Size and temporal-dependent efficacy of oltipraz-loaded PLGA nanoparticles for treatment of acute kidney injury and fibrosis

Cardiopulmonary bypass associated acute kidney injury: better understanding and better prevention

Cardiopulmonary bypass (CPB) is a common technique in cardiac surgery but is associated with acute kidney injury (AKI), which carries considerable morbidity and mortality. In this review, we explore the range and definition of CPB-associated AKI and discuss the possible impact of different disease recognition methods on research outcomes. Furthermore, we introduce the specialized equipment and procedural intricacies associated with CPB surgeries. Based on recent research, we discuss the potential pathogenesis of AKI that may result from CPB, including compromised perfusion and oxygenation, inflammatory activation, oxidative stress, coagulopathy, hemolysis, and endothelial damage. Finally, we explore current interventions aimed at preventing and attenuating renal impairment related to CPB, and presenting these measures from three perspectives: (1) avoiding CPB to eliminate the fundamental impact on renal function; (2) optimizing CPB by adjusting equipment parameters, optimizing surgical procedures, or using improved materials to mitigate kidney damage; (3) employing pharmacological or interventional measures targeting pathogenic factors.

Nanotechnology-Based Drug Delivery Systems for Treating Acute Kidney Injury

Acute kidney injury (AKI) is a disease that is characterized by a rapid decline in renal function and has a relatively high incidence in hospitalized patients. Sepsis, renal hypoperfusion, and nephrotoxic drug exposure are the main causes of AKI. The major therapy measures currently include supportive treatment, symptomatic treatment, and kidney transplantation. These methods are supportive treatments, and their results are not satisfactory. Fortunately, many new treatments that markedly improve the AKI therapy efficiency are emerging. These include antioxidant therapy, ferroptosis therapy, anti-inflammatory therapy, autophagy therapy, and antiapoptotic therapy. In addition, the development of nanotechnology has further promoted therapeutic effects on AKI. In this review, we highlight recent advances in the development of nanocarriers for AKI drug delivery. Emphasis has been placed on the latest developments in nanocarrier modification and design. We also summarize the applications of different nanocarriers in AKI treatment. Finally, the advantages and challenges of nanocarrier applications in AKI are summarized, and several nanomedicines that have been approved for clinical trials to treat diverse kidney diseases are listed.

Physiological principles underlying the kidney targeting of renal nanomedicines

Kidney disease affects more than 10% of the global population and is associated with considerable morbidity and mortality, highlighting a need for new therapeutic options. Engineered nanoparticles for the treatment of kidney diseases (renal nanomedicines) represent one such option, enabling the delivery of targeted therapeutics to specific regions of the kidney. Although they are underdeveloped compared with nanomedicines for diseases such as cancer, findings from preclinical studies suggest that renal nanomedicines may hold promise. However, the physiological principles that govern the in vivo transport and interactions of renal nanomedicines differ from those of cancer nanomedicines, and thus a comprehensive understanding of these principles is needed to design nanomedicines that effectively and specifically target the kidney while ensuring biosafety in their future clinical translation. Herein, we summarize the current understanding of factors that influence the glomerular filtration, tubular uptake, tubular secretion and extrusion of nanoparticles, including size and charge dependency, and the role of specific transporters and processes such as endocytosis. We also describe how the transport and uptake of nanoparticles is altered by kidney disease and discuss strategic approaches by which nanoparticles may be harnessed for the detection and treatment of a variety of kidney diseases.

Self-Assembling P38 Peptide Inhibitor Nanoparticles Ameliorate the Transition from Acute to Chronic Kidney Disease by Suppressing Ferroptosis

Accumulating evidence highlights p38 as a crucial factor highly activated during the process of acute kidney injury (AKI), but the application of p38 inhibitor in AKI is quite limited due to the low efficiency and poor kidney-targeting ability. Herein, a novel self-assembling peptide nanoparticle with specific p38-inhibiting activity is constructed, which linked mitogen-activated protein kinase kinase 3b (MKK3b), the functional domain of p38, with the cell-penetrating TAT sequence, ultimately self-assembling into TAT-MKK3b nanoparticles (TMNPs) through tyrosinase oxidation. Subsequent in vitro and in vivo studies demonstrated that TMNPs preferably accumulated in the renal tubular epithelial cells (RTECs) through forming protein coronas by binding to albumin, and strongly improved the reduced renal function of ischemia-reperfusion injury (IRI)-induced AKI and its transition to chronic kidney disease (CKD). Mechanically, TMNPs inhibited ferroptosis via its solute carrier family 7 member 11 (SLC7A11)/glutathione peroxidase 4 (GPX4) axis-inducing capacity and synergistic potent antioxidant property in AKI. The findings indicated that the multifunctional TMNPs exhibited renal targeting, ROS-scavenging, and ferroptosis-mitigating capabilities, which may serve as a promising therapeutic agent for the treatment of AKI and its progression to CKD.

Targeting the Kidneys at the Nanoscale: Nanotechnology in Nephrology

Kidney diseases, both acute and chronic, are a substantial burden on individual and public health, and they continue to increase in frequency. Despite this and an intense focus on the study of disease mechanisms, few new therapeutic approaches have extended to the clinic. This is in part due to poor pharmacology of many, if not most, therapeutics with respect to the sites of kidney disease within the glomerulus or nephron. Considering this, within the past decade, and more pointedly over the past 2 years, there have been substantial developments in nanoparticle systems to deliver therapeutics to the sites of kidney disease. Here, we provide a broad overview of the various classes of nanomaterials that have been developed to improve therapeutic development for kidney diseases, the strategy used to provide kidney accumulation, and briefly the disease models they focused on, if any. We then focus on one specific system, polymeric mesoscale nanoparticles, which has broadly been used over 13 publications, demonstrating targeting of the tubular epithelium with 26-fold specificity compared with other organs. While there have been several nanomedicines that have advanced to the clinic in the past several decades, including mRNA-based coronavirus disease vaccines and others, none have focused on kidney diseases specifically. In total, we are confident that the rapid advancement of nanoscale-based kidney targeting and a concerted focus by clinicians, scientists, engineers, and other stakeholders will push one or more of these technologies into clinical trials over the next decade.

CD44-targeted melanin-based nanoplatform for alleviation of ischemia/reperfusion-induced acute kidney injury

Ischemia/reperfusion (I/R)-induced acute kidney injury (AKI) is a serious kidney disease with high morbidity and mortality. However, there is no effective clinical treatment strategy. Herein, we developed a CD44 targeting nanoplatform based on HA-assembled melanin NPs covalently coupled with dexamethasone for I/R-induced AKI therapy by alleviating oxidative/inflammatory- induced damage. The constructed HA-MNP-DXM NPs had good dispersion, stability, and broad-spectrum scavenging capabilities against multiple reactive free radicals. Moreover, the NPs could be efficiently internalized and exhibited antioxidative, anti-inflammatory, and antiapoptotic effects in CoCl2-stimulated renal tubular epithelial NRK-52E cells. Furthermore, the I/R-induced AKI murine model was established to evaluate the in vivo performance of NPs. The results suggested the NPs could specifically target impaired kidneys upon intravenous administration according to NIR-II fluorescence imaging and showed high biosafety. Importantly, the NPs could improve renal function, alleviate oxidative stress and inflammatory reactions, inhibit apoptosis of tubular cells, and restore mitochondrial structure and function, exhibiting excellent therapeutic effects. Further therapeutic mechanism indicated the NPs maintained the cellular/mitochondrial redox balance by modulating the Nrf2 and HO-1 expression. Therefore, the NPs can be a promising therapeutic candidate for the treatment of I/R-induced AKI.

