Magnetogenetics is the remote activation of cells using magnetic fields. Magnetogenetics is related to optogenetics, which is the manipulation of cell behavior using light. Magnetogenetics instead use magnetic stimuli to manipulate cell behavior, which can be less invasive in sensitive tissues, like neural tissue, since magnetogenetic methods do not require invasive surgery. This field developed from combining principles observed in various magnetotactic bacteria with optogenetic techniques, helping researchers manipulate cell behaviors and gene expression in the presence of magnetic fields. There are multiple tissues in the body that can be combined with magnetic proteins or with magnetosomes from bacteria, including brain tissue, tumors, and others. The activation of the magnetic compounds can cause effects on the organism via either mechanical or thermal effects.
, which are utilized for the applications of magnetogenetics, are typically found in aquatic environments and uniquely contain an organelle called a magnetosome. Microbes used to be thought as randomly spaced throughout an environment, research has been showing that magnetism of the earth and nearby magnet field may impact the locations of microbes. Now there is a significant amount of data found that can correlate the magnetic fields of objects and the earth, there is still more data required in order to make this correlation connected to causation. This membraned organelle contains a microscopic crystalline structure of a magnetic iron mineral. Magnetosomes are organized in long, chains which assists in the cells motile ability to align and swim parallel to magnetic fields, known as magnetotaxisThese orientations caused by the magnetosome can have various implications on eukaryotic cells that they inhabit. Two magnetotactc bacteria commonly used in laboratory settings are Magnetospirillummegneticum and Magnetosprillium gryphiswaldense due their ease in cultivation and ability to produce the compounds necessary for crystalline structure formation. To synthesize the magnetosomes first the cell invaginates it outer membrane to create a vesicle and allows for the magnetosome proteins to be sorted in the vesicle membrane. Iron is the imported into the magnetosome as crystal-coated structures, and the magnetosomes aggregate as a chain
Mechanisms
Brain stimulation
Magnetogenetic techniques involve first fusing TRPV class receptors, which are selective calcium transporters, with a paramagnetic protein. These paramagnetic proteins, which typically contain iron or have iron-containing cofactors, are then stimulated with a magnetic field exerted on the brain. The next steps in the activation of the neurons is still unclear, but it is thought that the ion channels are activated and opened either by a mechanical force exerted by the paramagnetic proteins, or by the heating of these proteins in response to the stimulation by the magnetic field.
Cancer
Magnetosomes can be engulfed by certain eukaryotic cells, and this allows the eukaryotic cells to be manipulated in specific ways. One such application is using magnetic resonance imaging. The paramagnetic particles contained within the magnetosomes in these bacteria can be used to positive or negative contrast agents. Magnetotactic bacteria have been found to be preferentially taken up by tumor cells allowing for these tumors to be imaged in an MRI. Magnetic hyperthermia is another potential application of the magnetosomes produced by these bacteria. Hyperthermia therapy is a current clinical technique used to treat cancers; however, magnetic hyperthermia could offer a more specific targeted cancer treatment.
