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

Abstract

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.

Loss of endothelial glucocorticoid receptor accelerates organ fibrosis indb/dbmice

“…Indeed, in our study we did observe a 30-40% decrease in peak glucose concentration after glucose tolerance testing in HFD-fed, metformin-treated mice compared to controls. One potential solution to this problem is the development of a targeted drug delivery systems which involves the synthesis of nanoparticles comprised of grafted chitosan which acts as a metformin carrier and can be specifically delivered to renal tubular cells by megalin-mediated endocytosis (20).…”

“…; https://doi.org/10.1101/2023.03. 20.533532 doi: bioRxiv preprint Despite the rising incidence of fibrotic kidney disease, driven to a great extent by a continued increase in the prevalence of diabetes (1,2), molecular mechanisms of renal fibrosis remain incompletely understood. One important tool to study this phenomenon is the C57BL/6 db/db mouse model which demonstrates type 2 diabetes, significant albuminuria, renal histological damage and reduced renal function by 32 weeks of age (3).…”

Nanomedicine in kidney disease

“…Furthermore, reduced GFR increases the risk of metformin-associated lactic acidosis preventing this treatment for fibrosis. Once loaded within nanoparticles and targeted to RTEC, metformin demonstrated superior antiapoptotic, anti-inflammatory, and antifibrotic effects compared with its free form [18 ▪ ].…”

Targeting the Kidneys at the Nanoscale: Nanotechnology in Nephrology

“…Several passive targeting approaches were used, including: (1) small NPs (,10 nm) which pass through the glomerular filtration barrier and are reabsorbed in the nephron, (2) somewhat larger NPs which pass through the glomerular endothelial fenestrations and arrest in the glomerular mesangium (typically up to 80 nm), (3) somewhat larger (approximately 100 nm) NPs which pass through only disrupted glomerular filtration barriers and are reabsorbed in the nephron, and (4) NPs which do not interact with the glomerulus and cross from the peritubular endothelium into the tubular epithelium. Active targeting of NPs to the kidneys has taken several different approaches, including serine modifications which purportedly bind kidney injury molecule-1, 64,71,83,93 charge-based binding to the megalin receptor, 55,59,60,75 or other cell surface receptor or basement membrane binding. 51,68,70,85 Regarding therapeutic cargoes, we found that many of the active pharmaceutical ingredients (APIs) involved short interfering RNA (siRNA) delivery-about 10 of those we found.…”

“…Chitosan NPs with metformin 59 Tubular epithelium Megalin-mediated endocytosis Antiapoptotic, anti-inflammatory, and antifibrotic effect in ureteralUUO mice Chitosan/siRNA NPs targeting AQP1 60 Tubular epithelium Megalin-mediated endocytosis AQP1 gene silencing in healthy mice Chitosan/siRNA NPs targeting COX-2 61 Renal macrophages Phagocytic uptake by macrophages Prevention of unilateral ureteral obstruction-induced kidney damage PEG-PLGA NPs loaded with dexamethasone acetate 62 Glomerular mesangium Penetration through glomerular endothelium fenestrae due to 90 nm diameter…”