Organoids, Volume 2, Issue 1 (March 2023) – 5 articles

Chronic Kidney Disease (CKD) is a major cause of morbidity and mortality characterized by progressive renal fibrosis, and in extreme cases, renal failure. Human CKD models that replicate the biological complexity of the kidney and CKD are lacking and will be invaluable in identifying drugs to revert and/or prevent fibrosis. To address this unmet need, we developed 3D renal organoids where human induced pluripotent stem cells (hiPSCs) were differentiated to renal progenitors within a renal extracellular matrix (rECM) gel, based on the premise that an rECM could recreate the renal niche to facilitate hiPSC-derived renal progenitor generation. We used mouse kidneys as a source of rECM and identified that superior detergent-mediated decellularization of mouse kidneys was achieved with a combination of 0.5% w/v Sodium Dodecyl Sulphate and 1% v/v Triton-X and mechanical agitation for 60 h. HiPSCs that underwent specification to become metanephric mesenchyme (MM) were subsequently cultured within the rECM gel and, notably, mesenchymal to epithelial transition (MET) was observed, as judged by expression of nephron markers K-cadherin, Nephrin and WT1. These data demonstrate a role for rECM gel in developing human renal organoids from hiPSCs, which will aid the further development of a human disease model for renal fibrosis. Full article

Human brain organoids provide a remarkable opportunity to model prenatal human brain biology in vitro by recapitulating features of in utero molecular, cellular and systems biology. An ethical concern peculiar to human brain organoids is whether they are or could become capable of supporting sentience through the experience of pain or pleasure and/or consciousness, including higher cognitive abilities such as self-awareness. Identifying the presence of these traits is complicated by several factors, beginning with consciousness—which is a highly contested concept among neuroscientists, cognitive scientists, and philosophers and so there is no agreed definition. Secondly, given human brain organoids are disembodied, there is no practical way to identify evidence of consciousness as we might in humans or animals. What would count as evidence of organoid consciousness is an emerging area of research. To address concerns about consciousness and human brain organoids, in this paper we clarify the morally relevant aspects of human consciousness, phenomenal experience and embodied development and explore the empirical basis of consciousness to develop a defensible framework for informed decision-making on the moral significance and utility of brain organoids, which can also guide regulation and future research of these novel biological systems. Full article

Organoids are 3D organ-like structures grown from stem cells in vitro that mimic the organ or disease from which they are derived. Due to their stem cell origin, organoids contain a heterogeneous population of cells reflecting the diversity of cell types seen in vivo. Similarly, tumour organoids reflect intratumoural heterogeneity in a way that traditional 2D cell culture and cell lines do not, and, therefore, they show greater promise as a more relevant model for effective disease modelling and drug testing. Tumour organoids arise from cancer stem cells, which contribute to many of the greatest challenges to cancer treatment, including therapy resistance, tumour recurrence, and metastasis. In this review, we outline methods for generating colon organoids from patient-derived normal and tumour tissues. Furthermore, we discuss organoid biobanking, applications of organoids in disease modelling, and a range of platforms applicable to high-throughput drug testing, including apical-out/reverse-polarity colon organoids. Full article

Human brain organoids present a new paradigm for modeling human brain organogenesis, providing unprecedented insight to the molecular and cellular processes of brain development and maturation. Other potential applications include in vitro models of disease and tissue trauma, as well as three-dimensional (3D) clinically relevant tissues for pharmaceuticals development and cell or tissue replacement. A key requirement for this emerging technology in both research and medicine is the simple, scalable, and reproducible generation of organoids using reliable, economical, and high-throughput culture platforms. Here we describe such a platform using a defined, clinically compliant, and readily available hydrogel generated from gelatin methacrylate (GelMA). We demonstrate the efficient production of organoids on GelMA from human induced pluripotent stem cells (iPSCs), with scalable production attained using 3D printed GelMA-based multiwell arrays. The differentiation of iPSCs was systematic, rapid, and direct to enable iPSCs to form organoids in their original position following seeding on GelMA, thereby avoiding further cell and organoid disruption. Early neural precursors formed by day 5, neural rosettes and early-stage neurons by day 14, and organoids with cellular and regional heterogeneity, including mature and electrophysiologically active neurons, by day 28. The optimised method provides a simplified and well-defined platform for both research and translation of iPSCs and derivative brain organoids, enabling reliable 3D in vitro modelling and experimentation, as well as the provision of clinically relevant cells and tissues for future therapeutics. Full article

Technical advances in microscopy and automation have enabled image-based phenotypic screening of spheroids and organoids to become increasingly high throughput and high content at the same time. In particular, matrix-embedded 3D structures can recapitulate many aspects of parent (e.g., patient) tissues. Live-cell imaging of growing structures allows tremendous insight into population heterogeneity during drug treatment. However, screening for targeted markers and more detailed morphological analyses typically require fixation of 3D structures, and standard formaldehyde (FA) incubation conditions can dissolve collagen-based extracellular matrices such as Matrigel. The dislocation and clumping of the spheroids make image-based segmentation very difficult and the tracking of structures from the live cell stage to their fixed cell location virtually impossible. In this method, we present a fixation and staining protocol that is gentle enough to maintain 3D structures exactly in their live-cell location and does not alter their morphology. This opens up analytical strategies that connect the spheroid’s growth kinetics and heterogeneity of treatment responses with the more targeted fixed cell stains. Furthermore, we optimized the automated seeding and imaging of spheroids so that screening and phenotypic characterization can be performed in high-throughput at either low or high magnification and yield the same result, independent of the microscope used. Full article