Simulation Study Of Gene Electrotransfection Induced By Pulsed Electric Field In Biological Cells

In order to solve the problem of parameter selection in the clinical application of gene electrotransfection（GET）induced by the pulsed electric field（PEF）,this thesis based on mathematical models studies the response law of cell gene electrotransfection induced by pulsed electric field.Firstly,a calculation model of cell transmembrane voltage is constructed based on the equivalent circuit,and then a gene electrotransfection calculation model including electroporation and DNA transfer equations is established;next on the basis of the above research,the spatial distribution of transmembrane voltage on the cell surface is fully considered,then the gene electrotransfection calculation model of spherical cells based on the finite element is established;finally,based on the above model,gene electrotransfection model based on finite element,the electroporation characteristics of cells（transmembrane voltage,number of pores,the radius of pore,fractional pore area）and the DNA transfection efficiency under different pulsed electric fields are studied in depth.The main work and achievements of the thesis are as follows:1.Based on the equivalent circuit,a calculation model of cell gene electrotransfection is constructed,and the electroporation characteristics and DNA transmission efficiency of cells under different pulse parameters are simulated and analyzed.The results show that when the pulse width and field strength vary between 100ns-1ms and 0.25-1k V/cm respectively,the increase of pulse width and field strength can promote the transfection of DNA molecules,and the highest intracellular DNA concentration can reach 6.45×10^-7mol/m³.At the same time,under the action of a double pulse consisting of a pulse of 100μs,1k V/cm and a pulse of 1ms,0.6k V/cm,the effects of the time interval（0-1s）and the order of application on the uptake of DNA are studied.The results show that when the 100μs pulse is applied first and then the 1ms pulse is applied,the intracellular DNA concentration under different time intervals is 3.94×10^-7mol/m³;and after changing the pulse application sequence the DNA concentration is 1.91×10^-7mol/m³.In addition,under certain conditions the DNA concentration is positively correlated with the second pulse amplitude.2.In order to study the electroporation characteristics and DNA transmission efficiency of cells from the perspective of space and time,discretize the non-nucleus spherical cells and cell fluid,establish a gene electrotransfection calculation model of spherical cell based on the finite element,and analyze the changes of electroporation parameters under the action of a pulse of 3k V/cm,1ms.The results show that in the polar regions of the cell membrane the peak value of the transmembrane voltage is lower,the number of pores is small,and the radius of pore is larger;in the middle regions the peak value of the transmembrane voltage is higher,the number of pores is more,and the radius of pore is smaller.The DNA molecules enter the cell mainly through the polar regions of the cell,so the intracellular DNA concentration is 4.1×10^-9mol/m³ under the action of the pulse.3.Based on the above model,the effects of different pulse parameters on gene electrotransfection are simulated and analyzed.The simulation results show that:under the action of a pulse of 3k V/cm,1ms,when the rise time increases from 1μs to 100μs,the intracellular DNA concentration increases from 1.1×10^-8mol/m³ to 2×10^-8mol/m³;when the pulse width and field strength vary between 1μs-100μs and 2-10k V/cm respectively,both the pulse width and the field strength can promote gene electrotransfection,and the highest intracellular DNA concentration can be up to 4.6×10^-9mol/m³.When the double pulse is composed of a pulse 100μs,10k V/cm and a puls 1ms,5k V/cm,under the action of the double pulse combination of 1ms+100μs the DNA concentration is 4.3×10^-8mol/m³ and is higher than that under the action of the double pulse of 100μs+1ms;besides the time interval of the double pulse has no effect on cell gene electrotransfection.In summary,this article deeply studies the electroporation characteristics of cells and the efficiency of gene electrotransfection under the action of pulsed electric fields,and analyzed the influence of different pulse parameters on the transmission of DNA molecule,which provides guidance of the selection of pulses parameters for experimental studies of gene electrotransfection.