Self-assembled tumor-targeting hyaluronic acid nanoparticles for photothermal ablation in orthotopic bladder cancer

Abstract

Bladder cancer is one of the most frequent malignancies in the urinary system. Radical cystectomy is inevitable when bladder cancer progresses to a muscle-invasive disease. However, cystectomy still causes a high risk of death and a low quality of life (such as ureter-abdomen ostomy, uroclepsia for ileal-colon neobladder). Therefore, more effective treatments as well as bladder preservation are needed. We developed self-assembled tumor-targeting hyaluronic acid-IR-780 nanoparticles for photothermal ablation in over-expressing CD44 (the receptor for HA) bladder cancer, which show high tumor selectivity, high treatment efficacy, good bioavailability, and excellent biocompatibility. The nanoparticles demonstrated a stable spherical nanostructure in aqueous conditions with good mono-dispersity, and their average size was 171.3±9.14nm. The nanoparticles can be degraded by hyaluronidase when it is over-expressed in bladder cells; therefore, they appear to have a hyaluronidase-responsive "OFF/ON" behavior of a fluorescence signal. HA-IR-780 NPs also showed high photothermal efficiency; 2.5, 5, 10 and 20μg/mL of NPs had a maximum temperature increase of 11.2±0.66°C, 18.6±0.75°C, 26.8±1.11°C and 32.3±1.42°C. The in vitro cell viability showed that MB-49 cells could be efficiently ablated by combining HA-IR-780 NPs with 808nm laser irradiation. Then, in vivo biodistribution showed the HA-IR-780 NPs are targeted for accumulation in bladder cancer cells but have negligible accumulation in normal bladder wall. The photothermal therapeutic efficacy of HA-IR-780 NPs in the orthotopic bladder cancer model showed tumors treated with NPs had a maximum temperature of 48.1±1.81°C after 6min of laser irradiation. The tumor volume was approximately 65-75mm³ prior to treatment. After 12days, the tumor sizes for the PBS, PBS plus laser irradiation and HA-IR-780 NPs-treated groups were 784.75mm³, 707.5mm³, and 711.37mm³, respectively. None of the tumors in the HA-IR-780 NPs plus laser irradiation-treated group were visible to the naked eye. A toxicity study showed HA-IR-780 NPs (2.5-20mg/kg, i.v.) were nontoxic and safe for in vivo applications. HA-IR-780 nanoparticles address current clinical challenges, treating locally aggressive lesions and preserving the bladder. They have enormous potential to improve the bladder cancer treatment strategies in clinic.

Statement of significance: 1) Bladder cancer is one of the most frequent malignancies in the urinary system. Radical cystectomy is inevitable while bladder cancer progress to muscle-invasive disease. 2) We developed self-assembled tumor-targeting hyaluronic acid-IR-780 nanoparticles for photothermal ablation in over-expressing CD44 (the receptor for HA) bladder cancer. 3) Photothermal therapeutic efficacy of HA-IR-780 NPs in orthotopic bladder cancer model showed tumors were completely ablated. 4) HA-IR-780 nanoparticles address current clinical challenges, treating locally aggressive lesions as well as for bladder preservation.

Keywords: Hyaluronic acid (HA); IR-780; Orthotopic bladder cancer; Photothermal ablation; Self-assembled nanoparticles.