Hyaluronic acid nanocapsules for the intracellular delivery of anticancer drugs

Resumo

The main goal of this thesis has been the development of hyaluronic acid nanocapsules (HA NCs) as a multifunctional platform for the encapsulation and delivery of diverse anticancer drugs, such as hydrophobic drugs and hydrophilic biomolecules. The first step was the development of a spontaneous emulsification method, where HA NCs were formulated without the need of organic solvents, heat or high energy input, providing conditions for the incorporation of sensitive biomolecules while decreasing the environmental impact. Another advantage of this system is based on the use of a hydrophobically-modified HA derivative that allowed the preparation of HA NCs by hydrophobic interactions rather than electrostatic forces and thus, reducing the toxicity associated to the addition of a cationic surfactant as a counterion. Once formulated, HA NCs had a size around 130 nm and a negative zeta potential about -20 mV. Moreover, these nanocapsules were markedly stable under storage conditions and diluted in human plasma, taking forward this system as a potential carrier for intravenous administration. The versatility of this nanocarrier was confirmed by the incorporation of different molecules: docetaxel, a cytostatic drug, was incorporated into the oil core, whereas a therapeutic protein was entrapped into the polymeric shell. Docetaxel was highly encapsulated, released in a sustained manner and its cytotoxicity in A549 lung cancer cell line was maintained. Finally, the therapeutic protein was successfully associated to the polymeric shell of HA NCs and its intracellular delivery confirmed by confocal microscopy. Once inside the cell, the therapeutic protein was able to escape the endosomal compartment and to target the an intracellular oncoprotein, promoting an important decrease in the migratory and invasive behavior of HCC1954 breast cancer cell line. All these results highlight the potential of self-emulsifying HA NCs as multifunctional systems to transport diverse anticancer drugs, with special emphasis in the intracellular delivery of therapeutic proteins, an ambitious challenge that could open new avenues to fight cancer.