DEVICE FOR THERAPEUTIC PURPOSES ON HUMAN TISSUE, FOR INFLUENCING INJECTED MAGNETIC PARTICLES WITH AN ALTERNATING ELECTRO-MAGNETIC GRADIENT FIELD

Abstract: A new device for therapeutic influence, change, decomposition of various biological structures in vivo or in vitro by means of an externally applied alternating magnetic gradient field is described.

Description: DEVICE FOR THERAPEUTIC PURPOSES ON HUMAN TISSUE, FOR INFLUENCING INJECTED MAGNETIC PARTICLES WITH AN ALTERNATING ELECTRO- MAGNE IC GRADIENT FIELD. The present invention relates to equip-ent for changing, weakening or destroying biological structures in vivo and in vitro by means of a magnetic gradient field. BACKGROUND OF THE INVENTION Magnetism and magnetically responsible parcicles have been used for a long time in various biochemical and medical applications. When paramagnetic materials are exposed to an " externally alternating homogeneous magnetic field, heat is generated due to hysteresis. This generation of heat, m particular m combination v.ich super- paramagnetic nanopart icles , is used m cancer therapy and is then referred to as magnetic fluid hyperthermia (1) . A cancer cell normally has a higher temperature than a healthy cell and therefore does not tolerate as high a temperature rise as a healthy cell. Thus, tr.e cancer cells can be selectively destroyed or weakened without affecting the host organism. An alternative ~ethod is that the composition of the superparamagnetic particles is cf sucπ type that cancer cells are made it take m said particles into the cell, whereby the te~ρerature is raised more efficiently in the cancer cell without any considerable neat loss to the environment. Tr.is type of therapy has been found to be promising, whicr. is de- scribed, inter alia, m the patent literature (2, 3, 4, 5 , even If there is no clinically approved ~ agr.etιc equipment for this purpose for the time beir.g. A cell membrane is, inter alia, composed of lipids and', fatty acids, which both have poor therral conductiv- ity, which makes it difficult to fight the target cell efficiently with only extracellular heat generated by r , vs'-eresιs SUMMARY OF THE INVENTION According to the present invention, a device is provided which solves the above-mentioned problems. Thus, a device is provided for increasing the thermal and/or ki- netic energy of magnetically responsible particles, said device containing at least two magnetic field generating means, of which at least one is a coil, between which means an alternating magnetic gradient field can be generated m a spatially defined area, into which spatially defined area human or animal tissue can be introduced, said alternating magnetic gradient field causing an increase of the thermal and/or kinetic energy of magnetically responsible particles which have been added to said tissue, the increased thermal and/or kinetic energy of the magnetically responsible particles selectively reducing, deactivating or destroying endogenous or exogenous biological structures m said tissue. In one embodiment of the invention, one of the magnetic field generating means is a permanent magnet. In another embodiment of the invention, the device contains at least two coils and these coils are fed with alternating currents having different frequencies and/or amplitudes and/or phases, or alternatively said coils are fed with either the positive or the negative part of the fed alternating current. Furthermore, the device can suitably be equipped with a thermostat for careful temperature control of said tissue and/or with variable time setting for careful control of the time during which said tissue is exposed to the alternating magnetic gradient field. In one embodiment of the device, the alternating magnetic gradient field alternates with frequencies of up to 30 MHz and the field strength inside said coils amounts to at least 10 mT . The tissue which is to be treated can be a body part or an inner organ or blood, which are returned to the host organism after completed exposure to the alternating magnetic gradient field. The magnetically responsible particles suitably comprise a core of a metal oxide and a coating containing antibodies or parts thereof and have a size of 0.1- 300 nm. The magnetically responsible particles have been added to the host organism before the exposure of its tissue to the alternating magnetic gradient field, or alternatively after the tissue has been temporarily removed from the host organism. The endogenous or exogenous biological structures consist, for instance, of mammal cells, malignant cells, plant cells, nerve cells, bacteria, viruses, cellular organelles, cell membranes, cell walls, liposomes, proteins, protozoa, parasites, peptides, drugs, toxins, organic compounds, inorganic compounds, or combinations thereof . According to one aspect, the device is intended for m vivo or m vitro treatment of tumour diseases, endocrine disorders or infectious diseases. