The loss and restoration of fertility after busulfan treatment are direct consequences of SSC loss and expansion. Our data suggest that there is a threshold in SSC numbers that allows for male fertility restoration and that the testicular somatic environment responds rapidly and temporarily to the loss of spermatogonia, including SSCs, by altering GDNF mRNA levels. This study provides fundamental information to clinically apply SSCs for male fertility restoration in the future.

Human spermatogonial stem cells (SSCs) play critical roles in lifelong maintenance of male fertility and regeneration of spermatogenesis. These cells are expected to provide an important resource for male fertility preservation and restoration. A basic strategy has been proposed that would involve harvesting testis biopsy specimens from a cancer patient prior to cancer therapies, and transplanting them back to the patient at a later time; then, SSCs included in the specimens would regenerate spermatogenesis. To clinically apply this strategy, isolating live human SSCs is important. In this study, we investigated whether CD9, a known rodent SSC marker, is expressed on human male germ cells that can repopulate recipient mouse testes upon transplantation. Testicular tissues were obtained from men with obstructive azoospermia. Using immunohistochemistry, we found that CD9 was expressed in human male germ cells in the basal compartment of the seminiferous epithelium. Following immunomagnetic cell sorting, CD9-positive cells were enriched for germ cells expressing MAGEA4, which is expressed by spermatogonia and some early spermatocytes, compared with unsorted cells. We then transplanted CD9-positive cells into nude mouse testes and detected an approximately 3- to 4-fold enrichment of human germ cells that repopulated mouse testes for at least 4 mo after transplantation, compared with unsorted cells. We also observed that some cell turnover occurred in human germ cell colonies in recipient testes. These results demonstrate that CD9 identifies human male germ cells with capability of long-term survival and cell turnover in the xenogeneic testis environment.

Cryopreservation of human gametes and embryos has become an essential part of assisted reproduction. Successful cryopreservation of human blastocysts is increasingly relevant as extended in-vitro culture of human embryos becomes more common, permitting routine use of blastocyst transfer in IVF programmes. This reduces the number of embryos transferred, thereby reducing multiple pregnancies and maximizing cumulative pregnancy rates per oocyte retrieval. The superiority of blastocyst freezing over earlier stage freezing in terms of implantation per thawed embryo transferred improves overall expectations for the cryopreservation programme. Therefore, a reliable procedure for the cryopreservation of blastocysts is needed because, after transfer, only a small number of supernumerary blastocysts are likely to be available for cryopreservation. Since the early 1980s, two common techniques have been used in cryopreservation: the conventional slow cooling method and the more recent rapid procedure known as vitrification. Vitrification has become an attractive alternative to slow freezing, since it appears to result in significantly higher survival and pregnancy rates. The aim of this review is to focus on the cryopreservation of human blastocysts using slow and rapid protocols and to assess the impact of the crypreservation protocol used on the survival, implantation and pregnancy rates.

High DNA fragmentation index (DFI) may be associated with poor outcome after IVF. Our aim was to determine whether DFI impacts blastocyst quality or clinical outcome. This retrospective study included 134 couples who underwent 177 IVF-ICSI and pre-implantation genetic screening (PGS) cycles during January 1st, 2014—March 31st, 2016 and had documented previous DFI. Group 1 (DFI>30%) encompassed 25 couples who underwent 36 cycles; Group 2 (DFI 15–30%) included 45 couples and 57 cycles; group 3 (DFI<15%) included 64 couples and 83 cycles. Male partners within group 1 were older (45.1 compared to 40.6 and 38.3 years, respectively, p<0.05), had higher BMI (32.4 compared to 26.6 and 25.8 respectively, p<0.05) and lower sperm count and motility (46*106/ml and 35.5%, respectively) compared to groups 2 (61.8*106/ml and 46.6%, respectively) and 3 (75.8*106/ml and 55.1%, respectively, p<0.05). Female parameters including ovarian reserve and response and embryo development were similar. Total numbers of biopsied blastocysts were 116, 175 and 259 in groups 1, 2 and 3, respectively. PGS for 24 chromosomes revealed comparable euploidy rate of 46–50.4%, with a similar morphological classification. No significant differences were found regarding pregnancy rates or pregnancy loss. It seems that DFI doesn't correlate with blastocyst aneuploidy or morphological grading.

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