Preface

Organoids are tiny in vitro 3D models that imitate the architecture and functioning of specific tissues and organs. These near-physiological models provide unique prospects for different fundamental and translational applications in human research. Organoid technology is a multidisciplinary technique that utilizes stem cells' ability to self-renew, differentiate into many lineages, and self-organize into organoids. Scientists have used organoid bioengineering techniques and explored the use of induced pluripotent stem cells (iPSCs), embryonic stem cells (ESCs), and tissue-resident adult stem cells (ASCs) in an attempt to create small tissue-replicating organoids. Several research teams have now manipulated stem cells in vitro to derive endodermal, mesodermal, and ectodermal organoids. Technological advances have made it possible to generate several tissue-specific organoids, including the kidney, brain, lung, colon, intestine, breast, retina, and liver. Considering the disparity between animal-based models and human disease pathology, a paradigm shift was needed to imitate human diseases correctly. The 3D human organoid platform offers an unparalleled chance to generate better models and a deeper understanding of human disease pathophysiology. Organoids give information on human disease-associated processes like disease-specific altered signaling, cell–cell interactions, therapeutic target identification, therapeutic screening, and discovery.

Advances in genome editing, hybrid culture techniques, single-cell transcriptomics, the establishment of biobanks, 3D printing, microfluidics, high-resolution imaging, nanotechnology, and other cutting-edge technologies are facilitating the development of physiologically accurate human disease models, hence impacting the discovery of new treatments. The combination of these approaches has the potential to push the limits of present scientific study, and future developments will undoubtedly lead to the development of new paradigms for treating human diseases. Tumor organoids are 3D cultures of cancer cells that may be successfully generated from individual patients. This facilitates the construction of a genetic mutation-specific tumoroid biobank with relevant patient samples that can be used for drug screening and development. Due to advances in biobanking, it is now feasible to use a person's stem cells or tumor cells for customized disease modeling and personalized therapy. Organoid-based disease modeling is a rapidly emerging field with enormous promise for revolutionary research possibilities, including preclinical research and theranostics. This collection of chapters aims to shed light on the expanding resources addressing the principles of organoids and disease modeling, including cancer. The primary areas covered in this book are organ-specific organoids, patient-derived organoids, tumoroids, and organoid commercialization. The chapters in this collection are intended for biologists, clinicians, and translational scientists.

> **Manash K. Paul** Department of Pulmonary and Critical Care Medicine, University of California Los Angeles (UCLA), Los Angeles, USA

Section 1 Introduction
