Cell and Developmental Biology Commons^™

Inactivation Of Myeloma Cancer Cells By Helium And Argon Plasma Jets: The Effect Comparison And The Key Reactive Species, Zeyu Chen, Qingjie Cui, Chen Chen, Dehui Xu, Dingxin Liu, H. L. Chen, Michael G. Kong

Bioelectrics Publications

In plasma cancer therapy, the inactivation of cancer cells under plasma treatment is closely related to the reactive oxygen and nitrogen species (RONS) induced by plasmas. Quantitative study on the plasma-induced RONS that related to cancer cells apoptosis is critical for advancing the research of plasma cancer therapy. In this paper, the effects of several reactive species on the inactivation of LP-1 myeloma cancer cells are comparatively studied with variable working gas composition, surrounding gas composition, and discharge power. The results show that helium plasma jet has a higher cell inactivation efficiency than argon plasma jet under the same discharge …

Cellular Regulation Of Extension And Retraction Of Pseudopod-Like Blebs Produced By Nanosecond Pulsed Electric Field, Mikhail A. Rassokhin, Andrei G. Pakhomov

Bioelectrics Publications

Recently we described a new phenomenon of anodotropic pseudopod-like blebbing in U937 cells exposed to nanosecond pulsed electric field (nsPEF). In Ca²⁺ -free buffer such exposure initiates formation of pseudopod-like blebs (PLBs), protrusive cylindrical cell extensions that are distinct from apoptotic and necrotic blebs. PLBs nucleate predominantly on anode-facing cell pole and extend toward anode during nsPEF exposure. Bleb extension depends on actin polymerization and availability of actin monomers. Inhibition of intracellular Ca²⁺ , cell contractility, and RhoA produced no effect on PLB initiation. Meanwhile, inhibition of WASP by wiskostatin causes dose-dependent suppression of PLB growth. Soon after …

Dielectric Characterization Of Coastal Cartilage Chondrocytes, Michael W. Stacey, Ahmet C. Sabuncu, Ali Beskok

Bioelectrics Publications

BACKGROUND: Chondrocytes respond to biomechanical and bioelectrochemical stimuli by secreting appropriate extracellular matrix proteins that enable the tissue to withstand the large forces it experiences. Although biomechanical aspects of cartilage are well described, little is known of the bioelectrochemical responses. The focus of this study is to identify bioelectrical characteristics of human costal cartilage cells using dielectric spectroscopy.

METHODS: Dielectric spectroscopy allows non-invasive probing of biological cells. An in house computer program is developed to extract dielectric properties of human costal cartilage cells from raw cell suspension impedance data measured by a microfluidic device. The dielectric properties of chondrocytes are …

Inhibition Of Voltage-Gated Na+ Current By Nanosecond Pulsed Electric Field (Nspef) Is Not Mediated By Na+ Influx Or Ca²+ Signaling, Vasyl Nesin, Andrei G. Pakhomov

Bioelectrics Publications

In earlier studies, we found that permeabilization of mammalian cells with nsPEF was accompanied by prolonged inhibition of voltage-gated (VG) currents through the plasma membrane. This study explored if the inhibition of VG Na⁺ current (I_Na) resulted from (i) reduction of the transmembrane Na⁺ gradient due to its influx via nsPEF-opened pores, and/or (ii) downregulation of the VG channels by a Ca²⁺ -dependent mechanism. We found that a single 300?ns electric pulse at 1.65.3?kV/cm triggered sustained Na⁺ influx in exposed NG108 cells and in primary chromaffin cells, as detected by increased fluorescence of a …

Selective Field Effects On Intracellular Vacuoles And Vesicle Membranes With Nanosecond Electric Pulses, Ephrem Tekle, Hammou Oubrahim, Sergey M. Dzekunov, Juergen F. Kolb, Karl H. Schoenbach

Bioelectrics Publications

Electric pulses across intact vesicles and cells can lead to transient increase in permeability of their membranes. We studied the integrity of these membranes in response to external electric pulses of high amplitude and submicrosecond duration with a primary aim of achieving selective permeabilization. These effects were examined in two separate model systems comprising of 1), a mixed population of 1,2-di-oleoyl-sn-glycero-3-phosphocholine phospholipid vesicles and in 2), single COS-7 cells, in which large endosomal membrane vacuoles were induced by stimulated endocytosis. It has been shown that large and rapidly varying external electric fields, with pulses shorter than the charging time of …

Mechanism For Membrane Electroporation Irreversibility Under High-Intensity, Ultrashort Electrical Pulse Conditions, R. P. Joshi, K. H. Schoenbach

Bioelectrics Publications

An improved electroporation model is used to address membrane irreversibility under ultrashort electric pulse conditions. It is shown that membranes can survive a strong electric pulse and recover provided the pore distribution has a relatively large spread. If, however, the population consists predominantly of larger radii pores, then irreversibility can result. Physically, such a distribution could arise if pores at adjacent sites coalesce. The requirement of close proximity among the pore sites is more easily satisfied in smaller organelles than in outer cell membranes. Model predictions are in keeping with recent observations of cell damage to intracellular organelles (e.g., mitochondria), …

Theoretical Predictions Of Electromechanical Deformation Of Cells Subjected To High Voltages For Membrane Electroporation, R. P. Joshi, Q. Hu, K. H. Schoenbach, H. P. Hjalmarson

Bioelectrics Publications

An electromechanical analysis based on thin-shell theory is presented to analyze cell shape changes in response to external electric fields. This approach can be extended to include osmotic-pressure changes. Our calculations demonstrate that at large fields, the spherical cell geometry can be significantly modified, and even ellipsoidal forms would be inappropriate to account for the deformation. Values of the surface forces obtained from our calculations are in very good agreement with the 1–10 mN/m range for membrane rupture reported in the literature. The results, in keeping with reports in the literature, demonstrate that the final shape depends on membrane thickness. …