A Simple Bioreactor-Based Method to Generate Kidney Organoids from Pluripotent Stem Cells

Abstract

SummaryKidney organoids made from pluripotent stem cells have the potential to revolutionize how kidney development, disease, and injury are studied. Current protocols are technically complex, suffer from poor reproducibility, and have high reagent costs that restrict scalability. To overcome some of these issues, we have established a simple, inexpensive, and robust method to grow kidney organoids in bulk from human induced pluripotent stem cells. Our organoids develop tubular structures by day 8 and show optimal tissue morphology at day 14. A comparison with fetal human kidneys suggests that day-14 organoid tissue most closely resembles late capillary loop stage nephrons. We show that deletion of HNF1B, a transcription factor linked to congenital kidney defects, interferes with tubulogenesis, validating our experimental system for studying renal developmental biology. Taken together, our protocol provides a fast, efficient, and cost-effective method for generating large quantities of human fetal kidney tissue, enabling the study of normal and aberrant kidney development.

Kidney organoids: accurate models or fortunate accidents

“…Indeed, with time in culture the center of organoids show deposition of extracellular matrix and a decline in endothelial populations . Several approaches to generating kidney organoids in suspension show clear evidence of cyst formation and fibrotic expansion with time (Przepiorski et al 2018;Kumar et al 2019). This suggests that while we have managed to replicate early patterning events, we have not created an environment suitable for tubular proliferation and continued development.…”

“…What is possible outside of the embryo is to modify culture format to optimize such models for one or other application, even when this does not necessarily involve creating a perfect model of the developing organ. A variety of studies have now claimed improvements in scale up or relative maturation, including the use of dis-tinct culture formats and changes in culture materials (Table 2; Cruz et al 2017;Czerniecki et al 2018;Przepiorski et al 2018;Garreta et al 2019;Gupta et al 2019;Kumar et al 2019). In addition, protocols for the generation of specific renal cell subtypes, such as podocyte or collecting duct epithelium, are being reported (Musah et al 2017;Taguchi and Nishinakamura 2017;Hale et al 2018;Yoshimura et al 2019).…”

“…Cruz et al (2017) reported that this allowed for the presentation of epithelial cysts within cultures derived from stem cell lines into which autosomal dominant polycystic kidney disease gene mutations (homozygous PKD1 mutations) were engineered (Table 2). Two more recent adaptations of the Takasato protocol have cultured early EBs, or micro-organoids generated from IM in suspension cultures, achieving a significant scale up in terms of final cell number (Table 2; Przepiorski et al 2018;Kumar et al 2019). However, both of these studies reported inappropriate stromal expansion and epithelial cyst formation even within organoids generated from control cell lines, either suggesting that these cultures failed to progress without pathological change or that they did not pattern as accurately when cultured in this format.…”

From organoids to transplantable artificial kidneys

“…Recently, Przepiorski et al . reported a simple and cost‐effective protocol using a bioreactor. These protocols share certain features but also have some distinct aspects.…”

“…These protocols share certain features but also have some distinct aspects. Although the similarities and differences between the nephron progenitors and nephrons induced by these different protocols need to be determined, the induced proximal renal tubules have been shown to carry out some functions, including reabsorption of low‐molecular‐weight dextran and selective cell death in response to nephrotoxic drugs .…”