Using the male gamete for assisted reproduction: past, present, and future

Intracytoplasmic spermatid injection and in vitro maturation: fact or fiction?

Intracytoplasmic injection with testicular spermatozoa has become a routine treatment in fertility clinics. Spermatozoa can be recovered in half of patients with nonobstructive azoospermia. The use of immature germ cells for intracytoplasmic injection has been proposed for cases in which no spermatozoa can be retrieved. However, there are low pregnancy rates following intracytoplasmic injection using round spermatids from men with no elongated spermatids or spermatozoa in their testes. The in vitro culture of immature germ cells to more mature stages has been proposed as a means to improve this poor outcome. Several years after the introduction of intracytoplasmic injection with elongating and round spermatids, uncertainty remains as to whether this approach can be considered a safe treatment option. This review outlines the clinical and scientific data regarding intracytoplasmic injection using immature germ cells and in vitro matured germ cells.

Viable rabbits derived from oocytes by intracytoplasmic injection of spermatozoa from an infertile male

Intracytoplasmic sperm injection (ICSI) is an assisted fertilization technique and has been widely applied in human medicine to overcome some obstacles of infertility. However, this technology has not yet been used as a mainstream technique for animal production, including the rabbit, due to its limited success. The aim of this study was to improve ICSI techniques and establish an efficient ICSI method for rabbits. Spermatozoa used for ICSI were collected from mature New Zealand white male rabbits. They were washed two to three times with HEPES-buffered TCM199 containing 10% FBS and then mixed with 10% polyvinylpyrrolidone (PVP) prior to microinjection. Oocytes were harvested from superovulated donor rabbits after 14-15 h hCG treatment and were fertilized by microinjection of a single living spermatozoon into the ooplasm of each oocyte without additional activation treatment. A total of 317 injected oocytes resulted in the high survival rate of 86.1%. Among the surviving oocytes, 273 were placed into culture dishes for in vitro development. The fertilization, cleavage and blastocyst rates were 59.0%, 88.2% and 45.3% respectively. Furthermore, ICSI embryos were produced with spermatozoa from an infertile male rabbit, and 21 early-stage embryos (2-cell and 4-cell) were surgically transferred into the oviducts of two adult female rabbits. On day 31 after transfer, one out of the two recipients gave birth to two normal and healthy young rabbits. These results demonstrate that rabbit oocytes can be successfully activated and fertilized by the new ICSI protocol. Spermatozoa derived from infertile rabbits can successful fertilize oocytes and produce offspring by the simple ICSI technique.

Limiting the number of injected oocytes to three impairs ICSI outcomes in patients with nonobstructive azoospermia

BACKGROUND

Since March 2004, only a maximum of three oocytes were allowed to be subjected to ICSI at one time in Italy. A previous study failed to show an impact of this restriction on fresh embryo transfer outcomes. The objective of this study was to compare ICSI outcomes before and after this restriction in patients with nonobstructive azoospermia.

METHODS

Patients underwent testicular sperm extraction followed by ICSI. Biological (fertilization rate and the percentage of good-morphology zygotes and embryos) and clinical (clinical pregnancy and implantation rates) outcomes of the last 100 ICSI attempts before the restriction and outcomes of the first 100 ICSI attempts after the restriction were compared.

RESULTS

Despite comparable fertilization rates (58.8% versus 59.2%; P > 0.05), there was a significant decrease in the percentage of good-morphology zygotes (41.1% versus 88.4%; P < 0.05) and embryos (36.7% versus 74.0%; P < 0.05) in the cohort of embryos transferred, clinical pregnancy rate (22.7% versus 42.4%; P < 0.05) and cumulative pregnancy rate from fresh and frozen embryo transfers (22.7% versus 53.5%; P < 0.05) after the restriction.

CONCLUSION

The oocyte number restriction reduces dramatically the chance of achieving a clinical pregnancy in cases of nonobstructive azoospermia.

