Deep in vivo two-photon imaging of blood vessels with a new dye encapsulated in pluronic nanomicelles.

Our purpose is to test if Pluronic® fluorescent nanomicelles can be used for in vivo two-photon imaging of both the normal and the tumor vasculature. The nanomicelles were obtained after encapsulating a hydrophobic two-photon dye: di-stryl benzene derivative, in Pluronic block copolymers. Their performance with respect to imaging depth, blood plasma staining, and diffusion across the tumor vascular endothelium is compared to a classic blood pool dye Rhodamin B dextran (70 kDa) using two-photon microscopy. Pluronic nanomicelles show, like Rhodamin B dextran, a homogeneous blood plasma staining for at least 1 h after intravenous injection. Their two-photon imaging depth is similar in normal mouse brain, using 10 times less injected mass. In contrast with Rhodamin B dextran, no extravasation is observed in leaky tumor vessels due to their large size: 20-100 nm. In conclusion, Pluronic nanomicelles can be used as a blood pool dye, even in leaky tumor vessels. The use of Pluronic block copolymers is a valuable approach for encapsulating two-photon fluorescent dyes that are hydrophobic and not suitable for intravenous injection.

[1]  P. Low,et al.  Fast release of lipophilic agents from circulating PEG-PDLLA micelles revealed by in vivo forster resonance energy transfer imaging. , 2008, Langmuir : the ACS journal of surfaces and colloids.

[2]  Timothy C. Parker,et al.  One- and Two-Photon Spectroscopy of Donor−Acceptor−Donor Distyrylbenzene Derivatives: Effect of Cyano Substitution and Distortion from Planarity , 2002 .

[3]  W. Webb,et al.  Water-Soluble Quantum Dots for Multiphoton Fluorescence Imaging in Vivo , 2003, Science.

[4]  W. Denk,et al.  Two-photon laser scanning fluorescence microscopy. , 1990, Science.

[5]  M. Blanchard‐Desce,et al.  Synthesis and Characterization of Fluorescently Doped Mesoporous Nanoparticles for Two-Photon Excitation , 2008 .

[6]  Rakesh K. Jain,et al.  Transport of molecules across tumor vasculature , 2004, Cancer and Metastasis Reviews.

[7]  H. Dvorak,et al.  Identification and characterization of the blood vessels of solid tumors that are leaky to circulating macromolecules. , 1988, The American journal of pathology.

[8]  J. Rieger,et al.  Organic Nanoparticles in the Aqueous Phase-Theory, Experiment, and Use. , 2001, Angewandte Chemie.

[9]  V A Convertino,et al.  Blood volume: importance and adaptations to exercise training, environmental stresses, and trauma/sickness. , 2000, Medicine and science in sports and exercise.

[10]  S. Charpak,et al.  Water-soluble dendrimeric two-photon tracers for in vivo imaging. , 2006, Angewandte Chemie.

[11]  D. Kleinfeld,et al.  Correlations of Neuronal and Microvascular Densities in Murine Cortex Revealed by Direct Counting and Colocalization of Nuclei and Vessels , 2009, The Journal of Neuroscience.

[12]  S. Lesieur,et al.  Characterization of fluorescein isothiocyanate-dextrans used in vesicle permeability studies. , 2002, Analytical chemistry.

[13]  T-Y Lee,et al.  Serial changes in CT cerebral blood volume and flow after 4 hours of middle cerebral occlusion in an animal model of embolic cerebral ischemia. , 2007, AJNR. American journal of neuroradiology.

[14]  R. Jain,et al.  Angiogenesis, microvascular architecture, microhemodynamics, and interstitial fluid pressure during early growth of human adenocarcinoma LS174T in SCID mice. , 1992, Cancer research.

[15]  Patrice Baldeck,et al.  Fluorescent Pluronic nanodots for in vivo two-photon imaging , 2009, Nanotechnology.

[16]  Borivoj Vojnovic,et al.  Intravital imaging of tumour vascular networks using multi-photon fluorescence microscopy. , 2005, Advanced drug delivery reviews.

[17]  Chantal Rémy,et al.  A Direct Method for Measuring Mouse Capillary Cortical Blood Volume Using Multiphoton Laser Scanning Microscopy , 2007, Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism.