Development/Validation of Rete Testis Microcannulation for the Assessment of Novel Chemical Scaffolds That Penetrate the Blood Testis Barrier

PROJECT SUMMARY The innermost compartments of the testes’ seminiferous tubules are shielded from the general circulation by the molecular and cellular anatomy of Sertoli cells that form a highly effective blood-tissue barrier. The BTB presents a hurdle to scientific efforts aimed at developing male-directed contraceptives or fertility-enhancing therapeutics that target developing sperm cells uniquely locatedwithin the “adluminal” compartment of seminiferous tubules. Additionally, the adluminal compartment of seminiferous tubules is an “immune privileged site”, providing a safe harbor where pathogens escape both host immunity and anti-pathogenic therapeutics. Thus, developing this specialized tool will provide unique resources needed for institutions to improve the effectiveness of drugs targeting a broad spectrum of human health issues. Our central hypothesis is based on the premise that novel methods for sampling tissues and fluids located behind the BTB will be of great benefit to de-risk drug discovery programs focused on developing therapeutics directed at viral diseases, cancer, parasites and contraception. Our long-term research goals are to expedite the development of pharmaceuticals that will be effective against targets located within the adluminal compartment of the testes. Our objective for the R61 phase of this project is to develop and validate procedures by which we can sample and analyze fluid from the rat’s rete testis, behind its BTB. Sampling fluid from behind the rat BTB will allow researchers to verify how effectively their test drugs are able to cross the BTB and interact with targets located in the testes’ pharmacologically privileged sites. Furthermore, we will identify and validate molecular reference standards that will be used to compare relative abilities of test compounds to cross the BTB. Finally, we will determine the feasibility of adapting the rat procedure to a mouse system. Our objective for the R33 phase of this project is to identify unique chemical structures and/or scaffolds that will penetrate the BTB and to also establish and validate a robust sampling method in the mouse since it is the predominant species used for efficacy models ranging from fertility/contraception, infectious disease and cancer. Although similar in structure and function, rat and mouse BTB can differ significantly in a host of factors such as transporter and macromolecule composition.