The Biological Cell Responses To Short Duration Electric Pulse And Their Applications In Cancer Cell Apoptosis Induction

With the development of human's understanding to the electric pulse and its applications,the effect of electric pulses on life gains more attentions recently.Particularly,due to the high frequency and amplitude,short duration electric pulse can easily penetrate cell plasma membrane and influence cell interior.Thus,the cell intracellular effects induced by short duration electric pulses with different parameters and its applications become the hotspot in bioelectromagnetic research in recent years.By far,short duration electric pulse has already been a direct or indirect method for various disease treatment,especially for cancer treatment.However,there are still lack of deep research in the effects induced by short duration pulse and its application in cancer treatment.Therefore,the study on the cell response to short duration electric pulse with various parameters can help others develop a more comprehensive understanding.Meanwhile,by introducing some supplementary meas including drugs and carbon nanotubes,the efficiency of cancer cell apoptosis caused by nanosecond electric pulse(nsEP)can be improved,ultimately supporting its application in anti-tumor treatment.Previous studies shows that nsEP can induce the nanopores on cell plasma and obtain various intracellular responses.Though the size of the pores in plasma membrane is relatively small,there are still some nanomoleculars and ions passing through these pores,ultimately arousing the unexpected physiological processes.Thus,based on the conclusion that shorter duration of the electric pulses affects less on plasma membrane and more on organelles,in the first part of the thesis,we employ the picosecond electric pulses to stimulate a complex cell system with two organelles of different size and study their electroresponses.Also,we compare and analyze how the pulse amplitude,organelle size and resting potential influence the electroresponses.Our results suggest that we can selectively induce the cell interior electroporated firstly when keep the permeability of plasma membrane stay intact if the amplitude of picosecond electric pulse is adjusted reasonably.This is much different from the electroporation caused by nsEP.Besides,the picosecond electric pulse will choose the organelle with large size to be electroporated which is the same as nsEP.Furthermore,the applicability of the quasi-static model used to calculate the TMV under the stimulation of a few hundred picosecond electric pulse is firstly illustrated in this paper.As one of the original application of electroporation in cancer treatment,traditional electrochemotherapy generally use the long duration electric pulse to induce the aqueous pores for drug delivery which can improve the efficiency of chemotherapy.However,drugs utilized in electrochemotherapy is mostly bleomycin whose concentration is relatively high to enhance the therapeutic effects.In addition,under the combined concern of thermal effects probably induced by long duration pulses,the traditional electrochemotherapy may cause some side effects including inflammation.So,in the second part,we introduce a new method which combined employs the nsEPs and paclitaxel(PTX)to induce the human breast cancer cell(MDA-MB-231)death.Via molecular dynamic simulation and experiments,we analyze the combination effects and the mechanisms.Results indicate that nsEPs can sufficiently decrease the barrier for the penetration of PTX through plasma membrane,increasing the percentage of PTX arriving the cell interior and thus reduce the initially utilized PTX concentration.Besides,the study on the synergy demonstrates that these two agents have different action targets and coordinately enhance MDA-MB-231 cell death.Therefore,the combination treatment with nsPEFs and PTX might provide an advantageous treatment for breast cancer in vitro.Nanosecond electric pulse is able to induce intracellular effects that are utilized to trigger cell apoptosis which may followed by the immune responses,inhibiting tumor regrowth.Thus,nsEP has already been employed in cancer treatment.However,due to the high strength of nsEP required for the induction of cell apoptosis,the widespread utilization of nsEP is restricted owing to the hardware technology limitation.Furthermore,high strength nsEP may also damage the healthy tissues and induce various side-effects since it is not tumor targeted.Therefore,we introduce the carbon nanotube(CNT)to figure out these problems in the thirdly part.Due to the outstanding electronic,tumor-targeted and biocompatible properties,CNT is employed in the stimulation process of human colon cancer cells(HCT 116)by nsEPs in order to realize a highly efficient cell apoptosis in the precise of reducing side effects.Results show that combination treatment with CNTs and low intensity nsPEFs can improve the HCT116 cell mortality while the low intensity nsEPs may not cause significantly damage to human normal colon epithelial cells(NCM460).Besides,the ability of CNTs to amplify the electric field around its tips and enhance the permeability of plasma membrane is confirmed in our study via theoretical and experimental research.The mechanisms of the combined effects are suggested as follows:By promoting the stimulation of nsEPs to plasma membrane and intracellular organells,CNTs help nsEPs perturb calcium handling which finally trigger the mitochondrial signaling pathway-mediated cell apoptosis.And these results may provide a new and highly efficient strategy for tumor therapy.