Engineering functional kidney tissue using human iPS cells
Item statusRestricted Access
Embargo end date07/07/2021
Elhendawi, Mona Mohamed Mostafa Elsaeed
Recent advances in the field of stem cell research have enabled the derivation of renal organoids from hiPSCs; these organoids might be a powerful tool with important implications for regenerative medicine, but meticulous assessment of the functional abilities of the induced nephrons is key to the use of these organoids in any application. Here, I show that hiPSC-derived renal organoids possess proximal tubular transporters and receptors; I present optimised techniques to assess the function of these receptors in-vitro and show that these organoids have anion and cation uptake capacities similar to what can be seen in foetal kidney tissue or isolated proximal tubules, implying tubular functional capacity, an aspect of renal physiology that has particular importance in the renal handling of drugs and toxins. Due to high blood flow and the primary role of the kidney in clearing toxins and metabolites, renal cells are highly vulnerable to drug toxicity. The lack of in-vitro high throughput models to screen pharmaceutical compounds for potential nephrotoxicity during drug development has always hindered the field of drug development and increased the cost of delivering drugs into the market; in this study, I demonstrate that hiPSCs-derived renal organoids are able to predict nephrotoxicity with reasonable accuracy. Combining this ability with the possibility of cryopreserving renal-differentiated cells and to the use of HMOX1 reporter cell line, to detect oxidative stress, could streamline the use of these organoids in nephrotoxicity screening and could potentially flourish the field of drug development. While the current model of renal organoids could be used for drug screening without further manipulation, the use of such tissue for therapeutic purposes necessitates a higher degree of organisation and complexity. In-vivo kidney function is based on the complex interplay of a range of highly specialised cells together with their three-dimensional structure and organisation. Scientists are adopting different strategies to build kidney tissue, from hiPSCs, that could be suitable for use in therapeutic applications. Common to any of these strategies is the need to generate the correct cell types in sufficient numbers and purity, and most important, in the right location. I aim in this study to isolate correctly differentiated ureteric bud (UB) structures from surrounding cells and to induce branching from single UB-like structure to recapitulate branching morphogenesis in-vitro. I conjugated GDNF protein to a fluorophore and used it to label the UB structures and isolate them. I show that the combination of GDNF, FGF1, CHIR99021 and RA was able to induce branching in the isolated UBlike structures. The ability to isolate pure differentiated UB structures from surrounding contaminant tissue and to induce them to branch forming contiguous collecting duct tree could be a step further towards engineering a more realistic kidney tissue with single continuous collecting duct system, yet optimising culture conditions and techniques to build such a tissue is still needed.