Characterization of the immunogenicity of ipsc-derived kidney organoids

A.S. Shankar, S.S. Korevaar, T.P.P. van den Bosch, M.C. Clahsen-van Groningen, J. Gribnau, C.C. Baan, E.J. Hoorn, M.J. Hoogduijn

Wednesday 13 march 2019

14:04 - 14:06h at Koningin Máximazaal

Categories: Basaal, Parallelsessie

Parallel session: Parallelsessie III - Basaal I

Background: There is an increasing interest in iPSC-based therapies for kidney regeneration. Recently protocols for the in vitrogeneration of kidney organoids have been developed. For successful implementation into clinical practice, immunological acceptance of the iPSC-derived cells is crucial. Therefore, our aim was to study the immunogenicity of iPSC-derived kidney organoids.

Methods: Three human iPSC lines were grown on Geltrex and treated with CHIR99201 and fibroblast growth factor 9.

Results: The resulting organoids showed a 10- to 40-fold increase in mRNA for kidney-specific markers after 25 days of differentiation. Immunostaining confirmed that organoids contained essential renal structures. The kidney organoids were cultured together with peripheral blood mononuclear cells from two healthy donors for 7 days. Subsequently, a >100-fold increase in the mRNA expression of the leukocyte marker CD45 was observed in the organoids. Immunostaining confirmed the presence of infiltrating CD45+ cells in the organoids. The response appeared to be T-cell mediated as there was a 10-fold mRNA increase in CD4 and CD8, while macrophage marker CD68 was also highly expressed. At the protein level, T-cells predominantly clustered around glomerular structures while macrophages were diffusely distributed throughout the organoid. A mixed pattern of macrophages could be observed, as both pro-inflammatory (M1) and anti-inflammatory (M2) macrophage markers were substantially increased at the mRNA level. Even though a 10-fold mRNA increase of inflammatory factors such as TNFαand Granzyme B was suggestive of a pro-inflammatory response, immunofluorescence showed that the infiltrating cells did not proliferate as observed by the absence of Ki-67+CD45+ cells. The mRNA expression of kidney differentiation markers remained stable throughout the co-culture. Yet, immunohistochemistry revealed that the expression of WT1, a podocyte marker, was decreased 4-fold in comparison to control organoids, indicating that specifically podocytes may be a target of the immune response.

Conclusions: Although further characterization of the immune response to kidney organoids and its influence on differentiation is required, these preliminary results offer novel insights into the in vitrointeraction of immune cells with iPSC-derived kidney organoids.