This Phase I SBIR proposal will investigate the feasibility of using a unique fusion tag system for the high level expression and purification of native human and mouse neuroserpin. Our collaborators at the University of Michigan have shown in animal models that the neuroserpin protein appears to have profound neuroprotective effects and therefore has great therapeutic potential in the treatment of ischemic stroke. To date, the material has proven to be exceeding difficult to obtain in the quantities necessary to conduct more detailed animal studies and the lack of the reagent has created a bottleneck in the development of more detailed and elaborate studies. We propose to produce the neuroserpin protein reagents in a stable insect cell line on a large scale and to subsequently test them in an in vitro assay for functional biological activity. These proteinase inhibitors will form the basis of an eventual Phase II study where they will be used therapeutically in a mouse stroke model. This model will allow for the evaluation of their efficacy in the attenuation of neuronal cell death associated with induced stroke. If successful, the new fusion tag system will also have a broader scope than just this proposal. This new tag will be very be generalized and have the potential to be commercialized for the purification of other important academic and industrial protein based reagents. Neuroserpin protein represents a promising new therapeutic in the treatment of ischemic stroke, which is the second leading cause of death and disability throughout the world. Medigenix LLC proposes to develop a new method for the production of this protein on a large scale. This methodology may also prove useful in many other protein-based therapeutics in the future. [unreadable] [unreadable] [unreadable]