A retrospective cohort study of geographic differences in the semen of 1,012 sperm donors in China.

Background: Male reproductive health has become a serious public health concern, and semen quality is essential to male reproduction. We aimed to investigate geographical differences in the semen quality of sperm donors from northern and southern China by enrolling donors across the country. Methods: A total of 1,012 sperm donors were enrolled in this study between 2015 and 2019. Donors were first divided into two parts based on their birthplace according to the "Qinling-Huaihe" line, and secondly, by their residential latitude. Finally, donors were re-classified into two groups (typically north and south) which contained 667 samples. Results: Statistically significant differences in sperm concentration were observed among men from different latitudes in China (P=0.04). The sperm concentrations of males from 18° to 27° north latitude were significantly lower than those from 36° to 45° and 45° to 54° [median 131, 134, and 146, respectively, P=0.021 (18° to 27° vs. 36° to 45°) and P=0.01 (18° to 27° vs. 45° to 54°)]. Conclusion: We hypothesize environmental pollution and mental stress due to the increased population size may be the main factors underlying differences in the sperm quality of men in northern and southern China.

Assessment of growth and metabolism characteristics in offspring of dehydroepiandrosterone-induced polycystic ovary syndrome adults.

Polycystic ovary syndrome (PCOS) is a common reproductive disorder that has many characteristic features including hyperandrogenemia, insulin resistance and obesity, which may have significant implications for pregnancy outcomes and long-term health of women. Daughters born to PCOS mothers constitute a high-risk group for metabolic and reproductive derangements, but no report has described potential growth and metabolic risk factors for such female offspring. Hence, we used a mouse model of dehydroepiandrosterone (DHEA)-induced PCOS to study the mechanisms underlying the pathology of PCOS by investigating the growth, developmental characteristics, metabolic indexes and expression profiles of key genes of offspring born to the models. We found that the average litter size was significantly smaller in the DHEA group, and female offspring had sustained higher body weight, increased body fat and triglyceride content in serum and liver; they also exhibited decreased energy expenditure, oxygen consumption and impaired glucose tolerance. Genes related to glucolipid metabolism such as Pparγ, Acot1/2, Fgf21, Pdk4 and Inhbb were upregulated in the liver of the offspring in DHEA group compared with those in controls, whereas Cyp17a1 expression was significantly decreased. However, the expression of these genes was not detected in male offspring. Our results show that female offspring in DHEA group exhibit perturbed growth and glucolipid metabolism that were not observed in male offspring.

Ascorbic acid improves pluripotency of human parthenogenetic embryonic stem cells through modifying imprinted gene expression in the Dlk1-Dio3 region.

INTRODUCTION: Human parthenogenetic embryonic stem cells (hpESCs) are generated from artificially activated oocytes, however, the issue of whether hpESCs have equivalent differentiation ability to human fertilized embryonic stem cells remains controversial. METHODS: hpESCs were injected into male severe combined immunodeficiency (SCID) mice and the efficiency of teratoma formation was calculated. Then the gene expression and methylation modification were detected by real time-PCR and bisulfate methods. RESULTS: Comparison of five hpESCs with different differentiation abilities revealed that levels of paternal genes in the Dlk1-Dio3 region on chromosome 14 in the hpESCs with high differentiation potential are enhanced, but strictly methylated and silenced in the hpESCs with lower differentiation potential. Treatment with ascorbic acid, rescued their ability to support teratoma formation and altered the expression profiles of paternally expressed genes in hpESCs that could not form teratoma easily. No differences in the expression of other imprinting genes were evident between hpESCs with higher and lower differentiation potential, except for those in the Dlk1-Dio3 region. CONCLUSIONS: The Dlk1-Dio3 imprinting gene cluster distinguishes the differentiation ability of hpESCs. Moreover, modification by ascorbic acid may facilitate application of hpESCs to clinical settings in the future by enhancing their pluripotency.

Basic fibroblast growth factor promotes the development of human ovarian early follicles during growth in vitro.

