Photodynamic effect on cancer cells influenced by electromagnetic fields

The synergism of low-frequency electromagnetic field treatment and photodyn amic effect on killing of human cancer cells is presented. The weak pulsati ng electromagnetic field (PEMF) generated by Helmholtz coils in the mT rang e influences the permeability of cell membranes for photosensitizers. Sever al types of sensitizers were excited by visible light during incorporation without and with two kinds of PEMF treatment. In the first part suitable ph otosensitizers were selected in the absorption range between 400 and 700 ru n against human myeloid leukaemia K562 and human histiocytic lymphoma U937 cells by treatment of PEMF consisting of rectangular pulse groups. In the s econd part amplitude and frequency dependencies were measured using sinuous PEMF and white light with the result that after 12 min the PEMF treatment enhanced photodynamic effectivity by more than 40% over the control value. Taking into account the influence of many parameters, an additional optimiz ation will be possible by photodynamic PEMF synergism for an increased drug delivery in general. (C) 2001 Elsevier Science B.V. All rights reserved.