Abstract 1346: Magnetoelectric particles cross blood brain barrier to deliver anti-tumor peptide to glioblastoma cells with on-demand release
Authors: Stewart Tiffanie , Stimphil Emmanuel , Guduru Rakesh , Rodzinski Alexandra , Liang Ping , Runowicz Carolyn , Cai Ren-Zhi , Salgueiro Luis , Schally Andrew , Khizroev Sakhrat 
Published: July 2016

Background: Despite significant progress in targeted drug delivery, glioblastoma is one of the least treatable tumors today. Delivering therapy across the blood-brain barrier (BBB) and overcoming resistance of tumor cells to current treatments remains a formidable task. The objective of the current in vitro and in vivo study was to show how a new class of multifunctional nanoparticles termed magnetoelectric nanoparticles (MENs) are used to achieve high-efficacy delivery of a therapeutic load across BBB, then release the load on demand, without affecting normal cells, via application of a specially tailored command sequence of D.C. and A.C. magnetic fields.

Methods: Growth hormone (GH)-releasing hormone (GHRH) antagonists, a class of anti-tumor peptides, block the release of tumorigenic insulin-like growth factors. Glioblastoma cell line U87 MG were treated with 1 μM of GHRH antagonist MIA-690 bound to GMO-MENs in MEM media supplemented with 5% FBS and 1% penstrep. In parallel, an in vitro BBB experiment, designed using transwells, applied a D.C. magnetic field gradient to determine optimal field and exposure time for MENs to penetrate the BBB. Next, experimental cells were placed on a D.C. magnetic field (100 Oe) for 12 h to induce nanoelectroporation, then an A.C. field (∼50 Hz) for 2 h to release the peptide intracellularly. Control cells were treated with MIA-690 peptide only, GMO-MENs only, and MIA-690 bound to GMO-MENs at varying magnetic fields and exposure times. Cells were incubated at 37°C with 5% CO2 in a humidified atmosphere. At 24 h and 48 h post-treatment, trypan-blue vital stain assessed cell growth inhibition. Cells were then washed and lysed to measure the concentration of MENs, and MIA-690 using ICP-MS and spectrophotometry, respectively. AFM and SEM-EDS imaged MENs in cell lysate and brain tissue from mice IV injected with MENs, to find signature peaks of Ba and Ti representing the outer core of MENs, to ascertain if particles cross the BBB in vivo.

Summary of data: Glioblastoma cells treated with MIA-690 bound to GMO-MENs on a D.C. magnetic field for 12 h, then an A.C. field for 2 h exhibited the greatest penetration of MENs and inhibition of tumor growth. AFM and SEM-EDS imaging showed MENs in cell lysate treated with D.C. for 12 h, but not 2 h or with no magnetic field, confirming application of a low D.C. field for 12 h triggers MENs’ penetration. On-demand MIA-690 intracellular release was highest after exposure to 12 h of D.C. field, then A.C. field at 50 Hz. Confocal microscopy confirmed a transfer of at least 50% of drug-loaded MENs across in vitro BBB, requiring 200 Oe/cm for 5 h. SEM-EDS images of brain slices taken from mice treated with MENs confirmed the presence of Ba and Ti, indicating MENs are able to cross BBB in vivo.

Conclusion: Functionalized MENs are effective in treating glioblastomas using targeted, on-demand release of anti-tumor drug with the ability to cross the BBB.

Citation Format: Tiffanie Stewart, Emmanuel Stimphil, Rakesh Guduru, Alexandra Rodzinski, Ping Liang, Carolyn Runowicz, Ren-Zhi Cai, Luis Salgueiro, Andrew Schally, Sakhrat Khizroev. Magnetoelectric particles cross blood brain barrier to deliver anti-tumor peptide to glioblastoma cells with on-demand release. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1346.