Functional Investigation of Meningeal Lymphatic System in Experimental Intracerebral Hemorrhage.

BACKGROUND: Promotion of hematoma resolution in a timely manner reduces intracerebral hemorrhage (ICH) brain injury induced by toxic blood components and subsequent neuroinflammation. The meningeal lymphatic system is responsible for clearance of macromolecules and pathogenic substances from the central nervous system; however, its role in intraparenchymal hematoma clearance and ICH outcomes is unknown. In the present study, we aimed to understand the contribution of the meningeal lymphatic system to ICH pathologies and to test whether pharmacological enhancement of meningeal lymphatic function promotes hematoma resolution and brain recovery after ICH. METHODS: Immunofluorescence of whole-mount meninges was used to measure complexity and coverage level of meningeal lymphatic vasculature following ICH induction. Fluorescent microbeads and PKH-26-labeled erythrocytes were used to evaluate drainage function of the meningeal lymphatic system. Visudyne treatment, deep cervical lymph node ligation, and VEGF (vascular endothelial growth factor)-C injection were performed to manipulate meningeal lymphatic function. Neurobehavioral performance and hematoma volume were assayed by the cylinder test and histological measurements. Iron deposition, residual erythrocytes, neuronal loss, and astrogliosis were assessed by immunohistochemistry and antibody-based fluorescence staining. RESULTS: Meningeal lymphangiogenesis and enhanced lymphatic drainage occurred during the late phase of ICH. Ablation and blockage of meningeal lymphatic vessels impeded hematoma clearance, whereas pharmacological enhancement of their function reduced hematoma volume, improved behavioral performance, and reduced brain residual erythrocytes, iron deposition, neuronal loss, and astroglial activation. CONCLUSIONS: Early enhancement of meningeal lymphatic function is beneficial for ICH recovery. Targeting the meningeal lymphatic system is therefore a potential therapeutic approach for treating ICH.

Widespread gene transfer to malignant gliomas with In vitro-to-In vivo correlation.

Gene therapy of malignant gliomas has shown a lack of clinical success to date due in part to inability of conventional gene vectors to achieve widespread gene transfer throughout highly disseminated tumor areas within the brain. Here, we demonstrate that newly engineered polymer-based DNA-loaded nanoparticles (DNA-NP) possessing small particle diameters (~50 nm) and non-adhesive surface polyethylene glycol (PEG) coatings efficiently penetrate brain tumor tissue as well as healthy brain parenchyma. Specifically, this brain-penetrating nanoparticle (BPN), following intracranial administration via convection enhanced delivery (CED), provides widespread transgene expression in heathy rodent striatum and an aggressive brain tumor tissue established orthotopically in rats. The ability of BPN to efficiently traverse both tissues is of great importance as the highly invasive glioma cells infiltrated into normal brain tissue are responsible for tumor recurrence. Of note, the transgene expression within the orthotopic tumor tissue occurred preferentially in glioma cells over microglial cells. We also show that three-dimensional (3D) multicellular spheroids established with malignant glioma cells, unlike conventional two-dimensional (2D) cell cultures, serve as an excellent in vitro model reliably predicting gene vector behaviors in vivo. Briefly, DNA-NP possessing greater surface PEG coverage exhibited more uniform and higher-level transgene expression both in the 3D model and in vivo, whereas the trend was opposite in 2D culture. The finding here alerts that gene transfer studies based primarily on 2D cultures should be interpreted with caution and underscores the relevance of 3D models for screening newly engineered gene vectors prior to their in vivo evaluation.