Organoids and Spheroids as Models for Studying Cholestatic Liver Injury and Cholangiocarcinoma

Abstract

Cholangiopathies, such as primary sclerosing cholangitis, biliary atresia, and cholangiocarcinoma, have limited experimental models. Not only cholangiocytes but also other hepatic cells including hepatic stellate cells and macrophages are involved in the pathophysiology of cholangiopathies, and these hepatic cells orchestrate the coordinated response against diseased conditions. Classic two-dimensional monolayer cell cultures do not resemble intercellular cell-to-cell interaction and communication; however, three-dimensional cell culture systems, such as organoids and spheroids, can mimic cellular interaction and architecture between hepatic cells. Previous studies have demonstrated the generation of hepatic or biliary organoids/spheroids using various cell sources including pluripotent stem cells, hepatic progenitor cells, primary cells from liver biopsies, and immortalized cell lines. Gene manipulation, such as transfection and transduction can be performed in organoids, and established organoids have functional characteristics which can be suitable for drug screening. This review summarizes current methodologies for organoid/spheroid formation and a potential for three-dimensional hepatic cell cultures as in vitro models of cholangiopathies. (Hepatology 2021;74:491-502).I n vitro cell culture models are key in liver research to supplement the lack of human samples or in vivo animal models. (1) Importantly, the human body consists of three-dimensional (3D) cellular interactions and structures with noncellular components, and classic two-dimensional (2D) monolayer culture models do not mimic this interaction between cells and components or matrices. In the past decade, techniques of 3D cell culture systems, such as organoids and spheroids, have been developed to mimic hepatic structure and cellular interaction in vitro. (2) These 3D cell culture models have more accurate physiological environmental conditions resembling in vivo complex architecture, microenvironment, and cellular functions and may be more appropriate for biomedical studies than monolayer models. (2,3) The definitions of the terms "organoid" and "spheroid" can vary or overlap depending on previous studies. Organoids are generally recognized as an in vitro "miniorgan" or complex tissue-like structure with multiple cell types. (3) Spheroids are often referred to as "simple cell aggregates" with a single cell type. Organoids are generated from (1) tissue-derived primary cells, (2) progenitors, (3) embryonic stem cells (ESCs), or (4) induced pluripotent stem cells (iPSCs), which can selfassemble and differentiate into organ-like cell clusters

Biliary Atresia – emerging diagnostic and therapy opportunities

“…Liver organoids, i.e., 3D-cultured mini organs, are increasingly used to study different aspects of disease processes, including liver diseases [47] , [48] , [49] . Liver organoids can be differentiated towards both cholangiocyte and hepatocyte fates and have been used to study an increasing number of liver diseases, including a1-antitrypsin (A1AT) deficiency and ALGS [ 49 , 50 ], for review see [51] . Organoids can be generated from induced pluripotency cells (iPS) or embryonic stem cells (ES cells), hepatic progenitor cells, as well as directly from tissue-derived cells [51] .…”

“…Liver organoids can be differentiated towards both cholangiocyte and hepatocyte fates and have been used to study an increasing number of liver diseases, including a1-antitrypsin (A1AT) deficiency and ALGS [ 49 , 50 ], for review see [51] . Organoids can be generated from induced pluripotency cells (iPS) or embryonic stem cells (ES cells), hepatic progenitor cells, as well as directly from tissue-derived cells [51] . In one study, differences between intra- and extrahepatic organoids, notably with regard to their response to Wnt signaling, were observed [52] .…”

Targeting Lymphangiogenesis and Lymph Node Metastasis in Liver Cancer

“…Several experimental models are currently in use for developing a better understanding of drug resistance in liver cancers. These include both in vitro culture based models, multicellular 3-D models (spheroids and organoids) 96 that mimic the TME as well as several in vivo orthotopic mouse tumor xenografts or chemically or genetically induced liver carcinogenesis in mouse models. These are extensively reviewed by Marin et al 97 Critically important regulators of therapeutic resistance in liver cancers are the ATP-binding cassette (ABC) transporters such as multidrug resistance protein1/P-glycoprotein (MDR1/P-gp) (ABCB1), MRP2 (ABCC2) in hepatoblastoma (HB) and HCC and MRP3(ABCC3) in CCA.…”

Advanced In Vitro Lung Models for Drug and Toxicity Screening: The Promising Role of Induced Pluripotent Stem Cells

“…[62,63] Of note, although the terms "spheroid" and "organoid" are often used interchangeably, they actually differ in a few key aspects: spheroids are usually considered simpler structures capable of self-assembly without requiring a scaffold or 3D matrix to guide the self-organization process. [64] They are commonly used as tumor models, due to their hierarchical structure of external layers composed of active and proliferative cells and an internal necrotic core that arises from nutrient and oxygen deprivation, as well as waste accumulation in this area. [65][66][67][68][69] However, as spheroids are most commonly derived from cell lines [66][67][68] or primary, patient-derived cells, [69,70] they frequently lack the presence of stem or progenitor cells capable of self-renewal and endowed with differentiation potential, resulting in a greater difficulty in sustaining the 3D culture and generating complex, multicellular structures.…”