Reconsideration Of Human Round Spermatid Injection Into The Oocyte (Rosi) Usefulness.

To date, the application of ROSI in clinical IVF has been disappointing due to difficulties in accurate identification of round spermatids among other round spermatogenic cells and insufficient oocyte activation. The existence of round spermatids has been believed to be associated with testicular spermatozoon. That is, no testicular spermatozoa means no round spermatid. However this theory was overturned by the report that in men, mutation of Crem, TAF4B and ZMYND15 gene were found to cause maturation arrest at the stage of round spermatid. We believe now it is time to reconsider the usefulness of ROSI. Retrospective cohort study to ROSI. Ninety non-obstructive azoospermic men whose first Micro-TESE conducted by andrologists showed no testicular spermatozoa or late staged spermatids but had had round spermatids found at our hospital and received ROSI from September 2011 to December 2014 participated in this study. The Institutional Review Board of the Saint Mother Obstetrics and Gynecology Clinic approved this study and it was registered and adhered to International Committee of Medical Journal Editors criteria. Round spermatids, cytologically selected after thawing, were injected into ooplasm which was activated 10 minutes before the injection by electrical stimulation with an alternating current pulse of 2V/cm for 8s + direct current pulse of a single 1.2kV/cm for 99μs. We examined pattern of Ca2+ oscillation in oocytes after electrical stimulation and ROSI plus electrical stimulation to know the efficacy of the oocyte activation. Although round spermatid injection alone could induce only small Ca2+ oscillations, ROSI with prior electrical stimulation showed effective in inducing repetitive, large Ca2+ oscillations. Fertilization and rate to develop over 4 cell stage were 58.8% (590/1004), 50.6% (508/1004) respectively. The pregnancy rate per transferred cycle, miscarriage rate and birth rate in fresh embryo transfer cycles and freezing-thawed transfer cycles were [16.7%(26/156), 65.3%(17/26), 5.8%(9/156)], [23.9%(16/67), 50.0%(8/16), 11.9%(8/67)] respectively and 19 babies (6 female and 13 male) were born. All of them are healthy and no serious physical or cognitive disorders have been reported so far. The limitation of this clinical study concerns the small size of the study group and electrical stimulation for oocyte activation could not be the optimal one judging from the high percentage of miscarriages and immature centrosome. The inefficient demethylation and remethylation of DNA after ROSI might be a prime concern. However this study presents evidence that ROSI has a high potential to help many non-obstructive azoospermic men whose most advanced spermatogenic cells are round spermatids. After confirmation of the safety of ROSI, it could be chosen in the future as a first line treatment instead of ICSI using dead or anomalous spermatozoa.