Letter to the Editor Electric and Magnetic Fields in Cryopreservation Brian Wowk 21st Century Medicine, Inc., 14960 Hilton Drive, Fontana, California 92336, USA Abstract Electromagnetic warming has a long history in cryobiology as a preferred method for recovering large tissue masses from cryopreservation, especially from cryopreservation by vitrification. It is less well-known that electromagnetic fields may be able to influence ice formation during cryopreservation by non-thermal mechanisms. Both theory and published data suggest that static and oscillating electric fields can respectively promote or inhibit ice formation under certain conditions. Evidence is less persuasive for magnetic fields. Recent claims that static magnetic fields smaller than 1 mT can improve cryopreservation by freezing are specifically questioned. Keywords: Electric field; Magnetic Field; Freezing; Ice Formation There have been several recent articles in the scientific literature and popular press concerning cryobiology applications of CAS (“Cell Alive System”) freezers from ABI Corporation Ltd. (Abiko, Japan). In 2010, Cryobiology reported findings by Kaku et al in which a CAS freezer was used to produce very weak magnetic fields during freezing of periodontal ligament (PDL) cells and tissues in 10% dimethyl sulfoxide (9). Superior cell viability and tissue histology was observed compared to control cells cryopreserved without a magnetic field. A follow-up study by the same group in 2011 in Cryobiology reported favorable comparisons between frozen-thawed PDL tissue vs. unfrozen controls, and clinical results after transplantation of teeth cryopreserved by the CAS process (1), again using a very weak magnetic field (0.01 mT). Other papers suggested that ice crystal damage might be reduced by “slightly magnetizing” a whole ovary during freezing without cryoprotectant (24,14). Forbes magazine reported in 2008 that 47 researchers were experimenting with ABI Corporation freezing technology to preserve human organs (11). The proposed use of magnetic fields to improve cryopreservation by freezing raises many questions. Before asking them, a brief review of what is known about effects of electric and magnetic fields on ice formation follows. Electric fields and ice formation Water molecules have an intrinsic electric dipole moment, making water a dielectric material. Water molecules rotate in response to an applied electric field, which is the mechanism by which oscillating electric fields heat pure water (dielectric heating). Electric fields oscillating at radio or microwave frequencies are a preferred method for achieving rapid and uniform warming of cryopreserved materials (13,15,32).