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Millimeter wave induced reversible externalization of phosphatidylserine molecules in cells exposed in vitro
Author(s) -
Szabo Imre,
Kappelmayer Janos,
Alekseev Stanislav I.,
Ziskin Marvin C.
Publication year - 2006
Publication title -
bioelectromagnetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.435
H-Index - 81
eISSN - 1521-186X
pISSN - 0197-8462
DOI - 10.1002/bem.20202
Subject(s) - hacat , phosphatidylserine , chemistry , biophysics , flow cytometry , in vitro , annexin , microbiology and biotechnology , membrane , biology , biochemistry , phospholipid
In vitro exposure of refrigerated samples (4 °C) of anti‐coagulated blood with millimeter waves (MMWs) at incident power densities (IPDs) between 0.55 and 1.23 W/cm 2 has been found to induce clot formation. We found a small but statistically significant change in clot size with increasing IPD value. MMW exposure of blood samples starting at room temperature (22 °C) did not induce blood coagulation; neither did conventional heating at temperatures up to 40 °C. Since cell‐free plasma did not clot upon MMW exposure, the role of blood cells was particularly analyzed. Experiments on various mixtures of blood cells with plasma revealed an important role of red blood cells (RBC) in the coagulation process. Plasma coagulation also developed within the MMW beam above dense keratinocyte (HaCaT) monolayers suggesting it lacked cell‐type specificity. We hypothesized that alteration of the membrane surface in exposed cells might be responsible for the circumscribed coagulation. The thrombogenic role of externalized phosphatidylserine (PS) molecules is well known. Therefore, we carried out experiments for immunolabeling PS molecules with fluorescein isothiocyanate (FITC)‐conjugated Annexin V on exposed cells. Fluorescence microscopy of the adherent human keratinocytes (HaCaT) and murine melanoma cells (B16F10) showed that MMW exposure at an IPD of 1.23 W/cm 2 is capable of inducing reversible externalization of PS molecules in cells within the beam area without detectable membrane damage. Nonadherent Jurkat cells exposed to MMW at an IPD of 34.5 mW/cm 2 also showed reversible PS externalization with flow cytometry, whether the cell temperature was held constant or permitted to rise. These results suggest that certain biological effects induced by MMWs could be initiated by membrane changes in exposed cells. Bioelectromagnetics 27:233–244, 2006. © 2006 Wiley‐Liss, Inc.