Determinants of preferential renal accumulation of synthetic polymers in acute kidney injury

Acute kidney injury (AKI) is a major kidney disease associated with high mortality and morbidity. AKI may lead to chronic kidney disease and end-stage renal disease. Currently, the management of AKI is mainly focused on supportive treatments. Previous studies showed macromolecular delivery systems as a promising method to target AKI, but little is known about how physicochemical properties affect the renal accumulation of polymers in ischemia-reperfusion AKI. In this study, a panel of fluorescently labeled polymers with a range of molecular weights and net charge was synthesized by living radical polymerization. By testing biodistribution of the polymers in unilateral ischemia-reperfusion mouse model of AKI, the results showed that negatively charged and neutral polymers had the greatest potential for selectively accumulating in I/R kidneys. The polymers passed through glomerulus and were retained in proximal tubular cells for up to 24 h after injection. The results obtained in the unilateral model were validated in a bilateral ischemic-reperfusion model. This study demonstrates for the first time that polymers with specific physicochemical characteristics exhibit promising ability to accumulate in the injured AKI kidney, providing initial insights on their use as polymeric drug delivery systems in AKI.