Bubbles against Cancer

25. September 2007
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Diagnostics and therapy all in one go? What's working with cardiac catheters, for sure works with tumors as well. Synthetic blebs and gold constructs provide for clear vision in ultrasound - and then wipe out the rogue tissue.

Wild bubbling in the vein.A few curves further down, right inside the tumor – the grand hello again:Thousands of tiny nano-bubbles are flowing to join for larger vesicles.Suddenly the ultrasound “rings its bell”. The party begins. Since the blebs areworking as contrast agent,the physician is able to see exactly where they collect and what the tumorlooks like. Another, different sound impulse and the bubbles gush out tumortoxic Doxorubicin into the tissue – exactly where it is supposed to go.

Bubbles beat “Doxopur”

Nano-bubbles aretiny blebs of polymeres, i. e. plastics, often similar to those surgeons use assuture. It's nothing new that such bubbles can be used to carrychemotherapeutics to a tumor. They have also been known to burst on the spotwith the aid of ultrasound impulses. But a one-hundred-percent targeted localtherapy was difficult so far, since there was no opportunity to display animage of the tumor during respectively immediately prior to the nano-therapy.That is about to change now. New nano-particles combined with modifiedultrasound devices make an imaging possible without the particles immediatelyflying apart. The therapeutic ultrasound impact needed to set free thechemotherapeutic is placed a lot more targeted. Just how such a “dual”nano-medicine functions practically, scientists at the Utah University have shown in a mouse model. They covered those tests in theprofessional magazine Journal of the National Cancer Institute: “the nano-bubbleswere more effective suppressing the tumor growth than a Doxorubicin-therapy byitself”, says NatalyaRapoport, head of the experiments.

Gold adds pressure…

But they don't just work onthis in US desert states – at the Fraunhofer Institute in St. Ingbert a group of scientists ispottering around on dual nano-medicine – although with a different biologicalbasic approach. In this EU-promoted Adonis-project,the team and its head Dr. Robert Lemor pit on gold as the carrier, not onbubbles. “It's one of the interesting aspects of nano-medicine: Constructs usedfor diagnostic purposes, can be used for therapeutic purposes as well once theyare on-site” says Lemor. The scientist couples antibodies aiming against theprostate-specific antigen (PSA) with the goldparticles. As the name suggests – the Adonis-project is concentrating on the prostate carcinoma.Thanks to antibodies, the gold gets to the PSA-rich tumor, but hardly anywhereelse. To use this gold now for an ultrasound contrast mediait is attacked with a short laser impulse instead of a sound wave. Thus itslightly warms up which causes a pressure wave showing with the ultrasoundhead. The result are high solution images of the prostate tumor if anultrasound device developed especially design fort his purposes is used.

… and gives the tumorhell.

Different from thecolleagues in Utah, Lemor does not need any chemotherapeutics for that stepfrom diagnostics to therapy. Once the ultrasound diagnostic is concluded thescientists in St. Ingbert are able to shoot certain regions of the tumortargeted with additional, now a bit more intensive, laser impulses. The arisingheat would lead to the thermic destruction of the surrounding tumor tissue – atleast that is how it's planned. The experiments are just now being prepared.

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