Augmented therapeutic efficacy of Gemcitabine conjugated self-assembled nanoparticles for cancer chemotherapy

Abstract

Gemcitabine (Gem) is an FDA-approved anticancer drug used for the treatment of various solid tumors. Clinical applications of Gem are limited due to plasma instability, drug resistance and high dose. To overcome these limitations, we successfully conjugated Gem to a triblock copolymer (PCL-b-PEG-b-PCL) which self-assembled as nanoparticles (NPs) into aqueous media. Conjugation of Gem to triblock copolymer has been chemically confirmed by 1H NMR and biologically by a nucleoside transporter inhibition assay. The amount of Gem conjugated in NPs was quantified by UPLC-MS/MS and characterized by particle size, surface charge, Osmolality, Transmission Electron Microscopy (TEM), Differential Scanning Calorimetry (DSC) and X-ray Powder Diffraction (XRD). The self-assembled NPs improved plasma stability of Gem and reduced blood hemolysis. In vitro cytotoxicity of the NPs was evaluated against MCF-7, A549, and 4T1 cells by MTT assay. The nucleoside transporter inhibition study demonstrated that NPs are not dependent on nucleoside transporters for entry into the cells. The cytotoxicity of NPs was conquered through enhanced cellular internalization and loss of mitochondrial membrane potential. In vivo efficacy study demonstrated that Gem conjugated NPs showed 1.7-fold more potent in tumor growth inhibition as compared to free Gem in the 4T1 bearing Balb/c mice. Furthermore, there were no histological abnormalities observed in major organs after treatment across the groups. The finding demonstrated that developed Gem conjugated self-assembled NPs could be a potential and improved therapeutic clinical outcome of anticancer drugs.