System for optical stimulation of target cells

Abstract

Stimulation of target cells using light, e.g., in vivo, is implemented using a variety of methods and devices. In one example, embodiments involve methods for stimulating target cells using a photosensitive protein that allows the target cells to be stimulated in response to light. In another specific example embodiment, target cells are stimulated using an implantable arrangement. The arrangement includes an electrical light-generation means for generating light and a biological portion. The biological portion has a photosensitive bio-molecular arrangement that responds to the generated light by stimulating target cells in vivo. Other aspects and embodiments are directed to systems and methods for screening chemicals based screening chemicals to identify their effects on cell membrane ion channels and pumps, and to systems and methods for controlling an action potential of neuron (e.g., in vivo and in vitro environments).

What is claimed is: 
     
         1 . A method for generating an inhibitory-current flow in neurons, the method comprising:
 in a neuron, engineering an inhibitory protein that responds to light by producing an inhibitory current to dissuade depolarization of the neuron, wherein the inhibitory protein uses an endogenous cofactor to produce the inhibitory current.   
     
     
         2 . The method of  claim 1 , wherein the inhibitory protein is an anion pump that includes a halorhodopsin derived from one of  Halobacterium salinarum  and  Natronomonas pharanois.    
     
     
         3 . The method of  claim 1 , the method further includes the step of, in the neuron, engineering an excitation protein that responds to light by producing an excitation current to encourage depolarization of the neuron. 
     
     
         4 . The method of  claim 3 , wherein the inhibitory protein has a first excitation wavelength maxima and the excitation protein has a second excitation wavelength maxima that is different from the first excitation wavelength maxima. 
     
     
         5 . The method of  claim 4 , further including the steps of
 controlling a first light source to produce a series of optical pulses each having a duration sufficient to induce individual depolarization events and   controlling a second light source to produce a series of optical pulses each having a duration sufficient to dissuade individual depolarization events.   
     
     
         6 . The method of  claim 5 , wherein the inhibitory protein includes halorhodopsin and the excitation protein includes channelrhodpsin, wherein the first light source is operated near the first excitation wavelength maxima, and wherein the second light source is operated near the second excitation wavelength maxima. 
     
     
         7 . The method of  claim 3 , wherein the inhibitory current includes chloride ions and the excitation current includes sodium ions. 
     
     
         8 . The method of  claim 1 , wherein the step of engineering includes at least one of: transduction of the neuron using a viral vector containing a halorhodopsin protein, transfection of the neuron, microinjection of DNA into the neuron, and genetically targeting the inhibitory protein to specific classes of neurons. 
     
     
         9 . The method of  claim 1 , wherein the inhibitory current substantially dissuades depolarization of the neuron in less than 500 milliseconds after introduction of light. 
     
     
         10 . The method of  claim 1 , further including the steps of introducing light to the protein to produce the inhibitory current, measuring a resulting ion concentration in the neuron using an optical sensor. 
     
     
         11 . The method of  claim 1 , wherein the inhibitory protein uses all-trans-retinal as a cofactor. 
     
     
         12 . The method of  claim 1 , wherein the inhibitory protein includes halorhodopsin derived from one of  Halobacterium salinarum  and  Natronomonas pharanois.    
     
     
         13 . A method for controlling action potential of a neuron, the method comprising:
 engineering a first light responsive protein in the neuron;   producing, in response to light, an inhibitory current in the neuron from the first light responsive protein;   engineering a second light responsive protein in the neuron; and   producing, in response to light, an excitation current in the neuron from the second light responsive protein.   
     
     
         14 . The method of  claim 13 , wherein the first light responsive protein has a first excitation wavelength maxima and the second light responsive protein has a second excitation wavelength maxima that is different from the first excitation wavelength maxima 
     
     
         15 . The method of  claim 14 , further including the steps of controlling individual action potentials in an action potential train using light pulses sufficiently near the first and second excitation wavelength maxima to produce the inhibitory current and the excitation current, respectively. 
     
     
         16 . The method of  claim 15 , wherein the light pulses have a frequency between 5 and 30 Hertz. 
     
     
         17 . The method of  claim 13 , wherein the steps of producing an inhibitory current and the step of producing an excitation current include implanting a light source near the neuron. 
     
     
         18 . The method of  claim 13 , wherein the first light responsive protein has a first excitation wavelength maxima and the second light responsive protein has a second excitation wavelength maxima that is different from the first excitation wavelength maxima and wherein the first light responsive protein includes halorhodopsin and the second light responsive protein includes channelrhodpsin. 
     
