Magnetic Drug Carriers Producing Magnetic Mechanical Force For Tumors Therapy

Due to the side-effects of chemotherapeutics in hematological cancer treatment,targeting efficacy and the safety issues of traditional active targeting therapy,we propose a new method that can be applied to the treatment of hematological cancer:based on the extracorporeal circulation and magnetic manipulating drug delivery system.Firstly let the blood containing cancer cells flow to the extracorporeal circulation circuit,and the blood is mixed with the magnetic nano-carriers with targeting molecule and medicine.During the mixing process,the carrier is targeting to the cancer cell membrane and endocytose.Then rotating magnetic field is applied to drive the magnetic carrier to collide with the cell membrane.The magnetic force may mechanically destroys cancer cells,or alters the permeability of the membrane,allowing the drug to act synergistically to kill the cancer cells.Then the magnetic carrier in the blood is magnetically separated and recovered by the static magnetic field to prevent excessive carriers from entering the body.Finally blood returns the body by circulation circuit.The drug delivery system achieves accurate,highly effective,and low toxicity drug delivery according to the following three steps:First step is cell targeting.Polyethylene glycol-polylactide-doxorubicin?PEG-PLA-Dox?was synthesized by a pH-responsive hydrazone linkage.Through carbodiimide synthetic method,folic acid?FA?targeting polymer polylactide-polyethylene glycol-folic acid?PLA-PEG-FA?was synthesized.The structure of the product was characterized by ¹H-NMR and FT-IR.The content of FA is 18.61%,and the content of Dox is 2.03%.Then chain shaped targeting carriers?FA-MNCs-Dox?were prepared by solvent exchange and static magnetic field self-assembly method with Fe₃O₄@OA as core,Dox-PLA-PEG and PLA-PEG-FA as shell.The hydrodynamic size of the nanochain is bimodal?20-50 nm and 100-295 nm?;the zeta potential is-16 mV;the size under transmission electron microscope is 100-200 nm;and the saturation magnetization is 165.47 emu/g.It has been studied and confirmed that the carriers has good stability in water,PBS,or 10%FBS medium.FA-MNCs-Dox is pH-responsive and exhibits rapid drug release in an acidic environment and slow drug release in a neutral environment.Targeted nanochains?FA-MNCs?have low cytotoxicity.Prussian blue staining and iron content assays show that FA-MNCs can target K562 cells.Second step is cancer cell inhibition by magnetic manipulation.A rotating magnetic field?RMF?was firstly constructed.According to the test,the appropriate height of RMF was 5-15 mm above the magnets and the range of magnetic field strength was 30-70 mT.After three consecutive days?1 h of every day?of RMF applied,the cell survival rate of FA-MNCs group decreased by 25%and the degree of cell damage was severely under the light microscope.At the same time,the edge of the vesicles or lysosomes plasma membrane is obscured by TEM observation,which proves that the mechanical force of carriers has the effect of destroying the organelle membrane.Under RMF,the drugs and the magnetic force had a synergistic effect.The results of cytotoxicity and flow cytometry experiments indicated that FA-MNCs-Dox had the ability of targeting drug release;under RMF,the cells of FA-MNCs-Dox group were more sensitive and more susceptible to be destroyed under mechanical forces.The third step are the construction of based-extracorporeal blood circulatory magnetic targeting drug delivery system and the separation of the carriers.A rat-based extracorporeal blood circulatory system was successfully established:blood circulatory system capacity was 3 mL,blood flow rate was 0.3-0.5 mL/min,and nanochain solution flow rate was 0.1 mL/min.The magnetic nano-carrier can be adsorbed and recovered by slowing the flow in micro-reservoir and static magnetic field with adsorbing rate of 60.41%±6.24%,reducing amount of carriers entering in animals.Then the safety of the system is evaluated.The hemolytic rate of targeted drug-loaded nanochains is less than 5%and can be used for intravenous injection.Heparin sodium can effectively prolong the clotting time.The drug delivery system has no significant damage to the blood and organs of rats.After adsorption by the static magnetic field,the blue spots accumulated in the organs were significantly reduced,effectively preventing excessive carriers from entering the body.This study paves the way to investigate the therapeutic benefit of magnetic manipulation of inhibiting cancer cell in conditions such as metastatic cancer or leukemia.