October 2011

The team, led by Dr Olga Vasiljeva and Dr Boris Turk from the Jožef Štefan Institute and including researchers from the Centre of Excellence for Integrated Approaches in Chemistry and Biology of Proteins, the Centre of Excellence in Nanoscience and Nanotechnology, the Centre of Excellence in the fields of Chemistry, Biochemistry, Physics and Pharmacy, and the Faculty of Chemistry and Chemical Technology of the University of Ljubljana, has developed a new, highly efficient drug-delivery system based on magnetic iron oxide nanoparticle clusters encapsulated inside a liposome.

Using an animal model of human breast cancer, the researchers demonstrated considerably improved effects of the standard cancer chemotherapy drug doxorubicin. At the same time, they also demonstrated the efficient delivery of a protease inhibitor, which inhibited tumour growth considerably.

The work of the Slovenian scientists has been published in the renowned science magazine Nature Nanotechnology . The achievement is especially important because it may pave the way for a new efficient tool in the fight against cancer.

This is a new, efficient drug-delivery system, which, according to experiments performed on animals to date, effectively limits the growth of mammary tumours and has a similar effect on other types of cancerous tumour. The system is based on magnetic iron oxide nanoparticle clusters encapsulated in a liposome. Slovenian scientists have succeeded in loading nanoparticles with an active substance or encapsulating the drug independently from nanoparticles. They encapsulated them into liposomes or ferri-liposomes, which are sensitive to a magnetic field. With the help of an external magnet, they directed drug-loaded ferri-liposomes to the tumour and its microenvironment in transgenic mice. Because the new nanoparticles have outstanding contrast properties, they can be detected and visualised by MRI scanning and used for non-invasive monitoring of drug delivery to cancerous tumour cells in vivo.

The tests conducted on mice showed that, compared to the control group, tumours reduced substantially in animals injected with ferri-liposomes carrying nanoparticles, even after a single-dose treatment. The preliminary toxicity tests showed that the nano-carriers of drugs do not accumulate in the body but are excreted through the kidneys, which means that the Slovenian scientists have succeeded in overcoming all three major problems compromising existing chemotherapy cancer treatment; with successful targeted drug-delivery, they have prevented the drug from having toxic effects in healthy parts of the body and increased its bioaccessibility and treatment efficiency.

Prof. Boris Turk:

The tests showed that we can improve not only the effectiveness of the existing anticancer drugs but also the bioaccessibility of potential substances. Our system, based on magnetic nanoparticles, which can be led anywhere by means of a magnet, and a shell in which anything can be put, is aimed not only at improving the effects of one particular drug but at improving the properties of a number of existing drugs. The system is therefore generally applicable and is not limited only to cancer treatment. A number of researchers have worked on these kinds of system. Magnetic liposomes in themselves are not a new discovery, but the nanoparticles and the fact that we have succeeded in using them effectively in the drug-delivery system are.

Nanoparticles were previously used either in diagnostics or in delivery, both not in both. So nobody before has developed such a complex system. We do not know yet whether it will prove to be entirely useful, but if it proves to be non-toxic, the chances are good.

The scientists will continue their work on the project in Slovenia, but clinical work will most likely be done abroad. They are thinking of setting up a company and are looking for partners that would be willing to invest 20 to 30 million dollars in the next stage. Here they are thinking in terms of a country, private capital or the EU. Their input would be knowledge protected by intellectual property rights; new knowledge can always be re-tested, but of course this is a slow process. The project is not yet completed, but it has reached a turning point and is now entering its second stage. It will now be tested in practice – the challenge is to apply it to medicine. But the newly developed drug-delivery system has also opened up many other possibilities as it facilitates the study of the role of different proteins in cancer development.

Jožef Stefan Institute  - The main fields of activity of its employees are natural sciences, life sciences and technical sciences.  The Institute performs top-level research and the development of technologies, such as nanotechnologies, new materials, biotechnologies, management and production technologies, communication technologies, ... 

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