BRAIN THERAPY USING ULTRASOUND MEDIATED DRUG DELIVERY

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Disorders of the brain, including cancer and various forms of neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease are currently among the leading causes of illness and death in the United States. The financial burden of these diseases is enormous. The research proposed in this study will, therefore, address a critical need to develop safe, non-invasive and non-chemical methods to enhance the delivery of nonlipophilic neuropharmaceuticals to the brain through the use of ultrasound, which has been shown to enhance membrane transport phenomena in a non-invasive manner. However, the clinical use of ultrasound-enhanced transport of therapeutic agents across the blood- brain barrier (BBB) has yet to be demonstrated, nor have optimal therapeutic ultrasound parameters been defined. Therefore, in this proposal, the major goals are to A) delineate the parameter space for safe administration of ultrasound to mediate the transport of nonlipophilic compounds across the BBB, and (B) verify the safety and effectiveness of ultrasound in mediating the transport of nonlipophilic drugs across the BBB in animals. To accomplish these goals, the project will: (1) develop custom ultrasound units to perform both an enhanced range of in vitro measurements on a cell-culture model of the BBB and in vivo measurements on live rats, (2) determine the effects of various ultrasonic parameters (intensity, frequency, waveform) on the BBB permeability of a polar molecule; (3) determine the effects of various ultrasonic parameters on biochemical and morphological characteristics of the BBB cells by (a) following the functional expression of various BBB-specific enzymes and membrane-bound protein, (b) studying the morphological and cytological characteristics of BBB cells using standard histological techniques, and (c) determining the BBB cell viability, as a function of various ultrasound parameters; (4) determine the conditions for effective trans-cranial delivery of ultrasound using phantoms constructed to model in vivo brain; (5) verify the safety and effectiveness of ultrasound in mediating BBB drug transport in rats by examining the ultrasound-treated rat brain for the presence of lesions using standard histological techniques, and by determining whether trans-cranial application of ultrasound can promote BBB transport of a nonlipophilic drug (cisplatin) to alter the mean survival times of rats with one-week established brain tumors. In order to reduce costs and the unnecessary use of animals, specific aims 2 through 4 of the proposed study will be addressed using a well- established in vitro BBB cell culture model based on growing bovine brain microvessel endothelial cells (BBMEC) on a cell culture insert. It is anticipated that this study will also provide fundamental insights into the underlying mechanisms of ultrasound drug transport across the BBB as well as the knowledge needed for the design of a safe and effective trans-cranial ultrasound delivery system.