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

TLDR

Microtubules align with static magnetic fields in vitro due to diamagnetic anisotropy, yet it has not been experimentally shown whether mitotic spindles in cells align under ultra‑high magnetic fields above 20 T. We demonstrate that 27 T static magnetic fields orient and deform mitotic spindles in human CNE‑2Z and RPE1 cells, with alignment governed more by chromosome planar arrangement than microtubules, marking the first report of cellular responses to ultra‑high magnetic fields and offering a tool to probe spindle orientation in biology.

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 cells can be aligned by magnetic field has not been experimentally proved. In particular, the biological effects of SMF of above 20 T (Tesla) 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 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.