title: Differential viability response of prokaryotes and eukaryotes to high strength pulsed magnetic stimuli.
abstract: The present study examines the efficacy of a high strength pulsed magnetic field (PMF) towards bacterial inactivation in vitro, without compromising eukaryotic cell viability. The differential response of prokaryotes [Staphylococcus aureus (MRSA), Staphylococcus epidermidis, and Escherichia coli], and eukaryotes [C2C12 mouse myoblasts and human mesenchymal stem cells, hMSCs] upon exposure to varying PMF stimuli (1-4 T, 30 pulses, 40 ms pulse duration) is investigated. Among the prokaryotes, ~60% and ~70% reduction was recorded in the survival of staphylococcal species and E. coli, respectively at 4 T PMF as evaluated by colony forming unit (CFU) analysis and flow cytometry. A 2-5 fold increase in intracellular ROS (reactive oxygen species) levels suggests oxidative stress as the key mediator in PMF induced bacterial death/injury. The 4 T PMF treated staphylococci also exhibited longer doubling times. Both TEM and fluorescence microscopy revealed compromised membranes of PMF exposed bacteria. Under similar PMF exposure conditions, no immediate cytotoxicity was recorded in C2C12 mouse myoblasts and hMSCs, which can be attributed to the robust resistance towards oxidative stress. The ion interference of iron containing bacterial proteins is invoked to analytically explain the PMF induced ROS accumulation in prokaryotes. Overall, this study establishes the potential of PMF as a bactericidal method without affecting eukaryotic viability. This non-invasive stimulation protocol coupled with antimicrobial agents can be integrated as a potential methodology for the localized treatment of prosthetic infections.
authors.affiliation: Laboratory for Biomaterials, Materials Research Centre, Indian Institute of Science, Bangalore 560012, India.
authors.forename: Sunil Kumar
authors.initials: SK
authors.lastname: Boda
authors.affiliation: Laboratory for Biomaterials, Materials Research Centre, Indian Institute of Science, Bangalore 560012, India.
authors.forename: K
authors.initials: K
authors.lastname: Ravikumar
authors.affiliation: Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore 560012, India; Centre for Biosystems Science and Engineering, Indian Institute of Science, Bangalore 560012, India.
authors.forename: Deepak K
authors.initials: DK
authors.lastname: Saini
authors.affiliation: Laboratory for Biomaterials, Materials Research Centre, Indian Institute of Science, Bangalore 560012, India; Centre for Biosystems Science and Engineering, Indian Institute of Science, Bangalore 560012, India. Electronic address: bikram@mrc.iisc.ernet.in.
authors.forename: Bikramjit
authors.initials: B
authors.lastname: Basu
mesh_terms: D000818:Animals; D017209:Apoptosis; D002478:Cells, Cultured; D015169:Colony Count, Microbial; D004926:Escherichia coli / Q000254:growth & development / Q000502:physiology; D005057:Eukaryotic Cells / Q000502:physiology*; D005434:Flow Cytometry / Q000379:methods; D006801:Humans; D060526:Magnetic Fields; D055624:Methicillin-Resistant Staphylococcus aureus / Q000254:growth & development / Q000502:physiology; D051379:Mice; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D018384:Oxidative Stress; D011387:Prokaryotic Cells / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D013212:Staphylococcus epidermidis / Q000254:growth & development / Q000502:physiology
chemical_list: D017382:Reactive Oxygen Species
keywords: Eukaryotes; Flow cytometry; PMF; Prokaryotes; Pulsed magnetic field; Reactive oxygen species (ROS)