A new, practical method of freezing and storing human sperm and a preliminary report on its use

Cryopreservation of Gametes and Embryos and Their Molecular Changes

The process of freezing cells or tissues and depositing them in liquid nitrogen at -196 °C is called cryopreservation. Sub-zero temperature is not a physiological condition for cells and water ice crystals represent the main problem since they induce cell death, principally in large cells like oocytes, which have a meiotic spindle that degenerates during this process. Significantly, cryopreservation represents an option for fertility preservation in patients who develop gonadal failure for any condition and those who want to freeze their germ cells for later use. The possibility of freezing sperm, oocytes, and embryos has been available for a long time, and in 1983 the first birth with thawed oocytes was achieved. From the mid-2000s forward, the use of egg vitrification through intracytoplasmic sperm injection has improved pregnancy rates. Births using assisted reproductive technologies (ART) have some adverse conditions and events. These risks could be associated with ART procedures or related to infertility. Cryopreservation generates changes in the epigenome of gametes and embryos, given that ART occurs when the epigenome is most vulnerable. Furthermore, cryoprotective agents induce alterations in the integrity of germ cells and embryos. Notably, cryopreservation extensively affects cell viability, generates proteomic profile changes, compromises crucial cellular functions, and alters sperm motility. This technique has been widely employed since the 1980s and there is a lack of knowledge about molecular changes. The emerging view is that molecular changes are associated with cryopreservation, affecting metabolism, cytoarchitecture, calcium homeostasis, epigenetic state, and cell survival, which compromise the fertilization in ART.

On Ice: The impact of vitrification on the use of eggs in fertility treatment

The possibility to freeze sperm and embryos has long been available to men and women facing infertility as a result of an illness or medical treatment. However, the ability to successfully cryopreserve human eggs is comparatively recent. The introduction and increasing use of egg vitrification from the mid-2000s onwards, alongside the use of intracytoplasmic sperm injection, has seen improved ongoing clinical pregnancy rates compared with slow freezing methods. Despite concerns, the technology has been widely embraced by the scientific community and in recent years has been applied in a greater variety of contexts. In this short perspective paper, we consider two specific applications for the vitrification of human eggs in routine assisted reproduction practice: social egg freezing and the use of frozen eggs in egg donation. We suggest that vitrification is transforming the reproductive landscape in novel and complex ways and that we must be alert to the challenges, complexities and ethics of such developments, especially for those who may be excluded or marginalised by these techniques.

Analysis of peptides of human seminal plasma by mass spectrometry

A procedure is described to isolate peptides from complex biological fluids (e.g. seminal plasma) in pure form within a short time. The sequence of the isolated peptides was determined by liquid secondary ion mass spectrometry in combination with enzymatic cleavage reactions. The method was used for the structure elucidation of a peptide of molecular weight 2766 u with an N-terminal pyroglutamine residue.

Relative efficiency of therapeutic donor insemination using a luteinizing hormone monitor

A prospective randomized study was performed to evaluate the use of a urinary luteinizing hormone (LH) detection kit with 1 insemination as compared with 2 alternate day inseminations with timing based on previous cycle length and basal body temperature changes. The study involved 60 patients who underwent a total of 264 therapeutic donor insemination cycles using cryopreserved semen specimens. Patients alternated LH-kit timed cycles with cycles timed by non-LH methods for a total of 6 cycles or until pregnancy was achieved. Fecundability rates were 12.3% for LH-kit cycles and 5.3% for non-LH method cycles. The difference in outcome was not statistically significant. However, when the LH kit plus 1 insemination was compared with 2 inseminations timed by conventional methods, there appeared to be a distinct monetary and time expenditure advantage. These findings suggest that sufficient advantage may be derived from use of an LH kit to recommend its use on a routine basis for the timing of therapeutic donor insemination.

Cryopreservation of human semen

A review is given of the techniques for the cryopreservation of human semen, including the preparation of cryoprotective media, the use of ampoules, straws, and pellets, and freezing and thawing techniques. The use of cryopreserved semen for therapeutic artificial insemination by donor is described. The advantages of cryopreserved semen over fresh donor semen mostly lie in the ability to exclude infections before use and the extra convenience, in spite of the lower success rate and increased cost. The recovery of sperm motility on thawing is described, as are other methods for assessing the degree of damage to the spermatozoa by the freezing procedure. The success rates reported by large semen banks are summarized.

