Prog. Biomed. Eng. 4 (2022) 022006 https://doi.org/10.1088/2516-1091/ac6e18 Progress in Biomedical Engineering RECEIVED 20 November 2021 REVISED 23 March 2022 ACCEPTED FOR PUBLICATION 9 May 2022 PUBLISHED 19 May 2022 TOPICAL REVIEW Hydrogel and nanoparticle carriers for kidney disease therapy: trends and recent advancements Xurui Gu 1 , Zhen Liu 2 , Yifan Tai 2 , Ling-yun Zhou 1 , Kun Liu 1 , Deling Kong 2,* , Adam C Midgley 2,*  and Xiao-cong Zuo 1,* 1 Department of Pharmacy, Third Xiangya Hospital, Central South University, Changsha, Hunan, People’s Republic of China 2 State Key Laboratory of Medicinal Chemical Biology and Key Laboratory of Bioactive Materials for the Ministry of Education, College of Life Sciences, Nankai University, Tianjin, People’s Republic of China * Authors to whom any correspondence should be addressed. E-mail: kongdeling@nankai.edu.cn, midgleyac@nankai.edu.cn and zuoxc777@163.com Keywords: carrier materials, kidney diseases, targeted therapy, hydrogels, nanoparticles Abstract Achieving local therapeutic agent concentration in the kidneys through traditional systemic administration routes have associated concerns with off-target drug effects and toxicity. Additionally, kidney diseases are often accompanied by co-morbidities in other major organs, which negatively impacts drug metabolism and clearance. To circumvent these issues, kidney-specific targeting of therapeutics aims to achieve the delivery of controlled doses of therapeutic agents, such as drugs, nucleic acids, peptides, or proteins, to kidney tissues in a safe and efficient manner. Current carrier material approaches implement macromolecular and polyplex hydrogel constructs, prodrug strategies, and nanoparticle (NP)-based delivery technologies. In the context of multidisciplinary and cross-discipline innovations, the medical and bioengineering research fields have facilitated the rapid development of kidney-targeted therapies and carrier materials. In this review, we summarize the current trends and recent advancements made in the development of carrier materials for kidney disease targeted therapies, specifically hydrogel and NP-based strategies for acute kidney disease, chronic kidney disease, and renal cell carcinoma. Additionally, we discuss the current limitations in carrier materials and their delivery mechanisms. 1. Introduction The global health and socioeconomic burden of kidney diseases continues to rise on an annual basis [1]. Cumulatively, kidney diseases are currently estimated to afflict more than 750 million people worldwide [2]. The term ‘kidney diseases’ encompass a wide variety of pathological renal-associated conditions with heterogenous initiation routes that includes, but is not limited to, acute kidney injury (AKI), chronic kidney disease (CKD), and renal cell carcinoma (RCC). In addition, nomenclature describing the cause of kidney disease is also used to further categorize and narrow the disease classification (e.g. glomerulonephritis, polycystic kidney disease, diabetic nephropathy) [3]. At present, clinically effective and safe therapeutic options for patients with kidney disease are limited. Current clinically approved drug choices only slow down the development of the disease. Inevitably, most patients progress to end stage renal disease (ESRD) and kidney failure. Invasive, costly and time expensive treatments such as peritoneal dialysis and hemodialysis are required to counteract diminished kidney function in advanced stage renal disease and ESRD patients, whereas kidney transplantation serves as a last resort [4]. 1.1. Limitations of current therapeutics for kidney disease Traditional routes of drug administrations are typically systemic (oral, intravenous), which is associated with difficulty for therapeutic agents to reach effective bioactive and therapeutic concentration ranges within kidney tissues. Often, increased dosage and frequency of dosing, or combinatory drug synergism are the only available options to achieve therapeutic effect. The onset of kidney disorders has been associated with © 2022 IOP Publishing Ltd