Targeting therapeutics to the glomerulus with nanoparticles

Glomerulus-Targeted ROS-Responsive Polymeric Nanoparticles for Effective Membranous Nephropathy Therapy

Membranous nephropathy (MN) is a common immune-mediated glomerular disease that requires the development of safe and highly effective therapies. Celastrol (CLT) has shown promise as a therapeutic molecule candidate, but its clinical use is currently limited due to off-target toxicity. Given that excess levels of reactive oxygen species (ROS) contributing to podocyte damage is a key driver of MN progression to end-stage renal disease, we rationally designed ROS-responsive cationic polymeric nanoparticles (PPS-CPNs) with a well-defined particle size and surface charge by employing poly(propylene sulfide)-polyethylene glycol (PPS-PEG) and poly(propylene sulfide)-polyethylenimine (PPS-PEI) to selectively deliver CLT to the damaged glomerulus for MN therapy. Experimental results show that PPS-CPNs successfully crossed the fenestrated endothelium, accumulated in the glomerular basement membrane (GBM), and were internalized by podocytes where rapid drug release was triggered by the overproduction of ROS, thereby outperforming nonresponsive CLT nanotherapy to alleviate subepithelial immune deposits, podocyte foot process effacement, and GBM expansion in a rat MN model. Moreover, the ROS-responsive CLT nanotherapy was associated with significantly lower toxicity to major organs than free CLT. These results suggest that encapsulating CLT into PPS-CPNs can improve efficacy and reduce toxicity as a promising treatment option for MN.

Cavitation-on-a-Chip Enabled Size-Specific Liposomal Drugs for Selective Pharmacokinetics and Pharmacodynamics

The size of liposomal drugs has been demonstrated to strongly correlate with their pharmacokinetics and pharmacodynamics. While the microfluidic method successfully achieves the production of liposomes with well-controlled sizes across various buffer/lipid flow rate ratio (FRR) settings, any adjustments to the FRR inevitably influence the concentration, encapsulation efficiency (EE), and stability of liposomal drugs. Here we describe a controllable cavitation-on-a-chip (CCC) strategy that facilitates the precise regulation of liposomal drug size at any desired FRR. The CCC-enabled size-specific liposomes exhibited striking differences in uptake and biodistribution behaviors, thereby demonstrating distinct antitumor efficacy in both tumor-bearing animal and melanoma patient-derived organoid (PDO) models. Intriguingly, as the liposome size decreased to approximately 80 nm, the preferential accumulation of liposomal drugs in the liver transitioned to a predominant enrichment in the kidneys. These findings underscore the considerable potential of our CCC approach in influencing the pharmacokinetics and pharmacodynamics of liposomal nanomedicines.

Nanocarrier-based localized and effective treatment of renal disorders: currently employed targeting strategies

Renal disorders pose a global health threat, with targeted drug-delivery systems emerging as a promising strategy to enhance therapy safety and efficacy. Recent efforts have harnessed targeted nanomaterials for kidney disease treatment. While some systems remain in the early stages, they show immense potential in delivering cargo to specific sites. Through animal model experimentations, it has been demonstrated to reduce systemic side effects and enhance treatment effectiveness. This review presents current strategies for kidney disorder treatment, emphasizing site-specific targeting critical to renal disease pathophysiology. Recent advancements in nano-drug delivery systems for kidney targeting are explored. Finally, toxicological aspects and prospects of the most promising kidney-targeting delivery systems are discussed in this review article.

Potential Medicinal Value of Rhein for Diabetic Kidney Disease

Diabetic kidney disease (DKD) is the primary cause of mortality among diabetic patients. With the increasing prevalence of diabetes, it has become a major concern around the world. The therapeutic effect of clinical use of drugs is far from expected, and therapy choices to slow the progression of DKD remain restricted. Therefore, research on new drugs and treatments for DKD has been a hot topic in the medical field. It has been found that rhein has the potential to target the pathogenesis of DKD and has a wide range of pharmacological effects on DKD, such as anti-nephritis, decreasing blood glucose, controlling blood lipids and renal protection. In recent years, the medical value of rhein in the treatment of diabetes, DKD and renal disease has gradually attracted worldwide attention, especially its potential in the treatment of DKD. Currently, DKD can only be treated with medications from a single symptom and are accompanied by adverse effects, while rhein improves DKD with a multi-pathway and multi-target approach. Therefore, this paper reviews the therapeutic effects of rhein on DKD, and proposes solutions to the limitations of rhein itself, in order to provide valuable references for the clinical application of rhein in DKD and the development of new drugs.

Low molecular weight fucoidan modified nanoliposomes for the targeted delivery of the anti-inflammation natural product berberine

The inflammatory response is the basis of many diseases, such as atherosclerosis and ulcerative colitis. Inhibiting inflammatory response is the key to treating these diseases. Berberine hydrochloride (BBR), a natural product, has shown effective inflammation inhibitory activity. However, its distribution throughout the body results in a variety of serious side effects. Currently, there is a lack of targeted delivery systems for BBR to inflammatory sites. In view of the fact that the recruitment of inflammatory cells by activated vascular endothelial cells is a key step in inflammation development. Here, we design a system that can specifically deliver berberine to activated vascular endothelial cells. Low molecular weight fucoidan (LMWF), which can specifically bind to P-selectin, was coupled to PEGylated liposomes (LMWF-Lip), and BBR is encapsulated into LMWF-Lip (LMWF-Lip/BBR). In vitro, LMWF-Lip significantly increases the uptake by activated human umbilical vein endothelial cells (HUVEC). Injection of LMWF-Lip into the tail vein of rats can effectively accumulate in the swollen part of the foot, where it is internalized by the characteristics of activated vascular endothelial cells. LMWF-Lip/BBR can effectively inhibit the expression of P-selectin in activated vascular endothelial cells, and reduce the degree of foot edema and inflammatory response. In addition, compared with free BBR, the toxicity of BBR in LMWF-Lip/BBR to main organs was significantly reduced. These results suggest that wrapping BBR in LMWF-Lip can improve efficacy and reduce its systemic toxicity as a potential treatment for various diseases caused by inflammatory responses.

Targeted nanotherapy for kidney diseases: a comprehensive review

Kidney diseases represent a major public health problem, affecting millions of people worldwide. Moreover, the treatment of kidney diseases is burdened by the problematic effects of conventional drug delivery, such as systemic drug toxicity, rapid drug clearance, and the absence of precise targeting of the kidney. Although the use of nanotechnology in medicine is in its early stage and lacks robust translational studies, nanomedicines have already shown great promise as novel drug-delivery systems for the treatment of kidney disease. On the basis of our current knowledge of renal anatomy and physiology, pathophysiology of kidney diseases, and physicochemical characteristics of nanoparticles, an expansive repertoire and wide use of nanomedicines could be developed for kidney diseases in the near future. Some limitations have slowed the transition of these agents from preclinical studies to clinical trials, however. In this review, we summarize the current knowledge on renal drug-delivery systems and recent advances in renal cell targeting; we also demonstrate their important potential as future paradigm-shifting therapies for kidney diseases.