ROS-responsive curcumin-encapsulated nanoparticles for AKI therapy via promoting lipid degradation in renal tubules

Lipid accumulation is a factor contributing to the pathogenesis of acute kidney injury (AKI), yet there are currently no approved pharmacotherapies aside from adjuvant therapy. A developed reactive oxygen species (ROS)-responsive drug delivery system (NPSBG@Cur) was developed to deliver the autophagy activator curcumin (Cur) in order to alleviate AKI by activating autophagy and promoting lipid droplet degradation. The nanoparticles were shown to be ROS-responsive in the H2O2 medium and demonstrate ROS-responsive uptake in palmitate (PA)-induced oxidative stress-damaged cells. NPSBG@Cur was found to effectively inhibit lipid accumulation by autophagosome transport in kidney tubular cells. Additionally, in a mouse AKI model, NPSBG@Cur was observed to significantly ameliorate renal damage by activating autophagy flux and improving lipid transport. These results suggest that the ROS-responsive drug delivery system augmented the therapeutic effect of Cur on AKI by improving lipid metabolism through autophagy activation. Therefore, targeting lipid metabolism with NPSBG@Cur may be a promising AKI treatment strategy.

Recent Advances in Nanomaterials for the Treatment of Acute Kidney Injury

Acute kidney injury (AKI) is a serious clinical syndrome with high morbidity, elevated mortality, and poor prognosis, commonly considered a "sword of Damocles" for hospitalized patients, especially those in intensive care units. Oxidative stress, inflammation, and apoptosis, caused by the excessive production of reactive oxygen species (ROS), play a key role in AKI progression. Hence, the investigation of effective and safe antioxidants and inflammatory regulators to scavenge overexpressed ROS and regulate excessive inflammation has become a promising therapeutic option. However, the unique physiological structure and complex pathological alterations in the kidneys render traditional therapies ineffective, impeding the residence and efficacy of most antioxidant and anti-inflammatory small molecule drugs within the renal milieu. Recently, nanotherapeutic interventions have emerged as a promising and prospective strategy for AKI, overcoming traditional treatment dilemmas through alterations in size, shape, charge, and surface modifications. This Review succinctly summarizes the latest advancements in nanotherapeutic approaches for AKI, encompassing nanozymes, ROS scavenger nanomaterials, MSC-EVs, and nanomaterials loaded with antioxidants and inflammatory regulator. Following this, strategies aimed at enhancing biocompatibility and kidney targeting are introduced. Furthermore, a brief discussion on the current challenges and future prospects in this research field is presented, providing a comprehensive overview of the evolving landscape of nanotherapeutic interventions for AKI.

Mechanistic Analysis of Temperature-Dependent Curcumin Release from Poly(lactic-co-glycolic acid)/Poly(lactic acid) Polymer Nanoparticles

In this study, we investigated the mechanism of curcumin (CUR) release from poly(lactic-co-glycolic acid) (PLGA) and poly(lactic acid) (PLA) nanoparticles (NPs) by evaluating the temperature-dependent CUR release. NPs were prepared by the nanoprecipitation method using various PLGA/PLA polymers with different lactic:glycolic ratios (L:G ratios) and molecular weights. Increasing the polymer molecular weight resulted in a decrease in the particle size of NPs. The wet glass transition temperature (Tg) of PLGA/PLA NPs was lower than the intrinsic polymer Tg, which can be derived from the water absorption and nanosizing of the polymer. The reduction in Tg was more significant for the PLGA/PLA NPs with lower polymer L:G ratios and lower polymer molecular weight. The greater decrease of Tg in the lower polymer L:G ratios was possibly caused by the higher water absorption due to the more hydrophilic nature of the glycolic acid segment than that of the lactic acid segment. The efficient water absorption in PLGA/PLA NPs with lower molecular weight could cause a significant reduction of Tg as it has lower hydrophobicity. CUR release tests from the PLGA/PLA NPs exhibited enhanced CUR release with increasing temperatures, irrespective of polymer species. By fitting the CUR release profiles into mathematical models, the CUR release process was well described by an initial burst release followed by a diffusion-controlled release. The wet Tg and particle size of the PLGA/PLA NPs affected the amount and temperature dependence of the initial burst release of CUR. Above the wet Tg of NPs, the initial burst release of CUR increased sharply. Smaller particle sizes of PLGA/PLA NPs led to a higher fraction of initial CUR burst release, which was more pronounced above the wet Tg of NPs. The wet Tg and particle sizes of the PLGA/PLA NPs also influenced the diffusion-controlled CUR release. The diffusion rate of CUR in the NPs increased as the wet Tg values of the NPs decreased. The diffusion path length of CUR was affected by the particle size, with larger particle size resulting in a prolonged diffusion-controlled release of CUR. This study highlighted that for the formulation development of PLGA/PLA NPs, suitable PLGA/PLA polymers should be selected considering the physicochemical properties of PLGA/PLA NPs and their correlation with the release behavior of encapsulated drugs at the application temperature.

A quantitative review of nanotechnology-based therapeutics for kidney diseases

Kidney-specific nanocarriers offer a targeted approach to enhance therapeutic efficacy and reduce off-target effects in renal treatments. The nanocarriers can achieve organ or cell specificity via passive targeting and active targeting mechanisms. Passive targeting capitalizes on the unique physiological traits of the kidney, with factors like particle size, charge, shape, and material properties enhancing organ specificity. Active targeting, on the other hand, achieves renal specificity through ligand-receptor interactions, modifying nanocarriers with molecules, peptides, or antibodies for receptor-mediated delivery. Nanotechnology-enabled therapy targets diseased kidney tissue by modulating podocytes and immune cells to reduce inflammation and enhance tissue repair, or by inhibiting myofibroblast differentiation to mitigate renal fibrosis. This review summarizes the current reports of the drug delivery systems that have been tested in vivo, identifies the nanocarriers that may preferentially accumulate in the kidney, and quantitatively compares the efficacy of various cargo-carrier combinations to outline optimal strategies and future research directions. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Emerging Technologies.

The application of nanotechnology in kidney transplantation

Kidney transplantation is a crucial treatment option for end-stage renal disease patients, but challenges related to graft function, rejection and immunosuppressant side effects persist. This review highlights the potential of nanotechnology in addressing these challenges. Nanotechnology offers innovative solutions to enhance organ preservation, evaluate graft function, mitigate ischemia-reperfusion injury and improve drug delivery for immunosuppressants. The integration of nanotechnology holds promise for improving outcomes in kidney transplantation.

H2O2-stimulated Janus-shaped self-propelled nanomotors as an active treatment for acute renal injury

As emerging nanosystems, nanomotors have been applied in the active treatment of many diseases. In this paper, Pt@chitosan-loaded melatonin asymmetrical nanomaterials embedded with L-serine (S, kidney injury molecule 1-targeting agent) were constructed to alleviate acute kidney injury (AKI). The Janus nanocarriers arrived at the renal injury site via the bloodstream and exhibited high permeability. Because of melatonin distribution in the kidneys combined with H2O2-stimulated O2 release, the administration of the Janus nanosystem resulted in active treatment through the motion of nanomotors by asymmetrical O2 release.

