Low‐Energy Ultrasound Treatment Improves Regional Tumor Vessel Infarction by Retargeted Tissue Factor

• Published in: Journal of ultrasound in medicine 2015-07, Vol.34 (7), p.1227-1236
• Main Authors: Brand, Caroline, Dencks, Stefanie, Schmitz, Georg, Mühlmeister, Mareike, Stypmann, Jörg, Ross, Rebecca, Hintelmann, Heike, Schliemann, Christoph, Müller-Tidow, Carsten, Mesters, Rolf M., Berdel, Wolfgang E., Schwöppe, Christian
• Format: Article
• Language: English
• Subjects: Angiogenesis Inhibitors - pharmacology; Animals; Cell Line, Tumor; Disease Models, Animal; Endothelium, Vascular; Female; Fibrosarcoma - blood supply; Fibrosarcoma - drug therapy; Fibrosarcoma - therapy; Flow Cytometry; Humans; Infarction - etiology; low-energy ultrasound treatment; Mice; Mice, Nude; Microbubbles; Neovascularization, Pathologic - prevention & control; regional cancer therapy; Thromboplastin - pharmacology; truncated tissue factor; Ultrasonic Therapy; vascular infarction; vascular targeting; vascular ultrasound
• ISSN: 0278-4297; 1550-9613
• DOI: 10.7863/ultra.34.7.1227

Objectives To enhance the regional antitumor activity of the vascular‐targeting agent truncated tissue factor (tTF)‐NGR by combining the therapy with low‐energy ultrasound (US) treatment. Methods For the in vitro US exposure of human umbilical vein endothelial cells (HUVECs), cells were put in the focus of a US transducer. For analysis of the US‐induced phosphatidylserine (PS) surface concentration on HUVECs, flow cytometry was used. To demonstrate the differences in the procoagulatory efficacy of TF‐derivative tTF‐NGR on binding to HUVECs with a low versus high surface concentration of PS, we performed factor X activation assays. For low‐energy US pretreatment, HT1080 fibrosarcoma xenotransplant‐bearing nude mice were treated by tumor‐regional US‐mediated stimulation (ie, destruction) of microbubbles. The therapy cohorts received the tumor vessel‐infarcting tTF‐NGR protein with or without US pretreatment (5 minutes after US stimulation via intraperitoneal injection on 3 consecutive days). Results Combination therapy experiments with xenotransplant‐bearing nude mice significantly increased the antitumor activity of tTF‐NGR by regional low‐energy US destruction of vascular microbubbles in tumor vessels shortly before application of tTF‐NGR (P < .05). Mechanistic studies proved the upregulation of anionic PS on the outer leaflet of the lipid bilayer of endothelial cell membranes by low‐energy US and a consecutive higher potential of these preapoptotic endothelial cells to activate coagulation via tTF‐NGR and coagulation factor X as being a basis for this synergistic activity. Conclusions Combining retargeted tTF to tumor vessels with proapoptotic stimuli for the tumor vascular endothelium increases the antitumor effects of tumor vascular infarction. Ultrasound treatment may thus be useful in this respect for regional tumor therapy.