Todd Valerius (PI)
Brigham and Women's Hospital
Our objective is to aid RBK studies of in vitro cell populations by generating kidney cell type specific human pluripotent stem cell (hPSC) reporter lines. Such cell lines will enable both the optimization of differentiation protocols tailored to achieve specific cell types, and comparisons to in vivo human kidney cell types that will advance our understanding of in vitro tissue development and maintenance. We will use CRISPR/Cas9 gene editing to create GFP knock-in cell lines, targeting genes expressed in discrete cell types and according to consortium needs. These lines will be designed to label nephron and stromal progenitors, podocytes, and proximal and distal tubules. Additionally, cell type transition points offer glimpses into the factors that drive differentiation. We will create three dual-label reporter lines to illuminate transitions between progenitor and advanced cell types including nephron progenitors, fibrotic interstitium, and the juxtaglomerular apparatus.
Homan, Kimberly A.; Gupta, Navin; Kroll, Katharina T.; Kolesky, David B.; Skylar-Scott, Mark; Miyoshi, Tomoya; Mau, Donald; Valerius, M. Todd; Ferrante, Thomas; Bonventre, Joseph V.; Lewis, Jennifer A.; Morizane, Ryuji. Nature Methods. February 2019.
Kidney organoids derived from human pluripotent stem cells have glomerular- and tubular-like compartments that are largely avascular and immature in static culture. Here we report an in vitro method for culturing kidney organoids under flow on millifluidic chips, which expands their endogenous pool of endothelial progenitor cells and generates vascular networks with perfusable lumens surrounded by mural cells. We found that vascularized kidney organoids cultured under flow had more mature podocyte and tubular compartments with enhanced cellular polarity and adult gene expression compared with that in static controls. Glomerular vascular development progressed through intermediate stages akin to those involved in the embryonic mammalian kidney’s formation of capillary loops abutting foot processes. The association of vessels with these compartments was reduced after disruption of the endogenous VEGF gradient. The ability to induce substantial vascularization and morphological maturation of kidney organoids in vitro under flow opens new avenues for studies of kidney development, disease, and regeneration.
Oxburgh, L; Carroll, TJ; Cleaver, O; Gossett, DR; Hoshizaki, DK; Hubbell, JA; Humphreys, BD; Jain, S; Jensen, J; Kaplan, DL; Kesselman, C; Ketchum, CJ; Little, MH; McMahon, AP; Shankland, SJ; Spence, JR; Valerius, MT; Wertheim, JA; Wessely, O; Zheng, Y; Drummond, IA. J Am Soc Nephrol. 28(5):1370–1378. May 2017.
(Re)Building a Kidney is a National Institute of Diabetes and Digestive and Kidney Diseases-led consortium to optimize approaches for the isolation, expansion, and differentiation of appropriate kidney cell types and the integration of these cells into complex structures that replicate human kidney function. The ultimate goals of the consortium are two-fold: to develop and implement strategies for in vitro engineering of replacement kidney tissue, and to devise strategies to stimulate regeneration of nephrons in situ to restore failing kidney function. Projects within the consortium will answer fundamental questions regarding human gene expression in the developing kidney, essential signaling crosstalk between distinct cell types of the developing kidney, how to derive the many cell types of the kidney through directed differentiation of human pluripotent stem cells, which bioengineering or scaffolding strategies have the most potential for kidney tissue formation, and basic parameters of the regenerative response to injury. As these projects progress, the consortium will incorporate systematic investigations in physiologic function of in vitro and in vivo differentiated kidney tissue, strategies for engraftment in experimental animals, and development of therapeutic approaches to activate innate reparative responses.