Endogenous stimuli-responsive drug delivery nanoplatforms for kidney disease therapy

Kidney disease is one of the most life-threatening health problems, affecting millions of people in the world. Commonly used steroids and immunosuppressants often fall exceptionally short of outcomes with inescapable systemic toxicity. With the booming research in nanobiotechnology, stimuli-responsive nanoplatform has come an appealing therapeutic strategy for kidney disease. Endogenous stimuli-responsive materials have shown profuse promise owing to their enhanced spatiotemporal control and precise to the location of the lesion. This review focuses on recent advances stimuli-responsive drug delivery nano-architectonics for kidney disease. First, a brief introduction of pathogenesis of kidney disease and pathological microenvironment were provided. Then, various endogenous stimulus involved in drug delivery nanoplatforms including pH, ROS, enzymes, and glucose were categorized based on the pathological mechanisms of kidney disease. Next, we separately summarized literature examples of endogenous stimuli-responsive nanomaterials, and outlined the design strategies and response mechanisms. Finally, the paper was concluded by discussing remaining challenges and future perspectives of endogenous stimuli-responsive drug delivery nanoplatform for expediting the speed of development and clinical applications.

Engineered nanodrug targeting oxidative stress for treatment of acute kidney injury

Acute kidney injury (AKI) is a clinical syndrome characterized by a rapid decline in renal function, and is associated with a high risk of death. Many pathological changes happen in the process of AKI, including crucial alterations to oxidative stress levels. Numerous efforts have thus been made to develop effective medicines to scavenge excess reactive oxygen species (ROS). However, researchers have encountered several significant challenges, including unspecific biodistribution, high biotoxicity, and in vivo instability. To address these problems, engineered nanoparticles have been developed to target oxidative stress and treat AKI. This review thoroughly discusses the methods that empower nanodrugs to specifically target the glomerular filtration barrier and presents the latest achievements in engineering novel ROS-scavenging nanodrugs in clustered sections. The analysis of each study's breakthroughs and imperfections visualizes the progress made in developing effective nanodrugs with specific biodistribution and oxidative stress-targeting capabilities. This review fills the blank of a comprehensive outline over current progress in applying nanotechnology to treat AKI, providing potential insights for further research.

Marine biomaterials in biomedical nano/micro-systems

Marine resources in unique marine environments provide abundant, cost-effective natural biomaterials with distinct structures, compositions, and biological activities compared to terrestrial species. These marine-derived raw materials, including polysaccharides, natural protein components, fatty acids, and marine minerals, etc., have shown great potential in preparing, stabilizing, or modifying multifunctional nano-/micro-systems and are widely applied in drug delivery, theragnostic, tissue engineering, etc. This review provides a comprehensive summary of the most current marine biomaterial-based nano-/micro-systems developed over the past three years, primarily focusing on therapeutic delivery studies and highlighting their potential to cure a variety of diseases. Specifically, we first provided a detailed introduction to the physicochemical characteristics and biological activities of natural marine biocomponents in their raw state. Furthermore, the assembly processes, potential functionalities of each building block, and a thorough evaluation of the pharmacokinetics and pharmacodynamics of advanced marine biomaterial-based systems and their effects on molecular pathophysiological processes were fully elucidated. Finally, a list of unresolved issues and pivotal challenges of marine-derived biomaterials applications, such as standardized distinction of raw materials, long-term biosafety in vivo, the feasibility of scale-up, etc., was presented. This review is expected to serve as a roadmap for fundamental research and facilitate the rational design of marine biomaterials for diverse emerging applications.

Reactive X (where X = O, N, S, C, Cl, Br, and I) species nanomedicine

Reactive oxygen, nitrogen, sulfur, carbonyl, chlorine, bromine, and iodine species (RXS, where X = O, N, S, C, Cl, Br, and I) have important roles in various normal physiological processes and act as essential regulators of cell metabolism; their inherent biological activities govern cell signaling, immune balance, and tissue homeostasis. However, an imbalance between RXS production and consumption will induce the occurrence and development of various diseases. Due to the considerable progress of nanomedicine, a variety of nanosystems that can regulate RXS has been rationally designed and engineered for restoring RXS balance to halt the pathological processes of different diseases. The invention of radical-regulating nanomaterials creates the possibility of intriguing projects for disease treatment and promotes advances in nanomedicine. In this comprehensive review, we summarize, discuss, and highlight very-recent advances in RXS-based nanomedicine for versatile disease treatments. This review particularly focuses on the types and pathological effects of these reactive species and explores the biological effects of RXS-based nanomaterials, accompanied by a discussion and the outlook of the challenges faced and future clinical translations of RXS nanomedicines.

A Polymeric Nanosponge as a Broad-Spectrum Reactive Oxygen Species Scavenger for Acute Kidney Injury Treatment

Acute kidney injury (AKI) is closely associated with the overproduction of reactive oxygen species (ROS), which can cause multiple organ dysfunctions without timely treatment. However, only supportive treatments are currently available for AKI in clinics. Here, we developed nanomaterials of hyperbranched polyphosphoester (PPE) containing abundant thioether (S-PPE NP) and thioketal bonds (TK-PPE NP). Our data demonstrates that S-PPE NP exhibits an excellent capability of absorbing and scavenging multiple types of ROS, including H2O2, •OH, and •O2-, via thioether oxidation to sulfone or sulfoxide; it was also determined that S-PPE NP efficiently eliminates intracellular ROS, thus preventing cellular damage. Moreover, S-PPE NP was able to efficiently accumulate in the injured kidneys of AKI-bearing mice. As a result, the administration of S-PPE NP provided a superior therapeutic effect in AKI-bearing mice by downregulating ROS- and inflammation-related signaling pathways, thus reducing cell apoptosis. This thioether-containing polymer represents a promising broad-spectrum ROS scavenger that can be used for effective AKI treatments.

Delivering drugs to tubular cells and organelles: the application of nanodrugs in acute kidney injury

Acute kidney injury (AKI) is a common clinical syndrome with limited treatment options and high mortality rates. Proximal tubular epithelial cells (PTECs) play a key role in AKI progression. Subcellular dysfunctions, including mitochondrial, nuclear, endoplasmic reticulum and lysosomal dysfunctions, are extensively studied in PTECs. These studies have led to the development of potential therapeutic drugs. However, clinical development of those drugs faces challenges such as low solubility, short circulation time and severe systemic side effects. Nanotechnology provides a promising solution by improving drug properties through nanocrystallization and enabling targeted delivery to specific sites. This review summarizes advancements and limitations of nanoparticle-based drug-delivery systems in targeting PTECs and subcellular organelles, particularly mitochondria, for AKI treatment.

Niclosamide-loaded nanoparticles (Ncl-NPs) reverse pulmonary fibrosis in vivo and in vitro

INTRODUCTION

Idiopathic pulmonary fibrosis (IPF), a life-threatening interstitial lung disease, is characterized by excessive activation and proliferation of fibroblasts and epithelial-mesenchymal transition (EMT) of alveolar epithelial cells (AEC) accompanied by a large amount of extracellular matrix aggregation. There are no therapies to reverse pulmonary fibrosis, and nintedanib and pirfenidone could only slow down the decline of lung function of IPF patients and delay their survival time. Niclosamide (Ncl) is an antihelminthic drug approved by FDA, which has been reported to have pleiotropic pharmacological activities in recent years, but it's almost complete insolubility in water limits its clinical application.

