Abstract 263: Ultrasound Enhancement of Bevacizumab Release from Echogenic Liposomes for Inhibition of Atheroma Progression

Abstract

Background: Vascular endothelial growth factor (VEGF) is a signal protein that induces vasculogenesis and angiogenesis, which are important to atheroma progression. Bevacizumab is a humanized monoclonal antibody specific for VEGF that causes regression of existing microvessels and has been shown to inhibit atheroma progression. Previous studies demonstrated the inhibitory efficacy of bevacizumab and bevacizumab-loaded echogenic liposomes (BEV-ELIP) for human umbilical vein cell (HUVEC) proliferation and VEGF expression (assayed by VEGF ELISA). Hypothesis: Bevacizumab activity can be enhanced by pulsed Doppler ultrasound treatment of BEV-ELIP. Methods: Bevacizumab (1 μg/ml) was added to 18-hour HUVEC cultures in 96-well plates, followed by 10 nM phorbol 12-myristate 13-acetate (PMA) 4 hours later and incubated for 24 hours. Cell proliferation was measured by the tetrazolium dye MTT. BEV-ELIP in a latex condom was submerged in a water bath and exposed to 6 MHz color Doppler ultrasound (MI = 0.4 ) for 5 min for bevacizumab release. Results: BEV-ELIP treated with US inhibited VEGF expression by 90% relative to non-treated controls and by 70% relative to BEV-ELIP without US (Fig. 1). Also, BEV-ELIP inhibited cell proliferation by 64% relative to untreated controls and by 45% relative to BEV-ELIP without US (Fig. 2). Conclusions: Ultrasound treatment of BEV-ELIP enhanced the agent’s ability to inhibit cell proliferation in the MTT assay and VEGF expression in the VEGF ELISA, consistent with US-triggered BEV release observed in previous studies. This BEV-ELIP formulation can now be translated to in vivo studies for atheroma inhibition.