Static magnetic fields induce blood flow decrease and platelet adherence in tumor microvessels

Abstract

Red blood cell flow in striated muscle capillaries is reduced during exposure to strong static magnetic fields (SMFs). Intratumoral microcirculation is characterized by tortuous microvessels with chaotic architecture and by irregular, sluggish blood flow with unstable rheology.It was the aim of this study to analyze SMF exposure effects on tumor microcirculation with regard to interactions of corpuscular blood components with tumor microvessel walls. In vivo fluorescence microscopy was performed in A-Mel-3 tumors growing in dorsal skinfold chamber preparations of Syrian Golden hamsters. SMFs with varying field strength (<600 mT) were generated by changing the distance between a strong NdFeB rod magnet and the tissue region of interest.Short-time exposure above a magnetic flux density of about 150 mT resulted in a significant reduction of red blood cell velocity (v RBC ) and segmental blood flow in tumor microvessels. At the maximum strength of 587 mT, a reversible reduction of v RBC (~40%) and of functional vessel densitiy (~15%) was observed.Prolongation of the exposure time from one minute to up to 3 h resulted in comparable reductions. Microvessel diameters and leukocyte-endothelial cell interactions remained unaffected by SMF exposure. However, in contrast to tumor-free striated muscle controls, exposure at the maximum flux density induced a significant increase in platelet-endothelial cell adherence in a time-dependent manner that was reversible after reducing SMF strength.These reversible changes may have implications for functional measurements of tumor microcirculation by MRI and new therapeutic strategies using strong SMFs.

Static magnetic fields impair angiogenesis and growth of solid tumors in vivo

“…In that study we observed a reversible reduction of blood flow in tumor vessels as well as activation and adherence of platelets by direct visualization of tumor microcirculation in vivo. 8 proof that tumor microcirculation is affected by SMF exposure. Further, they might explain the previously described phenomenon of improved antitumoral efficacy of conventional chemotherapy if combined with SMF exposure.…”

Inhibitory Effects of Moderate Static Magnetic Field on Leukemia

“…The effects of magnetic field on tumors have been reported in some studies [12]- [15]. After Syrian Golden hamsters bearing A-Mel-3 tumors being exposed to a magnetic field of about 150 mT for short-time, the red blood cell velocity and segmental blood flow in tumor microvessels were significantly reduced [12].…”

“…After Syrian Golden hamsters bearing A-Mel-3 tumors being exposed to a magnetic field of about 150 mT for short-time, the red blood cell velocity and segmental blood flow in tumor microvessels were significantly reduced [12]. In vitro, after exposure under 1 T SMF for 72 h, the metabolic activity of human leukemia cell HL-60 was retarded to 81% [13], but exposure to the SMF of 6 mT did not induce any apoptogenic effects in HL-60 cells [14].…”

Clinical aspects of static magnetic field effects on circulatory system

“…In addition, using a dorsal skinfold chamber technique for intravital fluorescence microscopy, Strieth research group demonstrated that SMF exposure ranging 150-600 mT for 3 h induced a significant reduction of functional vessel density, vessel diameters, and red blood cell velocity in tumors (Brix et al 2008;Strieth et al 2008;Strelczyk et al 2009). Exposure to SMF (600 mT for 3 h) resulted in a significant retardation of tumor growth (*30%) (Strelczyk et al 2009).…”