Preclinical models to assess the pharmacological properties of NO derivatives

The field of pharmacology of nitric oxide (NO) has various clinical perspectives as cardiovascular and metabolic disorders, neurovascular and neurodegenerative diseases, muscular–skeletal disorders, ocular, respiratory, and a large series of inflammation-related pathologies, and, on top of these, infective and neoplastic diseases. Depending on the pathology and pathophysiological mechanisms, different pharmacological approaches can be developed and used, either to stimulate NO synthases (NOS), improve NO availability and activate downstream NO-related pathways or, on the opposite, to downregulate NOS, scavenge NO, and inhibit NO-related signaling. In either conditions, preclinical tools and models are needed to allow molecule or therapeutic strategy screening, evaluating the relative potency, efficacy, and safety in a reliable, simple, relatively cheap, and not time-consuming manner. Different models have been developed during time, starting from the classic isolated organs maintained in balanced buffers and measuring their typical functional responses as relaxation/contraction. The introduction of cell cultures, genetic manipulation, and molecular studies has allowed to go in deep detail on the cellular and molecular mechanisms controlling upstream and downstream NO signaling. The chapter will present the cell types and cellular models (2D and 3D) available to study functional aspects of NO related strategies as well as the control of cell–cell interaction. By using selective biochemical inhibitors of signaling pathways, the involvement of intracellular messengers can be assessed and verified in functional responses both on cell cultures and in isolated organs. Finally, animal models reproducing human diseases or their symptoms can be used to assess the efficacy of synthetic strategies, NO delivery systems, and potential drugs or drug combinations in controlling pathology progression or in inducing disorder regression. Efficacy studies on experimental models, together with safety assessment, indeed allow to obtain predictive information for the proper design of safe human clinical trials.