Transcription factor c-Maf deletion improves streptozotocin-induced diabetic nephropathy by directly regulating Sglt2 and Glut2

The transcription factor c-Maf has been widely studied and has been reported to play a critical role in embryonic kidney development; however, the postnatal functions of c-Maf in adult kidneys remain unknown as c-Maf-null C57BL/6J mice exhibit embryonic lethality. In this study, we investigated the role of c-Maf in adult mouse kidneys by comparing the phenotypes of tamoxifen-inducible (TAM-inducible) c-Maf-knockout mice (c-Maffl/fl; CAG-Cre-ERTM mice named "c-MafΔTAM") with those of c-Maffl/fl control mice, 10 days after TAM injection [TAM(10d)]. In addition, we examined the effects of c-Maf deletion on diabetic conditions by injecting the mice with streptozotocin, 4 weeks before TAM injection. c-MafΔTAM mice displayed primary glycosuria caused by sodium-glucose cotransporter 2 (Sglt2) and glucose transporter 2 (Glut2) downregulation in the kidneys without diabetes, as well as morphological changes and life-threatening injuries in the kidneys on TAM(10d). Under diabetic conditions, c-Maf deletion promoted recovery from hyperglycemia and suppressed albuminuria and diabetic nephropathy by causing similar effects as did Sglt2 knockout and SGLT2 inhibitors. In addition to demonstrating the potentially unique gene regulation of c-Maf, these findings highlight the renoprotective effects of c-Maf deficiency under diabetic conditions and suggest that c-Maf could be a novel therapeutic target gene for treating diabetic nephropathy.

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.

Ion channels and channelopathies in glomeruli

An essential step in renal function entails the formation of an ultrafiltrate that is delivered to the renal tubules for subsequent processing. This process, known as glomerular filtration, is controlled by intrinsic regulatory systems and by paracrine, neuronal, and endocrine signals that converge onto glomerular cells. In addition, the characteristics of glomerular fluid flow, such as the glomerular filtration rate and the glomerular filtration fraction, play an important role in determining blood flow to the rest of the kidney. Consequently, disease processes that initially affect glomeruli are the most likely to lead to end-stage kidney failure. The cells that comprise the glomerular filter, especially podocytes and mesangial cells, express many different types of ion channels that regulate intrinsic aspects of cell function and cellular responses to the local environment, such as changes in glomerular capillary pressure. Dysregulation of glomerular ion channels, such as changes in TRPC6, can lead to devastating glomerular diseases, and a number of channels, including TRPC6, TRPC5, and various ionotropic receptors, are promising targets for drug development. This review discusses glomerular structure and glomerular disease processes. It also describes the types of plasma membrane ion channels that have been identified in glomerular cells, the physiological and pathophysiological contexts in which they operate, and the pathways by which they are regulated and dysregulated. The contributions of these channels to glomerular disease processes, such as focal segmental glomerulosclerosis (FSGS) and diabetic nephropathy, as well as the development of drugs that target these channels are also discussed.

L-Serine-Modified Poly-L-Lysine as a Biodegradable Kidney-Targeted Drug Carrier for the Efficient Radionuclide Therapy of Renal Cell Carcinoma

In the present study, L-serine (Ser)-modified poly-L-lysine (PLL) was synthesized to develop a biodegradable, kidney-targeted drug carrier for efficient radionuclide therapy in renal cell carcinoma (RCC). Ser-PLL was labeled with ¹¹¹In/⁹⁰Y via diethylenetriaminepentaacetic acid (DTPA) chelation for biodistribution analysis/radionuclide therapy. In mice, approximately 91% of the total dose accumulated in the kidney 3 h after intravenous injection of ¹¹¹In-labeled Ser-PLL. Single-photon emission computed tomography/computed tomography (SPECT/CT) imaging showed that ¹¹¹In-labeled Ser-PLL accumulated in the renal cortex following intravenous injection. An intrarenal distribution study showed that fluorescein isothiocyanate (FITC)-labeled Ser-PLL accumulated mainly in the renal proximal tubules. This pattern was associated with RCC pathogenesis. Moreover, ¹¹¹In-labeled Ser-PLL rapidly degraded and was eluted along with the low-molecular-weight fractions of the renal homogenate in gel filtration chromatography. Continuous Ser-PLL administration over five days had no significant effect on plasma creatinine, blood urea nitrogen (BUN), or renal histology. In a murine RCC model, kidney tumor growth was significantly inhibited by the administration of the beta-emitter ⁹⁰Y combined with Ser-PLL. The foregoing results indicate that Ser-PLL is promising as a biodegradable drug carrier for kidney-targeted drug delivery and efficient radionuclide therapy in RCC.

Nano-Technological Approaches for Targeting Kidney Diseases With Focus on Diabetic Nephropathy: Recent Progress, and Future Perspectives

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease worldwide. With the rising prevalence of diabetes, the occurrence of DN is likely to hit pandemic proportions. The current treatment strategies employed for DN focus on the management of blood pressure, glycemia, and cholesterol while neglecting DN’s molecular progression mechanism. For many theranostic uses, nano-technological techniques have evolved in biomedical studies. Several nanotechnologically based theranostics have been devised that can be tagged with targeting moieties for both drug administration and/or imaging systems and are being studied to identify various clinical conditions. The molecular mechanisms involved in DN are discussed in this review to assist in understanding its onset and progression pattern. We have also discussed emerging strategies for establishing a nanomedicine-based platform for DN-targeted drug delivery to increase drug’s efficacy and safety, as well as their reported applications.

Polymer nanotherapeutics to correct autoimmunity

The immune system maintains homeostasis and protects the body from pathogens, mutated cells, and other harmful substances. When immune homeostasis is disrupted, excessive autoimmunity will lead to diseases. To inhibit the unexpected immune responses and reduce the impact of treatment on immunoprotective functions, polymer nanotherapeutics, such as nanomedicines, nanovaccines, and nanodecoys, were developed as part of an advanced strategy for precise immunomodulation. Nanomedicines transport cytotoxic drugs to target sites to reduce the occurrence of side effects and increase the stability and bioactivity of various immunomodulating agents, especially nucleic acids and cytokines. In addition, polymer nanomaterials carrying autoantigens used as nanovaccines can induce antigen-specific immune tolerance without interfering with protective immune responses. The precise immunomodulatory function of nanovaccines has broad prospects for the treatment of immune related-diseases. Besides, nanodecoys, which are designed to protect the body from various pathogenic substances by intravenous administration, are a simple and relatively noninvasive treatment. Herein, we have discussed and predicted the application of polymer nanotherapeutics in the correction of autoimmunity, including treating autoimmune diseases, controlling hypersensitivity, and avoiding transplant rejection.

