title: Low-intensity ultrasound and microbubbles enhance the antitumor effect of cisplatin.
abstract: Cell permeabilization using microbubbles (MB) and low-intensity ultrasound (US) have the potential for delivering molecules into the cytoplasm. The collapsing MB and cavitation bubbles created by this collapse generate impulsive pressures that cause transient membrane permeability, allowing exogenous molecules to enter the cells. To evaluate this methodology in vitro and in vivo, we investigated the effects of low-intensity 1-MHz pulsed US and MB combined with cis-diamminedichloroplatinum (II) (CDDP) on two cell lines (Colon 26 murine colon carcinoma and EMT6 murine mammary carcinoma) in vitro and in vivo on severe combined immunodeficient mice inoculated with HT29-luc human colon carcinoma. To investigate in vitro the efficiency of molecular delivery by the US and MB method, calcein molecules with a molecular weight in the same range as that of CDDP were used as fluorescent markers. Fluorescence measurement revealed that approximately 10(6)-10(7) calcein molecules per cell were internalized. US-MB-mediated delivery of CDDP in Colon 26 and EMT6 cells increased cytotoxicity in a dose-dependent manner and induced apoptosis (nuclear condensation and fragmentation, and increase in caspase-3 activity). In vivo experiments with xenografts (HT29-luc) revealed a very significant reduction in tumor volume in mice treated with CDDP + US + MB compared with those in the US + CDDP groups for two different concentrations of CDDP. This finding suggests that the US-MB method combined with chemotherapy has clinical potential in cancer therapy.
authors.affiliation: Graduate School of Biomedical Engineering, Tohoku University, Sendai, Miyagi 980-8575, Japan.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Atsuko
authors.initials: A
authors.lastname: Aoi
authors.forename: Sachiko
authors.initials: S
authors.lastname: Horie
authors.forename: Noriko
authors.initials: N
authors.lastname: Tomita
authors.forename: Shiro
authors.initials: S
authors.lastname: Mori
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Morikawa
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Matsumura
authors.forename: Georges
authors.initials: G
authors.lastname: Vassaux
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Kodama
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002277:Carcinoma / Q000188:drug therapy / Q000473:pathology; D002460:Cell Line; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology*; D003110:Colonic Neoplasms / Q000188:drug therapy*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005452:Fluoresceins / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism; D017930:Genes, Reporter; D019073:HT29 Cells; D006801:Humans; D007668:Kidney / Q000166:cytology / Q000196:embryology; D049410:Luciferases, Renilla / Q000378:metabolism; D015674:Mammary Neoplasms, Animal / Q000188:drug therapy*; D051379:Mice; D045423:Microbubbles; D010316:Particle Size; D014162:Transfection; D014465:Ultrasonics
chemical_list: D000970:Antineoplastic Agents; D005452:Fluoresceins; D005456:Fluorescent Dyes; D049410:Luciferases, Renilla; D002945:Cisplatin; C007740:fluorexon