A method of treating a warm-blooded vertebrate animal having a medical condition in need of treatment with a composition that exhibits PAI-1 inhibition activity is disclosed. The method includes the steps of administering a treatment effective amount of the composition to a warm-blooded vertebrate animal having a medical condition selected from the group consisting of alopecia, undesired weight loss, Alzheimer's Disease, systemic amyloidosis, myelofibrosis, male pattern baldness, glomerulosclerosis, veno-occlusive disease (VOD), pulmonary fibrosis, obesity, non-alcoholic steatohepatitis (NASH), osteoporosis, osteopenia, polycystic ovarian syndrome (PCOS), and combinations thereof; and observing an improvement in the medical condition in the warm-blooded vertebrate animal having the medical condition. A method of testing a candidate composition for PAI-1 inhibition activity is also 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 overexpression 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 is 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.