oregon-green-488-carboxylic-acid and Glioma

Glioblastoma (GBM) is the most malignant primary brain tumor in adults, and its prognosis remains very limited despite decades of research. Enhanced drug delivery to GBM using liposomes represents a promising therapeutic strategy. In this study, we describe a novel cationic and pH-sensitive liposome formulation composed of DPPC:DC-Chol:DOPE:DHPE Oregon Green producing efficient internalization and intracellular delivery to F98 and U-118 GBM cells. With a series of derived modifications of the lipid composition, we investigated the impact of membrane fluidity, steric stabilization and loss of both cationic and pH-sensitive components on cellular uptake and intracellular release kinetics by flow cytometry and confocal microscopy, respectively. DPPC:DC-Chol:DOPE:DHPE Oregon Green liposomes were strongly internalized in both cell lines within 6h. Following cellular uptake, liposomes traveled towards the nucleus (12h) and gradually released their cargo in the cytosol (over 24h). Modifications in liposomal composition of our original formulation had detrimental consequences on both the uptake and intracellular release kinetics in the two tested cell lines. Thus, we report a novel potent liposomal formulation for efficient cytosolic delivery of intracellular therapeutics such as chemotherapy agents and siRNAs to GBM cells.

Topics: 1,2-Dipalmitoylphosphatidylcholine; Animals; Biological Transport; Brain Neoplasms; Carboxylic Acids; Cell Line, Tumor; Chemistry, Pharmaceutical; Cholesterol; Flow Cytometry; Glioma; Humans; Hydrogen-Ion Concentration; Kinetics; Lipid Metabolism; Liposomes; Membrane Fluidity; Microscopy, Confocal; Microscopy, Electron, Transmission; Particle Size; Phosphatidylethanolamines; Phosphatidylglycerols; Polyethylene Glycols; Rats

The preferential accumulation of sickle blood cells in tumor vasculature is demonstrated noninvasively using MRI and sickle red blood cells loaded with Gd-DTPA and invasively by two other techniques. The distribution of red blood cells in rat brain tumors relative to normal brains were measured using three separate techniques: MRI of Gd-DTPA loaded cells, fluorescent microscopy detection of Oregon Green 488 fluorescence conjugated to a streptavidin-biotin complex that binds to red blood cell surface proteins, and autoradiography using a technetium (99m)Tc-labeling kit. Labeled red cells were infused intravenously in rats with brain tumors. Sickle cells preferentially accumulated in tumor relative to normal brain, with highest concentrations near the tumor / normal tissue boundary, whereas control normal red cells did not preferentially aggregate at the tumor periphery. This demonstrates the potential of sickle red blood cells to accumulate in the abnormal tumor vessel network, and the ability to detect their aggregation noninvasively and at high spatial resolution using MRI. The application of the noninvasive measurement of sickle cells for imaging tumor neovasculature, or as a delivery tool for therapy, requires further study.

Topics: Anemia, Sickle Cell; Animals; Autoradiography; Brain; Brain Neoplasms; Carboxylic Acids; Cell Line, Tumor; Contrast Media; Erythrocytes; Fluorescent Dyes; Gadolinium DTPA; Glioma; Humans; Magnetic Resonance Imaging; Male; Microscopy, Confocal; Neoplasm Transplantation; Rats; Rats, Inbred F344; Sodium Pertechnetate Tc 99m