STUDY QUESTION: What is the effect of basic fibroblast growth factor (bFGF) on the growth of individual early human follicles in a three-dimensional (3D) culture system in vitro? SUMMARY ANSWER: The addition of 200 ng bFGF/ml improves human early follicle growth, survival and viability during growth in vitro. WHAT IS KNOWN ALREADY: It has been demonstrated that bFGF enhances primordial follicle development in human ovarian tissue culture. However, the growth and survival of individual early follicles in encapsulated 3D culture have not been reported. STUDY DESIGN, SIZE, DURATION: The maturation in vitro of human ovarian follicles was investigated. Ovarian tissue (n= 11) was obtained from 11 women during laparoscopic surgery for gynecological disease, after obtaining written informed consent. One hundred and fifty-four early follicles were isolated by enzymic digestion and mechanical disruption. They were individually encapsulated into alginate (1% w/v) and randomly assigned to be cultured with 0, 100, 200 or 300 ng bFGF/ml for 8 days. PARTICIPANTS/MATERIALS, SETTING, METHODS: Individual follicles were cultured in minimum essential medium α (αMEM) supplemented with bFGF. Follicle survival and growth were assessed by microscopy. Follicle viability was evaluated under confocal laser scanning microscope following Calcein-AM and Ethidium homodimer-I (Ca-AM/EthD-I) staining. MAIN RESULTS AND THE ROLE OF CHANCE: After 8 days in culture, all 154 follicles had increased in size. The diameter and survival rate of the follicles and the percentage with good viability were significantly higher in the group cultured with 200 ng bFGF/ml than in the group without bFGF (P < 0.05). The percentage of follicles in the pre-antral stage was significantly higher in the 200 ng bFGF/ml group than in the group without bFGF (P < 0.05), while the percentages of primordial and primary follicles were significantly lower (P < 0.05). LIMITATIONS, REASONS FOR CAUTION: The study focuses on the effect of bFGF on the development of individual human early follicles in 3D culture in vitro and has limited ability to reveal the specific effect of bFGF at each different stage. The findings highlight the need to improve the acquisition and isolation of human ovarian follicles. WIDER IMPLICATIONS OF THE FINDINGS: The in vitro 3D culture of human follicles with appropriate dosage of bFGF offers an effective method to investigate their development. Moreover, it allows early follicles to be cultured to an advanced stage and therefore has the potential to become an important source of mature oocytes for assisted reproductive technology; particularly as an option for fertility preservation in women, including patients with cancer. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the National Basic Research Program of China (2011|CB944504, 2011CB944503) and the National Natural Science Foundation of China (81200470, 81000275, 31230047, 8110197). There are no conflicts of interest to declare.

Improvement in the quality of heterotopic allotransplanted mouse ovarian tissues with basic fibroblast growth factor and fibrin hydrogel.

STUDY QUESTION: Does basic fibroblast growth factor (bFGF) in combination with fibrin hydrogel improve follicle development and revascularization of heterotopically transplanted mouse ovarian tissues? SUMMARY ANSWER: Treatment of transplanted ovarian tissues with higher concentrations (75, 100 and 150 µg/ml), but not lower concentrations (25 and 50 µg/ml), of bFGF significantly improved primordial follicle survival and angiogenesis, while apoptosis of follicles and stromal cells was significantly decreased. WHAT IS KNOWN ALREADY: Use of transplanted ovarian tissues in female fertility preservation is limited by the massive loss of follicles and ischemia-reperfusion injury due to the expected delay in revascularization. STUDY DESIGN, SIZE AND DURATION: Ovarian tissues from 18-day-old ICR mice were encapsulated in fibrin hydrogel mixed with different concentrations of bFGF, then transplanted under the skin of adult female mice for 1 week. The ovarian tissues treated without fibrin hydrogels and bFGF were designated as Control group I, and the ovarian tissues treated with fibrin hydrogels but without bFGF were designated as Control group II. The ovarian tissues treated with 25 and 50 µg/ml bFGF were designated as the lower concentration group, and the ovarian tissues treated with 75, 100 and 150 µg/ml bFGF were designated as the higher concentration group. MATERIALS, SETTING AND METHODS: Assessment of follicular quantity and follicle classification was carried out by histologic analysis. Follicle proliferation was evidenced by immunostaining with proliferating cell nuclear antigen and apoptosis was verified by anti-active caspase-3 staining. Epithelial cells of new blood vessels were stained using CD31 antibody to evaluate neoangiogenesis, and the blood vessel density was analyzed by immunohistochemistry. MAIN RESULTS AND THE ROLE OF CHANCE: The ovarian tissues were recovered 1 week post-transplantation. Compared with the control group, the survival and proliferation of the follicles was significantly increased, the apoptosis of follicles and stromal cells was significantly decreased, and angiogenesis was significantly enhanced when the transplanted ovarian tissues were treated with a higher concentration of bFGF. Treatment with a lower concentration of bFGF did not improve follicle survival and blood revascularization. LIMITATIONS, REASONS FOR CAUTION: The results obtained may not be fully extrapolated to humans because of the physiologic differences between mice and humans. WIDER IMPLICATIONS OF THE FINDINGS: For the first time, the present study investigated the role of bFGF in transplanted ovarian tissues and demonstrated that bFGF might significantly improve the quality of transplanted ovarian tissues by increasing follicle quantity and promoting neoangiogenesis. This study sets the stage for further study and application of ovarian tissue transplantation in clinics, and may eventually benefit females for fertility preservation. STUDY FUNDING/COMPETING INTEREST(S): This work was partially supported by the Ministry of Science and Technology of China Grants (973 Program; 2011CB944503 to Q.J.), the Program for Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China (30825038 to Q.J.), and the National Natural Science Funds for Young Scholar (81200470 to Y.J. and 81000275 to Y.L.Y.). None of the authors have any conflicts of interest.