1457 Human renal proximal tubule-on-a-chip model to study prevention of ischemia and reperfusion injury

Abstract Background and Aims Renal ischemia/reperfusion injury (rIRI) is characterized by restriction of blood supply followed by restoration of blood flow and re-oxygenation and is a leading cause of acute kidney injury (AKI). While animal models are useful for studying systemic manifestations of AKI, their translational relevance is limited. Human in vitro models provide valuable mechanistic insights into rIRI, but often fail to incorporate crucial aspects such as reperfusion injury. To address these limitations, this study aims to develop an advanced in vitro model to study rIRI comprising a perfused three-dimensional (3D) human renal proximal tubule-on-a-chip. Method Our proximal tubule-on-a-chip model comprises a renal proximal tubule alongside a endothelial vessel, separated by extracellular matrix. A microfluidic platform, the OrganoPlate 3-Lane 40, was used to establish the model. The resulting coculture was characterized in terms of its three-dimensional structure, protein expression, and response to nephrotoxins. Subsequently, we simulated rIRI by manipulating oxygen levels, nutrient availability, and perfusion flow settings. The potential protective effect of adenosine was evaluated in the coculture model during ischemia and reperfusion. The extent of injury was assessed through morphological evaluation, caspase 3/7 activation, and cell viability measurements. Results The combination of low oxygen, reduced glucose, and interrupted flow exerted a potent disruptive effect on the proximal tubules, which was strongly amplified upon reperfusion. Endothelial vessels were less sensitive to the ischemia–reperfusion parameters. Adenosine treatment showed a protective effect on the disruption of the epithelium and on the caspase-3/7 activation. Conclusion We successfully developed a human in vitro model to study rIRI utilizing a coculture of a proximal tubule and a blood vessel on-a-chip. This model allowed us to characterize the renoprotective effect of adenosine. The robustness of the model and assays, coupled with the platform's high throughput capabilities, position it as a promising tool for advancing pathophysiological research and facilitating the development of innovative therapeutic modalities aimed at treating rIRI and improving AKI outcomes. Figure 1: Adenosine protected against disruption of the epithelium and caspase-3/7 activation after rIRI in a proximal tubule-on-a-chip model. The proximal tubule-on-a-chip model comprises of a proximal tub