structures derived from either stem cells or primary cells, emerging as powerful in vitro models for studying developmental biology, disease pathology, and drug discovery. These organoids more accurately mimic cell-cell interactions and complexities of human tissues compared to traditional cell cultures. However, challenges such as limited nutrient supply and biomechanical cue replication hinder their maturation and viability. Microfluidic technologies, with their ability to control fluid flow and mimic the mechanical environment of tissues, have been integrated with organoids to create organoid-on-chip models that address these limitations. These models not only improve the physiological relevance of organoids but also enable more precise investigation of disease mechanisms and therapeutic responses. By combining microfluidics and organoids, several advanced organoids-on-chip models have been developed to investigate mechanical and biochemical cues involved in disease progression. This review discusses various methods to develop organoids-on-chip and the recently established organoids-on-chip models with their advanced functions. Finally, we highlighted potential strategies to enhance the functionality of organoid models, aiming to overcome current limitations and bridge the gap between current cell culture models and clinical applications, advancing personalized medicine, and improving therapeutic testing.

Strategies to overcome the limitations of current organoid technology - engineered organoids

Organoids, as 3D in vitro models derived from stem cells, have unparalleled advantages over traditional cell and animal models for studying organogenesis, disease mechanisms, drug screening, and personalized diagnosis and treatment. Despite the tremendous progress made in organoid technology, the translational application of organoids still presents enormous challenges due to the complex structure and function of human organs. In this review, the limitations of the translational application of traditional organoid technologies are first described. Next, we explore ways to address many of the limitations of traditional organoid cultures by engineering various dimensions of organoid systems. Finally, we discuss future directions in the field, including potential roles in drug screening, simulated microphysiology system and personalized diagnosis and treatment. We hope that this review inspires future research into organoids and microphysiology system.

Advancements in Microphysiological systems: Exploring organoids and organ-on-a-chip technologies in drug development -focus on pharmacokinetics related organs

This study explored the evolving landscape of Microphysiological Systems (MPS), with a focus on organoids and organ-on-a-chip (OoC) technologies, which are promising alternatives to animal testing in drug discovery. MPS technology offers in vitro models with high physiological relevance, simulating organ function for pharmacokinetic studies. Organoids composed of 3D cell aggregates and OoCs mimicking in vivo environments based on microfluidic platforms represent the forefront of MPS. This paper provides a comprehensive overview of their application in studying the gut, liver, and kidney and their challenges in becoming reliable alternatives to in vivo models. Although MPS technology is not yet fully comparable to in vivo systems, its continued development, aided by in silico, automation, and AI approaches, is anticipated to bring about further advancements. Collaboration across multiple disciplines and ongoing regulatory discussions will be crucial in driving MPS toward practical and ethical applications in biomedical research and drug development.

Brain organoids: A new tool for modelling of neurodevelopmental disorders

Neurodevelopmental disorders are mostly studied using mice as models. However, the mouse brain lacks similar cell types and structures as those of the human brain. In recent years, emergence of three-dimensional brain organoids derived from human embryonic stem cells or induced pluripotent stem cells allows for controlled monitoring and evaluation of early neurodevelopmental processes and has opened a window for studying various aspects of human brain development. However, such organoids lack original anatomical structure of the brain during maturation, and neurodevelopmental maturation processes that rely on unique cellular interactions and neural network connections are limited. Consequently, organoids are difficult to be used extensively and effectively while modelling later stages of human brain development and disease progression. To address this problem, several methods and technologies have emerged that aim to enhance the sophisticated regulation of brain organoids developmental processes through bioengineering approaches, which may alleviate some of the current limitations. This review discusses recent advances and application areas of human brain organoid culture methods, aiming to generalize optimization strategies for organoid systems, improve the ability to mimic human brain development, and enhance the application value of organoids.

Recent advances and applications of human brain models

Recent advances in human pluripotent stem cell (hPSC) technologies have prompted the emergence of new research fields and applications for human neurons and brain organoids. Brain organoids have gained attention as an in vitro model system that recapitulates the higher structure, cellular diversity and function of the brain to explore brain development, disease modeling, drug screening, and regenerative medicine. This progress has been accelerated by abundant interactions of brain organoid technology with various research fields. A cross-disciplinary approach with human brain organoid technology offers a higher-ordered advance for more accurately understanding the human brain. In this review, we summarize the status of neural induction in two- and three-dimensional culture systems from hPSCs and the modeling of neurodegenerative diseases using brain organoids. We also highlight the latest bioengineered technologies for the assembly of spatially higher-ordered neural tissues and prospects of brain organoid technology toward the understanding of the potential and abilities of the human brain.

Vascularized organoid-on-a-chip: design, imaging, and analysis

Vascularized organoid-on-a-chip (VOoC) models achieve substance exchange in deep layers of organoids and provide a more physiologically relevant system in vitro. Common designs for VOoC primarily involve two categories: self-assembly of endothelial cells (ECs) to form microvessels and pre-patterned vessel lumens, both of which include the hydrogel region for EC growth and allow for controlled fluid perfusion on the chip. Characterizing the vasculature of VOoC often relies on high-resolution microscopic imaging. However, the high scattering of turbid tissues can limit optical imaging depth. To overcome this limitation, tissue optical clearing (TOC) techniques have emerged, allowing for 3D visualization of VOoC in conjunction with optical imaging techniques. The acquisition of large-scale imaging data, coupled with high-resolution imaging in whole-mount preparations, necessitates the development of highly efficient analysis methods. In this review, we provide an overview of the chip designs and culturing strategies employed for VOoC, as well as the applicable optical imaging and TOC methods. Furthermore, we summarize the vascular analysis techniques employed in VOoC, including deep learning. Finally, we discuss the existing challenges in VOoC and vascular analysis methods and provide an outlook for future development.