Development and characterization of methylene blue-loaded nanoparticles for glioblastoma

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 (surgery, radiation, and chemotherapy); this necessitates the development of more effective, less toxic therapies for diagnosed patients. Methylene blue (MB), a blue dye with noted medicinal applications, has received recent consideration as a potential neurotherapeutic due to its ability to infiltrate the blood-brain barrier (BBB), improve cellular processes within distinct brain cell compartments and types, and preferential accumulation in the brain. While MB displays these advantages, 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 submicron-sized nanoparticles (NPs) composed of the biodegradable/biocompatible co-polymer, poly(lactic-co-glycolic) acid (PLGA). Our lab, as well as others, have shown the application of PLGA NPs as potential cancer therapies, as well as their preferential accumulation in the brain, as a means to improve passive drug delivery. With this knowledge, our goal is to develop a MB-loaded PLGA NP capable of permeating the BBB in order to treat GBM, based on our hypothesis that encapsulation of MB 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 via particle size, surface charge, drug loading, and encapsulation efficiency. Additionally, we analyzed their in vitro effects to establish biological, and potentially therapeutic, activity. Following MB loading and comparison to blank NPs, we obtained preparations comparable to those published sized at 162.4nm, a surface charge of -31.7, and drug loading and encapsulation efficiency values of 2.2% and 29.2%, respectively. With this data, MBNPs were further analyzed and determined to produce a peak release at 24hrs. Additionally, in in vitro cell death studies, MBNPs were found to induce cell death comparable to, if not better than, free MB, in GBM cell lines. Lastly, MBNP treatment enhanced cellular metabolism, an capability noted in free MB. We are currently completing additional studies on MBNPs’ effects in vitro, as well as establishing a protocol for a PK study. In conclusion, our formulation displays MB’s therapeutic potential, displayed by its enhanced effectiveness in in vitro studies compared to free MB.