Why does medicine need nanotechnologies? Since cells and sometimes macromolecules are the main object for modern drugs and treating agents, said “instruments” should have appropriate size fitting the object – nanometers in diameter. Definition of nano-size for medics is not so limited as for physicists and chemists – everything less than one micrometer, fits the definition. The most important property of a nano-object is its ability to penetrate capillaries with 100-200 micrometers in diameter.

Another essential fact is that very small size allows nano-objects to obtain absolutely new properties. Nano-pharmaceuticals are drugs, whose molecules are packed into nano-containers, liposomes, for instance. These containers help treating agents to penetrate all tissue barriers and enter target cells, where they decompose to safe chemical compounds, excreted by an organism. Nano-pharmaceuticals appear to have some wonderful properties. For example, solubility of many treating agents increases, while in a liposome, which is crucial for their therapeutical effect. On the contrary, toxicity of treating agents falls down due to liposome membrane, covering an agent. All mentioned factors make a drug act only in a target cell, without being degraded or starting treatment on its way to the cell, as well as allow lowering effective amount of a drug, which is good news for cancer patients, receiving chemical therapy.

Two mechanisms contribute to target delivery of nano-drugs – first is passive targeting, when capillaries in inflammation zone get wider, allowing liposomes penetrate tissues and get to the desired site. Second mechanism is active transport, which is a molecular probe, leading a nano-particle directly to receptors on target cells’ membranes.

  All mentioned characteristics have already been tested on nano-agents, developed in Moscow, which are either being used or tested successfully. Scientists have also developed a liposome form of anti-Parkinson disease substance DOFA, reducing effective dose ten-fold and increasing effective drug duration two-fold or three-fold. Liposomes also allow using neurotransmitter dopamine instead of its precursor for treatment – experiments show that dopamine introduction has no effect without liposomes, and with help of liposomes its concentration in cerebellum reaches healthy level.

Another nano-pharmaceutical is balarpan, liposome form of which regenerates cornea with keratopathy five times better than usual form. Betulinic acid, which affects melanoma, dissolves better, when in liposome, penetrating melanoma cells by means of endocytosis. One more development of Russian scientists is liposome form of birch bark extract, being incredibly biologically active – researchers detected antioxidant, immuno-modulating, anti-mutagen and other activities. Birch bark extract nano-particles are shown to contact with immune cells.

Three nano-pharmaceuticals, developed in Russia – liposome doxorubicine Lipodox, anti-hypoxic Lipin and liver-protecting Lioliv are already in production. Two anti-tumor agents Cisplatin and Pluorouracil are in clinical trials, as well as three more drugs with anti-hemorrhagic, wound-healing and anti-inflammatory effects. Other drugs with various healing effects, fighting melanoma, other tumors and tuberculosis, for instance, are waiting for trials to begin.

Source:
    Russian Science News

Kizilova Anna