Advancing renal tissue engineering: equipping tissue-engineered kidneys with a ureter.

This proposal will significantly improve the realism and completeness of human renal organoids, 'mini-kidneys' that can be made in the lab from human induced pluripotent stem cells (hiPSC). At present, even the most realistic kidneys lack an exit tube, the ureter: the applicant lab has managed to make parts of the ureter but to make the whole thing requires the involvement of a further cell type. In this project, we will develop and optimize methods to make this cell type from stem cells, and will build it into kidney organoids, beginning with simple organoids made from mouse embryos and ending with ones made from human hiPSC.

The advance is important for several reasons. In the long-term, it is an essential step towards the goal of making transplantable kidneys from patients' own stem cells. In the shorter term, more realistic human mini-kidneys will give medical researchers, in academia and also in industry, an accessible human-based tissue on which they can study health, disease, and therapy, quickly, cheaply and with no ethical barriers. Our existing links with both academic and industrial groups will ensure that our improved organoids will make their intended impact on the research community.

This proposal addresses the need for renal organoids to have ureters. We have already solved and published the problem of making the epithelial part of the ureter, attached to a collecting duct, but the muscular and stromal parts of the ureter have a different embryonic origin. We propose to use mouse ex-fetu progenitor cells to validate fully our pilot data indicating that transplanting Tbx18+, tailbud-derived peri-Wolffian mesenchyme (PWM) next to induced urothelial tubes will result in correct ureter mesenchyme development. This will be shown first in organoids made from ex-fetu renogenic cells and then in organoids made from mouse ES cells. We will then adapt existing mouse ES cell differentiation protocols to make PWM from ES cells, and verify they behave like ex-fetu ones in organoids of both types just mentioned. Having constructed all-ES-derived renal organoids complete with ureters, we will finally adapt (concentrations, timing) the technique to human iPS cells to make an all-human renal organoid complete with a ureter.

The outcome will be important to the science of tissue engineering, to discovery science directly through its data and through providing more realistic human-derived renal organoids accessible to experiment, to disease modelling, and to testing of potential nephrotoxicants by pharma. It will also be an important step towards the long-term goal of making transplantable kidneys from human induced pluripotent stem cells (iPSC).

Impact on academic research communities: We will have three main impacts here. First, we will make some direct discoveries, about differentiation of tailbud cells and about mouse-human differences, and our data will inform embryological and evolutionary research. Second, our organoids will provide a platform for studying physiological processes in normal mouse and, importantly, human organoids. This would include organoids made to model disease, using progenitor cells with mutations or using from patient-specific hiPS cells. Third, our improved organoids are a step towards the eventual construction of transplantable organoids and future steps will build on them. We intend to be part of this endeavour ourselves. As a measure that the lab does know how to make an academic impact, JAD's publications have been cited over 7,000 times (source: Scholar Google).

Impact on industrial pharma: We will have two impacts here. The first is by providing a disease modelling platform, as above. The second is by providing an improved human renal organoid for assessing risk of nephrotoxicity in candidate drugs (nephrotoxicity is a major problem in clinical trials because animal models predict human renal sensitivity badly). We have close contact with, and have been working with, a pharma company in this area (see Pathways to Impact) so we know that there is very strong interest.

Impact on clinicians and patients: In the medium term, use of our organoids by pharma should make a difference to the risk of unexpected human renal nephrotoxicity from lead compounds. When a subset of these compounds become drugs, long-term, there will be direct benefit to patients in lower levels of iatrogenic kidney injury (currently more than 25% of acute renal injury in the over 60s arises from drugs).

Impact on the dialogue between research and public: We intend that public engagement be a part of our work (see Communications Strategy), including direct contact with patient groups, which happens to be easy for us to achieve because of connections with a major renal charity and we already do this (see Pathways to Impact). We will continue to make a contribution to the two-way dialogue between researchers and the public they serve through our public outreach. Obviously, it will be difficult to assess the effects of our specific contribution in this area as we are among many scientists who operate effectively in public engagement in broadly similar ways, often loosely coordinated by the same medical charities.