Evaluation of activation treatments for blastocyst production and birth of viable calves following bovine intracytoplasmic sperm injection

The objective of this study was to compare the effectiveness of different methods of bovine oocyte activation following intracytoplasmic sperm injection (ICSI) in terms of oocyte cleavage and blastocyst rates, and calf production. Oocytes were harvested, post mortem, from the ovaries of Japanese Black heifers or cows. ICSI was carried out using a piezo-electric actuator. The injected or sham-injected oocytes that were assigned to three activation treatments, each replicated three times, were studied: (1) exposure to 5 microM ionomycin for 5 min (ionomycin); (2) exposure to 5 microM ionomycin for 5 min followed by culture in TCM199 for 3 h and a further 3h culture in 1.9 mM 6-dimethylaminopurine (DMAP-ionomycin+DMAP); (3) exposure to 7% ethanol in TCM199 for 5 min, 4 h after ICSI (ethanol). One or two blastocysts from the ionomycin+DMAP (8 recipients) and ethanol (17 recipients) oocyte activation treatments were non-surgically transferred into Holsteins for the study of calf production. The highest cleavage and blastocyst production rates were observed in the ionomycin+DMAP treatment (83.9% and 40.1%) by the ICSI. These rates were significantly (P<0.05) higher than those for the ionomycin oocyte activation treatment (57.6% and 18.2%) but did not differ from the ethanol treatment (75.6% and 29.4%). In the sham-injected, the highest blastocyst production rates were observed for the ionomycin+DMAP and ethanol treatments (10.7% and 11.3%). Pregnancy and birth rates for blastocysts derived from the ethanol oocyte activation treatment (58.8% and 47.4%) were significantly higher (P<0.05) than those of the ionomycin+DMAP treatment (12.5% and 9.2%). The results showed that post-ICSI oocyte activation with ethanol is more effective than activation with ionomycin alone or with ionomycin+DMAP for the production of viable blastocysts and calves.

Live birth following intracytoplasmic sperm injection after a 15-hour weather-related delay in cryopreservation of testicular sperm

OBJECTIVE

To report a live birth after transfer of cryopreserved blastocysts derived from testicular sperm that were cryopreserved 15 hours after biopsy due to inclement weather.

DESIGN

Case report.

SETTING

University-affiliated private clinic.

PATIENT(S)

Couple undergoing IVF with intracytoplasmic sperm injection (ICSI) using testicular extracted sperm for male factor infertility due to unexplained obstructive azoospermia.

INTERVENTION(S)

An IVF case involving testicular biopsy, cryopreservation, and thawing of testicular tissue, ICSI, embryo freezing, and transfer of cyropreserved blastocysts.

MAIN OUTCOME MEASURE(S)

The ability to use cryopreserved testicular tissue in which optimal time from biopsy to freezing had been delayed because the weather was inclement.

RESULT(S)

In spite of a 15-hour delay in processing and cryopreservation of the testicular biopsy, subsequent thawing yielded viable sperm that resulted in viable embryos after ICSI. Transfer of fresh embryos was unsuccessful. However, subsequent use of supernumerary viable blastocysts that were frozen resulted in the live birth of a baby.

CONCLUSION(S)

A 15-hour delay in processing and cryopreservation of a testicular biopsy did not affect the viability of the extracted sperm after thawing. Although it is desirable to freeze the testicular specimen as soon as possible, the delay in processing in this case due to inclement weather did not affect the potential for fertilization and implantation of a viable cryopreserved blastocyst.

Implications of systemic malignancies on human fertility

Cancer patients have now longer life expectancy due to improved treatment modalities. As the mortality rate decreased and the survival rate increased, the consequences of cancer treatment in terms of impaired fertility became more frequently encountered. The objective of this review is to highlight fertility issues associated with systemic malignancies. Systemic malignancies lead to deterioration of human fertility directly or indirectly as a result of cytotoxic treatment regimens. A variety of measures may be used to decrease the incidence of fertility decline that occurs. Gamete cryopreservation represents a widely accepted method for fertility preservation in cancer patients. In addition, other procedures such as germ cell transplantation and ovarian cryopreservation, which are currently being developed, are expected to make significant contribution in these cases. However, there are some ethical issues that should be considered before offering patients any of these options.