Influence of Static Magnetic Field on Cell Viability in a Miniaturized Optically Accessible Bioreactor

Several previous studies have shown how static magnetic fields are capable or not to influence cell constructs with both positive or negative effects. Several devices have been developed to expose cells in culture to a static magnetic field. Their main shortages were the absence of perfusion, the possibility to host only 2D cell monolayers and the lack of optical accessibility. Given the great dimensions and the complexity of those systems, difficulties in terms of reproducibility of the measurements were often encountered. To overcome these limitations, a Miniaturized Optically Accessible Bioreactor (MOAB) was developed and exploited to investigate the influence of a static magnetic field of moderate intensity on cell viability. The exposure system was characterized by the presence of two coupled neodymium-made permanent magnetic rings. Perfusion, accomodation of 3D cellularised constructs in polystyrene scaffolds of 400 microns in thickness and optical accessibility to fluorescence diagnostics for imaging and also Oxygen measurement are the three main features of the MOAB bioreactor. The MOAB is already extensively validated for advanced cell modelling in several fields including neuroscience and cancer. A bioreactor without magnets was also developed to have a control system for the investigation. A numerical characterization of the magnets was performed to show the static magnetic field intensity range and distribution to which cell constructs were exposed. The simulations showed that the magnetic field intensity inside the chamber ranges from 320 to 570 Tesla. The experimental analysis was performed with a Neuroblastoma cell line exploiting the novel bioreactor for the dynamic analysis while static tests both in monolayer and 3D culture configuration were carried out inside a custom-made system with magnets integrated for exposure and without magnets for controls. An hydraulic testing of the two kind of bioreactors has preceeded in order to evaluate the tolerance in terms of hydraulic sealing of both kind of bioreactors: the devices showed they were able to tolerate pressures and flow rates several times higher than the standard ones used during the experimental investigations. In both static and dynamic investigations, cell viability and proliferation did not show statistical differences between the perfused constructs exposed to the magnetic field and the controls.