Seminiferous tubule cannulation (STC): a new, sensitive technique for detecting gene transfer in developing sperm

As gene therapy vectors, strategies, and disease targets continue to expand and diversify, the likelihood that developing germ cells will be exposed to gene transfer vectors increases. Insertion of exogenous genetic material into the germ line might have devastating effects on normal development which could be heritable. Accordingly, it is important that vectors be tested for their potential to insert genes into developing gametes. Such tests are most difficult in males, where differentiating sperm are sequestered behind the blood-testis barrier. In this communication we report the development of a new technique, which we call seminiferous tubule cannulation (STC). We demonstrate that STC allows delivery of high quantities of gene therapy vector directly to spermatogenic cells without significantly disturbing the cytoarchitecture of the seminiferous tubule. To demonstrate the effectiveness of this technique, three promoters driving lacZ gene expression in adenovirus vectors were tested for their ability to transduce cells within the seminiferous tubule. Results indicate that the cytomegalovirus promoter, but not the Rous sarcoma virus or elongation factor 1alpha promoters, is active within the seminiferous tubule. Further development of this technique promises to lead to a standardized test for male germ cell transduction by gene therapy vectors.