Biodegradable brain-penetrating DNA nanocomplexes and their use to treat malignant brain tumors

Abstract

The discovery of powerful genetic targets has spurred clinical development of gene therapy approaches to treat patients with malignant brain tumors. However, lack of success in the clinic has been attributed to the inability of conventional gene vectors to achieve gene transfer throughout highly disseminated primary brain tumors. Here, we demonstrate ex vivo that small nanocomplexes composed of DNA condensed by a blend of biodegradable polymer, poly(β-amino ester) (PBAE), with PBAE conjugated with 5 kDa polyethylene glycol (PEG) molecules (PBAE-PEG) rapidly penetrate healthy brain parenchyma and orthotopic brain tumor tissues in rats. Rapid diffusion of these DNA-loaded nanocomplexes observed in fresh tissues ex vivo demonstrated that they avoided adhesive trapping in the brain owing to their dense PEG coating, which was critical to achieving widespread transgene expression throughout orthotopic rat brain tumors in vivo following administration by convection enhanced delivery. Transgene expression with the PBAE/PBAE-PEG blended nanocomplexes (DNA-loaded brain-penetrating nanocomplexes, or DNA-BPN) was uniform throughout the tumor core compared to nanocomplexes composed of DNA with PBAE only (DNA-loaded conventional nanocomplexes, or DNA-CN), and transgene expression reached beyond the tumor edge, where infiltrative cancer cells are found, only for the DNA-BPN formulation. Finally, DNA-BPN loaded with anti-cancer plasmid DNA provided significantly enhanced survival compared to the same plasmid DNA loaded in DNA-CN in two aggressive orthotopic brain tumor models in rats. These findings underscore the importance of achieving widespread delivery of therapeutic nucleic acids within brain tumors and provide a promising new delivery platform for localized gene therapy in the brain.

Strategies to enhance the distribution of nanotherapeutics in the brain

“…We have previously demonstrated that NP up to 114 nm in diameters, if shielded with a dense layer of hydrophilic and neutrally charged polyethylene glycol (PEG; ≥ 9 PEG polymer chains per 100 nm 2 particle surface [6]), resist adhesive interactions with the brain ECM and rapidly diffuse within the healthy brain ICS [6, 18]. We have also shown that the ECM mesh spacings could be smaller depending on the type of tumor [19, 20]. More recently, we demonstrated that a marriage of CED and densely PEGylated NP enabled synergistically enhanced distribution of various therapeutic NP formulations following intracranial administration, while non-PEGylated or conventionally PEGylated NP were unable to do so [13-15, 20].…”

“…We have also shown that the ECM mesh spacings could be smaller depending on the type of tumor [19, 20]. More recently, we demonstrated that a marriage of CED and densely PEGylated NP enabled synergistically enhanced distribution of various therapeutic NP formulations following intracranial administration, while non-PEGylated or conventionally PEGylated NP were unable to do so [13-15, 20]. …”

Focused Ultrasound Preconditioning for Augmented Nanoparticle Penetration and Efficacy in the Central Nervous System

“…The high density of PEG in these systems has been shown to greatly reduce, if not eliminate, toxicity caused by the cationic nature of PEI . Nanoparticles containing similar size and charge characteristics have been shown to penetrate brain tissue when infused intracranially, providing uniform reporter gene expression . ZsGreen‐BPN transfected tissue volume was assessed at 48 h postadministration.…”

Brain tumor segmentation and classification via adaptive CLFAHE with hybrid classification

“…Two kinds of brain tumor are existed called benign and malignant 2 . Meningiomas and low grade gliomas are the other names of benign tumors, 3 whereas malignant tumors 4 are further named as glioblastoma multiforme and high grade gliomas. The most common occurred primary brain neoplasm is referred as malignant tumors.…”