Ultrasound-Enhanced Delivery of Medications to the Eye

描述（由申请人提供）：该项目的目标是开发一种安全有效的方法，将大分子药物输送穿过眼壁，以治疗疾病，特别是年龄相关性黄斑变性（AMD）。AMD是一种影响多达1500万美国人的进行性眼病，并且是美国65岁以上成人视力丧失和法律的失明的头号原因。目前正在评估几种有前途的大分子药物用于治疗AMD。由于眼睛的外壳（巩膜）相对不能渗透高分子量药物，眼内注射是实现递送至视网膜和脉络膜的最广泛使用的手段。因此，必须通过每隔几周的玻璃体内注射来完成大分子药物向眼睛中的递送，并发症（感染、视网膜脱离、眼内压升高）的发生累积增加。出于这个原因，用于递送大分子药物的非侵入性方法受到极大关注。超声在过去已被证明能够使组织对大分子更具渗透性。我们建议研究不同频率，强度和持续时间的超声波对荧光标记分子（葡聚糖）经巩膜转运到兔眼的影响。我们将使用分子量为10-kDa、70-kDa和500-kDa的葡聚糖，每种葡聚糖具有不同波长的荧光标记。（现在用于治疗AMD的药物的分子量通常约为150 kDa。我们将进行两个系列的实验，第一个涉及使用一个未聚焦的20 kHz的超声源，第二个利用一种新的超声设备组成的两个900 kHz的共焦环。该装置提供了允许聚焦和避免潜在敏感结构（例如角膜、透镜和黄斑）的优点。通过以略微不同的频率驱动两个元件，产生对应于频率差的较低频率的“拍”。我们将使用该设备将兔眼暴露于20-，60-和900-kHz的超声。然后将荧光标记葡聚糖的混合物在地球仪外结膜下注射。处理后24小时，将眼睛固定、冷冻切片并通过共聚焦显微镜检查。我们将可视化分子在巩膜、脉络膜和视网膜内的分布，以评估运输并表征可能在显微镜下和通过细胞凋亡测定发生的任何组织损伤。视网膜相关性黄斑变性（AMD）是一种影响多达1500万美国人的进行性眼病，并且是美国65岁以上成年人视力丧失和法律的失明的头号原因。用于治疗AMD的有前景的研究药物通常由必须通过重复注射直接进入眼睛而递送至视网膜的大分子组成，具有潜在的并发症。该项目涉及使用超声波透化兔眼巩膜以允许大分子经巩膜扩散作为治疗AMD和其他眼部疾病的模型的研究。

DESCRIPTION (provided by applicant): The objective of this project is the development of a safe and effective means to deliver macromolecular drugs across the wall of the eye for treatment of disease, especially age-related macular degeneration (AMD). AMD is a progressive eye disease affecting as many as 15 million Americans and is the number one cause of vision loss and legal blindness in adults over 65 years of age in the U.S. Several promising macromolecular drugs are now being evaluated for treatment of AMD. Because the outer shell of the eye (the sclera) is relatively impermeable to high molecular weight drugs, intraocular injection is the most widely used means to accomplish delivery to the retina and choroid. Consequently, delivery of macromolecular medications into the eye must be accomplished by intravitreal injections every few weeks, with the occurrence of complications (infection, retinal detachment, increased intraocular pressure) increasing cumulatively. For this reason, non-invasive methods for delivery of macromolecular drugs are of great interest. Ultrasound has in the past been shown to be capable of making tissues more permeable to macromolecules. We propose to investigate the effect of ultrasound of various frequencies, intensities and durations on transscleral transport of fluorescently labeled molecules (dextrans) into the rabbit eye. We will use dextrans of molecular weights of 10-kDa, 70-kDa and 500-kDa, each with a different wavelength fluorescent label. (Molecular weights of drugs now used for treatment of AMD are typically around 150-kDa.) We will conduct two series of experiments, the first involving use of an unfocused 20-kHz ultrasound source and the second utilizing a novel ultrasound device consisting of two 900-kHz confocal annuli. This device provides the advantage of allowing focusing and avoidance of potentially sensitive structures such as the cornea, lens and macula. By driving the two elements at slightly different frequencies, 'beats' at a lower frequency corresponding to the frequency difference are generated. We will expose the rabbit eyes to 20-, 60- and 900-kHz ultrasound using this device. A mixture of the fluorescently labeled dextrans will then be injected subconjunctivally outside the globe. Twenty-four hours after treatment, the eyes will be fixed, cryosectioned and examined by confocal microscopy. We will visualize the distribution of the molecules within the sclera, choroid and retina to evaluate transport and characterize any tissue damage that might have occurred microscopically and by apoptosis assays. Age-related macular degeneration (AMD) is a progressive eye disease affecting as many as 15 million Americans and the number one cause of vision loss and legal blindness in adults over 65 years of age in the U.S. Promising investigational drugs for treatment of AMD often consist of macromolecules that must be delivered to the retina by repeated injections directly into the eye, with potential complications. This project involves investigation of the use of ultrasound to permeabilize the sclera in the rabbit eye to allow transscleral diffusion of macromolecules as a model for treatment of AMD and other ocular diseases.