Category Archives: Human Reproduction

BACKGROUND

Fertility in adult life may be severely impaired by gonadotoxic therapies. For young boys who do not yet produce spermatozoa, cryopreservation of immature testicular tissue (ITT) is an option to preserve their fertility, albeit still experimental. This paper covers current options for ITT cryopreservation and fertility restoration.

METHODS

Relevant studies were identified by an extensive Medline search of English and French language articles. Search terms were: gonadotoxicity, cytoprotection, cryopreservation, ITT, spermatogonia, testicular transplantation, testicular grafting and in vitro maturation (IVM).

RESULTS

Although no effective gonadoprotective drug is yet available for in vivo spermatogonial stem cell protection in humans, current evidence supports the feasibility of ITT cryopreservation before gonadotoxic treatment with a view to fertility preservation. Controlled slow freezing with dimethyl sulfoxide allows survival and proliferation of human spermatogonia after xenotransplantation, but only partial differentiation. Animal data look promising, since healthy offsprings have been obtained after transplantation of frozen testicular cell suspensions or tissue pieces. However, none of the fertility restoration options from frozen tissue, i.e. cell suspension transplantation, tissue grafting and IVM have proved efficient and safe in humans as yet.

CONCLUSION

While additional evidence is required to define optimal conditions for ITT cryopreservation with a view to transplantation or IVM, the putative indications for such techniques, as well as their limitations according to disease, are outlined.

BACKGROUND

It has been suggested that body mass index (BMI), especially obesity, is associated with subfertility in men. Semen parameters are central to male fertility and reproductive hormones also play a role in spermatogenesis. This review aimed to investigate the association of BMI with semen parameters and reproductive hormones in men of reproductive age.

METHODS

MEDLINE, EMBASE, Biological Abstracts, PsycINFO and CINAHL databases and references from relevant articles were searched in January and February 2009. Outcomes included for semen parameters were sperm concentration, total sperm count, semen volume, motility and morphology. Reproductive hormones included were testosterone, free testosterone, estradiol, FSH, LH, inhibin B and sex hormone binding globulin (SHBG). A meta-analysis was conducted to investigate sperm concentration and total sperm count.

RESULTS

In total, 31 studies were included. Five studies were suitable for pooling and the meta-analysis found no evidence for a relationship between BMI and sperm concentration or total sperm count. Overall review of all studies similarly revealed little evidence for a relationship with semen parameters and increased BMI. There was strong evidence of a negative relationship for testosterone, SHBG and free testosterone with increased BMI.

CONCLUSIONS

This systematic review with meta-analysis has not found evidence of an association between increased BMI and semen parameters. The main limitation of this review is that data from most studies could not be aggregated for meta-analysis. Population-based studies with larger sample sizes and longitudinal studies are required.