Stem cell-based therapies for fertility preservation in males: Current status and future prospects

With the decline in male fertility in recent years, strategies for male fertility preservation have received increasing attention. In this study, by reviewing current treatments and recent publications, we describe research progress in and the future directions of stem cell-based therapies for male fertility preservation, focusing on the use of spermatogonial stem cells (SSCs), SSC niches, SSC-based testicular organoids, other stem cell types such as mesenchymal stem cells, and stem cell-derived extracellular vesicles. In conclusion, a more comprehensive understanding of the germ cell microenvironment, stem cell-derived extracellular vesicles, and testicular organoids will play an important role in achieving male fertility preservation.     

Mitochondria: Participation to infertility as source of energy and cause of senescence

Mitochondria is a powerhouse organelle involved in ATP synthesis, calcium signaling, reactive oxygen species (ROS) by oxidative stress production, cell cycle arrest via apoptosis and sex steroid hormones biosynthesis. Improvement of sperm parameters such as motility, capacitation, acrosome reaction, and oocyte interaction, involve regulation of ROS levels by the mitochondria. In human, the relation between the quantitative level of mitochondrial DNA (mtDNA), oocyte cytoplasm maturation and fertilization potential, is not clear. It has been hypothesized that oocytes without sufficient wild type mtDNA and therefore able to generate ATP, would not normally be ovulated. This is reflected in the low numbers of mtDNA observed in degenerate oocytes obtained through super ovulation protocols during assisted reproductive technology programs. Different theories place mitochondria in a central role of oxidative damage to cells and tissues related to infertility declining and aging. Mitochondria-dependent apoptosis seems to be responsible for the pre and post-natal decline in germ cells, embryo development, implantation failure, and miscarriages.     

The life histories of American stepfathers in evolutionary perspective

This paper presents an analysis of the characteristics of men who become stepfathers, and their subsequent fertility patterns and lifetime reproductive success. Because women who already have children are ranked lower in the marriage market than women without children, men who marry women with children (e.g., stepfathers) are likely to have lower rankings in the marriage market as well. Using retrospective fertility and marital histories from the Panel Study of Income Dynamics (PSID), I show that men who become stepfathers have lower levels of education, less income, and are more likely to have been divorced before and to already have children, all characteristics that lower their rankings in the marriage market. Men with one or two stepchildren are just as likely to have children within a marriage as non-stepfathers, although men with three stepchildren show decreased fertility. Among men age 45 and older, stepfathers have lower lifetime fertility than non-stepfathers, although the difference disappears when men’s age at first marriage is controlled for. Additionally, stepfathers have significantly higher fertility than men who never marry. The results suggest that some men become stepfathers to procure mates and fertility benefits that they would otherwise have been unlikely to obtain; for these men, raising other men’s children serves as a form of mating effort. Preliminary versions of this paper were presented at the Evolution and Human Adaptation Program at the University of Michigan, and the Human Behavior and Evolution Society’s annual meeting at Amherst. Kermyt G. Anderson received his Ph.D. in anthropology from the University of New Mexico in 1999. He is currently a Mellon Postdoctoral Research Fellow at the Population Studies Center of the Institute for Social Research at the University of Michigan. His current research examines the relationship between family structure, parental investment, and children’s educational and employment outcomes in South Africa.     

What doesn’t kill her,will make her depressed

In this paper we study the long run effects of the 1959–61 Chinese Famine on mental health outcomes. We focus on cohorts that were born during the famine and examine their mental health as adults, when they are roughly 55 years of age. We find that early-life exposure to this famine leads to a large statistically significant negative impact on women’s mental health, while there is limited effect on men. This gender differential effect is observed because male fetuses experience a stronger natural selection as compared to female fetuses, which implies that in the longer run, surviving females may exhibit larger detrimental effects of early-life famine exposure. Thus, the observed effects are a composite of two well-established factors, the survival of the fittest and the Fetal Origins hypothesis.     

The gene of golden plumage colour linked with lower fertility in Mangurian Golden quail

Summary Relation between golden plumage colour and lowered fertility has been found in quails (Coturnix coturnix japonica). Golden colour of plumage is due to the presence of a single gene G, while its recessive alleles gg determine partridge-like colour. Homozygotic birds of GG pattern die during incubation.Project No. 09.3.1.3.1.6.     

Effects of cooling and equilibration in DMSO,and cryopreservation of mouse oocytes,on the rates of in vitro fertilization,development, and chromosomal abnormalities

In a previous study, we have shown that the cryopreservation of mouse oocytes caused increases in the rates of degeneration and of digynic polyploid embryos, while the fertility of frozen-thawed oocytes was decreased. In this study, we have attempted to determine the different stages in the complete freezing-thawing process which are deleterious for the oocytes and the subsequent zygotes. IVF assays showed that DMSO decreased the fertility of oocytes, whereas cooling to 0°C had no effect. DMSO, used at 0°C, was less deleterious for oocytes. Thus, the prefreezing manipulations seem to be important for the quality and fertility of oocytes. However, neither DMSO nor cooling increased the incidence of chromosomal abnormalities in embryos obtained from inseminated exposed oocytes. Therefore, the increased frequency of polyploidy observed in embryos after the cryopreservation of mouse oocytes must correspond to disruption occurring during the freezing-thawing process.     

