Optogenetic Vision Restoration

所有年龄段的超过10万美国人都患有遗传性视网膜疾病(IRD)，这些疾病会导致渐进性失明。在大多数IRD中，疾病始于视杆，导致从外围到中心的视力丧失，使患者无法导航他们的周围。电子视网膜假体恢复了受IRDS影响的患者的有用视力，光遗传学是一种替代治疗方法。微生物视黄素用于恢复视网膜光敏感性的一个主要限制是激活通道视紫红质所需的高光强。解决这一问题的一种方法是使用具有更高光敏感度但运动速度足够快的视蛋白，以实现有用的运动视觉。 我们提出了一种新的方法来恢复患者的视力，使用病毒来表达光敏感 蛋白质在特定的二级视网膜神经元中，使它们对光敏感。我们的方法使用了一个通用的 神经元受体，经过修改，为剩余的光不敏感视网膜增加了感光功能 光感受器退化后存活的神经元。受体使用两种视网膜中的一种，后者是可用的 或通过玻璃体内注射的合成化学光开关。通过这种方式，细胞中的细胞 感受器所在的位置通过神经放电的变化对光做出反应。这补偿了他们的损失 光感受器的输入，恢复对视网膜的光反应，并将信息发送到 恢复视力的大脑。在大多数情况下，此方法独立于导致 光感受器退化。这种方法的例外可能是导致RPE细胞死亡的疾病，如 脉络膜血症。 到目前为止，这种方法的版本，由共同PI开发的Isacoff和Flannery以及其他人在 FIELD使用了对光相当不敏感或反应非常慢的受体，所以不能 支持正常视力。我们现在提出一种新的策略，它使用了 GPCR信号可提高灵敏度(1000倍)和速度。GPCR信号级联是固有的 视杆细胞和视锥细胞，以及视网膜中的双极细胞、神经节细胞和其他细胞。我们还追求一种新的 发现，从我们的初步实验中出现，这使得组合方法能够使用 一次多个光学传感器分子，以重现自然生物多样性 在早些时候丢失的视网膜中发出信号。最后，我们使用复杂的行为分析来 测试不仅是恢复区分黑暗中的光或稳定光中的闪光的能力，而且要确定 如果动物能够看到图像的话。这一计划的成功将代表着在创建 一种基于基因疗法的视网膜假体。

Over 100,000 Americans of all ages suffer from inherited retinal diseases (IRD), which cause a progressive loss of vision. In most IRDs, disease begins in the rods, causing vision loss from the periphery to the center, leaving patients unable to navigate their surroundings. Electronic retinal prosthesis restore useful vision in patients affected by IRDs, and optogenetics is an alternative therapeutic. A major limitation of microbial opsins for restoration of retinal light sensitivity is the high light intensity required for activating channelrhodopsins. A solution to this caveat is the use of opsins with higher light sensitivity but sufficiently fast kinetics for useful motion vision. We propose a novel approach to restore vision to patients using a virus to express a light sensitive protein in specific, second-order retina neurons to make them light sensitive. Our approach uses a common neuronal receptor, modified to add a light receptive function to the remaining light-insensitive retinal neurons that survive after photoreceptor degeneration. The receptor uses either retinal, which is available in the eye, or a synthetic chemical photoswitch delivered by intravitreal injection. In this way, the cells in which the receptor is located respond to light with a change in neural firing. This compensates for their loss of input from photoreceptors, restoring light responsiveness to the retina and sending information to the brain to restore vision. In most cases, this approach is independent of the mutation that caused the photoreceptor degeneration. Exceptions to this approach may be diseases that cause RPE cell death, such as choroideremia. To date, versions of this approach, developed by Co-PIs Isacoff and Flannery, and others in the field, have employed receptors that are rather insensitive to light or very slow in response and so could not support normal vision. We now propose a new strategy that uses the natural amplification properties of GPCR signaling to increase sensitivity (by 1000 times) and speed. GPCR signaling cascades are intrinsic to rods and cones, as well as bipolar, ganglion cells and other cells in the retina. We also pursue a new discovery, emerging from our preliminary experiments, which enables a combinatorial approach that uses more than one optical sensor molecule at a time in order to recreate the natural diversity of natural signaling in the retina that had earlier been missing. Finally, we employ sophisticated behavioral analysis to test not only the restoration of the ability to tell light from dark or flashing from steady light, but to determine if the animal is able to see images. Success of this program would represent a major step in the creation of a retinal prosthetic based on gene therapy.