Device & Method for In-depth Activation of Genetically Targeted Excitable Cells with High Spatial Resolution Using Two-Photon Excitation with a Laser
Background: Recently light-assisted activation of selected groups (expressing the same gene) of electrically excitable cells such as neurons has been made possible with high temporal precision by introducing a light-activated molecular channel called channelrhodopsin -2 (ChR2). This method has advantage over electrical stimulation because it is non-invasive and exhibits cellular specificity. Selective activation of neurons by ms pulsed blue light has been demonstrated in cell culture, brain slices as well as in live animals. This light activation method is also practical as it only requires light of very low intensity (few mW/mm2) and can be achieved by a lamp with a bandpass filter or small laser diode. In this method, the penetration of the activating light beam is very much limited since the activation peak of ChR2 is around 460 nm, where absorption and scattering coefficients of biological tissue is very high. Although genetic targeting allows simultaneous activation of a defined cell population, some experiments may necessitate selective activation of single cells or even different positions of the same cell. Since the single photon (blue) light beam cannot be spatially confined to a very small volume, it is difficult to activate sub-regions of ChR2 expressing cells without affecting the neighboring cells. Therefore, in depth activation with high spatial resolution is difficult to achieve by single photon methods. Technology: Researchers at the University of California, Irvine have developed a method to use near-infrared (NIR) two-photon absorption in order to activate the genetically excitable cells at much larger depths (as compared to single-photon absorption) leading to better efficacy for in-vivo applications. The purpose of this invention is to activate excitable cells such as neurons (after making them express ChR2 in a promotor specific way) by a near infrared light beam that will allow larger penetration depth into tissues such as brain and also being very precise in both the spatial and temporal domains. The use of two-photon absorption will offer a new and better way to achieve activation of ChR2 as well as other molecules of a similar nature. The two-photon optical activation and imaging can help scientists to better understand and modulate physiological functions of various excitable cells in skeletal, cardiac and neuronal systems, and also accelerate high throughput ion-channel drug screening. Application: The invention being developed by the researchers at the University of California, Irvine can be used for the following purposes: a) controlled modulation of physiological functions of various excitable cells in skeletal, cardiac and neuronal systems, etc.; 2) a new method of performing minimally invasive in-depth activation of specific target areas of the excitable tissue; and 3) high through-put screening for drugs that modulate cellular responses to activation induced depolarization.Type of Offer: Licensing
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