VITALITY AND MORPHOLOGY OF TUMOR CELLS TREATED WITH

39 The development of new systems for delivery of the antineoplastic drugs with low toxicity, capability of addressed transportation of drugs to the tumor target cells, and visualization of their action in the body is one of the major problems in modern biopharmaceutics. Despite an intensive work on creation of new anticancer drugs, the problem of cancer treatment has not been solved. The main reasons for that are the development of tumor cell resistance to known and new chemotherapeutic drugs and general toxicity in the body, resulting in damage of cells of normal tissues and organs [1]. One of the main mechanisms underlying acquired resistance of tumor cells to cytotoxic anticancer drugs is cell membrane transport that ensures removal of various xenobiotics, including drugs, from the target cells. This phenomenon has been called a multi-drug resistance (MDR) [2]. Therefore, synthesis of new substances capable of killing cells resistant to anti-tumor drugs, and using special systems for delivery of these drugs are the priorities of the biopharmacology. The biocompatible and biodegradable polymers forming nanoscale particles possess high stability in the body, low toxicity and, because of their unique chemical structure, can be further functionalized in order to provide addressed delivery of the immobilized drugs to specific target cells and biomolecules. The use of these nanoscale systems can significantly reduce the effective therapeutic dose of the applied anticancer drug. A number of synthetic polymers which can significantly enhance the biological effects of anticancer drugs in vitro and in vivo were described [3, 4]. Drug “Doxil”, which is a liposome functionalized polyethylene glycol with encapsulated anticancer drug UDC 4.057+547.311+576.5+577+615.9+616-006 doi: 10.15407/biotech8.01.039