Development Of Medium Frequency Adjustable Pulsed Magnetic Fields And Regulation Of Magnetic Nanoparticles Labeled Mesenchymal Stem Cells

With the development of the demand for stem cells,magnetic nanoparticle-labeled stem cells have been more widely used in the biomedical field,however the efficiency of labeling stem cells with magnetic nanoparticles is not satisfactory.Due to the special magnetic properties of magnetic nanoparticles,we propose that we can use external physical field to regulate stem cell phagocytosis of magnetic nanoparticles.Firstly,we designed and developed a medium and low-frequency pulsed magnetic field generator that can be used for cell experiments with adjustable magnetic field strength,frequency,and duty cycle,and used this magnetic field generator to study stem cell phagocytosis of magnetic nanoparticles with external pulsed magnetic fields.The influence of various parameters on phagocytosis of magnetic nanoparticles by mesenchymal stem cells was studied.Then,a series of characterizations of the pulsed magnetic field regulation under different parameters were performed.The main research was on the properties of the cells such as viability,total number,morphology change,and phagocytosis.Quantitative and qualitative characterization of cellular uptake of nanoparticles by ICP-OES and transmission electron microscopy.The specific work is as follows:1?Using PLECS software to simulate the pulsed magnetic field circuit and using Ansoft Maxwell software to simulate the pulsed magnetic field.Based on the data from simulation,a mid-low frequency pulsed magnetic field with adjustable magnetic field intensity,frequency,and duty ratio was designed,developed,and calibrated.Various parameters of the pulsed magnetic field were calibrated.Pulse magnetic field strength adjustment range is 1.9m T ~ 4.6m T,magnetic field frequency adjustment range is 3k Hz ~ 5k Hz,magnetic field area is about 4cm2,in line with the requirements of cell experiments.2?The magnetic nanoparticles which wsa used have been characterized in detail,the effects of pulsed magnetic fields with different parameters on cell viability,total number,and surface morphology of adipose-derived mesenchymal stem cells and human umbilical cord mesenchymal stem cells were studied.The pulsed magnetic field was found to have no significant effect on the viability,total number,and surface morphology of mesenchymal stem cells and is safe for cells.The effects of pulsed magnetic fields with different frequencies on the phagocytosis of magnetic nanoparticles by mesenchymal stem cells were studied.It was found that the intermediate-frequency(3k Hz-5k Hz)pulsed magnetic field can inhibit stem cells from phagocytosis of magnetic nanoparticles,and the low-frequency(5Hz to 20Hz)pulsed magnetic field can promote stem cells to phagocytose magnetic nanoparticles.The effects of pulsed magnetic field on the engulfment of gold nanoparticles by adipose tissue-derived mesenchymal stem cells in SD rats under the same conditions were studied.It was found that the pulsed magnetic field had no significant effect on the phagocytosis of gold nanoparticles by stem cells.Description of the pulsed magnetic field acting on stem cells phagocytic magnetic nanoparticles is mainly magnetic.