     
         19 . A method for controlling a voltage level across a cell membrane of a cell, the method comprising:
 engineering a first light responsive protein in the cell;   measuring the voltage level across the cell membrane; and   producing, in response to light of a first wavelength and using the first light responsive protein, a first current across the cell membrane that is responsive to the measured voltage level.   
     
     
         20 . The method of  claim 19 , further including the steps of
 engineering a second light responsive protein in the cell; and   producing, in response to light of a second wavelength and using the second light responsive protein, a second current across the cell membrane that is responsive to the measured voltage level.   
     
     
         21 . The method of  claim 19 , wherein the production of the first current is controlled to clamp the voltage level across the cell membrane. 
     
     
         22 . The method of  claim 20 , wherein the step of producing the first current is in response to the measured voltage level across the cell membrane having a voltage more positive than a threshold voltage range and wherein the first current results in a negative change in the voltage level across the cell membrane. 
     
     
         23 . The method of  claim 22 , wherein the step of producing the second current is in response to the measured voltage level across the cell membrane having a voltage more negative than a threshold voltage range and wherein the second current results in a positive change in the voltage level across the cell membrane. 
     
     
         24 . A system for controlling an action potential of a neuron in vivo, the system comprising:
 a delivery device that introduces a light responsive protein to the neuron, wherein the light responsive protein produces an inhibitory current;   a light source that generates light for stimulating the light responsive protein; and   a control device that controls the generation of light by the light source.   
     
     
         25 . The system of  claim 24 , wherein the delivery device introduces the light responsive protein by one of transfection, transduction, electroporation and microinjection. 
     
     
         26 . The system of  claim 24 , wherein the light source introduces light to the neuron via one of an implantable light generator and fiber-optics. 
     
     
         27 . A method for treatment of a disorder, the method comprising:
 in a group of neurons associated with the disorder, engineering inhibitory proteins that use an endogenous cofactor to respond to light by producing an inhibitory current to dissuade depolarization of the neurons; and   exposing the neurons to light, thereby dissuading depolarization of the neurons.   
     
     
         28 . The method of  claim 27 , further comprising the step of imaging neurons to determine the effectiveness of the treatment. 
     
     
         29 . An implantable arrangement for in vivo use, comprising:
 light-generation means for generating light; and   a biological portion that modifies target cells to facilitate stimulation of the target cells in response to the light generated by the light-generation means.   
     
     
         30 . The implantable arrangement of  claim 29 , wherein the implantable arrangement is scopically-deliverable. 
     
     
         31 . The implantable arrangement of  claim 29 , wherein the implantable arrangement is stereotactically deliverable. 
     
     
         32 . The implantable arrangement of  claim 29 , wherein the biological portion modifies the target cells to produce a light-activatable ion channel protein in the target cells. 
     
     
         33 . The implantable arrangement of  claim 32 , wherein the light-activated ion channel protein is coded for by a virus configured to infect the target cells. 
     
     
         34 . The implantable arrangement of  claim 32 , wherein the light activated ion channel protein one of Channelrhodopsin-2, Chop2, ChR2-310 and Chop2-310. 
     
     
         35 . The implantable arrangement of  claim 29 , wherein the light-generation means includes a light-emitting-diode responsive to an input signal. 
     
     
         36 . The implantable arrangement of  claim 29 , wherein the biological portion includes a viral matrix containing viral vectors. 
     
     
         37 . The implantable arrangement of  claim 29 , wherein the biological portion includes a membrane layer containing viral vectors. 
     
     
         38 . The implantable arrangement of  claim 33 , wherein the light-activated ion channel protein is one of Channelrhodopsin-2, Chop2, ChR2-310 and Chop2-310. 
     
     
         39 . The implantable arrangement of  claim 33 , wherein the light-activated ion channel protein is halorhodopsin. 
     
     
         40 . The implantable arrangement of  claim 29 , wherein the target cells are neurons. 
     
     
         41 . The implantable arrangement of  claim 29 , wherein the stimulation includes electrical current due to depolarization of the target cell. 
     
     
         42 . An implantable device for stimulating target cells modified to have a photosensitive bio-molecular structure, comprising:
 a light generator to generate light in response to an external signal; and   a biological arrangement that modifies the target cells to include the photosensitive bio-molecular structure.   
     
     
         43 . The device of  claim 42 , wherein the photosensitive bio-molecular structure is a light-activatable ion channel protein. 
     
     
         44 . The device of  claim 42 , wherein the photosensitive bio-molecular structure is Channelrhodopsin-2. 
     