Atypical Renal Clearance of Nanoparticles Larger Than the Kidney Filtration Threshold

In recent years, several publications reported that nanoparticles larger than the kidney filtration threshold were found intact in the urine after being injected into laboratory mice. This theoretically should not be possible, as it is widely known that the kidneys prevent molecules larger than 6–8 nm from escaping into the urine. This is interesting because it implies that some nanoparticles can overcome the size limit for renal clearance. What kinds of nanoparticles can “bypass” the glomerular filtration barrier and cross into the urine? What physical and chemical characteristics are essential for nanoparticles to have this ability? And what are the biomolecular and cellular mechanisms that are involved? This review attempts to answer those questions and summarize known reports of renal-clearable large nanoparticles.

Renal Cell-Targeted Drug Delivery Strategy for Acute Kidney Injury and Chronic Kidney Disease: A Mini-Review

Kidney diseases, including acute kidney injury (AKI) and chronic kidney disease (CKD), have become a global public health concern associated with high morbidity, mortality, and healthcare costs. However, at present, very few effective and specific drug therapies are available, owing to the poor therapeutic efficacy and systemic side effects. Kidney-targeted drug delivery, as a potential strategy for solving these problems, has received great attention in the fields of AKI and CKD in recent years. Here, we review the literature on renal targeted, more specifically, renal cell-targeted formulations of AKI and CKD that offered biodistribution data. First, we provide a broad overview of the unique structural characteristics and injured cells of acute and chronic injured kidneys. We then separately summarize literature examples of renal targeted formulations according to the difference of target cells and elaborate on the appropriate formulation design criteria for AKI and CKD. Finally, we propose a hypothetic strategy to improve the renal accumulation of glomerular cell-targeted formulation by escaping the uptake of the reticuloendothelial system and provide some perspectives for future studies.

An evaluation of a novel nanoformulation of imatinib mesylate in a mouse model of lupus nephritis

Studies have suggested imatinib mesylate (ImM) as a potential treatment for systemic lupus erythematosus nephritis (SLEN). However, ImM has limited renal excretion. The goal of the current research was to develop an ImM containing nanoformulation, conduct studies to evaluate pharmacokinetics, and determine whether kidney deposition can be enhanced in a mouse model of SLEN. A fish oil-based ImM oil-in-water nanoemulsion was developed and characterized for particle size, zeta potential, pH, and stability. MRL/MpJ-Faslrp (model of SLEN) and MRL/MpJ (control) mice (12-13 weeks) received one dose of ImM as either a nanoemulsion or naked drug. Pharmacokinetics and kidney deposition studies were performed. Statistics were conducted with a student's T-test. The nanoemulsion characteristics included particle size range of 60-80 nm, zeta potential of -6.6 to -7.8 mV, polydispersity index < 0.3, 3-day stability at 4 °C, and limited ImM leakage from the nanoemulsion in serum. Pharmacokinetics of the nanoformulation showed changes to pharmacokinetic parameters suggesting reduced systemic exposures (with reduced potential for toxicities) to ImM. Kidney deposition of ImM was threefold higher after 4 h in the MRL/MpJ-Faslrp mice that received the nanoformulation vs. naked drug. The current study showed encouraging results for development of a stable and well-characterized nanoemulsion for optimizing kidney deposition of ImM. Future strategies will define dose-efficacy and dose-toxicity relationships and evaluate approaches to further enhance kidney delivery and optimize deposition to the mesangial location of the kidney.

Formoterol PLGA-PEG Nanoparticles Induce Mitochondrial Biogenesis in Renal Proximal Tubules

Formoterol is a long-acting β₂ agonist (LABA). Agonism of the β₂-adrenergic receptor by formoterol is known to stimulate mitochondrial biogenesis (MB) in renal proximal tubules and recover kidney function. However, formoterol has a number of cardiovascular side effects that limits its usage. The goal of this study was to design and develop an intravenous biodegradable and biocompatible polymeric nanoparticle delivery system that targets formoterol to the kidney. Poly(ethylene glycol) methyl ether-block-poly(lactide-co-glycolide) nanoparticles containing encapsulated formoterol were synthesized by a modified single-emulsion solvent evaporation technique resulting in nanoparticles with a median hydrodynamic diameter of 442 + 17 nm. Using primary cell cultures of rabbit renal proximal tubular cells (RPTCs), free formoterol, encapsulated formoterol polymeric nanoparticles, and drug-free polymeric nanoparticles were biocompatible and not cytotoxic over a wide concentration range. In healthy male mice, polymeric nanoparticles were shown to localize in tubules of the renal cortex and improved the renal localization of encapsulated formoterol compared to the free formoterol. At a lower total formoterol dose, the nanoparticle localization resulted in increased expression of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), the master regulator of MB, and increased electron transport chain proteins, markers of MB. This was confirmed by direct visual quantification of mitochondria and occurred with both free formoterol and the encapsulated formoterol polymeric nanoparticles. At the same time, localization of nanoparticles to the kidneys resulted in reduced induction of MB markers in the heart. These new nanoparticles effectively target formoterol to the kidney and successfully produce MB in the kidney.

Catalogue of self-targeting nano-medical inventions to accelerate clinical trials

Repetitive outbreaks and prolonged epidemics represent mortal threats to global health, creating chaos in our globalized world. To date, scientists have been compelled to follow FDA guidelines for conventional clinical trials, which decelerates the release of effective therapies to battle outbreaks and safeguard global health security. Developing multi-purpose platform nanotechnologies to self-target specific organs in response to the disease microenvironment could greatly help to rapidly anticipate and efficiently manage outbreaks. Nano-interventions in the form of self-targeting nanoparticles (NPs) could accelerate the clinical translation of potential drugs to fight future outbreaks via innovating their clinical trials. This review sets the foundation of the self-targeting concept to govern the in vivo fate of NPs without the need to complicate the engineering designs with targeting ligands. The proposed catalogue of accelerated nano-innovations offers self-targeting, physiological trafficking, bio-compliance, and controllable drug release in response to associated smart linkers.

The ameliorating approach of nanorobotics in the novel drug delivery systems: a mechanistic review

Nanoscale robotics have the ability that it can productively transform multiple energy sources into motion and strength which reflects an expeditiously appearing and captivating area for research of robotics. In today's plethora, biomedical nanorobotics played an intricate character with numerous units of robots working at the pathological site in a coordinated manner. The synergistic action of the several nanorobotics has been employed for the fulfilment of the task such as large-scale detoxification, delivery of the large pharmacological/therapeutic efficacious payloads, etc. that is nearly unfeasible or unalterable practically by using single nanorobot. The collective intelligence of the nanorobot is advancing progressively at the nanoscale to reinforce their precision treatment potentially. Conclusively, after obtaining certain consideration regarding the nanorobotics sciences, many professionals are compendiously involving in the emerging highly efficacious therapeutic technology that encourages the scientist or designing of the tissues specific for the site-specific nanorobotic diagnostic devices. As a result, the closed and professional type between the field of Nanotechnology and Medical Sciences will provide another new highly oriented level to the domain of nanorobotics.