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic illustration of the behaviour of magnetically responsible materials m one embodiment of the device according to the invention. Fig. 2 is a schematic illustration of the structure of one embodiment of the device according to the invention for generating a magnetic gradient field with alternating gradient direction. Fig. 3 is an illustration of an electronic circuit which can be used to feed the coils m one embodiment of the device according to the invention with alternating current DETAILED DESCRIPTION OF THE INVENTION By the present invention, a new device is provided for use m a completely new method which combines the generation of heat by hysteresis with a powerful intro- duction of shearing forces. The shearing forces initiate dislocations m the biological structure, for instance m cell membranes, cell walls (m cases where the target cell is e.g. a bacterium) or m mtracellular components due to mechanical fatigue, which causes damage m the structures . The method is based on the use of an externally applied gradient magnetic field. Below, the invention will be described m more detail by means of the drawings, which show embodiments of the invention. Fig. 1 illustrates how a magnetically responsible particle is affected by a magnetic gradient field. Without the action of an external magnetic field, the dipoles 1 m the magnetically responsible particles are randomly oriented (Fig. 1A) . When the particles are exposed to a homogeneous magnetic field 2, the dipoles are oriented according to the direction of the field (Fig. IB) . When the direction of the homogeneous field alternates, the dipoles will alternate according to the field direction of the external homogeneous field. When the applied magnetic field is non-homogeneous, i.e. is a gradient magnetic field 3, the dipoles m the magnetically responsible particles will be aligned with the field direction at trie same time as the magnetically responsible par- tides will move towards the gradient according to Furthermore, by alternating the direction of the gradient, the magnetically responsible particle can be brought into mechanical vibration (due to the influence of forces it will alternately change directions) . Moreover, a combination of said magnetic gradient field with a homogeneous magnetic field can be provided either simultaneously or with a time shift so that a better orientation of the dipoles and greater shearing forces can be obtained. The generation of a gradient magnetic field whose direction periodically alternates (periodically shifts) requires a device according to the invention, for instance, as illustrated m Fig. 2. The functional principle is based on two coils A and B (with or without a ferrite core) being placed opposite to each other. A control unit C controls the current through the coils so that only one of the coils at a time has a current flowing through its windings. This alternation of current, whose frequency is controlled by the oscillator (OSC) , causes the coils to alternately create the gra- dient magnetic fields D and E with different gradient directions. A biological structure or a magnetically responsible particle P located between the coils will be exposed to a gradient magnetic field with periodically alternating direction, which will induce a mechanical vibration according to the description above. The present invention also comprises variants, m which, for instance, the current intensity or its direction through the windings of the coils can be controlled so that more efficient vibrations can be ob- tamed. A very useful special case is to let the gradient direction alternate but maintain the orientation of the dipoles by always letting the field direction be the same. This results m advantages, such as no provision of hysteresis (no generation of heat) , while the vibration frequency (=kmetιc energy) can be increased since the alternation rate of the dipoles will not be limited by the tendency of the magnetic material to counteract the alternation of the dipole directions. It is also possible to introduce additional coils to obtain more efficient or more directional vibrations. Fig. 3 illustrates an example of an electronic circuit which can be used to feed the coils the device according to the invention with alternating current. The circuit contains an oscillator 4 based on the circuit XR2206, whose output signal 5 is amplified by a power amplifying step 6, which is connected parallel and based on 5 circuits of the type PBD 3548/1 (manufactured by Ericsson) , whose output signal 7 can drive an alternating current (maximum 1 MHz, 10 A) through one or more coils . It is obvious to the one skilled m the art that the above-described electronic circuit m Fig. 3 is easy to modify and that the same result can be obtained by means of various alternative prior-art connections of oscillators and power amplifiers. One example of the connection of the coils is that each coil constitutes a part of an oscillation circuit consisting of a 0.5 Ω resistor, a 127 pF capacitor and a 200 μH coil, which are connected series, which oscillation circuit is fed with alternating current such as shown Fig . 3. An alternating gradient field is obtained between two coils which are part of said oscillation circuit and applied to an electronic circuit each, as shown Fig. 3, with the difference, however, that the coils are fed with 1.0 MHz and 0.9 MHz, respectively. The variation of the gradient field will be dependent on the difference frequency 1.0 MHz - 0.9 MHz. It is obvious to the one skilled the art that the above-described example is easy to modify and that the same result can be achieved by means of various alter- native connections and coils. REFERENCES 1. Jordan A., Wust P., Scholz R., Faehling H., Krause J. & Felix R. Magnet Fluid Hyperthermia, 569-597, m Scien- tific and Clinical Applications of Magnetic Carriers, edited by Hafeli U. , Schutt W., Teller J. and Zborowski M. Plenum Press 1997. 2. Gordon R.T. Cancer treatment. US Patent No. 4,303,636, 1981. 3. Gordon R.T. Cancer treatment method. US Patent No. 4,662,952, 1986. 4. Gordon R.T. Use of magnetic susceptibility probes in the treatment of cancer. US Patent No. 4,662,359, 1987. 5. Borelli N.F., Luderer A. A. & Panzar o J. N. Radio frequency induced hyperthermia for tumor therapy. US Patent No. 4,323,056, 1982.

