A bioartificial kidney device with polarized secretion of immune modulators

Abstract

The accumulation of protein-bound toxins in dialyzed patients is strongly associated with their high morbidity and mortality. The bioartificial kidney device (BAK), containing proximal tubule epithelial cells (PTECs) seeded on functionalized synthetic hollow fibre membranes, may be a powerful solution for the active removal of those metabolites. In an earlier study, we developed an upscaled BAK containing conditionally immortalized human PTEC with functional organic cationic transporter 2. Here, we first extended this development to a BAK device having cells with the organic anionic transporter 1, capable of removing anionic uraemic wastes. We confirmed the quality of the conditionally immortalized human PTEC monolayer by confocal microscopy and paracellular inulin-fluorescein isothiocyanate leakage, as well as by the active transport of anionic toxin, indoxyl sulphate. Furthermore, we assessed the immune safety of our system by measuring the production of relevant cytokines by the cells after lipopolysaccharide stimulation. Upon lipopolysaccharide treatment, we observed a polarized secretion of proinflammatory cytokines by the cells: 10-fold higher in the extraluminal space, corresponding to the urine compartment, as compared with the intraluminal space, corresponding to the blood compartment. To the best of our knowledge, our work is the first to show this favourable cell polarization in a BAK upscaled device.

Influence of Dialysis Membranes on Clinical Outcomes: From History to Innovation

“…Bioartificial kidneys (BAKs) (Figure 3) are membranes that mimic native kidney processes by engaging a monolayer of conditionally immortalized proximal tubule epithelial cells (ciPTECs) cultured on polymeric membranes and collagen IV [42]. Two in-vitro studies demonstrated that ciPTECs are living cells that perform their functions well: they secrete proinflammatory cytokines and organic cation transporter 2, transport ions well, and are inhibited by H2-receptor antagonists [48,49]. They have been shown to achieve the secretory clearance of human serum albumin-bound uremic toxins that cannot be removed by commercial membranes, including IS (MW: 213 Da) and kynurenic acid (MW: 189 Da), as well as of albumin (MW: 66,500 Da) [49].…”

Microphysiological systems in absorption, distribution, metabolism, and elimination sciences

“…Cultures of renal epithelial cells in hollow fiber membranes demonstrate differential transport of organic cation compounds with scaled up versions of this format intended to serve to treat patients with uremic syndrome. [73][74][75] The device demonstrates OCT2 and OAT1 transporter functions with correct cellular localization. A similar bioartificial kidney is under development at the University of Michigan to treat patients with acute kidney failure.…”

Substrate Elasticity Governs Differentiation of Renal Tubule Cells in Prolonged Culture

“…[20][21][22][23] Although expression of kidney-specific transporters can be observed in vitro, renal tubule cells in 2D and 3D culture lack fully elaborated brush borders and may not express a complete complement of transporters. 2,1,15 Apicobasal fluid transport independent of hydrostatic pressure gradients has to our knowledge only been observed in fresh intact tubules. 24 Multiple investigators have reported enhanced expression of various kidney-specific proteins when tubule cells are cultured in three-dimensional hydrogels.…”

“…The stiffnesses chosen are similar to those used in a number of in vitro studies in multiple cell types, including kidney epithelial cells. 14,15…”