Cryopreservation of Indian red jungle fowl (Gallus gallus murghi) semen with polyvinylpyrrolidone

The Indian red jungle fowl is a sub-species of the genus Gallus native to South Asia; facing high risk of extinction in its native habitat. During cryopreservation, permeable cryoprotectants like glycerol are usually employed and we previously showed encouraging results with 20% glycerol. Because bird spermatozoa contain very little intracellular water, the possibility of replacing an internal cryoprotectant by an external one is opened. In the present study, we tested the replacement of internal cryoprotectant glycerol by the external cryoprotectant Polyvinylpyrrolidone (PVP). PVP is a non-permeable cryoprotectant and keeps the sperm in glassy state both in cooling and warming stages without making ice crystallization within the sperm cell. We evaluated the effect of various levels of polyvinylpyrrolidone (PVP) on Indian red jungle fowl semen quality and fertility outcomes. The qualifying semen ejaculates collected from eight mature cocks were pooled, divided into five aliquots, diluted (37 °C) with red fowl semen extender having PVP [0% (control) 4% (w/v), 6% (w/v), 8% (w/v) and 10% (w/v)]. Diluted semen was cryopreserved and stored in liquid nitrogen. The whole experiment was repeated/replicated for five times independently. Sperm motility, plasma membrane integrity, viability and acrosome integrity were recorded highest (P < 0.05) with 6% PVP at post-dilution, cooling, equilibration and freeze-thawing. Higher (P < 0.05) no. of fertile eggs, fertility, no. of hatched chicks, percent hatch and hatchability was recorded with 6% PVP compared to control. It is concluded that 6% PVP maintained better post-taw quality and fertility of Indian red jungle fowl spermatozoa than glycerol and can be used in routine practice avoiding the contraceptive effects of glycerol.     

Decrease in Methoprene tolerant and Taiman expression reduces juvenile hormone effects and enhances the levels of juvenile hormone circulating in males of the linden bug Pyrrhocoris apterus

Juvenile hormone (JH) produced by the corpus allatum (CA) stimulates vitellogenesis and reduces the synthesis of hexamerin proteins in adult females of Pyrrhocoris apterus. At present it is unknown whether the signaling pathway involving the JH receptor gene Methoprene tolerant (Met) and its binding partner Taiman (Tai), regulates the synthesis of accessory gland proteins (ACPs) and hexamerin proteins or effects male survival. Knockdown of genes by injecting Met dsRNA or Tai dsRNA, reduced the amount of ACPs whilst enhancing the amount of hexamerin mRNA in the fat body and the release of hexamerin proteins into haemolymph, as occurs after the ablation of CA. Lifespan was enhanced by injecting Met but not Tai dsRNA. Diapause associated with the natural absence of JH had a stronger effect on all these parameters than the ablation of CA or the knockdown of genes. This indicates there is an additional regulating agent. Both Met and Tai dsRNA induced a several fold increase in JH (JH III skiped bisepoxide) but a concurrent loss of Met or Tai disabled its function. This supports the view that the Met/Tai complex functions as a JH receptor in the regulation of ACPs and hexamerins.     

Epigallocatechin-3-gallate (EGCG) addition as an antioxidant in a cryo-diluent media improves microscopic parameters,and fertility potential,and alleviates oxidative stress parameters of buffalo spermatozoa

The disparity between the endogenous antioxidants concentration and free radicals in spermatozoa results in reactive oxygen species (ROS) generation. In this prospect, epigallocatechin-3-gallate (EGCG) preserves vigorous antioxidant features. Current study explored the influence of EGCG in a cryo-diluent media on microscopic parameters, oxidative stress parameters, and fertility potential of buffalo spermatozoa during cryopreservation. Concisely, collected semen from three donor bulls for four times were then evaluated for volume, motility, concentrations and then dilution in a cryo-diluent media with different concentrations of EGCG (EGCG-0 = control; EGCG-50 = 50 μM, EGCG-100 = 100 μM, EGCG-200 = 200 μM, and EGCG-300 = 300 μM) at 37 °C, cooled to 4 °C in 2 h, equilibrated for 4 h at 4 °C, and cryopreserved. At post-thawing, Computer-Assisted Sperm motion Analysis motilities (total and progressive, %) and rapid velocity (%), plasma membrane functionality, supravital plasma membrane integrity, and mitochondrial potential (%) were found higher (P < 0.05) in EGCG-200, and EGCG-300 than control, whereas average-path, straight-line, and curved-linear velocities (μm/sec), and acrosome integrity (%) were recorded higher in EGCG-300 than control. Further, comet length (μm), and tail length (μm), LPO (lipid peroxidation, μM/mL), and apoptosis-like changes (%) in spermatozoa were significantly decreased in EGCG-300 than control. Seminal plasma antioxidant enzymes activities (glutathione peroxidase, U/mL, and superoxide dismutase, U/mL) were increased with EGCG-300 than control. Moreover, EGCG-300 addition in a cryo-diluent media improves the fertility potential (%) of buffalo spermatozoa. In a nutshell, the inclusion of EGCG-300 in a cryo-diluent media enhances post-thaw microscopic parameters, and fertility potential, whereas decreases oxidative stress parameters in buffalo spermatozoa.