27 T ultra-high static magnetic field changes orientation and morphology of mitotic spindles in human cells

Abstract

Purified microtubules have been shown to align along the static magnetic field (SMF) in vitro because of their diamagnetic anisotropy. However, whether mitotic spindle in mammalian cells can be aligned by magnetic field has not been experimentally proved. In particular, the biological effects of SMF of above 20 T (Tesla) on mammalian cells have never been reported. Here we found that in both CNE-2Z and RPE1 human cells spindle orients in 27 T SMF. The direction of spindle alignment depended on the extent to which chromosomes were aligned to form a planar metaphase plate. Our results show that the magnetic torque acts on both microtubules and chromosomes, and the preferred direction of spindle alignment relative to the field depends more on chromosome alignment than microtubules. In addition, spindle morphology was also perturbed by 27 T SMF. This is the first reported study that investigated the mammalian cellular responses to ultra-high magnetic field of above 20 T. Our study not only found that ultra-high magnetic field can change the orientation and morphology of mitotic spindles, but also provided a tool to probe the role of spindle orientation and perturbation in developmental and cancer biology.DOI: http://dx.doi.org/10.7554/eLife.22911.001

Effect of static magnetic field on DNA synthesis: The interplay between DNA chirality and magnetic field left‐right asymmetry

“…For example, it is already known that DNA chain has relatively large diamagnetic anisotropy 60 and theoretical predictions suggested that mitotic chromosome arms might generate electromagnetic fields along the chromosome arm direction 61 and chromosomes theoretically should be fully aligned by SMFs of around 1.4 T. 62 We have previously shown that ultra-high SMF up to 27 T could affect the orientation of spindles in the cell after 4-hour exposure, which is determined by both microtubules and chromosomes. 63 Although different methods could be used for the alignment of individual DNA molecules, all these methods consider the immobilization and/or constriction of DNA by either chemically modified surfaces or geometry (pores, channels etc). As for the possibilities to use DNA fibers to test our hypothesis, it was recently demonstrated that a single chromatin fiber is torsionally softer than a braided one by direct torque measurements.…”

Cellular ATP levels are affected by moderate and strong static magnetic fields

“…We have previously studied the effects of different magnetic field intensities (1 T, 9 T, and 27 T) for their effects on mitotic spindles [Zhang et al, 2017a], and different magnetic field intensities (1 T, 9 T, and 27 T) for their effects on epidermal growth factor receptor (EGFR) protein alignment and cell proliferation [Zhang et al, 2016], and found that some cancer cell proliferation can be inhibited by 1 T and 9 T SMFs [Zhang et al, 2015[Zhang et al, , 2016[Zhang et al, , 2017b. We found that magnetic field intensity is a key factor for SMFinduced cellular effects.…”

Cells in the Non‐Uniform Magnetic World: How Cells Respond to High‐Gradient Magnetic Fields

“…[43] In general, stem cells as a "material" are softer than their mature differentiated counterparts and thus highly responsive to the application of small mechanical stress. [13] Finally, metastasizing cancer cells are able to adapt their nuclear size, cell deformability, and cell-to-substrate adhesion and tissue invasion efficiency. [46] The dynamic instability of microtubules and small forces that accompany mitosis are a distinctive feature of the soft mode.…”

“…Change of the orientation of the mitotic spindle Cancerous and normal human cells 27 T, Low gradient 4 h [13] 12…”

“…[10] Cells can miraculously sense magnetic forces [5,[11][12][13][14][15][16] and scientists rarely stop to consider how magnetic fields affect cellular functions and can be used to drive cell fate. [10] Cells can miraculously sense magnetic forces [5,[11][12][13][14][15][16] and scientists rarely stop to consider how magnetic fields affect cellular functions and can be used to drive cell fate.…”