OBJECTIVES

To improve the water solubility of Ncl, explore its ability to reverse BLM-induced pulmonary fibrosis and its specific mechanism of action.

METHODS

The Niclosamide-loaded nanoparticles (Ncl-NPs) were formed by emulsification solvent evaporation method. A mouse model induced by bleomycin (BLM) was established to evaluate its effects and mechanisms of inhibiting and reversing fibrosis in vivo. The cell models treated by transforming growth factor-β1 (TGF-β1) were used to examine the mechanism of Ncl-NPs inhibiting fibrosis in vitro. Flow cytometry, IHC, IL-4-induced macrophage model and co-culture system were used to assess the effect of Ncl-NPs on M2 polarization of macrophages.

RESULTS

The Ncl-NPs improved the poor water solubility of Ncl. The lower dose of Ncl-NPs (2.5 mg/kg) showed the same effect of reversing established pulmonary fibrosis as free Ncl (5 mg/kg). Mechanistic studies revealed that Ncl-NPs blocked TGF-β/Smad and signaling transducer and activator of transcription 3 (Stat3) signaling pathways and inhibited the M2 polarization of macrophages. Additionally, H&E staining of the tissues initially showed the safety of Ncl-NPs.

CONCLUSION

These results indicate Ncl-NPs may serve as a new idea for the treatment of pulmonary fibrosis.

Renal tissue engineering for regenerative medicine using polymers and hydrogels

Chronic Kidney Disease (CKD) is a growing worldwide problem, leading to end-stage renal disease (ESRD). Current treatments for ESRD include haemodialysis and kidney transplantation, but both are deemed inadequate since haemodialysis does not address all other kidney functions, and there is a shortage of suitable donor organs for transplantation. Research in kidney tissue engineering has been initiated to take a regenerative medicine approach as a potential treatment alternative, either to develop effective cell therapy for reconstruction or engineer a functioning bioartificial kidney. Currently, renal tissue engineering encompasses various materials, mainly polymers and hydrogels, which have been chosen to recreate the sophisticated kidney architecture. It is essential to address the chemical and mechanical aspects of the materials to ensure they can support cell development to restore functionality and feasibility. This paper reviews the types of polymers and hydrogels that have been used in kidney tissue engineering applications, both natural and synthetic, focusing on the processing and formulation used in creating bioactive substrates and how these biomaterials affect the cell biology of the kidney cells used.

Crotamine/siRNA Nanocomplexes for Functional Downregulation of Syndecan-1 in Renal Proximal Tubular Epithelial Cells

Proteinuria drives progressive tubulointerstitial fibrosis in native and transplanted kidneys, mainly through the activation of proximal tubular epithelial cells (PTECs). During proteinuria, PTEC syndecan-1 functions as a docking platform for properdin-mediated alternative complement activation. Non-viral gene delivery vectors to target PTEC syndecan-1 could be useful to slow down alternative complement activation. In this work, we characterize a PTEC-specific non-viral delivery vector composed of the cell-penetrating peptide crotamine complexed with a syndecan-1 targeting siRNA. Cell biological characterization was performed in the human PTEC HK2 cell line, using confocal microscopy, qRT-PCR, and flow cytometry. PTEC targeting in vivo was carried out in healthy mice. Crotamine/siRNA nanocomplexes are positively charged, about 100 nm in size, resistant to nuclease degradation, and showed in vitro and in vivo specificity and internalization into PTECs. The efficient suppression of syndecan-1 expression in PTECs mediated by these nanocomplexes significantly reduced properdin binding (p < 0.001), as well as the subsequent complement activation by the alternative complement pathway (p < 0.001), as observed in either normal or activated tubular conditions. To conclude, crotamine/siRNA-mediated downregulation of PTEC syndecan-1 reduced the activation of the alternative complement pathway. Therefore, we suggest that the present strategy opens new venues for targeted proximal tubular gene therapy in renal diseases.

Renal-Clearable Probe with Water Solubility and Photostability for Biomarker-Activatable Detection of Acute Kidney Injuries via NIR-II Fluorescence and Optoacoustic Imaging

Acute kidney injuries (AKI) have serious short-term or long-term complications with high morbidity and mortality rate, thus posing great health threats. Developing high-performance NIR-II probes for noninvasive in situ detection of AKI via NIR-II fluorescent and optoacoustic dual-mode imaging is of great significance. Yet NIR-II chromophores often feature long conjugation and hydrophobicity, which prevent them from being renal clearable, thus limiting their applications in the detection and imaging of kidney diseases. To fully exploit the advantageous features of heptamethine cyanine dye, while overcoming its relatively poor photostability, and to strive to design a NIR-II probe for the detection and imaging of AKI with dual-mode imaging, herein, we have developed the probe PEG3-HC-PB, which is renal clearable, water soluble, and biomarker activatable and has good photostability. As for the probe, its fluorescence (900-1200 nm) is quenched due to the existence of the electron-pulling phenylboronic group (responsive element), and it exhibits weak absorption with a peak at 830 nm. Meanwhile, in the presence of the overexpressed H₂O₂ in the renal region in the case of AKI, the phenylboronic group is converted to the phenylhydroxy group, which enhances NIR-II fluorescent emission (900-1200 nm) and absorption (600-900 nm) and eventually produces conspicuous optoacoustic signals and NIR-II fluorescent emission for imaging. This probe enables detection of contrast-agent-induced and ischemia/reperfusion-induced AKI in mice using real-time 3D-MSOT and NIR-II fluorescent dual-mode imaging via response to the biomarker H₂O₂. Hence, this probe can be used as a practicable tool for detecting AKI; additionally, its design strategy could provide insight into the design of other large-conjugation NIR-II probes with multifarious biological applications.

Nanodrugs alleviate acute kidney injury: Manipulate RONS at kidney

Currently, there are no clinical drugs available to treat acute kidney injury (AKI). Given the high prevalence and high mortality rate of AKI, the development of drugs to effectively treat AKI is a huge unmet medical need and a research hotspot. Although existing evidence fully demonstrates that reactive oxygen and nitrogen species (RONS) burst at the AKI site is a major contributor to AKI progression, the heterogeneity, complexity, and unique physiological structure of the kidney make most antioxidant and anti-inflammatory small molecule drugs ineffective because of the lack of kidney targeting and side effects. Recently, nanodrugs with intrinsic kidney targeting through the control of size, shape, and surface properties have opened exciting prospects for the treatment of AKI. Many antioxidant nanodrugs have emerged to address the limitations of current AKI treatments. In this review, we systematically summarized for the first time about the emerging nanodrugs that exploit the pathological and physiological features of the kidney to overcome the limitations of traditional small-molecule drugs to achieve high AKI efficacy. First, we analyzed the pathological structural characteristics of AKI and the main pathological mechanism of AKI: hypoxia, harmful substance accumulation-induced RONS burst at the renal site despite the multifactorial initiation and heterogeneity of AKI. Subsequently, we introduced the strategies used to improve renal targeting and reviewed advances of nanodrugs for AKI: nano-RONS-sacrificial agents, antioxidant nanozymes, and nanocarriers for antioxidants and anti-inflammatory drugs. These nanodrugs have demonstrated excellent therapeutic effects, such as greatly reducing oxidative stress damage, restoring renal function, and low side effects. Finally, we discussed the challenges and future directions for translating nanodrugs into clinical AKI treatment.

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AKI is a common clinical acute syndrome with high morbidity and mortality but without effective clinical drug available.

