DNA damage in round spermatids of mice with a targeted disruption of the Pp1c gamma gene and in testicular biopsies of patients with non-obstructive azoospermia

Non-obstructive azoospermia accounts for a considerable proportion of male factor infertility. Current therapies for treatment of this kind of inferti lity include procedures such as intracytoplasmic sperm injection (ICSI), ro und spermatid injection (ROSI), round spermatid nucleus injection (ROSNI) a nd elongated spermatid injection (ELSI). All involve injection of haploid g erm cells retrieved from testicular biopsies into recipient oocytes. We hav e investigated a mouse model of azoospermia for quality of haploid germ cel l genomes, based on 4,6-diamidino-2-phenylindole (DAPI)/TdT-mediated dUTP n ick-end labelling (TUNEL) labelling. The mouse model, a targeted mutation i n the protein phosphatase Icg gene, results in severe depletion of haploid germ cells from the round spermatid stage on. Mice homozygous for the mutat ion are completely infertile, and produce only the occasional spermatozoon. Spermatozoa and round spermatids retrieved from either the epididymides or the testes of mutant mice displayed very high rates of DNA fragmentation. In contrast, similar cells retrieved from heterozygous or wild-type litterm ates displayed low levers of DNA fragmentation. In some cases, the high rat es of DNA fragmentation in mutant cells could be lowered by inclusion of an tioxidants in the retrieval media. High rates of DNA fragmentation were als o observed in round spermatids retrieved from testicular biospies of human patients with non-obstructive azoospermia. These results suggest that one o f the features of the pathology associated with azoospermia is fragmented D NA in haploid germ cells. This raises questions about the suitability of us ing these cells for fertility treatment.