The Experimental Studies Of Biological Effects Of Cell Electroporation By ECSP

Electrochemotherapy mediated by electric pulse has become a multid-isciplinary biomedical engineering technique in modern medical science, form last 20 years , many document has emerged to confirm its mainly tu-moricidal mechanisms was the: enhancement of chemotherapeutic drugs into the inner part of tumor-cells mediated by mem-brane-electropermeabilization caused by electric pulse. As we know in our previous studies about Energy Controllable Steep Pulse(ECSP), the main mechanism of tumor-toxicity of ECSP is its membrane electropermeabili-zation effect, so in this succession, we plan to further investigate the bio-logical effect of such membrane electropermeabilization in living cells or tissues ,also give qualitation and quantitation analysis in some key issues concerning the development of ECSP. In the first chapter which titled "Experimental studies of modifying effect of multidrug resistance of human ovarian cancer cell line by sub-lethal dose of steep pulse". In order to investigate killing and modify-ing effects on human ovarian cancer multidrug resistant cell subline by Sub-lethal Dose of Steep Pulse (SLDSP), also discuss its possible mecha-nisms. Methods:Multidrug resistant human ovarian cancer cell subline SKOV3/ADM was derived from its parental cell line SKOV3 by stepwise exposure to adriamycin(ADM). Then parental and its resistant subline were exposed to SLDSP, using MTT assay to evaluate electrosensitivity and chemosensitivity for both parental and resistant subline; for resistant sub-line, using RT-PCR to analysis level of MDR1mRNA, immunocytochemis-try to detect expression of P-gp( P-glycoprotein), transmission electron mi-croscope(TEM) to detect ultrastructural changes. Results:Similar elec-trosensitivity was found for SKOV3 and SKOV3/ADM(P=0.642). After exposed to SLDSP, resistant subline present with following changes: en-hanced chemosensitivity with decreased IC50 (50% Inhibiting Concentra-tion, IC50) values and RI(Resistance Index, RI), no alteration for MDR1mRNA(P=0.947) in RT-PCR, significant decrease of P-gp inten-sity(P=0.001) were observed in immunocytochemistry, apoptosis of SKOV3/ADM also can be seen in TEM. Conclusion Our results showed that steep pulse can also effectively kill multidrug resistant subline; SLDSP can reverse the multidrug resistance in SKOV3/ADM, its possible mecha-nisms include the increasing membrane permeability and probably induc-ing lasting changes in normal P-gp conformation and functions. In the second chapter which titled "A qualitative study of in Vivo pulsed electric field distribution model in rabbit liver tissues. in order toexplore the feasibility of establishment a model of in vivo PEFs distribution in healthy rabbit liver tissues, also provide important reference for clinical electrochemotherapy and for electrotransfer. Pulsed electric fields(PEFs) with fixed frequency, width and gradually increased peak value of voltage was applied in 30 healthy rabbit liver tissues, Using repeated experiment and self-compare statistics design.When killed and removed the liver from rabbits for HE staining, necrotic borderline was visible 3 days after PEFs application, the necrotic shape of concentric circular was evident around the electrodes under optical microscope at lower voltage, as voltage in-creasing, two shape of concentric circle gradually enlarged, nuclei with chromatin condensation, fragmentation, lysis alterations can be seen in the middle region between the needles, concentric circle changing into ellipse fusiform and finally overlap each other forming irregular necrosis contours. Cell cavitation and tissues ischemia also can be observed within electric field, Shape of tissue necrosis from the experiment has a near correlation with theoretic simulation of electric field distribution. Therefore ,rabbit liver tissues can be a good carrier for in vivo modeling of electric field dis-tribution when investigate the lethal effects of PEFs in tissues, PEFs also show its safety for the surrounding normal tissue when effectively kill the target area. In the last...