Tuning the In Vivo Transport of Anticancer Drugs Using Renal-Clearable Gold Nanoparticles

Abstract

Precise control of in vivo transport of anticancer drugs in normal and cancerous tissues with engineered nanoparticles is key to the future success of cancer nanomedicines in clinics. This requires a fundamental understanding of how engineered nanoparticles impact the targeting-clearance and permeation-retention paradoxes in the anticancer-drug delivery. Herein, we systematically investigated how renal-clearable gold nanoparticles (AuNPs) affect the permeation, distribution, and retention of the anticancer drug doxorubicin in both cancerous and normal tissues. Renal-clearable AuNPs retain the advantages of the free drug, including rapid tumor targeting and high tumor vascular permeability. The renal-clearable AuNPs also accelerated body clearance of off-target drug via renal elimination. These results clearly indicate that diverse in vivo transport behaviors of engineered nanoparticles can be used to reconcile long-standing paradoxes in the anticancer drug delivery.

Keywords: drug delivery; enhanced permeability and retention effect; gold nanoparticles; renal clearance; tumor targeting.

Figure 1.. Renal-clearable AuNPs enhanced renal elimination and retained cytotoxicity of DOX.

a) Scheme of renal-clearable DOX@AuNPs, which consists of the gold core (2.06 ± 0.18 nm in diameter, Fig. S2), surface coating with poly(ethylene glycol) thiol (PEG-SH, MW. 800 Da) and mercaptobenzoic acid (MBA), and loaded DOX molecules. b) UV-Vis absorbance spectra in aqueous solution. The loaded DOX exhibited 8-nm redshift (from 488 to 496 nm) compared with free DOX, indicating the formation of J-aggregates. c) Hydrodynamic diameters of DOX@AuNPs (5 μM) in PBS with and without human serum albumin (HSA, 6 nm, 5 μM) at 37 °C for 3 h. d) Renal clearance of DOX after intravenous injection of DOX@AuNPs and free DOX (n = 3). Error bar indicates s.d. e) Blood DOX concentration in the MCF-7 tumor-bearing mice (n = 4). f) In vitro drug release study in neutral (pH 7.4) and acidic (pH 5.5) physiological environment. ***P<0.005 (n = 3, Student’s t-test). g) In vitro cytotoxicity study with MCF-7 cancer cells (n = 6). To be noted, the AuNPs without DOX loading showed very low toxicity to the cells (Fig. S4d).

Figure 2.. DOX@AuNPs enhanced anti-tumor efficacy of DOX among primary and metastatic tumor models.

a–d) Normalized tumor growth curves and survival rates of the MCF-7 tumor-bearing nude mice (a, b) and 4T1 tumor-bearing balb/c mice (c, d) during successive treatments. For a and c, ****P<0.0001 (Student’s t-test). For b, * indicates <0.005, <0.0005 for DOX@AuNPs versus free DOX and PBS, respectively; For d, ** indicates P <0.001, <0.0005 for DOX@AuNPs versus free DOX and PBS, respectively (Kaplan-Meier, n = 6 – 8). To be noted, the AuNPs without DOX loading showed no tumor inhibition (Fig. S6). e) Images of mice lungs after the successive treatments (day-23). Scale bar, 1 mm. f) Nodule counts of the metastatic lung tumors after treatments. ***P<0.005 (n = 5). Box indicates median and s.e.m. g) Lung tumor nodule sizes. ****P<0.0001. Box indicates median and 25–75% interquartile range (Student’s t-test).

Figure 3.. DOX@AuNPs increased tumor targeting and retention by improving tumor extravasation and penetration.

a) Drug delivery efficiencies to the MCF-7 tumors (n = 4). b-c) Fluorescence microscopy images of MCF-7 tumor tissues at 12 h post-injection of free DOX (b) and DOX@AuNPs (c). Red, DOX; green, stained vasculature (lectin-FITC). Scale bar, 50 μm.

Figure 4.. Renal-clearable AuNPs enhanced body clearance and minimized toxicity of the “off-target” DOX. a-d),

Blood chemistry analysis after successive treatments, indicating the acute toxicity of drug to liver function (aspartate transaminase, AST (a), alanine aminotransferase, ALT (b)) and kidney function (blood urea nitrogen, BUN (c), creatinine, CREA (d)). *P<0.05, ****P<0.0001, NS, not significant (n = 4 for DOX@AuNPs and PBS; n = 3 for free DOX, where one animal died prior to the end of the study). e) DOX distribution in liver and kidney for the injected DOX@AuNPs and free DOX (n = 3). f) Muscle DOX distribution at 1 and 24 h post-treatment (n = 3). *P<0.05. g-h) DOX distribution in vital organs as heart (g) and lungs (h) (n = 3). *P<0.05, **P<0.01, ***P<0.005, ****P<0.0001 (Student’s t-test).