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Hypoxia and accumulation of toxic substances are key pathological features of various heterogeneous AKI.

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Excessive RONS is the core of the pathological mechanism of AKI.

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The development of nanodrugs is expected to achieve successful treatment in AKI.

Silica Cross-Linked Micelle-Based Theranostic System for the Imaging and Treatment of Acute and Chronic Kidney Injury

Acute kidney injury (AKI) is a common and serious disease with high mortality and morbidity, and the persistent inflammatory environment brought about by AKI promotes its deterioration into chronic kidney disease (CKD). An efficient and timely targeted drug delivery to the renal tubules is crucial for AKI treatment. Here, we prepared silica cross-linked micelles (SCLMs) with different sizes and studied their targeting ability to the injured kidney. It is found that the SCLMs with a size of 13 nm could rapidly accumulate and remain in the damaged kidney. Immunofluorescence results confirmed that SCLMs are selectively located in the damaged tubular cells but cannot be found in healthy renal tissue. Therefore, fluorescent dye-labeled SCLMs were used for the imaging of the injured kidney, which could reflect the status of the kidney injury. Furthermore, atorvastatin, an antioxidative and anti-inflammatory drug, was loaded in SCLMs as the therapeutic agents for the treatment of ischemia/reperfusion-induced AKI and CKD. Renal function indexes, such as tubular necrosis, collagen deposition, and inflammation, were effectively improved after the treatment.

Advanced Drug Delivery Systems for Renal Disorders

Kidney disease management and treatment are currently causing a substantial global burden. The kidneys are the most important organs in the human urinary system, selectively filtering blood and metabolic waste into urine via the renal glomerulus. Based on charge and/or molecule size, the glomerular filtration apparatus acts as a barrier to therapeutic substances. Therefore, drug distribution to the kidneys is challenging, resulting in therapy failure in a variety of renal illnesses. Hence, different approaches to improve drug delivery across the glomerulus filtration barrier are being investigated. Nanotechnology in medicine has the potential to have a significant impact on human health, from illness prevention to diagnosis and treatment. Nanomaterials with various physicochemical properties, including size, charge, surface and shape, with unique biological attributes, such as low cytotoxicity, high cellular internalization and controllable biodistribution and pharmacokinetics, have demonstrated promising potential in renal therapy. Different types of nanosystems have been employed to deliver drugs to the kidneys. This review highlights the features of the nanomaterials, including the nanoparticles and corresponding hydrogels, in overcoming various barriers of drug delivery to the kidneys. The most common delivery sites and strategies of kidney-targeted drug delivery systems are also discussed.

Self-assembled hyaluronic acid-coated nanocomplexes for targeted delivery of curcumin alleviate acute kidney injury

Acute kidney injury (AKI) is a pathological process with high morbidity, and drug resistance is easy to occur due to untargeted drug therapy. Curcumin can repair acute kidney injury. The expression of the CD44 receptor in renal tubular epithelial cells is abnormally elevated during AKI, and hyaluronic acid (HA) has the ability to bind specifically to the CD44 receptor. In this study, we developed a hyaluronic acid-coated liposome (HALP) nanocomplexes that targeted renal epithelial cells and its effect of relieving AKI was investigated. HALP was formed by self-assembly through the electrostatic interaction of curcumin-loaded cationic liposomes (LP) with hyaluronic acid and responds to the release of curcumin in the acidic microenvironment of lesions to treat AKI. HALP had good stability and biocompatibility. The in vitro results showed that compared to LP, HALP exhibited higher antioxidant, anti-inflammatory, and anti-apoptotic capacities. The AKI model suggested that HALP could not only target and accumulate in the injured kidney but also had an excellent ability to reduce the inflammatory response, which decreased tubular necrosis and restored kidney function.

1,2-Bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic Acid Acetoxymethyl Ester Loaded Reactive Oxygen Species Responsive Hyaluronic Acid-Bilirubin Nanoparticles for Acute Kidney Injury Therapy via Alleviating Calcium Overload Mediated Endoplasmic Reticulum Stress

Calcium overload is one of the early determinants of the core cellular events that contribute to the pathogenesis of acute kidney injury (AKI), which include oxidative stress, ATP depletion, calcium overload, and inflammatory response with self-amplifying and interactive feedback loops that ultimately lead to cellular injury and renal failure. Excluding adjuvant therapy, there are currently no approved pharmacotherapies for the treatment of AKI. Using an adipic dihydride linker, we modified the hyaluronic acid polymer chain with a potent antioxidant, bilirubin, to produce an amphiphilic conjugate. Subsequently, we developed a kidney-targeted and reactive oxygen species (ROS)-responsive drug delivery system based on the flash nanocomplexation method to deliver a well-known intracellular calcium chelator, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester (BAPTA-AM, BA), with the goal of rescuing renal cell damage via rapidly scavenging of intracellularly overloaded Ca²⁺. In the ischemia-reperfusion (I/R) induced AKI rat model, a single dose of as-prepared formulation (BA 100 μg·kg^-1) 6 h post-reperfusion significantly reduced renal function indicators by more than 60% within 12 h, significantly alleviated tissular pathological changes, ameliorated tissular oxidative damage, significantly inhibited apoptosis of renal tubular cells and the expression of renal tubular marker kidney injury molecule 1, etc., thus greatly reducing the risk of kidney failure. Mechanistically, the treatment with BA-loaded NPs significantly inhibited the activation of the ER stress cascade response (IRE1-TRAF2-JNK, ATF4-CHOP, and ATF6 axis) and regulated the downstream apoptosis-related pathway while also reducing the inflammatory response. The BA-loaded NPs hold great promise as a potential therapy for I/R injury-related diseases.

Nanostructured polyvinylpyrrolidone-curcumin conjugates allowed for kidney-targeted treatment of cisplatin induced acute kidney injury

Acute kidney injury (AKI) leads to unacceptably high mortality due to difficulties in timely intervention and less efficient renal delivery of therapeutic drugs. Here, a series of polyvinylpyrrolidone (PVP)-curcumin nanoparticles (PCurNP) are designed to meet the renal excretion threshold (∼45 kDa), presenting a controllable delivery nanosystem for kidney targeting. Renal accumulation of the relatively small nanoparticles, ⁸⁹Zr-PCurNP M10 with the diameter between 5 and 8 nm, is found to be 1.7 times and 1.8 times higher than the accumulation of ⁸⁹Zr-PCurNP M29 (20–50 nm) and M40 (20–50 nm) as revealed by PET imaging. Furthermore, serum creatinine analysis, kidney tissues histology, and tubular injury scores revealed that PCurNP M10 efficiently treated cisplatin-induced AKI. Herein, PCurNP offers a novel and simple strategy for precise PET image-guided drug delivery of renal protective materials.

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PVP-curcumin nanosystems were investigated for treating cisplatin-induced acute kidney injury.

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Inherent oxygens of PCurNP nanoparticles facilitate Zr-89 radiolabeling for PET imaging.

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Modulating the sizes of PCurNP nanoparticles allowed for adjustable kidney targeting and retention as revealed by PET imaging.

Low dimensional nanomaterials for treating acute kidney injury

Acute kidney injury (AKI) is one of the most common severe complications among hospitalized patients. In the absence of specific drugs to treat AKI, hemodialysis remains the primary clinical treatment for AKI patients. AKI treatment has received significant attention recently due to the excellent drug delivery capabilities of low-dimensional nanomaterials (LDNs) and their unique therapeutic effects. Diverse LDNs have been proposed to treat AKI, with promising results and the potential for future clinical application. This article aims to provide an overview of the pathogenesis of AKI and the recent advances in the treatment of AKI using different types of LDNs. In addition, it is intended to provide theoretical support for the design of LDNs and implications for AKI treatment.

