Marianne Gauthier PhD, Presenter: Nothing to Disclose

Edward J. Roy PhD, Abstract Co-Author: Nothing to Disclose

William D. O'Brien PhD, Abstract Co-Author: Nothing to Disclose

We tested in vivo a newly designed protocol to produce FITC-polylactide (PLA) nanoparticles (NPs) loaded on microbubble (MB) surfaces by comparing the fluorescent uptake in tumors after injecting NP-loaded MBs or NPs only in mice, and then imaging with ultrasound (US) at high mechanical index (MI). 

MBs (3.6 108 MB/mL, 1 mL) were produced from the sonication (70 s, 450 W) of a 5% bovine serum albumin and 15% dextrose solution. NPs (5 mg/mL, 1 mL) were produced by mixing FITC-PLA and PLA-PEG-COOH conjugates and covalently linking them to the surface of the pre-produced MBs via the carbodiimide technique. Three BALB/c mice were subcutaneously injected with 4T1 breast tumor cells (105 cells) on both flanks. Each mouse was injected with 150 µL of NP-loaded MBs and NPs only, respectively, on right and left flanks. Each injection was followed by a 1-min US exposure at MI=1.0. Then, mice were euthanized and liver, and right and left tumors were snap-frozen in OCT medium for cryosectioning and immunostaining. 5-µm cryosections were fixed in cold 95% ethanol and blocked using Superblock. Sections were incubated with, respectively, collagen IV and Cy-5 labeled donkey anti-rabbit IgG as primary and secondary antibodies, and then analyzed by fluorescence microscopy. For each mouse, tumors were imaged at 200x using FITC, DAPI and Cy-5 filters.    

For each mouse, images showed the presence of the NPs in both tumors. However, right tumors (NP-loaded MBs) always exhibited a much higher NP concentration than the corresponding left tumors (NPs only). In addition, from the collagen IV stain, it appeared that NPs detected from the right tumor were not only confined to the blood vessels but also spread to the surrounding tissues. 

We tested in vivo our newly designed NP-loaded MBs. While undergoing high MI ultrasound, NP-loaded MBs exhibited a higher NP release into the tumor than NPs only: attaching NPs to the MB surface improved the local release of the NPs in tumors opening thus the way for future drug delivery techniques. This work was supported by NIH R37EB002641.

Newly designed FITC-PLA NPs loaded on albumin-coated MBs undergoing high MI ultrasound improves the local release of NPs in tumors.  

Gauthier, M, Roy, E, O'Brien, W, FITC-polylactide Nanoparticles Loaded on Albumin-coated Microbubbles: Preliminary In Vivo Observations.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14014923.html