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Lisa Satlin (PI)
Icahn School of Medicine at Mount Sinai
Within the cortical collecting duct (CCD) of the mammalian kidney, increases in urinary flow rate, induced by volume expansion or diuretics, subject principal (PCs) and intercalated (ICs) cells to (i) fluid shear stress (FSS), (ii) circumferential stretch (CS), and (iii) drag/torque on apical cilia of PCs. We hypothesize flow-stimulated ENaC-mediated Na+ absorption by PCs and BK channel-mediated Ca2+-dependent K+ secretion by ICs depend on cell-specific autocrine/paracrine signaling. Given the cell heterogeneity of the native CCD and uncertainty as to which hydrodynamic forces are physiologically relevant in a native cylindrical and distensible tubule, we propose to utilize a novel in vitro 3D bioprinted CCD model to: (1) examine the capacity of PC-only, IC-only, and hybrid tubules for flow-stimulated ENaC-mediated Na+ absorption and iberiotoxin (IbTX)-sensitive (and thus BK channel-mediated) flow-induced K+ secretion (FIKS); (2) identify cell-specific paracrine/autocrine effectors released by an increase in luminal flow in PC-only, IC-only, and hybrid tubules that modulate basal and flow-stimulated cation transport; and (3) determine whether flow-stimulated cation transport and autocrine/paracrine factor release are elicited by FSS, CS, and/or deformation of apical cilia by altering the composition of the engineered extracellular matrix (ECM) to increase/decrease stiffness, or deciliating tubules.