Nanomedicine in the treatment of diabetic nephropathy

Globally, diabetic nephropathy (DN) is the foremost cause of end-stage renal disease. With the incidence of diabetes increasing day by day, DN's occurrence is expected to surge to pandemic proportions. Current available therapeutic interventions associated with DN emphasize blood pressure, glycemia and lipid control while ignoring DN's progression mechanism at a molecular level. This review sheds light on the molecular insights involved in DN to help understand the initiation and progression pattern. Further, we summarize novel strategies with reported applications in developing a nanomedicine-based platform for DN-targeted drug delivery to improve drug efficacy and safety.

Biomedical nanoparticle design: What we can learn from viruses

Viruses are nanomaterials with a number of properties that surpass those of many synthetic nanoparticles (NPs) for biomedical applications. They possess a rigorously ordered structure, come in a variety of shapes, and present unique surface elements, such as spikes. These attributes facilitate propitious biodistribution, the crossing of complex biological barriers and a minutely coordinated interaction with cells. Due to the orchestrated sequence of interactions of their stringently arranged particle corona with cellular surface receptors they effectively identify and infect their host cells with utmost specificity, while evading the immune system at the same time. Furthermore, their efficacy is enhanced by their response to stimuli and the ability to spread from cell to cell. Over the years, great efforts have been made to mimic distinct viral traits to improve biomedical nanomaterial performance. However, a closer look at the literature reveals that no comprehensive evaluation of the benefit of virus-mimetic material design on the targeting efficiency of nanomaterials exists. In this review we, therefore, elucidate the impact that viral properties had on fundamental advances in outfitting nanomaterials with the ability to interact specifically with their target cells. We give a comprehensive overview of the diverse design strategies and identify critical steps on the way to reducing them to practice. More so, we discuss the advantages and future perspectives of a virus-mimetic nanomaterial design and try to elucidate if viral mimicry holds the key for better NP targeting.

Kidney-targeted astaxanthin natural antioxidant nanosystem for diabetic nephropathy therapy

Diabetic nephropathy (DN) is a frequent and severe microvascular complication associated with oxidative stress of diabetes mellitus. A novel astaxanthin-based natural antioxidant nanosystem, namely AST-GLU-LIP, with preferential renal uptake and bioavailability were prepared and applied for treatment of diabetic nephropathy in rats. Our results of kidney-targeted evaluation showed that glucose-PEG₆₀₀-DSPE ligand modified AST liposomes could be specifically transported by overexpressed GLUT1 on the membrane of glomerular mesangial cells and achieved excellent kidney-targeted drug delivery. In addition, the results of pharmacodynamics and therapeutics in DN rats demonstrated that AST-GLU-LIP could improve the bioavailability and antioxidant capacity of AST to scavenge redundant ROS induced by oxidative stress. AST-GLU-LIP could also significantly improve the renal pathological morphology to protect the kidney as a therapeutic drug for diabetic nephropathy.

Multifunctional Natural Polymer Nanoparticles as Antifibrotic Gene Carriers for CKD Therapy

BACKGROUND

Progressive fibrosis is the underlying pathophysiological process of CKD, and targeted prevention or reversal of the profibrotic cell phenotype is an important goal in developing therapeutics for CKD. Nanoparticles offer new ways to deliver antifibrotic therapies to damaged tissues and resident cells to limit manifestation of the profibrotic phenotype.

METHODS

We focused on delivering plasmid DNA expressing bone morphogenetic protein 7 (BMP7) or hepatocyte growth factor (HGF)-NK1 (HGF/NK1) by encapsulation within chitosan nanoparticles coated with hyaluronan, to safely administer multifunctional nanoparticles containing the plasmid DNA to the kidneys for localized and sustained expression of antifibrotic factors. We characterized and evaluated nanoparticles in vitro for biocompatibility and antifibrotic function. To assess antifibrotic activity in vivo, we used noninvasive delivery to unilateral ureteral obstruction mouse models of CKD.

RESULTS

Synthesis of hyaluronan-coated chitosan nanoparticles containing plasmid DNA expressing either BMP7 or NGF/NKI resulted in consistently sized nanoparticles, which-following endocytosis driven by CD44⁺ cells-promoted cellular growth and inhibited fibrotic gene expression in vitro. Intravenous tail injection of these nanoparticles resulted in approximately 40%-45% of gene uptake in kidneys in vivo. The nanoparticles attenuated the development of fibrosis and rescued renal function in unilateral ureteral obstruction mouse models of CKD. Gene delivery of BMP7 reversed the progression of fibrosis and regenerated tubules, whereas delivery of HGF/NK1 halted CKD progression by eliminating collagen fiber deposition.

CONCLUSIONS

Nanoparticle delivery of HGF/NK1 conveyed potent antifibrotic and proregenerative effects. Overall, this research provided the proof of concept on which to base future investigations for enhanced targeting and transfection of therapeutic genes to kidney tissues, and an avenue toward treatment of CKD.

Effect of glutathione liposomes on diabetic nephropathy based on oxidative stress and polyol pathway mechanism

A novel antioxidant glutathione liposomes (GSH-LIP) were prepared and applied for diabetic nephropathy therapy. GSH-LIP not only improve the bioavailability and antioxidant capacity of glutathione to scavenge redundant ROS inducing by oxidative stress, but also effectively inhibit the activity of AR and sorbitol accumulation in polyol pathway. The imaging in vivo showed that GSH-LIP could target kidney and significantly improve renal pathology. GSH-LIP may become a new AR inhibitor and antioxidant, which provides a new theoretical basis for the study of drugs for therapy diabetic nephropathy.

Macrophage metabolic reprogramming presents a therapeutic target in lupus nephritis

IgG antibodies cause inflammation and organ damage in autoimmune diseases such as systemic lupus erythematosus (SLE). We investigated the metabolic profile of macrophages isolated from inflamed tissues in immune complex (IC)-associated diseases, including SLE and rheumatoid arthritis, and following IgG Fcγ receptor cross-linking. We found that human and mouse macrophages undergo a switch to glycolysis in response to IgG IC stimulation, mirroring macrophage metabolic changes in inflamed tissue in vivo. This metabolic reprogramming was required to generate a number of proinflammatory mediators, including IL-1β, and was dependent on mTOR and hypoxia-inducible factor (HIF)1α. Inhibition of glycolysis, or genetic depletion of HIF1α, attenuated IgG IC-induced activation of macrophages in vitro, including primary human kidney macrophages. In vivo, glycolysis inhibition led to a reduction in kidney macrophage IL-1β and reduced neutrophil recruitment in a murine model of antibody-mediated nephritis. Together, our data reveal the molecular mechanisms underpinning FcγR-mediated metabolic reprogramming in macrophages and suggest a therapeutic strategy for autoantibody-induced inflammation, including lupus nephritis.

