A simple method for recovering the motile spermatozoa from extremely low quality sperm samples

Positive rheotaxis extended drop: a one-step procedure to select and recover sperm with mature chromatin for intracytoplasmic sperm injection

PURPOSE

The purpose of this study was to develop a novel one-step ICSI approach to select sperm with better chromatin maturity than the conventional method.

METHODS

This was a pilot diagnostic study, which prospectively recruited men during a 6-month period in a University-affiliated infertility centre. Forty consecutive semen samples were provided for analysis. The positive rheotaxis extended drop (PRED) was set up creating a pressure and viscosity gradient. Each semen sample was divided into four aliquots: one aliquot for density gradient centrifugation (DGC), two aliquots for PRED (fresh semen (PRED-FS) and processed semen (PRED-DGC)), and one aliquot as the control (FS). In PRED, a mean of 200 spermatozoa were collected consecutively without selection from the outlet reservoir. The aniline blue assay was used to assess chromatin immaturity.

RESULTS

The mean channel length, measured from inlet to outlet, was 32.55 ± 0.86 mm, with a mean width of 1.04 ± 0.21 mm. In 82.5% of cases (33/40), at least 50 spermatozoa were captured between 15 and 30 min. Improved chromatin maturity after the DGC preparation and the PRED approach was observed in all samples. This was reflected by a mean reduction from 28.65 ± 8.97% uncondensed chromatin in the native ejaculates to 17.29 ± 7.72% in DGC and 0.89 ± 1.31% in the PRED approach (P < 0.01).

CONCLUSIONS

The PRED method may improve the current ICSI technique by providing it with its own sperm selection process. ICSI would probably become an even more complete technique comprising selection, capture and injection of the male gamete.

Successful delivery derived from vitrified-warmed spermatozoa from a patient with nonobstructive azoospermia

OBJECTIVE

To report the clinical outcomes following intracytoplasmic sperm injection (ICSI) with vitrified sperm from patients with severe male factor infertility.

DESIGN

Retrospective case series.

SETTING

IVF unit of a medical center.

PATIENT(S)

Three patients with severe oligozoospermia or nonobstructive azoospermia (NOA).

INTERVENTION(S)

Cryopreservation of limited numbers of spermatozoa with the use of Cryotop and Cell Sleeper as nonbiologic containers.

MAIN OUTCOME MEASURE(S)

Four cycles underwent intracytoplasmic sperm injection (ICSI) with vitrified sperm.

RESULT(S)

A total of 148 spermatozoa in 18 containers (8.2 sperm per container) were vitrified and 36 of them (5 containers) were warmed. Thirty-three sperm (92%) were retrieved successfully and injected individually into 17 mature oocytes. Fertilization was observed in 12 oocytes (71%), and all zygotes (100%) cleaved. A couple with NOA achieved a singleton pregnancy and concluded with full-term delivery of a healthy boy (2,632 g).

CONCLUSION(S)

A successful delivery was achieved after transfer of a blastocyst derived from vitrified-warmed spermatozoa. A small number of vitrified sperm cells were used for ICSI to fertilize oocytes with predictable timing.

Simple vitrification for small numbers of human spermatozoa

Conventional freezing procedures and containers are not appropriate for spermatozoa from the testis because of their low number and poor in-situ motility, and various types of container have been utilized to freeze small numbers of spermatozoa. This study tried to develop a vitrification method for small numbers of spermatozoa using the Cell Sleeper, which is a closed type of cell-cryopreservation container. The container with spermatozoa were cooled in liquid nitrogen vapour and then stored in a cryotank. Sperm motility parameters improved significantly (P < 0.05) by vitrification in oil-free droplets rather than in droplets covered with oil. After vitrification of five spermatozoa per container, all spermatozoa were recovered and the viable sperm rate was significantly higher when spermatozoa were vitrified in a 3.5-ll droplet rather than in 0.5 ll (72.0% versus 38.0%; P < 0.01). Recovery, motility and viability rates of vitrified–warmed spermatozoa were similar between the Cell Sleeper and the CryoTop groups. In conclusion, the Cell Sleeper is a highly effective tool for the cryopreservation of small numbers of spermatozoa and limited cells can be vitrified quickly and simply without significant loss.

[Comparison of two methods of cryoconservation of sperm when in very small numbers]

OBJECTIVE

In case of severe oligozoospermia or following testicular biopsy in case of azoospermia, fertilization remains possible by intracytoplasmic sperm injection (ICSI). However, if there are only a few spermatozoa available to be preserved for a delayed ICSI, these gametes must be cryopreserved according to a specific method. We have found that, using the straw classical technique, less than 2 sperm were recovered at thawing when 20 sperm were frozen and no sperm were available following freezing-thawing of only 1 to 10 sperm per straw. Then, the feasibility of programmed ICSI is always uncertain in these cases and unnecessary medical acts (ovarian stimulation and egg collection) as well as patient disappointment are frequent.

MATERIAL AND METHODS

We have tested a new technique by introducing (with an ICSI pipette) 1 to 100 sperm in a microdrop (0.5 microl) of freezing medium setting in a culture dish under paraffin oil.

RESULTS

Following freezing-thawing the dish, all (100%) of the frozen spermatozoa were recovered.

DISCUSSION AND CONCLUSION

Since only motile sperm were frozen, the sperm which are non motile after thawing (more than 50%) are nevertheless considered usable for ICSI.

Late fertilization of unfertilized human oocytes in in vitro fertilization and intracytoplasmic sperm injection cycles: conventional insemination versus ICSI

PURPOSE

The aim of this study was to evaluate the efficacy of intracytoplasmic sperm injection (ICSI) in comparison with conventional reinsemination using fertilization failed oocytes by conventional in vitro fertilization (IVF).

METHODS

Oocytes were collected from patients of IVF or ICSI cycles. Patients were grouped by fertilization techniques: group 1: conventional IVF; group 2: reinsemination after conventional IVF failure; group 3: regular ICSI; group 4: 1-day-old ICSI after conventional IVF failure; group 5: 2-day-old ICSI after conventional IVF failure; group 6: re-ICSI after regular ICSI failure.

RESULTS

In different insemination groups, normal fertilization rate was higher (P < 0.001) in 1-day-old ICSI (47.1%) and 2-day-old ICSI groups (40.0%) than in reinsemination (14.7%). Abnormal fertilization rate was higher (P < 0.05) in re-ICSI group (21.7%) than any other groups (range: 0-8%). Cleavage rate was higher in 1-day-old (36.7%) and 2-day-old ICSI groups (36.0%) than in reinsemination (5.3%, P < 0.001) or re-ICSI groups (17.4%, P < 0.05). Pregnancy rate was 27.6% and 20.0% in conventional IVF and regular ICSI groups, respectively. However, 1-day-old ICSI (group 4) and 2-day-old ICSI (group 5) were attempted once embryo transfer (ET) but failed pregnancy occurred in each group.

CONCLUSIONS

In fertilization failure cycles, late ICSI increases the rate of fertilization and embryonic development and may rescue the completely failed attempt of pregnancy.