Reactive Oxygen Species- and Cell-Free DNA-Scavenging Mn3O4 Nanozymes for Acute Kidney Injury Therapy

Reactive oxygen species (ROS) scavenging therapy toward acute kidney injury (AKI) is promising, but no effective ROS scavenging drug has been developed yet. Moreover, cell-free DNA (cfDNA) is also involved in AKI, but the corresponding therapies have not been well developed. To tackle these challenges, Mn₃O₄ nanoflowers (Nfs) possessing both ROS and cfDNA scavenging activities were developed for better AKI protection as follows. First, Mn₃O₄ Nfs could protect HK2 cells through cascade ROS scavenging (dismutating ^·O₂^- into H₂O₂ by superoxide dismutase-like activity and then decomposing H₂O₂ by catalase-like activity). Second, Mn₃O₄ Nfs could efficiently adsorb cfDNA and then decrease the inflammation caused by cfDNA. Combined, remarkable therapeutic efficacy was achieved in both cisplatin-induced and ischemia-reperfusion AKI murine models. Furthermore, Mn₃O₄ Nfs could be used for the T₁-MRI real-time imaging of AKI. This study not only offered a promising treatment for AKI but also showed the translational potential of nanozymes.

Molecular Mechanisms of Rhabdomyolysis-Induced Kidney Injury: From Bench to Bedside

Rhabdomyolysis-induced acute kidney injury (RIAKI) occurs following damage to the muscular sarcolemma sheath, resulting in the leakage of myoglobin and other metabolites that cause kidney damage. Currently, the sole recommended clinical treatment for RIAKI is aggressive fluid resuscitation, but other potential therapies, including pretreatments for those at risk for developing RIAKI, are under investigation. This review outlines the mechanisms and clinical significance of RIAKI, investigational treatments and their specific targets, and the status of ongoing research trials.

Co-delivery of celastrol and lutein with pH sensitive nano micelles for treating acute kidney injury

To treat acute kidney injury with high efficiency and low toxicity, a novel nanoplatform was developed to remove excess reactive oxygen species (ROS). Lutein (LU) and celastrol (Cel) were loaded into low molecular weight chitosan (CS) to prepare Cel@LU-CA-CS nanomicelles. Renal tubular epithelial (HK-2) cell uptake experiments showed that the drugs could be internalized in renal tubular via the megalin receptor. In this study, the amide bond formed by the reaction of citraconic anhydride (CA) with an amino group of CS could be destroyed under acidic conditions. Therefore, the drugs were released in HK-2 cells due to the acidic environment of the lysosome. In vitro studies showed that the nanomicelles could reduce toxicity in non-target organs and enhance therapeutic efficacy in acute kidney injury (AKI). In addition, Cel@LU-CA-CS micelles had alleviated kidney oxidative stress disorder and stabilized the mitochondrial membrane potential quickly. Next, in vivo studies proved that Cel@LU-CA-CS micelles could inhibit the activation of the NF-κB p65 and p38 MAPK inflammatory signaling pathways. Therefore, the micelles further reduced the overexpression of related inflammatory factors. In conclusion, Cel@LU-CA-CS nanomicelles could treat AKI with high efficiency and low toxicity, and inhibit renal fibrosis.

A biocompatible nanoparticle-based approach to inhibiting renal ischemia reperfusion injury in mice by blocking thrombospondin-1 activity

Thrombospondin-1 (TSP-1) is a key mediator of renal ischemia-reperfusion injury (IRI), a major cause of kidney dysfunction under various disease conditions and a risk factor of renal allograft rejection. In this study, we developed a nanotechnology-based therapy targeting TSP-1 to prevent renal IRI. A biocompatible nanoparticle (NP) capable of specific binding to TSP-1 was prepared by conjugating NPs with TSP-1-binding (LSKL) peptides. LSKL/NPs not only effectively adsorbed recombinant TSP-1 proteins in vitro, but also efficiently neutralized TSP-1 in mice undergoing renal IRI. IRI-induced elevation of TSP-1 in the kidney was significantly inhibited by post-IR treatment with LSKL/NPs, but not free LSKL or NPs. Furthermore, TSP-1 proteins adsorbed on LSKL/NPs were functionally inactive and unable to induce apoptosis in renal tubular epithelial cells. Importantly, LSKL/NPs induced strong protection against renal IRI, as shown by markedly diminished serum creatinine levels and improved histological lesions of the kidney. Thus, LSKL/NPs provide a useful means of depleting and inactivating TSP-1 and a potential therapy for renal IRI.

Kidney-Targeted Drug Delivery System Based on Metformin-Grafted Chitosan for Renal Fibrosis Therapy

Our previous study demonstrated that metformin plays an anti-fibrotic role in addition to its hypoglycemic effect. Worryingly, it often requires more than 5 times the hypoglycemic dose to achieve a satisfactory anti-fibrotic effect, which greatly increases the risk of systemic acidosis caused by metformin overdose. Low-molecular-weight chitosan (LMWC) has natural kidney-targeting properties and good biocompatibility and degradability. Thus, we synthesized a novel carrier metformin-grafted chitosan (CS-MET) based on an imine reaction between oxidized chitosan and metformin. Then, GFP was recruited to form GFP-loaded CS-MET nanoparticles (CS-MET/GFP NPs) with controllable particle size. We hypothesized that CS-MET/GFP NPs would enrich in the kidney and be absorbed by HK-2 cells via megalin-mediated endocytosis by intravenous injection, which may avoid systemic acidosis caused by metformin overdose. Subsequently, the nanoparticle ruptures and releases metformin to exert its anti-apoptotic, anti-inflammatory, and anti-fibrotic effects. Our results showed that CS-MET/GFP NPs have great transfection efficiency and could enter HK-2 cells mainly through megalin-mediated endocytosis. Compared to the free metformin, CS-MET/GFP NPs showed similar anti-apoptotic ability but better therapeutic effects on cellular inflammation and fibrosis in vitro. On the other hand, CS-MET/GFP NPs showed great kidney-targeting ability and superior anti-apoptotic, anti-inflammatory, and anti-fibrotic effects in vivo.

Ceria nanoparticles prophylactic used for renal ischemia-reperfusion injury treatment by attenuating oxidative stress and inflammatory response

Renal ischemia-reperfusion (IR) injury (RIRI) is the leading cause of acute kidney injury (AKI), a common disease with high morbidity and mortality. However, due to the lack of effective diagnostic and therapeutic tools, patients have to resort to conservative treatment. To address this issue, we have developed a novel prophylactic strategy that involves the pre-treatment use of ceria nanoparticles (CNPs) before surgery. Based on our careful study of the three different sizes of CNPs that we synthesized, 46 nm (NP46), 81 nm (NP81), and 118 nm (NP118), we have found that NP118 can be used as effective prophylactic agents against RIRI and subsequent renal fibrosis. In our experiments, the CNPs exhibited excellent antioxidant and anti-inflammatory activities in vitro and effectively protected the kidney against RIRI and renal fibrosis in vivo, as proved by the decreases in renal lesions, serum creatinine, blood urea nitrogen, apoptotic cell, KIM-1 expression, and fibrotic area in CNPs treated samples relative to RIRI group. Mechanistically, not only did the CNPs reduce oxidative stress by regulating the Nrf2 pathway, but they also attenuated RIRI induced inflammatory response by decreasing macrophage infiltration and polarization to M1 phenotype, and reducing pro-inflammatory cytokine and chemokine production. In vitro results further confirmed that CNPs pre-treatment not only dramatically decreased intracellular ROS production in renal tubular epithelial cells and vascular endothelial cells, but also effectively attenuated lipopolysaccharide-induced inflammation in RAW264.7 cells. In addition, we found that one fourth of the NP118 persisted for more than 21 days in IR kidneys, and that out of the three sizes of CNPs, NP118 achieved the best results in all our experiments. Our study provides new insights into the usage and majorization of CNPs as a potential therapy to treat or prevent RIRI and renal fibrosis.