Formulation, Optimization, and Evaluation of Allopurinol-Loaded Bovine Serum Albumin Nanoparticles for Targeting Kidney in Management of Hyperuricemic Nephrolithiasis : Formulation, optimization, and evaluation of ABNPs for kidney targeting

The aim of present research work was to design, fabricate, optimize, and evaluate allopurinol (ALLO)-loaded bovine serum albumin nanoparticles (ABNPs) for kidney targeting of the drug and exploring the potential of fabricated ABNPs for management of hyperuricemia-related nephrolithiasis. ABNP formulation was prepared by employing desolvation technique, and its optimization was conducted by 2-factor-3-level central composite design (CCD) in order to achieve minimum particle size (PSA) and polydispersity index (PDI), maximum entrapment efficiency (EE), and zeta potential (ZP). Further, the optimized formulation (ABNPs_opt) was also assessed for in vitro drug release study, TEM, DSC, XRD analysis, FTIR spectroscopy, and in vivo animal study. The in vivo study revealed that after 2 h of ABNPs_opt administration, a significant concentration of ALLO was present in kidney (21.26-fold) as compared with serum while in case of standard pure drug group; no drug was seen in mice kidney and serum post 2 h administration, which indicates successful targeting of ALLO by formulating its albumin nanoparticles. Also, uric acid and pH levels were measured in serum and urine samples of mice which showed significant (P < 0.01) efficacy of ABNPs_opt formulation in management of hyperuricemia-related nephrolithiasis. Histological studies on kidney samples also confirmed these outcomes. Findings of present study indicate higher kidney uptake of allopurinol from formulated ABNPs_opt, which could be due to the specificity of albumin polymer for cubilin and megalin receptors, and it also serves as effective strategy in management of hyperuricemic-related nephrolithiasis.

Nanoparticles Mimicking Viral Cell Recognition Strategies Are Superior Transporters into Mesangial Cells

Poor drug availability in the tissue of interest is a frequent cause of therapy failure. While nanotechnology has developed a plethora of nanocarriers for drug transport, their ability to unequivocally identify cells of interest remains moderate. Viruses are the ideal nanosized carriers as they are able to address their embedded nucleic acids with high specificity to their host cells. Here, it is reported that particles endowed with a virus-like ability to identify cells by three consecutive checks have a superior ability to recognize mesangial cells (MCs) in vivo compared to conventional nanoparticles. Mimicking the initial viral attachment followed by a stepwise target cell recognition process leads to a 5- to 15-fold higher accumulation in the kidney mesangium and extensive cell uptake compared to particles lacking one or both of the viral traits. These results highlight the relevance that the viral cell identification process has on specificity and its application on the targeting strategies of nanomaterials. More so, these findings pave the way for transporting drugs into the mesangium, a tissue that is pivotal in the development of diabetic nephropathy and for which currently no efficient pharmacotherapy exists.

Kidney targeted delivery of asiatic acid using a FITC labeled renal tubular-targeting peptide modified PLGA-PEG system

Chronic kidney disease (CKD) is one of the leading public health problems worldwide and finally progresses to end-stage renal disease. The therapeutic options of CKD are very limited. Thus, development of drug delivery systems specific-targeting to kidney may offer more options. Here we developed an efficient kidney-targeted drug delivery system using a FITC labeled renal tubular-targeting peptide modified PLGA-PEG nanoparticles and investigated the intrarenal distribution and cell-type binding. We found that the modified nanoparticles with an approximate diameter of 200 nm exhibited the highest binding capacity with HK-2 cells and fluorescence and immunohistochemical analysis showed they mainly localized in renal proximal tubules by passing through the basolateral side. Furthermore, these kidney-specific nanoparticles could significantly enhance the therapeutic effects of asiatic acid, an insoluble triterpenoid compound as drug delivery carriers. In conclusion, these results suggest the potential of the peptide modified PLGA-PEG nanoparticles as kidneytargeted drug delivery system to proximal tubular cells in treatment of CKD.

Influences of different sugar ligands on targeted delivery of liposomes

Ligands are an important part of targeted drug delivery systems. Optimised lignads not only improve the target efficiency, but also enhance therapeutical effect of drugs. In our research, five sugar molecules (Mannose, Galactose, Glucose, Malt disaccharide, and Maltotriose) conjugated PEG₆₀₀-DSPE were synthesised, of which polysaccharides were first discovered by us as sugar ligands to modify liposomes, which interacts with over expressive GLUT on cancer cells. DiO was encapsulated as fluorescent probe to evaluate their cellular uptake abilities of targeting C6 glioma cells, and the distribution in different visceral organs of rats. The results demonstrated that Malt disaccharide and Glucose-PEG₆₀₀-DSPE had the strong efficiency of cellular uptake by C6 glioma cells. The distribution and accumulation of liposomes showed that different sugars modified liposomes could target different visceral organs in rats. It has provided a novel idea for ligand selectivity and optimisation of nanocarriers for tumour targeted therapy.

Recent advances in nanotechnology-based drug delivery systems for the kidney

The application of nanotechnology in medicine has the potential to make a great impact on human health, ranging from prevention to diagnosis and treatment of disease. The kidneys are the main organ of the human urinary system, responsible for filtering the blood, and concentrating metabolic waste into urine by means of the renal glomerulus. The glomerular filtration apparatus presents a barrier against therapeutic agents based on charge and/or molecular size. Therefore, drug delivery to the kidneys faces significant difficulties resulting in treatment failure in several renal disorders. Accordingly, different strategies have recently being explored for enhancing the delivery of therapeutic agents across the filtration barrier of the glomerulus. Nanosystems with different physicochemical properties, including size, shape, surface, charge, and possessing biological features such as high cellular internalization, low cytotoxicity, controllable pharmacokinetics and biodistribution, have shown promising results for renal therapy. Different types of nanoparticles (NPs) have been used to deliver drugs to the kidney. In this review, we discuss nanotechnology-based drug delivery approaches for acute kidney injury, chronic kidney disease, renal fibrosis, renovascular hypertension and kidney cancer.

