Kidney organoids for disease modeling

Developing liver organoids from induced pluripotent stem cells (iPSCs): An alternative source of organoid generation for liver cancer research

Primary liver cancer (PLC) represents a significant proportion of all human cancers and constitutes a substantial health and economic burden to society. Traditional therapeutic approaches such as surgical resection and chemotherapy often fail due to tumour relapse or innate tumour chemoresistance. There is a dearth of efficient treatments for PLC in part due to the poor capacity of current laboratory models to reflect critical features of the native tumour in vivo. The increasing incorporation of organoid systems has led to a resurgence of interest in liver cancer research. Organoid systems show promise as the gold standard for recapitulating tumours in vitro. Further, developments in culturing techniques will improve the various shortcomings of the current systems. Induced pluripotent stem cell (iPSC)-derived liver organoids are a promising alternative to the conventional liver organoid model as it circumvents the need to rely on primary resections which are often scarce. In this concise review, we will discuss novel techniques for organoid culture with a focus on organoid co-cultures and their advantages over traditional organoid systems. A detailed technical protocol for the generation of iPSC-derived liver organoids is provided as an appendix.

The myriad possibility of kidney organoids

Purpose of review

Human kidney development and the mechanisms of many kidney diseases are incompletely understood partly due to the lack of appropriate models. Kidney organoids derived from human pluripotent stem cells (hPSCs) are a new and rapidly developing in-vitro system covering the window of early nephrogenesis and having the capacity for disease modelling. The application of global analytic tools such as RNA sequencing and proteomics is providing new and unexpected insights into kidney organoids with relevance for development and disease. In this review, we focus on the most significant advances in the field over the last 2 years.

Recent findings

There have been several protocol modifications for the differentiation of hPSCs into kidney organoids, including the additional step of implantation into mice. These changes have improved the vascularization and maturity of the major cell types in the organoids, increased the production scale, and reduced the cost and labour intensity of culturing organoids. Single-cell RNA sequencing and global proteomics of kidney organoids have provided important insights into the multiple cell populations, origin of cells, and regulatory relationships between genes. There has been an increase in research using patient-derived induced pluripotent stem cells (iPSCs), or combining gene editing with iPSC-derived kidney organoids as a novel disease-modelling platform for improving our understanding of disease mechanisms, drug testing and discovery, and the potential for personalized therapy. Finally, there has been progress in culturing hPSCs-derived kidney cells in microfluidic kidney-on-a-chip devices and this may provide a means of further improving the maturity of kidney organoids.

Summary

The review summarizes the latest progress on kidney organoids including differentiation protocols, analysis tools, and applications. Despite some limitations, hPSC-derived kidney organoids are authentic and practical models for investigating kidney development and disease and progressing understanding about tissue regeneration, drug screening, and disease modelling.

Application of organoids in translational research of human diseases with a particular focus on gastrointestinal cancers

Gastrointestinal (GI) cancers constitute the largest portion of all human cancers and represent a significant health burden on modern society. Conventional therapeutic approaches such as chemotherapy and surgical resections often fail due to poor treatment response or tumour relapse. Unfortunately, drug discovery for GI cancers has stalled as current cancer models fail to recapitulate critical features of the parent tumour, leading to poor translation from bench to bedside. Recent advances in three-dimensional (3D) cell culturing techniques have driven the surge of interest in stem cell-derived organoid models, a promising platform with a plethora of potential applications due to its ability to retain crucial architectural, genomic and transcriptional properties of the native tissue. In this review article, we discuss current applications and advantages of organoid models in the translational research of GI cancers with a particular focus on primary liver cancer that currently lack effective curative treatments.

Recent advances in three-dimensional bioprinting of stem cells

In spite of being a new field, three-dimensional (3D) bioprinting has undergone rapid growth in the recent years. Bioprinting methods offer a unique opportunity for stem cell distribution, positioning, and differentiation at the microscale to make the differentiated architecture of any tissue while maintaining precision and control over the cellular microenvironment. Bioprinting introduces a wide array of approaches to modify stem cell fate. This review discusses these methodologies of 3D bioprinting stem cells. Fabricating a fully operational tissue or organ construct with a long life will be the most significant challenge of 3D bioprinting. Once this is achieved, a whole human organ can be fabricated for the defect place at the site of surgery.