Redox-sensitive And Intrinsically Fluorescent Hyaluronic Acid Nanocarriers For Targeted Delivery Of Anti-cancer Drugs And Proteins

Polymeric anticancer nanotherapeutics with prolonged drug circulation time, improved drug bioavailability, and reduced side effects, have exhibited a great potential in targeted tumor therapy. Currently, many polymeric nanotherapeutics such as Doxil", Abraxane(?), Genexol-PM, and Lupron Depot" have been approved by FDA for the treatment of breast cancer, lung cancer, ovarian cancer, multiple myeloma and pancreatic cancer. In the first chapter, various polymeric anticancer nanotherapeutics used in the clinic or clinical trials, and their advantages and challenges are discussed. Moreover, recent developments in multifunctional polymeric nanogels and polymeric nanoparticles, and their applications on the targeted tumor therapy and triggered release of anticancer drugs and proteins are highlighted.In the second chapter, we report that redox-sensitive and intrinsically fluorescent hyaluronic acid nanogels (HA-NGs) show highly efficient loading and targeted delivery of cytochrome C (CC) to xenografted breast tumor in mice. HA-NGs were obtained from hyaluronic acid-graft-oligo (ethylene glycol)-tetrazole (HA-OEG-Tet) via inverse nanoprecipitation and catalyst-free photo-click crosslinking with L-cystine dimethacryl amide (MA-Cys-MA). HA-NGs exhibited a superb CC loading content of up to 40.6 wt.%, intrinsic fluorescence with an emission wavelength of 510 nm, and a small size of ca.170 nm. Notably, CC-loaded nanogels (CC-NGs) showed a fast glutathione (GSH)-responsive protein release behavior. Importantly, released CC maintained its bioactivity. MTT assays revealed that CC-NGs were highly potent with a low half-maximal inhibitory concentration (IC50) of 3.07 μM to CD44 receptor overexpressing MCF-7 human breast cancer cells. Confocal microscopy observed efficient internalization of fluorescent HA-NGs into MCF-7 cells via a CD44 receptor-mediated endocytosis mechanism. Interestingly, HA-NGs exhibited also effective tumor penetration in human MCF-7 breast tumor-bearing nude mice. The therapeutic studies demonstrated that CC-NGs effectively inhibited the growth of MCF-7 breast tumors implanted in nude mice at a particularly low dose of 80 or 160 nmol CC equiv./kg. Moreover, CC-NGs did not cause any change in mice body weight, corroborating their low systemic side effects. These results highlight that redox-sensitive and intrinsically fluorescent photo-click hyaluronic acid nanogels are a "smart" protein delivery nanoplatform enabling safe, efficacious and targeted cancer therapy in vivo.In the third chapter, redox-sensitive and intrinsically fluorescent photo-click crosslinked hyaluronic acid-PLGA nanoparticles (HA-PLGA CLNPs) were designed and developed for active targeting and effective treatment of subcutaneous xenografted human breast tumor in nude mice. HA-PLGA CLNPs were obtained via inverse nanoprecipitation using HA-OEG-Tet as a surfactant followed by catalyst-free "tetrazole-alkene" photo-click crosslinking in the presence of MA-Cys-MA. HA-PLGA CLNPs exhibited intrinsic fluorescence and a small size of 109 nm. In vitro drug release results showed that DTX-loaded HA-PLGA CLNPs (DTX-CLNPs) exhibited high stability due to the surface crosslinking and could effectively inhibit the burst release of DTX at physiological conditions (pH 7.4,37℃), in which less than 20% of DTX was released in 24 h. On the contrary, about 76.6% DTX was released under a reductive condition containing 10 mM GSH. MTT assays revealed that DTX-CLNPs were highly potent with a low IC50 of 0.27 μg/mL to CD44 receptor overexpressing MCF-7 human breast cancer cells. Confocal microscopy observed efficient internalization of fluorescent HA-PLGA CLNPs into MCF-7 cells via a CD44 receptor-mediated endocytosis mechanism. The in vivo therapeutic studies demonstrated that DTX-CLNPs not only effectively inhibited the growth of subcutaneous xenografted MCF-7 human breast tumors in nude mice, but also caused insignificantly systemic side effects. These redox-sensitive and intrinsically fluorescent photo-click nanoparticles have emerged as a promising nanoplatform for targeted tumor therapy.