Co-delivery of p38α MAPK and p65 siRNA by novel liposomal glomerulus-targeting nano carriers for effective immunoglobulin a nephropathy treatment

Glomerulonephritis related renal failure is a frequent cause of end-stage renal disease, and immunoglobulin A nephropathy (IgAN) is the most frequent type of primary glomerulonephritis. As damage induced by IgAN mostly attributes to inflammation responses, inhibiting inflammation in glomerulus can protect normal renal function and delay the onset of renal failure. Hence, reducing levels of p38 MAPK and p65 which are essential regulators in p38 MAPK and NF-κB related inflammation responses could be effective against IgAN. Here, we rationally designed and constructed size- and surface charge- dependent glomerulus-targeting liposomal nanoparticles which are loaded with both p38α MAPK and p65 siRNA. Experiments show that our nanoparticles successfully crossed fenestrated endothelium, accumulated in mesangial cells and endothelial cells, efficiently silenced p38α MAPK and p65 genes, and eventually alleviated proteinuria, inflammation and excessive extracellular matrix deposition in mouse IgAN models. This siRNA co-delivery system thus represents a promising treatment option for IgAN and offers a versatile platform for other glomerular problems. Our work also highlights a novel strategy of glomerulus-targeting and an encouraging therapeutic route for other inflammatory diseases.

Antibody Fragment F(ab')2 Targeting Caveolae-Associated Protein PV1 for Selective Kidney Targeting and Retention

Targeted strategies to deliver and retain drugs to kidneys are needed to improve drug accumulation and efficacy in a myriad of kidney diseases. These drug delivery systems show potential for improving the therapeutic windows of drugs acting in the kidney. Biodistribution of antibody-based therapeutics in vivo is governed by several factors including binding affinity, size, and valency. Investigations of how the biophysical and biochemical properties of biologics enable them to overcome biological barriers and reach kidneys are therefore of interest. Although renal accumulation of antibody fragments in cancer diagnostics and treatment has been observed, reports on effective delivery of antibody fragments to the kidneys remain scarce. Previously, we demonstrated that targeting plasmalemma vesicle-associated protein (PV1), a caveolae-associated protein, can promote accumulation of antibodies in both the lungs and the kidneys. Here, by fine-tuning the binding affinity of an antibody toward PV1, we observe that the anti-PV1 antibody with reduced binding affinity lost the capability for kidney targeting while retaining the lung targeting activity, suggesting that binding affinity is a critical factor for kidney targeting of the anti-PV1 antibody. We next use the antibody fragment F(ab')₂ targeting PV1 to assess the dual effects of rapid kidney filtration and PV1 targeting on kidney-selective targeting. Ex vivo fluorescence imaging results demonstrated that after rapidly accumulating in kidneys at 4 h, PV1-targeted F(ab')₂ was continually retained in the kidney at 24 h, whereas the isotype control F(ab')₂ underwent urinary elimination with significantly reduced signaling in the kidney. Confocal imaging studies confirmed the localization of PV1-targeted F(ab')₂ in the kidney. In addition, the monovalent antibody fragment (Fab-C4) lost the capability for kidney homing, indicating that the binding avidity of anti-PV1 F(ab')₂ is important for kidney targeting. Our findings suggest that PV1-targeted F(ab')₂ might be useful as a drug carrier for renal targeting and highlight the importance of affinity optimization for tissue targeting antibodies.

Targeting kidneys by superparamagnetic allopurinol loaded chitosan coated nanoparticles for the treatment of hyperuricemic nephrolithiasis

PURPOSE

The major short coming of conventional therapy system is that they can't deliver the therapeutics specifically to a site within the body without producing nonspecific toxicity. Present research aimed at developing kidney targeted allopurinol (AP) loaded chitosan coated magnetic nanoparticles (A-MNPs) for the management of hyperuricemic nephropathy manifested in the form of nephrolithiasis.

METHODS

The work includes preparation of magnetic nanoparticles by chemical co-precipitation method and evaluation of the prepared batches for particle size analysis, Transmission electron microscopy, entrapment efficiency, in-vitro release study etc. Further, FTIR spectroscopy, X-ray diffraction, Differential Scanning Calorimetry, Vibrational sample magnetometer (VSM) and in-vivo animal studies were also performed.

RESULTS

VSM analysis demonstrates that the prepared nanoparticles exhibit superparamagnetic magnetic behaviour which was retained even after coating by chitosan. In-vivo studies of A-MNPs showed 19.07-fold increase in kidney uptake of AP as compared to serum post 2 h of administration in mice whereas no drug was detected in kidney and serum post 2 h administration of pure drug (free-form) indicating successful targeting to kidney as well as sustained release of AP from the formulated A-MNPs. The significant (p < 0.01) effectiveness of A-MNPs in management of hyperuricemic nephrolithiasis was observed through estimating pH and uric acid levels in urine and serum samples of mice. These findings were also confirmed by histological examination of isolated kidney samples.

CONCLUSION

Present investigation signifies that a simple external magnetic field is enough for targeting allopurinol to kidneys by formulating A-MNPs which further offers an effective approach for management of hyperuricemic nephrolithiasis. Graphical Abstract.

Kidney-targeted rhein-loaded liponanoparticles for diabetic nephropathy therapy via size control and enhancement of renal cellular uptake

The optimization of nanoparticle size for passing through glomerular filtration membrane, inefficient renal cellular uptake and rapid urinary excretion of nanoparticles are the major obstacles for renal disease treatment via a nanoparticle delivery system. Herein, we propose a concept of a two-step nanoparticular cascade of size control and enhancement of renal cellular uptake to overcome the renal delivery obstacles. Methods: We prepared kidney-targeted rhein (RH)-loaded liponanoparticles (KLPPR) with a yolk-shell structure composed by polycaprolactone-polyethyleneimine (PCL-PEI)-based cores and kidney targeting peptide (KTP)-modified lipid layers. The KLPPR size within the range of 30 ~ 80 nm allowed KLPPR distribute into kidney by passing through the glomerular filtration membrane and the KTP (sequence: CSAVPLC) decoration promoted the renal cellular uptake and endocytosis via a non-lysosomal pathway. Results: The KLPPR had an average size of 59.5±6.2 nm and exhibited high RH loading, sustained release, good stability and biocompatibility, rapid cellular uptake in HK-2 cells. In addition, intravenous administration of KLPPR resulted in excellent kidney-targeted distribution and low urinary excretion in mice with streptozocin-induced diabetic nephropathy (DN), lowered the parameters of urea nitrogen, serum creatinine and kidney index, as well as facilitated the recovery of renal physiological function in improving the levels of urinary creatinine and the creatinine clearance rate by suppressing secretion and accumulation of fibronectin and TGF-β1. Conclusion: Definitely, KLPPR were able to target the diseased kidney and improve the therapeutic effect of RH on DN by exploiting the two-step nanoparticular cascade of size control and enhancement of cellular uptake. This study offers a promising strategy for renal diseases treatment using liponanoparticle delivery system.

