TSEICSI - The End Of Male Infertility?

So far medicine has had nothing to offer the man with azoospermia because of testicular failure, in the way of treatment. His only treatment choices were: adoption, or donor insemination.

However, now it is possible to actually extract sperm from the testis of these patients, and inject them into their wives eggs. This is called TSEICSI (pronounced "sexy") - Testicular Sperm Extraction with IntraCytoplasmic Sperm injection.

ICSI, or microinjection is a new technique which has revolutionised IVF laboratory technology, and allows us to fertilise one egg with just one single sperm.

Formerly, ICSI was done for patients using the sperm found in the ejaculate. It was believed that testicular sperm would not be able to achieve a pregnancy, because they were immotile and immature. However, using ICSI, pregnancies have been achieved even using testicular sperm. These were done initially in patients with obstructive azoospermia, where spermatogenesis was normal. However, Dr DeVroey of the AZ-VUB Clinic in Belgium decided to explore the possibility of using testicular sperm even in patients with non-obstructive azoospermia (testicular failure). The rationale behind this was the finding that defects in sperm production were " patchy" - they did not affect the entire testis uniformly. This meant that even if sperm production was absent in a certain area, there would be other areas in the testis, where sperm production would be normal. This could be because the genetic defect which causes abnormal spermatogenesis may be "leaky". Thus, even if the testis biopsy is reported as showing complete germinal cell or maturation arrest, this means only that there is no sperm production in the area sent for histologic examination - and not that there is no sperm production at all in the entire testis. If the surgeon is willing to be patient, and take multiple biopsies, he may still be able to find areas of normal spermatogenesis, and extract sperm from these areas. Since such few sperm are needed for ICSI, it is possible to perform TSEICSI for over 80% of patients with testicular failure - even if their testes are as small as a peanut! Moreover, since the testicular sperm can be frozen and stored, in case a pregnancy does not result from the first attempt, the frozen sperm can be thawed and used in future cycles - thus obviating the need for repeated biopsies.

But what about the 20 % of patients in whom testicular sperm cannot be found even after taking multiple biopsies? There is hope, even for these men! A pregnancy has been reported from the NURTURE Group in Nottingham, UK, by microinjecting the round sperm precursor cells in the testis called spermatids. This is because spermatids contain the same genetic matter spermatozoa do, and differ from spermatozoa primarily in that they do not have tails. Thus, it appears that even spermatids have fertilising capability, when used for ICSI.

Of course, this now brings us to the thorny problem of what the role of a diagnostic testis biopsy is in modern times. A testis biopsy may be useful in selecting azoospermic patients for reconstructive surgery. However, it does not seem to provide any further useful information, and should be used very sparingly.

How do we extract the sperm from the testis? For patients with normal-sized firm testis (obstructive azoospermia), it is possible to recover enough sperm for ICSI from even a very tiny bit of tissue - so that one can even use fine needle aspiration, or a percutaneous closed biopsy for TSEICSI. However, for patients with testicular failure, since it may be necessary to take multiple biopsies, these should be done as open biopsies, under sedation, or under general anaesthesia. These procedures can take quite a lot of time - since multiple biopsies may be required before sperm are found.

The testicular tissue is removed atraumatically, and sent to the laboratory in culture medium. Here the testicular tubules are teased, and their contents dissected free from the tubule wall and connective tissue, under a stereo zoom microscope. The tubular contents are centrifuged, and the pellet examined under the microscope, to look for sperm. Testicular sperm are usually immotile (though they may have local twitching motility); and are often attached to Sertoli cells.

The TSEICSI process takes place in a superovulated cycle during which fertility drugs (GnRH analogs and HMG) are administered to the wife to aid in the production of multiple eggs. The eggs are removed under vaginal ultrasound guidance, as is done for IVF. The cluster of cells which surround the egg - known as the cumulus-corona complex cells, are then removed by a chemical called hyaluronidase before the sperm injection takes place. Only mature eggs (in metaphase II) are selected for ICSI.

Once the stripped eggs and the sperm are collected, the actual process of injecting a single sperm into the egg is carried out in a petri dish, using a micromanipulator. Quality tools are essential to the overall success of an ICSI program, and these are now commercially available. A glass holding pipette 40-50 microns in diameter is used to secure the egg, usually on the left side. An injection needle with an outer diameter of roughly five to six microns and an inner diameter of three to four microns, is used to pick up the sperm and inject it into the egg after piercing the egg membrane on the right side at about 3 o'clock.

A single sperm is selected (and this may take a lot of searching!) and its tail is broken or crushed to immobilize it. It is then aspirated into the injection pipettes and injected into centre of the egg, which is held in place by applying suction on the holding pipette.

Many factors must be mastered to ensure success of the ICSI process. It is especially important to confirm that the injection pipette breaks the membrane of the egg, to ensure that the sperm is injected into the cytoplasm. The skill of the embryologist is a critical factor in the success of the ICSI process.

Once each egg is injected with a single sperm, the injected eggs are placed in the CO2 incubator, and then observed approximately 14 hours later to see if fertilization has taken place. If fertilization occurs, the 2-4 cell embryos can be transferred into the wife's uterus about 48-72 hours after ICSI. Supernumary embryos can be stored in liquid nitrogen.

Fertilisation rates in the range of 60% have been achieved in experienced hands - which means, of 100 microinjected eggs, 60 form embryos after ICSI. The pregnancy rate in one ICSI cycle is about 25-30% per cycle. Surprisingly, the chance of achieving a pregnancy depends only on the number of eggs retrieved - which, in turn, depends upon the woman's age - the younger, the better! The quality of the sperm seems to be quite unimportant. The risk of having a baby with a birth defect is not increased with this technique. However, since the genetics of testicular failure are so poorly understood, it is possible that there is a risk of the male children born as a result of this technique being infertile as well (for example, if the cause for the testicular failure is a defective genetic locus on the Y chromosome).

References:

References

Van Steirteghem AC, Nagy ZP, Jrs H, et al. (1993) High fertilization and implantation rates after intracytoplasmic sperm injection. Hum Reprod, 8, 1061-66.

Devroey P, Liu J, Nagy P, et al. (1994) Normal fertilisation of human oocytes after testicular sperm extraction and intracytoplasmic sperm injection. Fertil Steril, 62, 639-641.

Devroey P, Liu J, Nagy P, et al. (1995) Pregnancies after testicular sperm extraction (TESE) and intracytoplasmic sperm injection (ICSI) in non-obstructive azoospermia. Hum Reprod, 10, 1457-1460.

Tournaye H, Liu J, Nagy P, et al. (1996) Correlation between testicular histology and outcome after intracytoplasmic sperm injection using testicular spermatozoa. Hum Reprod, 11, 127-132.

Silber SJ. (1995) What forms of male infertility are there left to cure? Hum Reprod, 10, 503-504.