Third party funded individual grant
Acronym: DFG-MU 3797/7-1
Start date : 16.11.2022
End date : 15.11.2025
In the kidney, the glomerulus is the functional unit in which the primary urine is filtered from the blood through the glomerular filtration barrier. This barrier consists of the fenestrated glomerular endothelial cells, the glomerular basement membrane and the podocytes. Damage to the podocytes in particular can lead to nephrotic syndrome. One cause of steroid-resistant nephrotic syndrome (SRNS) is mutations in podocyte genes. In the case of autosomal dominant mutations, the disease usually only manifests itself in young adulthood, so a second hit is expected. It is assumed that SRNS does not respond to drug therapy and that it leads to rapidly progressive renal insufficiency. Nevertheless, there is data that a combination of cyclosporin A and steroids can achieve promising remission rates. However, the exact mechanisms of this therapy are unknown. Cell culture models have been used for years to investigate glomerular diseases ex vivo. However, these models are limited because they do not have a 3D structure, there is no communication between different glomerular cell types, no patient's own cells are used and there is no vascularized environment. The aim of the project is to develop glomerular structures that enable a better understanding of glomerular function and interaction under physiological and pathological conditions. To this end, glomerular spheroids will first be generated in vitro from personalized iPSC podocytes, glomerular endothelial cells and mesangial cells in co-cultures and later vascularized in the rat model. Furthermore, the patient's own podocytes will be cultured together with human glomerular endothelial cells on an artificial basement membrane and also vascularized in the already established AV loop rat model. To generate the patients' iPSCs, skin fibroblasts from patients with WT1 mutation and INF2 mutation as well as from healthy volunteers are converted into iPSCs via episomal reprogramming and then differentiated into podocytes that carry the patient's own podocyte mutation. Finally, the vascularized models are explanted and subjected to various therapeutic and toxicological studies in vitro. Single cell seq analysis and morphological characterization of the vascularized co-culture models allows the patient's own podocytes to be examined in the context of the other glomerular cells with and without treatment. This allows both possible therapeutic options for SRNS and susceptibility to toxic substances ex vivo to be predicted for each individual patient.