Intravital microscopy reveals a novel mechanism of nanoparticles excretion in kidney

Developing nanocarriers that accumulate in targeted organs and are harmlessly eliminated still remains a big challenge. Nanoparticles (NP) biodistribution is governed by their size, composition, surface charge and coverage. The current thinking in bionanotechnology is that renal clearance is limited by glomerular basement membrane pore size (≈6 nm), although there is a growing evidence that NP exceeding the threshold can also be excreted with urine. Here we compare biodistribution of PEGylated 140 nm iron oxide cubes and clusters with a special focus on renal accumulation and excretion. Atomic emission spectroscopy, fluorescent microscopy and magnetic resonance imaging revealed rapid and transient accumulation of magnetic NP in kidney. Using intravital microscopy we tracked in real time NP translocation from peritubular capillaries to basal compartment of tubular cells and subsequent excretion to the lumen within 60 min after systemic administration. Transmission electron microscopy revealed persistence of intact full-sized NP in urine 2 h post injection. The results suggest that translocation through peritubular endothelium to tubular epithelial cells is an alternative mechanism of renal clearance enabling excretion of NP above glomerular cut-off size.

Design and evaluation of glomerulus mesangium-targeted PEG-PLGA nanoparticles loaded with dexamethasone acetate

Mesangial proliferative glomerulonephritis (MsPGN), one of the most common glomerulonephritis pathological types, often leads to end-stage renal disease over a prolonged period. But the current treatment of MsPGN is non-specific and causes serious side effects, thus novel therapeutics and targeting strategies are urgently demanded. By combining the advantages of PEG-PLGA nanoparticles and the size selection mechanism of renal glomerulus, we designed and developed a novel PEG-PLGA nanoparticle delivery system capable of delivering dexamethasone acetate (A-DEX) into glomerular mesangium. We determined that 90 nm was the optimum size to encapsulate A-DEX for glomerular mesangium targeting based on the size-selection mechanism of glomerulus. After intravenous administration in rats, 90 nm DiD-loaded NPs were found to accumulate to a greater extent in the kidney and kidney cortex compared with the free DiD solution. The 90 nm A-DEX NPs are also more stable at room temperature and showed a sustained release pattern. In rat glomerular mesangial cells (HBZY-1) in vitro, we found that the uptake of 90 nm A-DEX NPs was both temperature-dependent and energe-dependent, and they were mostly engulfed via clathrin-dependent endocytosis pathways. In summary, we have successfully developed a glomerular mesangium-targeted PEG-PLGA NPs, which is potential for the treatment of MsPGN.

Kidney-targeted drug delivery via rhein-loaded polyethyleneglycol-co-polycaprolactone-co-polyethylenimine nanoparticles for diabetic nephropathy therapy

Introduction

Diabetic nephropathy (DN) is the primary root of morbidity and mortality in diabetic patients. Unfortunately, currently, no effective therapeutic strategies are available to ameliorate and reverse the progression of DN. Rhein (RH) is an anthraquinone derivative extracted from herbal medicines with various pharmacological effects on DN. However, its clinical administration is limited by its poor solubility, low bioavailability, reduced distribution into the kidney and adverse effects.

Methods and results

To improve the delivery of RH into kidney and the therapeutic effect on DN, we synthesized and utilized polyethyleneglycol-co-polycaprolactone-co-polyethylenimine triblock amphiphilic polymers to prepare RH-loaded polyethyleneglycol-co-polycaprolactone-co-polyethylenimine nanoparticles (PPP-RH-NPs). PPP-RH-NP size was optimized to 75 ± 25 nm for kidney-targeted drug delivery; the positive zeta potential allowed an effective cellular uptake and the polyethylenimine amine groups facilitate the endosomal escape quickly. The distribution and pharmacodynamics of PPP-RH-NPs were studied in a streptozocin-induced DN model, which explicitly demonstrated kidney-targeted distribution and improved the therapeutic effects of RH on DN by ameliorating several pathological indicators.

Conclusion

Therefore, this study not only stimulates further clinical research on RH but also, more importantly, proposes a promising DN therapy consisting of an effective kidney-targeted drug delivery.

Targeting Anti-TGF-β Therapy to Fibrotic Kidneys with a Dual Specificity Antibody Approach

Targeted delivery of a therapeutic agent to a site of pathology to ameliorate disease while limiting exposure at undesired tissues is an aspirational treatment scenario. Targeting diseased kidneys for pharmacologic treatment has had limited success. We designed an approach to target an extracellular matrix protein, the fibronectin extra domain A isoform (FnEDA), which is relatively restricted in distribution to sites of tissue injury. In a mouse unilateral ureteral obstruction (UUO) model of renal fibrosis, injury induced significant upregulation of FnEDA in the obstructed kidney. Using dual variable domain Ig (DVD-Ig) technology, we constructed a molecule with a moiety to target FnEDA and a second moiety to neutralize TGF-β After systemic injection of the bispecific TGF-β + FnEDA DVD-Ig or an FnEDA mAb, chemiluminescent detection and imaging with whole-body single-photon emission computed tomography (SPECT) revealed significantly higher levels of each molecule in the obstructed kidney than in the nonobstructed kidney, the ipsilateral kidney of sham animals, and other tissues. In comparison, a systemically administered TGF-β mAb accumulated at lower concentrations in the obstructed kidney and exhibited a more diffuse whole-body distribution. Systemic administration of the bispecific DVD-Ig or the TGF-β mAb (1-10 mg/kg) but not the FnEDA mAb attenuated the injury-induced collagen deposition detected by immunohistochemistry and elevation in Col1a1, FnEDA, and TIMP1 mRNA expression in the obstructed kidney. Overall, systemic delivery of a bispecific molecule targeting an extracellular matrix protein and delivering a TGF-β mAb resulted in a relatively focal uptake in the fibrotic kidney and reduced renal fibrosis.

Selective Nanoparticle Targeting of the Renal Tubules

Direct targeting to the kidneys is a promising strategy to improve drug therapeutic index for the treatment of kidney diseases. We sought to investigate the renal selectivity and safety of kidney-targeted mesoscale nanoparticle technology. We found that direct intravenous administration of these particles resulted in 26-fold renal selectivity and localized negligibly in the liver or other organs. The nanoparticles targeted the renal proximal tubular epithelial cells, as evidenced by intravital microscopy and ex vivo imaging. Mice treated with the nanoparticles exhibited no negative systemic consequences, immune reaction, liver impairment, or renal impairment. The localization of material selectively to the renal tubules is uncommon, and this work portends the development of renal-targeted drugs for the treatment of kidney diseases.

Drug targeting to myofibroblasts: Implications for fibrosis and cancer

Myofibroblasts are the key players in extracellular matrix remodeling, a core phenomenon in numerous devastating fibrotic diseases. Not only in organ fibrosis, but also the pivotal role of myofibroblasts in tumor progression, invasion and metastasis has recently been highlighted. Myofibroblast targeting has gained tremendous attention in order to inhibit the progression of incurable fibrotic diseases, or to limit the myofibroblast-induced tumor progression and metastasis. In this review, we outline the origin of myofibroblasts, their general characteristics and functions during fibrosis progression in three major organs: liver, kidneys and lungs as well as in cancer. We will then discuss the state-of-the art drug targeting technologies to myofibroblasts in context of the above-mentioned organs and tumor microenvironment. The overall objective of this review is therefore to advance our understanding in drug targeting to myofibroblasts, and concurrently identify opportunities and challenges for designing new strategies to develop novel diagnostics and therapeutics against fibrosis and cancer.