Claims: CLAIMS 1. A device for increasing the thermal and/or kinetic energy of magnetically responsible particles, c h a r a c t e r i s e d that it contains at least two magnetic field generating means, of which at least one is a coil, between which means an alternating magnetic gradient field can be generated a spatially defined area, into which spatially defined area human or animal tissue can be introduced, said alternating magnetic gradient field causing an increase of the thermal and/or kinetic energy of magnetically responsible particles which have been added to said tissue, the increased thermal and/or kmetic energy of the magnetically responsible particles selectively reducing, deactivating or destroying endogenous or exogenous biological structures said tissue. 2. A device as claimed claim 1, c h a r a c t e r i s e d that one of the magnetic field generat- ing means is a permanent magnet. 3. A device as claimed claim 1 or 2 , c h a r a c t e r i s e d that it contains at least two coils, and that these coils are fed with alternating currents having different frequencies and/or amplitudes and/or phases, or alternatively that said coils are fed with either the positive or the negative part of the fed alternating current. 4. A device as claimed m one or more of claims 1-3, c h a r a c t e r i s e d m that it is equipped with a thermostat for careful temperature control of said tissue, and/or that it is equipped with variable time setting for careful control of the time during which said tissue is exposed to the alternating magnetic gradient field. 5. A device as claimed one or more of claims 1-4, c h a r a c t e r i s e d that the alternating magnetic gradient field alternates with frequencies of up to 30 MHz, and that the field strength inside said coils amounts to at least 10 mT . 6. A device as claimed m one or more of claims 1-5, c h a r a c t e r i s e d m that said tissue consists of a body part or an inner organ or blood, which are returned to the host organism after completed exposure to the alternating magnetic gradient field. 7. A device as claimed one or more of claims 1-6, c h a r a c t e r i s e d m that said magnetically re- sponsible particles comprise a core of a metal oxide and a coating containing antibodies or parts thereof and have 8. A device as claimed m one or more of claims 1-7, c h a r a c t e r i s e d m that said magnetically re- sponsible particles have been added to the host organism before the exposure of its tissue to the alternating magnetic gradient field, or alternatively that said magnetically responsible particles have been added to the tissue after the tissue has been temporarily removed from the host organism. 9. A device as claimed one or more of claims 1-8, c h a r a c t e r i s e d that said endogenous or exogenous biological structures consist of mammal cells, malignant cells, plant cells, nerve cells, bacteria, viruses, cellular organelles, cell membranes, cell walls, liposomes, proteins, protozoa, parasites, peptides, drugs, toxins, organic compounds, inorganic compounds, or combinations thereof. 10. A device as claimed one or more of claims 1- 9, c h a r a c t e r i s e d that it is intended for vivo or vitro use for treating tumour diseases, endocrine disorders or infectious diseases.

Inventors: FREDRIKSSON SARAH, KRIZ DARIO, FREDRIKSSON, SARAH, KRIZ, DARIO
Applicants: EUROP I OF SCIENCE AB, FREDRIKSSON SARAH, KRIZ DARIO, EUROPEAN INSTITUTE OF SCIENCE AB, FREDRIKSSON, SARAH, KRIZ, DARIO
Application year: 2000
Main classification: A61N2
IPC codes: A61N1, A61N2, C12M1