     
         45 . The device of  claim 42 , wherein the photosensitive bio-molecular structure is a light-activatable charged-ion membrane channel. 
     
     
         46 . The device of  claim 42 , wherein the photosensitive bio-molecular structure is Chop2. 
     
     
         47 . The device of  claim 42 , wherein the photosensitive bio-molecular structure is ChR2-310. 
     
     
         48 . The device of  claim 42 , wherein the photosensitive bio-molecular structure is Chop2-310. 
     
     
         49 . The device of  claim 42 , wherein the photosensitive bio-molecular structure is halorhodopsin. 
     
     
         50 . The device of  claim 42 , further including a signal-reception circuit, electrically coupled to the light generator, to respond to the external signal. 
     
     
         51 . The device of  claim 50 , wherein the external signal is an electromagnetic transmission, and wherein the signal-reception circuit includes at least one coil and a light-emitting diode, said at least one coil and the light-emitting diode being activated to provide the generated light in response to the electromagnetic transmission. 
     
     
         52 . The device of  claim 50 , wherein the external signal is a radio-frequency (RF) transmission, and wherein the signal-reception circuit includes an RF receiver being activated to provide the generated light in response to the RF transmission. 
     
     
         53 . The device of  claim 51 , wherein the electromagnetic transmission includes a power portion of the transmission that charges a power source and a signal portion of the transmission that is used to enable or disable the light generator. 
     
     
         54 . A method for stimulating target cells using a photosensitive protein that allows the target cells to be stimulated in response to light, the method comprising:
 implanting vectors that modify the target cells to include the photosensitive protein;   implanting a light generating device near the target cells; and   activating the light generating device to generate light to be received by the target cells, thereby stimulating the target cells in response to the generated light.   
     
     
         55 . The method of  claim 54 , wherein the steps of implanting is accomplished using stereotactic surgery. 
     
     
         56 . The method of  claim 54 , wherein the step of implanting vectors includes using a viral matrix to contain the vectors until implanted, wherein the vectors are released from the viral matrix in vivo thereby infecting the target cells to induce production of photosensitive proteins in vivo. 
     
     
         57 . The method of  claim 54 , further including the step of
 using a growth medium to grow the target cells, wherein the target cells contain the photosensitive protein.   
     
     
         58 . The method of  claim 54 , wherein the target cells are neurons and the photosensitive protein is part of a viral vector. 
     
     
         59 . The method of  claim 54 , wherein the step of activating the light generating device is in response to an external signal. 
     
     
         60 . The method of  claim 59 , wherein the external signal is an electromagnetic signal. 
     
     
         61 . The method of  claim 59 , wherein the external signal is a radio-frequency signal. 
     
     
         62 . The method of  claim 59 , wherein the external signal includes a power portion of the external signal that charges a power source and a signal portion of the external signal that is used to enable or disable the light generator. 
     
     
         63 . An arrangement for stimulating target cells using a photosensitive protein that allows the target cells to be stimulated in response to light, the arrangement including:
 means for implanting vectors that modify the target cells to include the photosensitive protein;   means for implanting a light generating device near the target cells; and   means for activating the light generating device to generate light to be received by the target cells, thereby stimulating the target cells in response to the generated light.   
     
     
         64 . The arrangement of  claim 63 , wherein the stimulation results in activation of the target cells. 
     
     
         65 . The arrangement of  claim 63 , wherein the stimulation results in suppression of activity by the target cells. 
     
     
         66 . A system for screening chemicals to identify their effects on cell membrane ion channels and pumps, comprising:
 screening cells having light responsive cation channels, anion pumps, voltage gated cation channels and fluorescence producing voltage sensors;   a chemical delivery device for introducing a chemical to be screened;   an optical delivery device to activate the light responsive cation channels;   an optical sensor to monitor fluorescence produced by the voltage sensors;   a processor to process data received from the optical sensor; and   memory for storing the data received from the optical sensor.   
     
     
         67 . A method for screening chemicals to identify their effects on cell membrane ion channels and pumps, comprising:
 introducing a chemical to be screened to cells having light responsive cation channels, anion pumps, voltage gated cation channels and fluorescence producing voltage sensors;   activating the light responsive cation channels by generating light pulses;   detecting fluorescence produced by the voltage sensors;   processing data from the detection to identify changes in electrical properties of the cells; and   storing the processed data.   
     
     
         68 . A method for controlling maturation of a stem or progenitor cell having a cell membrane, the method comprising:
 engineering a light responsive protein in the cell;   optically stimulating the light responsive protein to produce a current across the cell membrane to affect maturation of the cell.