Development of methylene blue-loaded nanoparticles for glioblastoma treatment

Glioblastoma (GBM) is the most common and aggressive primary brain tumor in adults over 45, resulting in an average survival of 15 months post-diagnosis and treatment. While recent research has provided essential information to aid diagnosis and treatment, GBM is known to cause relapse following traditional combinatorial regimens, necessitating the development of more effective and less toxic therapies. Methylene blue (MB), a dye with noted medicinal applications, has received recent consideration as a potential neurotherapeutic due to its ability to infiltrate the blood-brain barrier (BBB) and improve cellular processes within distinct brain cell compartments and types; however, one drawback is an increased administration to produce desired therapeutic effects, leading to excessive brain deposition and potential neurotoxicity. A method commonly used to enhance drug delivery while reducing unwanted side effects is via encapsulation in nanoparticles (NPs) composed of the biodegradable/biocompatible co-polymer, poly(lactic-co-glycolic) acid (PLGA). Based on our previous studies, we are developing a MB-loaded PLGA NP capable of permeating the BBB to treat GBM, to test our hypothesis that MB encapsulation into PLGA NPs will enhance accumulation in cancerous brain regions, resulting in reduced tumor size and prolonged survival. In this study, we formulated and characterized MB-loaded PLGA NPs, with a 3:1 molar ratio of sodium oleate to methylene blue at 5mg, based on particle size, drug loading, encapsulation efficiency, and release kinetics. Currently, we are establishing their in vitro effects in two different commercially-available GBM cell lines, according to their responses to commonly-used chemotherapeutics. Following loading of 5mg MB and their comparison to blank NPs, we obtained NP preparations in the range of 120-145nm, with encapsulation efficiencies from 25-40% and drug loading between 1-2%. Additionally, we have found that 50% of the MB initially added is released at 24 hours, and stays constant up to two weeks, demonstrating sustained drug release. In conclusion, based on studies that have demonstrated in vitro effects with MB at a minimum of 1μM (~0.3mg) and 150nm particles, our formulation should elicit comparable, if not better, results when treating GBM.