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

Abstract

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.

Keywords: Dexamethasone acetate; Glomerulonephritis; Mesangial cells; Mesangium; PEG-PLGA nanoparticles.

Fig. 1

A schematic overview of the composition of the glomerulus and the anticipated pathway of NPs. B blood cell, NPs nanoparticles, GBM glomerular basement membrane, E endothelium, P podocyte, FP foot processes, M mesangial cell, ECM extracellular matrix

Fig. 2

Size distribution of 70, 90, and 110 nm A-DEX NPs. Left: size distribution of A-DEX NPs detected by DLS. Right: TEM of A-DEX NPs. Scale bars: 100 nm

Fig. 3

The variations in particle sizes of 70, 90, and 110 nm nanoparticles at 25 °C (mean ± SD)

Fig. 4

Ex vivo imaging of DiD-NPs in the main organs and plasma. a Rats were intravenously injected with DiD solution or DiD-NPs of 70, 90, or 110 nm. Blood was collected and organs were harvested 1 h after the administration. b NP accumulation in kidneys. c Imaging of kidneys at different time points after injection of 90-nm DiD-NPs (15 min, 30 min, 1 h, 2 h, and 4 h)

Fig. 5

Immunofluorescence image of a rat glomerulus 1 h after administration of 90 nm DiD-NPs. Renal sections were co-stained for thymic antigen 1 (Thy1) mesangial marker with the OX-7 monoclonal antibody. Original magnification 400×. Scale bars: 20 μm

Fig. 6

Biodistribution of 90 nm A-DEX NPs and A-DEX solution in rats at 1 h post-injection. The kidney and kidney cortex concentrations of DEX in the 90 nm A-DEX NP-treated group were, respectively, 1.30-fold and 1.45-fold higher than those in the A-DEX solution-treated group. Data represent the mean ± SD (n = 5). ^##P < 0.01

Fig. 7

Concentration–time curve of DEX in the kidney (a) and kidney cortex (b) after the intravenous injection of 90 nm A-DEX NPs or A-DEX solution in rats. The AUC _(0→t) (μg/L*h) of 90 nm A-DEX NPs or A-DEX solution in the kidney was 1441.15 ± 65.41 or 1134.94 ± 56, respectively. The AUC _(0→t) (μg/L*h) of 90-nm A-DEX NPs or A-DEX solution in the kidney cortex was 1567.40 ± 32.57 or 1140.99 ± 36.26, respectively. Data for each time point are expressed as the mean ± SD (n = 5). ^#P < 0.05

Fig. 8

In vitro A-DEX release from 90 nm A-DEX NPs. a The stability of A-DEX in PBS (pH = 7.4) and ABS (pH = 4.5). b Cumulative release of A-DEX from A-DEX NPs and A-DEX solution. Data represent the mean ± SD (n = 3)

Fig. 9

a Cellular uptake of 90 nm A-DEX NPs over time at 37 °C compared with that of A-DEX solution. ^#P < 0.05, ^##P < 0.01. b Cellular uptake of A-DEX solution or 90-nm A-DEX NPs at 4 °C, at 37 °C, or in the presence of NaN_3. The cellular uptake of 90-nm A-DEX NPs at 37 °C was set as 100%. ^#P < 0.05, ^##P < 0.01. c Cellular uptake efficiency of 90 nm A-DEX NPs with inhibitors, including nystatin, chlorpromazine, and dimethyl amiloride. The cellular uptake of 90-nm A-DEX NPs without any treatment served as the control. Data represent the mean ± SD (n = 3). ^##P < 0.01