A simplified method for freezing and storage of human semen

The use of 10-cm-long plastic tuberculin syringes for freezing and storage of human semen is introduced. This new method reduces the number of prefreezing and postthawing manipulations to a minimum. Postthawing motility, penetration of spermatozoa into cervical mucus, and results of the hamster ovum test were similar for spermatozoa stored-frozen in tuberculin syringes and for spermatozoa stored-frozen in french straws. The results of the postinsemination test performed in six women were slightly better with fresh semen than with semen stored-frozen in tuberculin syringes. Donor insemination with fresh semen resulted in eight pregnancies per 24 insemination cycles; with semen stored-frozen in tuberculin syringes five pregnancies were achieved in 22 insemination cycles.

Antigenicity of sperm cells after freezing and thawing

Freezing and thawing is thought to result in removal of spermatozoal membrane antigens. We investigated the presence of sperm antigens before and after freezing and thawing by means of the immunoperoxidase assay (IPAMA), sperm immobilization test (SIT), and separation of proteins by gel electrophoresis. The results of the IPAMA and SIT assays showed no difference in the membrane antigens before and after freezing and thawing. Analysis of surface proteins by gel electrophoresis demonstrated that freezing and thawing did not remove any particular group of proteins from the surface membrane of spermatozoa. According to the evidence of the three tests performed, there is no meaningful removal of antigens from the sperm cell surface membrane by the process of freezing, preservation, and thawing when carried out by the specific methods used. This work does not support the suggestion that in cases of immunologic incompatibility between spermatozoa and cervical mucus it would be possible to overcome the couple's infertility by employing the process of freezing, preservation, and thawing.

A comparison of freezing and thawing methods for the cryopreservation of human semen

The purpose of this study was twofold. In the first part are compared cryosurvival rates for human semen following two different freezing and three different thawing techniques. In the second part a larger number of samples processed by the best of the six methods described were examined to ensure reproducibility. Eighteen human semen samples with initial motility greater than 60% and density greater than 20 X 10(6)/ml were mixed with a cryopreservative medium at 35 degree C and vacuumed into 0.5 ml straws. Six aliquots were prepared from as many specimens as possible. Three straws were frozen by a programmed method (P) and three by a rapid freezing technique (V). All six straws were stored in liquid nitrogen vapor (-196 degree C) for 1 week. The straws were thawed by 1 of 3 methods: (1) room temperature for 10 minutes and 37 degree C hot plate for 10 minutes, (2) ice water for 10 minutes and 37 degree C hot plate for 10 minutes, (3) 35 degree C water for 12 seconds and 37 degree C hot plate for 10 minutes. Postthaw motility was assessed for each aliquot. The freeze/thaw method P/1 was judged optimal. In the second part of the study a larger number of samples were processed by P/1. The mean +/- standard deviation postthaw motility o 57 semen specimens processed by this method was 61.4 +/- 12.1.

Clinical aspects of sperm bank

The ability to preserve human sperm by cryogenic methods has been developed and successfully applied to reproductive biology. Some of the advantages include 1) availability of sperm for heterologous (donor) insemination, 2) accumulation of multiple oligospermic specimens for homologous (husband) insemination, 3) preservation of sperm prior to vasectomy, 4) collection and preservation of sperm from men who face permanent injury to spermatogenesis through an operation, chemotherapy or radiation, 5) to obviate the potential genetic danger of man's exposure to environmental pollutants such as radiation and 6) availability of husband's sperm at ovulation time.

Further developed device for human sperm freezing by the twenty-minute method

A further developed, practical device for human sperm freezing is described by which the preparation of sperm and the freezing process are reduced to a simple procedure requiring about 20 minutes. The instrument is based on the principle of evaporation of liquid nitrogen, which acts as a refrigerant for the freezing plate under the control of a thermostat. Rapid-rate freezing can be performed for pellet production and slow-rat freezing for paillettes; a high degree of isolation of samples is maintained by easily interchangeable freezing plates. Typical stages of freezing are accomplished at temperatures of +5 degrees C and--80 degrees C, with storage at--196 degrees C. The recovery index is 50% to 70%. The treatment was applied to 56 patients, resulting in 19 normal deliveries, 3 abortions, and 9 current pregnancies.

Effect of caffeine on increasing the motility of frozen human sperm

A preliminary report on the effect of the addition of caffeine to 45 frozen sperm samples, in order to restore the effectiveness and motility of frozen stored human sperm, is presented. The addition of 7.2 mM caffeine proved optimal and resulted in 40% to 80% increased sperm motility after 30 days of frozen storage. The use of rapid-rate freezing to produce frozen sperm pellets and the addition of one frozen pellet of buffered caffeine (7.2 mM) to five sperm pellets before thawing are recommonded. For slow-rate freezing in paillettes, the addition of a caffeine solution (final concentration, 7.2 mM) to the sperm and protective medium is recommended. With these methods, frozen storage of hypomotile sperm, which previously could not be preserved by freezing, is now practical.