Feb 17, 2023
The Jennifer Lewis and Lisa Satlin labs of the Engineering Functional Kidneys group, led by Rolando Carrisoza-Gaytán (Mount Sinai), collaborated on a recent paper in American Journal of Physiology-Cell Physiology.
Functional maturation of kidney organoid tubules: Piezo1-mediated Ca2+ signaling Carrisoza-Gaytán R, Kroll KT, Hiratsuka K, Gupta NR, Morizane R, Lewis JA, Satlin LM. Am J Physiol Cell Physiol. 2023 Feb 6. doi: 10.1152/ajpcell.00288.2022. Epub ahead of print. PMID: 36745528.
Kidney organoids cultured on adherent matrices in the presence of superfusate flow generate vascular networks and exhibit more mature podocyte and tubular compartments compared to static controls (Homan et al., 2019; Takasato et al., 2015). However, their physiological function has yet to be systematically investigated. Here, we measured mechanoinduced changes in intracellular Ca2+ concentration ([Ca2+]i) in tubules isolated from organoids cultured for 21-64 d, microperfused in vitro or affixed to the base of a specimen chamber, and loaded with fura-2 to measure [Ca2+]i. A rapid >2.5-fold increase in [Ca2+]i from a baseline of 195.0±22.1 nM (n=9; p≤0.001) was observed when microperfused tubules from organoids >40 d in culture were subjected to luminal flow. In contrast, no response was detected in tubules isolated from organoids <30 d in culture. Nonperfused tubules (41 d) subjected to a 10-fold increase in bath flow rate also exhibited a 3-fold increase in [Ca2+]i from baseline (p<0.001). Mechanosensitive Piezo1 channels contribute to the flow-induced [Ca2+]i response in mouse distal tubule (Carrisoza-Gaytan et al., EB 2019). Immunodetectable apical and basolateral PIEZO1 was identified in tubular structures by 21 d in culture. Basolateral PIEZO1 appeared to be functional as basolateral exposure of nonperfused tubules to the PIEZO1 activator Yoda 1 increased [Ca2+]i (p≤0.001) in segments from organoids cultured for >30 d, with peak [Ca2+]i increasing with advancing days in culture. These results are consistent with a maturational increase in number and/or activity of flow/stretch-sensitive Ca2+ channels, including PIEZO1, in tubules of static organoids in culture.
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