Folic acid-targeted pluronic F127 micelles improve oxidative stress and inhibit fibrosis for increasing AKI efficacy

The oxidative stress and activation of the fibrosis pathway are essential pathological mechanisms of acute kidney injury (AKI). In this article, we designed a drug delivery system that could effectively improve oxidative stress and relieve fibrosis by the combination of precise targeting, solubilization, and reducing the toxicity of nano-transport system to strengthen the efficacy of AKI. Folic acid (FA) was used as the targeting molecule, and curcumin (Cur) and resveratrol (Res), which are Chinese medicine monomers with anti-inflammatory and antioxidant effects, were used as model drugs. Here, the targeting nanosystem (Cur/Res@FA-F127/TPGS) co-loaded with Cur and Res was successfully synthesized. Finally, the comprehensive therapeutic effect of the nanosystem was evaluated through the targeted and pharmacodynamic researches on the AKI models induced by cisplatin (CDDP) in vitro and in vivo. The studies in vitro proved that the nanosystem could not only specifically target HK-2 cells and promote the effective accumulation of Cur and Res in the kidney, but also effectively improve oxidative stress by eliminating reactive oxygen species (ROS), stabilizing mitochondrial membrane potential (MMP), and reducing the expression of apoptosis-related proteins. The studies in vivo showed that the nanosystem could effectively play the role of anti-oxidation, anti-inflammatory and alleviate fibrosis to reduce the apoptosis and necrosis of renal tubular cells. The nanosystem could coordinately repair damaged HK-2 cells by improving oxidative stress, inhibiting inflammation and tissue fibrosis, which provided a new idea for the treatment of AKI.

Kidney functional stages influence the role of PEG end-group on the renal accumulation and distribution of PEGylated nanoparticles

Modification with polyethylene glycol (PEG), or PEGylation, has become a popular method to improve the efficiency of drug delivery in vivo using nanoparticle-based delivery systems. The PEG end-group plays an important role in the in vivo fate of PEGylated nanoparticles through its interactions with proteins in the serum and the cell membrane. However, the effects of PEG end-groups on the renal clearance of PEGylated nanoparticles remain unclear. Kidney function may also affect the renal accumulation and distribution of nanoparticles. Herein, we demonstrate that the accumulation and distribution of PEGylated nanoparticles in kidneys are significantly affected by both the PEG end-group and kidney function damage. Interestingly, compared to PEG with an amino or methoxy end-group, PEG with maleimide as the end-group markedly enhanced the accumulation of PEGylated nanoparticles in normal kidneys, which may improve renal clearance. However, obvious enhancements in the renal accumulation and medullary distribution of PEGylated nanoparticles are detected in kidneys with functional impairment. Damage to renal function further affects how the PEG end-group influences the accumulation and distribution of PEGylated nanoparticles in kidneys in vivo. Collectively, the findings provide deep insights into the interactions between PEGylated nanoparticles and kidneys in vivo.

Delivery of sorafenib by myofibroblast-targeted nanoparticles for the treatment of renal fibrosis

Fibrosis is an excessive accumulation of the extracellular matrix within solid organs in response to injury and a common pathway that leads functional failure. No clinically approved agent is available to reverse or even prevent this process. Herein, we report a nanotechnology-based approach that utilizes a drug carrier to deliver a therapeutic cargo specifically to fibrotic kidneys, thereby improving the antifibrotic effect of the drug and reducing systemic toxicity. We first adopted in vitro-in vivo combinatorial phage display technology to identify peptide ligands that target myofibroblasts in mouse unilateral ureteral obstruction (UUO)-induced fibrotic kidneys. We then engineered lipid-coated poly(lactic-co-glycolic acid) nanoparticles (NPs) with fibrotic kidney-homing peptides on the surface and sorafenib, a potent antineoplastic multikinase inhibitor, encapsulated in the core. Sorafenib loaded in the myofibroblast-targeted NPs significantly reduced the infiltration of α-smooth muscle actin-expressing myofibroblasts and deposition of collagen I in UUO-treated kidneys and enhanced renal plasma flow measured by Technetium-99m mercaptoacetyltriglycine scintigraphy. This study demonstrates the therapeutic potential of the newly identified peptide fragments as anchors to target myofibroblasts and represents a strategic advance for selective delivery of sorafenib to treat renal fibrosis. SIGNIFICANCE STATEMENT: Renal fibrosis is a pathological feature accounting for the majority of issues in chronic kidney disease (CKD), which may progress to end-stage renal disease (ESRD). This manuscript describes a myofibroblast-targeting drug delivery system modified with phage-displayed fibrotic kidney-homing peptides. By loading the myofibroblast-targeting nanoparticles (NPs) with sorafenib, a multikinase inhibitor, the NPs could suppress collagen synthesis in cultured human myofibroblasts. When given intravenously to mice with UUO-induced renal fibrosis, sorafenib loaded in myofibroblast-targeting NPs significantly ameliorated renal fibrosis. This approach provides an efficient therapeutic option to renal fibrosis. The myofibroblast-targeting peptide ligands and nanoscale drug carriers may be translated into clinical application in the future.

Design, Development, Physicochemical Characterization, and In Vitro Drug Release of Formoterol PEGylated PLGA Polymeric Nanoparticles

Polymeric nanoparticles’ drug delivery systems represent a promising platform for targeted controlled release since they are capable of improving the bioavailability and tissue localization of drugs compared to traditional means of administration. Investigation of key parameters of nanoparticle preparation and their impact on performance, such as size, drug loading, and sustained release, is critical to understanding the synthesis parameters surrounding a given nanoparticle formulation. This comprehensive and systematic study reports for the first time and focuses on the development and characterization of formoterol polymeric nanoparticles that have potential application in a variety of acute and chronic diseases. Nanoparticles were prepared by a variety of solvent emulsion methods with varying modifications to the polymer and emulsion system with the aim of increasing drug loading and tuning particle size for renal localization and drug delivery. Maximal drug loading was achieved by amine modification of polyethylene glycol (PEG) conjugated to the poly(lactic-co-glycolic acid) (PLGA) backbone. The resulting formoterol PEGylated PLGA polymeric nanoparticles were successfully lyophilized without compromising size distribution by using either sucrose or trehalose as cryoprotectants. The physicochemical characteristics of the nanoparticles were examined comprehensively, including surface morphology, solid-state transitions, crystallinity, and residual water content. In vitro formoterol drug release characteristics from the PEGylated PLGA polymeric nanoparticles were also investigated as a function of both polymer and emulsion parameter selection, and release kinetics modeling was successfully applied.

