A method of testing a candidate composition for PAI-1 inhibition activity is disclosed. The method includes the steps of obtaining a transgenic non-human warm blooded vertebrate animal having incorporated into its genome a PAI-1 gene encoding a biologically active PAI-1 polypeptide, the PAI-1 gene being present in the genome in a copy number effective to confer over-expression in the transgenic non-human animal of the PAI-1 polypeptide; administering the composition to the transgenic non-human animal; and observing the transgenic non-human animal for determination of a change in the transgenic non-human animal indicative of inhibition of the activity of PAI-1. A transgenic non-human animal useful in such a method is also disclosed, as is a PAI-1 transgene construct encoding a biologically active PAI-1 polypeptide useful for preparing the transgenic non-human animal.