Camouflaged nanoparticles against cancer

Cancer therapy: Chemotherapies could be significantly improved by camouflaged nanoparticles

06/21/2011

Cancer therapy could be significantly improved by the use of nanoparticles. Tiny plastic capsules can transport the intended drugs directly to the damaged cells, say US scientists at the University of California, San Diego in the latest issue of the journal „Proceedings of the National Academy of Sciences“ (PNAS).

In recent attempts to use nanoparticles for the treatment of cancer, the tiny transport capsules were always recognized by the body as a foreign body and accordingly fought by the immune system, the US scientists explained the starting point of their current research. The active ingredients of chemotherapy could stay so relatively short in the body. Therefore, Liangfang Zhang of the University of California and colleagues have camouflaged the tiny plastic capsules - the nanoparticles were coated with the red cell envelope membrane. Thus, the transport capsules could develop much longer effect in the organism, said the US scientists.

Nanoparticles as transport capsules in chemotherapy
For a long time, nanoparticles have been used on a trial basis for chemotherapy, which serve as a means of transport for the intended active ingredients. Thus, the preparations can develop their full effect directly in the area of ​​the tumors. Since the less than 100 nanometers (one nanometer equals one millionth of a millimeter), made of well-tolerated, easily degradable plastic transport capsules recognized by the immune system as a foreign body and correspondingly quickly excreted, the previous methods could only achieve limited effect. However, the US scientists at the University of California have now been able to cover the nanoparticles with a protective cover from the membranes of the red blood cells, thus generating a kind of camouflage shell for the transport vehicles. The researchers ruptured blood cells and mixed the empty cell shells with nanoparticles around 70 nanometers in diameter. The mixture of nanoparticles and cell membranes was then pressed through a narrow-pored filter so that the cell membranes wrapped tightly around the tiny transport capsules. In this way, the immune defense could no longer distinguish the nanoparticles from the blood cells, so that the tiny transport capsules remain significantly longer in the body, report Liangfang Zhang and colleagues.

Camouflaged nanoparticles remain much longer in the organism
In their study, the researchers tested the new method in mice, with impressive results. As described, the US scientists isolated red blood cells from the blood of mice and caused them to burst. Subsequently, with the help of the cell membrane camouflaged nanoparticles were produced, which lingered in the body of the animals much longer than the previous transport capsules. After injection, the nanoparticles remained detectable in the blood of the mice for three days, whereas the residence time for the synthetic transport vehicles was only a few hours, the US researchers report in the journal „Proceedings of the National Academy of Sciences“. „You pull the envelope over the nanoparticles and they look like red blood cells“, Liangfang Zhang explained. The US researchers emphasized that their studies were the first attempt, „to develop a drug delivery form that combines a natural cell membrane with a synthetic nanoparticle“. Although the camouflage of nanoparticles would have to be prepared directly from the membranes of the respective patient's red blood cells in order to avoid immune system rejection, the use of a small blood sample would be sufficient for this purpose. researcher.

Optimization of chemotherapy by camouflaged nanoparticles
The use of nanoparticles for chemotherapy could significantly improve the treatment of cancer in the future, the US scientists hope. After all, medicines that normally spread throughout the body with the blood and can therefore only be used in low concentrations because of the threatening side effects could be transported directly to their destination with the aid of the tiny transport capsules. So that the active ingredients of chemotherapy are not released earlier, the surfaces of the transport capsules additionally receive special binding proteins that dock exclusively on the surface structures of the cancer cells. The cancer drugs are released only after docking and can develop their full effect directly in the tumor cells, the US researchers report. The damage to healthy cells is minimized and the risk of side effects decreases significantly, Liangfang Zhang and colleagues continue. In addition, since the effect is locally limited could be worked with much higher concentrations. In addition, the treatment with several different preparations would be possible simultaneously, since in the transport vehicle various drugs can be accommodated, said the US researchers. In this way, the new method not only significantly improved the effectiveness of chemotherapy, but also minimized the risk of resistance, according to Liangfang Zhang and colleagues. (Fp)

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