Fine tuning the extracellular environment accelerates the derivation of kidney organoids from human pluripotent stem cells

Abstract

The generation of organoids is one of the biggest scientific advances in regenerative medicine. Here, by lengthening the time that human pluripotent stem cells (hPSCs) were exposed to a three-dimensional microenvironment, and by applying defined renal inductive signals, we generated kidney organoids that transcriptomically matched second-trimester human fetal kidneys. We validated these results using ex vivo and in vitro assays that model renal development. Furthermore, we developed a transplantation method that utilizes the chick chorioallantoic membrane. This approach created a soft in vivo microenvironment that promoted the growth and differentiation of implanted kidney organoids, as well as providing a vascular component. The stiffness of the in ovo chorioallantoic membrane microenvironment was recapitulated in vitro by fabricating compliant hydrogels. These biomaterials promoted the efficient generation of renal vesicles and nephron structures, demonstrating that a soft environment accelerates the differentiation of hPSC-derived kidney organoids.

Kidney organoids: accurate models or fortunate accidents

“…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).…”

“…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). Finally, a variety of approaches have now been proposed to improve vascularization in vitro (Homan et al 2019) or provide vascular flow in vivo (Sharmin et al 2016;Bantounas et al 2018;van den Berg et al 2018;Garreta et al 2019;Gupta et al 2019). In most instances, these involve modifications of prior differentiation protocols (Table 2; Taguchi et al 2014;Freedman et al 2015;Morizane et al 2015;.…”

“…Hence, it is quite feasible that optimization of the biomaterials upon which an organoid is grown may influence the outcome. A recent study claims that the initial culture of undifferentiated iPSC on a hydrogel environment improves the maturation of the resulting organoids, while culture of the end product on a compliant hydrogel tuned to the stiffness of the chick chorioallantoic membrane is said to promote the relative amount of WT1-and LTL-positive structures within kidney organoids (Garreta et al 2019). Given the apparent technical variation between lines and between experiments with the same line, which has now been documented at the level of global and single cell RNAseq (Phipson et al 2019), such claims may need more careful examination.…”

“…What is evident is that the provision of an ex vivo blood supply does improve tubular ultrastructure. This has been achieved via transplantation either under the renal capsule or subcutaneously in immunocompromised mice or culture of organoids on the chick chorioallantoic membrane (Bantounas et al 2018;van den Berg et al 2018;Garreta et al 2019). In both examples, a nascent host-derived vasculature grows into the grafted organoid with TEM evidence for the presence of glomerular capillaries.…”

Ureteric Bud Cells Programmed from Embryonic Stem Cells Obtain Competence for Secondary Induction in the Kidney

“…Recently, multiple reports presented protocols enabling generation of renal lineages from mouse and human PSCs. We and several other groups reported induction of nephron progenitors, which have the potential to develop into epithelial nephron like structures , Garreta et al, 2019, Homan et al, 2019, Taguchi et al, 2014, Takasato et al, 2014, Takasato et al, 2015, Tan et al, 2018, Low et al, 2019. Other groups have shown the derivation of ureteric bud (UB) progenitors, however, they didn't show nephron progenitor induction (Xia et al, 2013) and also lacked the connection between collecting ducts and nephrons (Xia et al, 2013, Takasato et al, 2015.…”