Targeted delivery of celastrol to mesangial cells is effective against mesangioproliferative glomerulonephritis

Mesangial cells-mediated glomerulonephritis is a frequent cause of end-stage renal disease. Here, we show that celastrol is effective in treating both reversible and irreversible mesangioproliferative glomerulonephritis in rat models, but find that its off-target distributions cause severe systemic toxicity. We thus target celastrol to mesangial cells using albumin nanoparticles. Celastrol-albumin nanoparticles crosses fenestrated endothelium and accumulates in mesangial cells, alleviating proteinuria, inflammation, glomerular hypercellularity, and excessive extracellular matrix deposition in rat anti-Thy1.1 nephritis models. Celastrol-albumin nanoparticles presents lower drug accumulation than free celastrol in off-target organs and tissues, thereby minimizing celastrol-related systemic toxicity. Celastrol-albumin nanoparticles thus represents a promising treatment option for mesangioproliferative glomerulonephritis and similar glomerular diseases.

Mesangial cell-mediated glomerulonephritis is a frequent cause of kidney disease. Here the authors show that celastrol loaded in albumin nanoparticles efficiently targets mesangial cells, and is effective in rat models.

Store-operated calcium entry suppressed the TGF-β1/Smad3 signaling pathway in glomerular mesangial cells

Our previous study demonstrated that the abundance of extracellular matrix proteins was suppressed by store-operated Ca²⁺ entry (SOCE) in mesangial cells (MCs). The present study was conducted to investigate the underlying mechanism focused on the transforming growth factor-β1 (TGF-β1)/Smad3 pathway, a critical pathway for ECM expansion in diabetic kidneys. We hypothesized that SOCE suppressed ECM protein expression by inhibiting this pathway in MCs. In cultured human MCs, we observed that TGF-β1 (5 ng/ml for 15 h) significantly increased Smad3 phosphorylation, as evaluated by immunoblot. However, this response was markedly inhibited by thapsigargin (1 µM), a classical activator of store-operated Ca²⁺ channels. Consistently, both immunocytochemistry and immunoblot showed that TGF-β1 significantly increased nuclear translocation of Smad3, which was prevented by pretreatment with thapsigargin. Importantly, the thapsigargin effect was reversed by lanthanum (La³⁺; 5 µM) and GSK-7975A (10 µM), both of which are selective blockers of store-operated Ca²⁺ channels. Furthermore, knockdown of Orai1, the pore-forming subunit of the store-operated Ca²⁺ channels, significantly augmented TGF-β1-induced Smad3 phosphorylation. Overexpression of Orai1 augmented the inhibitory effect of thapsigargin on TGF-β1-induced phosphorylation of Smad3. In agreement with the data from cultured MCs, in vivo knockdown of Orai1 specific to MCs using a targeted nanoparticle small interfering RNA delivery system resulted in a marked increase in abundance of phosphorylated Smad3 and in nuclear translocation of Smad3 in the glomerulus of mice. Taken together, our results indicate that SOCE in MCs negatively regulates the TGF-β1/Smad3 signaling pathway.

Healing the damaged mesangium in nodular glomerulosclerosis using mesenchymal stem cells (MSCs): Expectations and challenges

It has been shown experimentally that mesenchymal stem cells (MSCs) can be delivered to the mesangium in some conditions such as amyloidosis to clear debris and foreign material, and eventually transform into functional mesangial cells (MCs) and change the altered mesangial areas into normal collagen IV-rich matrix. A more challenging situation is when the matrix is rich in abnormal extracellular matrix proteins, especially those difficult to destroy such as tenascin, and, as a result, assumes a nodular appearance - what is known in pathology jargon as nodular glomerulosclerosis. MSCs find it difficult to dispose of the altered mesangial constituents, an initial step required for mesangial repair to occur successfully. The ability of MSCs to repair damaged mesangium represents a novel therapeutic intervention to reverse mesangial injury and is potentially a powerful and unique approach to prevent progression ending in end-stage renal disease (ESRD). This review will highlight progress that has been made in glomerular, and more specifically mesangial, repair, and will address future expectations and challenges to be confronted as the use of MSCs continues to be explored as a potential application for clinical practice.

Nanomedicines for renal disease: current status and future applications

Treatment and management of kidney disease currently presents an enormous global burden, and the application of nanotechnology principles to renal disease therapy, although still at an early stage, has profound transformative potential. The increasing translation of nanomedicines to the clinic, alongside research efforts in tissue regeneration and organ-on-a-chip investigations, are likely to provide novel solutions to treat kidney diseases. Our understanding of renal anatomy and of how the biological and physico-chemical properties of nanomedicines (the combination of a nanocarrier and a drug) influence their interactions with renal tissues has improved dramatically. Tailoring of nanomedicines in terms of kidney retention and binding to key membranes and cell populations associated with renal diseases is now possible and greatly enhances their localization, tolerability, and efficacy. This Review outlines nanomedicine characteristics central to improved targeting of renal cells and highlights the prospects, challenges, and opportunities of nanotechnology-mediated therapies for renal diseases.

A kidney-selective biopolymer for targeted drug delivery

Improving drug delivery to the kidney using renal-targeted therapeutics is a promising but underdeveloped area. We aimed to develop a kidney-targeting construct for renal-specific drug delivery. Elastin-like polypeptides (ELPs) are nonimmunogenic protein-based carriers that can stabilize attached small-molecule and peptide therapeutics. We modified ELP at its NH₂-terminus with a cyclic, seven-amino acid kidney-targeting peptide (KTP) and at its COOH-terminus with a cysteine residue for tracer conjugation. Comparative in vivo pharmacokinetics and biodistribution in rat and swine models and in vitro cell binding studies using human renal cells were performed. KTP-ELP had a longer plasma half-life than ELP in both animal models and was similarly accumulated in kidneys at levels fivefold higher than untargeted ELP, showing renal levels 15- to over 150-fold higher than in other major organs. Renal fluorescence histology demonstrated high accumulation of KTP-ELP in proximal tubules and vascular endothelium. Furthermore, a 14-day infusion of a high dose of ELP or KTP-ELP did not affect body weight, glomerular filtration rate, or albuminuria, or induce renal tissue damage compared with saline-treated controls. In vitro experiments showed higher binding of KTP-ELP to human podocytes, proximal tubule epithelial, and glomerular microvascular endothelial cells than untargeted ELP. These results show the high renal selectivity of KTP-ELP, support the notion that the construct is not species specific, and demonstrate that it does not induce acute renal toxicity. The plasticity of ELP for attachment of any class of therapeutics unlocks the possibility of applying ELP technology for targeted treatment of renal disease in future studies.