ABSTRACT
Sources of exposure for the magnetic control of cell growth can be static or time-varying (pulsed) magnetic fields. Magneto-mechanical effects and magnetically induced electric currents are the basic mechanisms of physical stimuli in the magnetic control of cell growth. A static magnetic field generates magneto-mechanical effects known as “magnetic orientation” and “magnetic force,” although this chapter only focuses on medical applications of the former effect. Historically, the first instance of the magnetic control of cell growth by a static magnetic field was the polymerization of fibrin gel in strong magnetic fields, performed by Torbet et al. (1981) and Torbet and Ronziere (1984). Torbet el al. demonstrated the polymerization of fibrin fibers in an 11 T static magnetic field and reported that the fibers aligned in a particular direction with respect to the magnetic field (known as the “magnetic orientation”) when the polymerization was carried out slowly (Torbet et al. 1981). Magnetic orientation has been observed in various biological molecules such as collagen (Murthy 1984; Torbet and Ronziere 1984; Kotani et al. 2000), and cells such as osteoblast cells (Kotani et al. 2000, 2002), Schwann cells (Eguch et al. 2003; Eguchi and Ueno 2005), vascular endothelial cells, and smooth muscle cells (Umeno et al. 2001; Umeno and Ueno 2003; Iwasaka and Ueno 2003a,b; Iwasaka et al. 2003). Owing to these experiments, this phenomenon is now a scientifically established effect of static magnetic fields (WHO EHC 232 2006; ICNIRP 2009). Medical applications of the magnetic orientation have been demonstrated in various targets (Ueno and Sekino 2006).