Fucoidans from Cucumaria frondosa ameliorate renal interstitial fibrosis via inhibition of the PI3K/Akt/NF-κB signaling pathway

The effects of Cucumaria frondosa polysaccharides (CFPs) on renal interstitial fibrosis by regulating the phosphatidylinositol-3-hydroxykinase/protein kinase-B/nuclear factor-κB (PI3K/AKT/NF-κB) signaling pathway were investigated in vivo and in vitro in this research. The common unilateral urethral obstruction (UUO) model was used to examine the renoprotective effect and its mechanism in vivo. Compared to the UUO group, CFP administration could ameliorate renal function, inhibit inflammation and fibrosis, and reduce the deposition of the extracellular matrix and epithelial-mesenchymal transition. Mechanistic results indicated that CFPs could inhibit the expression of the total protein of PI3K and the conversion of the AKT and NF-κB p65 phosphorylated proteins, thereby inhibiting the transduction of the PI3K/AKT/NF-κB pathway. In addition, CFP treatment could improve inflammation and fibrosis in HK-2 cells induced by TGF-β1, and its in vitro mechanism was also verified to inhibit the PI3K/Akt/NF-κB signaling pathway. Overall, these results showed that CFP could alleviate renal interstitial fibrosis related to the PI3K/AKT/NF-κB signaling pathway.

Role of Nanotechnology and Their Perspectives in the Treatment of Kidney Diseases

Nanoparticles (NPs) are differing in particle size, charge, shape, and compatibility of targeting ligands, which are linked to improved pharmacologic characteristics, targetability, and bioavailability. Researchers are now tasked with developing a solution for enhanced renal treatment that is free of side effects and delivers the medicine to the active spot. A growing number of nano-based medication delivery devices are being used to treat renal disorders. Kidney disease management and treatment are currently causing a substantial global burden. Renal problems are multistep processes involving the accumulation of a wide range of molecular and genetic alterations that have been related to a variety of kidney diseases. Renal filtration is a key channel for drug elimination in the kidney, as well as a burgeoning topic of nanomedicine. Although the use of nanotechnology in the treatment of renal illnesses is still in its early phases, it offers a lot of potentials. In this review, we summarized the properties of the kidney and characteristics of drug delivery systems, which affect a drug’s ability should focus on the kidney and highlight the possibilities, problems, and opportunities.

Renal Nano-drug delivery for acute kidney Injury: Current status and future perspectives

Acute kidney injury (AKI) causes considerable morbidity and mortality, particularly in the case of post-cardiac infarction or kidney transplantation; however, the site-specific accumulation of small molecule reno-protective agents for AKI has often proved ineffective due to dynamic fluid and solute excretion and non-selectivity, which impedes therapeutic efficacy. This article reviews the current status and future trajectories of renal nanomedicine research for AKI management from pharmacological and clinical perspectives, with a particular focus on appraising nanosized drug carrier (NDC) use for the delivery of reno-protective agents of different pharmacological classes and the effectiveness of NDCs in improving renal tissue targeting selectivity and efficacy of said agents. This review reveals the critical shift in the role of the small molecule reno-protective agents in AKI pharmacotherapy - from prophylaxis to treatment - when using NDCs for delivery to the kidney. We also highlight the need to identify the accumulation sites of NDCs carrying reno-protective agents in renal tissues during in vivo assessments and detail the less-explored pharmacological classes of reno-protective agents whose efficacies may be improved via NDC-based delivery. We conclude the paper by outlining the challenges and future perspectives of NDC-based reno-protective agent delivery for better clinical management of AKI.

Preferential siRNA delivery to injured kidneys for combination treatment of acute kidney injury

Acute kidney injury (AKI) is characterized by a sudden loss of renal function and is associated with high morbidity and mortality. Tumor suppressor p53 and chemokine receptor CXCR4 were both implicated in the AKI pathology. Here, we report on the development and evaluation of polymeric CXCR4 antagonist (PCX) siRNA carrier for selective delivery to injured kidneys in AKI. Our results show that PCX/siRNA nanoparticles (polyplexes) provide protection against cisplatin injury to tubule cells in vitro when both CXCR4 and p53 are inhibited. The polyplexes selectively accumulate and are retained in the injured kidneys in cisplatin and bilateral ischemia reperfusion injury models of AKI. Treating AKI with the combined CXCR4 inhibition and p53 gene silencing with the PCX/sip53 polyplexes improves kidney function and decreases renal damage. Overall, our results suggest that the PCX/sip53 polyplexes have a significant potential to enhance renal accumulation in AKI and deliver therapeutic siRNA.

Self-polymerized polydopamine-based nanoparticles for acute kidney injury treatment through inhibiting oxidative damages and inflammatory

The polydopamine nanoparticles (PDA NPs) as a self-polymerized form of dopamine have occurred with growing interest in biomedical applications in late years. Its natural-inspired feature as a conjugated polymer endows excellent inactivating capability for radical species to PDA-based nanoparticles that provide a theoretical foundation for applications in preventing inflammation-mediated acute kidney injury (AKI) from ROS. Here, we develop a polydopamine wrapped manganese ferrite nanoparticles (PDA@MF NPs) strategy for acute kidney injury therapy by synergistically scavenging ROS and producing O₂, which further regulates macrophages amounts by decreasing M1-type and increasing M2-type. Water-soluble PDA@MF NPs were prepared in one step after the oxidative and self-polymerized process of the dopamine monomer. Here, the biodegradable PDA NPs were applied to scavenge ROS. MF NPs undertake continuous O₂ production in an H₂O₂-based hypoxic environment. Based on this system, we aim to relieve the hypoxia, pathological symptoms, and inflammation via scavenging ROS during the O₂ production process, and effective polarization to M2-type macrophages. PDA@MF NPs in this study were verified could significantly attenuate oxidative stress in vivo, reduce inflammatory events in renal, and improve renal function, which might be a potential treatment to inhibit oxidative damages and inflammatory events in renal AKI disease.

Real-Time Monitoring Renal Impairment Due to Drug-Induced AKI and Diabetes-Caused CKD Using an NAG-Activatable NIR-II Nanoprobe

Real-time in vivo optical imaging of kidney function is important for the diagnosis of renal diseases, such as acute kidney injury (AKI) and chronic kidney disease (CKD), with high morbidity and mortality worldwide. However, the reported optical imaging agents still have limitations for identifying AKI or CKD in the early stage due to their low sensitivity, poor tissue penetration, and significant background interference. Herein, an N-acetyl-β-d-glucosaminidase (NAG)-activatable second near-infrared (NIR-II) fluorescent nanoprobe (BOD-II-NAG-NP) is developed for monitoring the progression of drug-induced AKI and in vivo imaging of diabetes-caused CKD. NAG, as a biomarker of renal diseases, is able to specifically activate BOD-II-NAG-NP to release NIR-II fluorescence signals, enabling in vivo imaging of kidney dysfunctions in living mice. Importantly, such an active imaging mechanism allows BOD-II-NAG-NP to noninvasively detect the onset of drug-induced AKI at least 32 h earlier than the most existing assays, which indicates that BOD-II-NAG-NP has the potential to be an optical imaging agent for the early diagnosis of AKI. Moreover, NIR-II fluorescence produced by BOD-II-NAG-NP could deeply penetrate into the relatively thick layers of fat in diabetic nephropathy mice and provide in vivo imaging with high resolution, indicating that BOD-II-NAG-NP has clinical potential for precision diagnosis of CKD.