Vanadocene-mediated in vivo male germ cell apoptosis.

Vanadocenes are potent apoptosis-inducing cytotoxic agents against human testicular cancer cells in vitro. The present study investigated the ability of four vanadocenes-vanadocene diazide (VDA), vanadocene dicyanate (VDCN), vanadocene dioxycyanate (VDOCN), and vanadocene monochloro oxycyanate (VDCO)-to induce male germ cell apoptosis in vivo in mouse testes by repetitive intratesticular injection of vanadocenes (7.5 mg/kg/testis) for 28 days. Germ cell loss in vivo was measured by epididymal sperm count, testes weights, and histologic evaluation of the testes. Repetitive intratesticular injection of vanadocenes led to decreased sperm counts and reduced testicular weights. Histopathological examination revealed seminiferous tubular atrophy, inhibition of spermatogenesis, and the preferential loss of maturing and elongated spermatids. In situ evaluation by the terminal deoxynucleotidyl transferase-mediated FITC-deoxyuridine triphosphate nick-end labeling (TUNEL) of seminiferous tubule cross sections and laser confocal microscopy showed characteristic apoptotic cells identified primarily as pachytene spermatocytes delineating the periphery of the seminiferous tubules. The ability of vanadocenes to induce germ cell apoptosis in vivo may have potential utility in the treatment of testicular seminomas in humans.