Local delivery system of cytotoxic agents to tumors by focused sonoporation

Abstract

Recently, ultrasound-targeting microbubble destruction has been employed in molecular gene therapy, and a new potent nonviral gene transfer method known as 'sonoporation' has been developed. We investigated the efficiency of sonoporation toward growth inhibition of human gingival squamous carcinoma cell line, Ca9-22, in vitro and in vivo. The cytotoxicity of bleomycin (BLM) was investigated using flow-cytometric analysis and Hoechst's staining in vitro assay systems. We found that the delivery of BLM by sonoporation induced cytotoxic effect toward Ca9-22 cells in vitro. Our in vivo results showed that tumors nearly disappeared in Ca9-22 cell-implanted nude KSN/slc mice treated with a low dose of BLM followed by sonoporation during the 4-week experimental period. Histological analysis revealed that the cytotoxic effect was mainly apoptosis. We previously reported that the cytolethal distending toxin B (cdtB) from Actinobacillus actinomycetemcomitans, a periodontopathic bacterium, is responsible for cell cycle arrest and apoptosis in vitro. Thus, we used sonoporation to transfect a cdtB-expressing plasmid into Ca9-22 cells and examined cell viability in vitro and in vivo. We found that an administration of cdtB-expressing plasmid followed by sonoporationinduced marked growth inhibition of Ca9-22 cells and apoptotic cells were also observed in vitro and in vivo. These findings suggest that local administration of cytotoxic agents with sonoporation is a useful method for molecular cancer therapy.

Ultrasound-contrast agent mediated naked gene delivery in the peritoneal cavity of adult rat

“…In in vivo gene delivery experiments under similar ultrasonic intensity, frequency and duration, the temperature rise was found to be less than 2 1C. 39 Interestingly, we also found that Optison alone could enhance gene delivery in peritoneal tissues at levels lower than ultrasoundmicrobubble-mediated delivery. These findings are in accord with the observation by Lu et al 37 that microbubbles alone significantly increase the gene transfer in mouse skeletal muscle in vivo even in the absence of ultrasound, but contrast to the observation by Manome et al 36 that no expression of delivered gene Figure 2 Hematoxylin-eosin staining of parietal and visceral peritoneum in rats.…”

Targeted Inhibition of CD133+ Cells in Oral Cancer Cell Lines

“…Based on these findings, we mutated the primary receptor binding subunit (CdtA) of the toxin to eliminate intoxication of normal cells. Sonoporation has been used to deliver a plasmid containing the A. actinomycetemcomitans cdtB gene into Ca9-22, a human gingival squamous cell carcinoma cell line (Iwanaga et al, 2007). Transfected cells underwent apoptosis when treated in vitro and in mice.…”

Recent advances in gene delivery with ultrasound and microbubbles

“…In a separate study Hauff has demonstrated that 50% reduction of pancreas adenocarcinoma tumour growth can be obtained after three intra-tumoural administrations of plasmid encoding p16 combined with US (color Doppler mode, MI ¼ 1.5) and microbubbles [43]. Recently, a significant effect has been reported on gingival squamous carcinoma cells implanted in nude mice [44]. A complete suppression of tumour growth was obtained in mice transfected with Optison Õ and plasmid encoding cytolethal bacterial toxin A using a transducer of 1 MHz with an output of 2W/cm 2 and 50% DC.…”