Kaoru Yanagida

Successful pregnancy after ICSI with strontium oocyte activation in low rates of fertilization

Fertilization failure (complete fertilization failure or low fertilization rates) after intracytoplasmic sperm injection (ICSI) can occur in rare cases. In the majority of these cases, the unfertilized oocytes are inactivated. Assisted oocyte activation was applied as a treatment option for a case of low fertilization rate as a clinical trial. A patient with a low fertilization rate (ranging from 0% to 33.3%; mean = 17.0%) after eight previous ICSI cycles at another hospital, was diagnosed with fertilization failure. The most likely cause of fertilization failure was failure of oocyte activation. Therefore, artificial oocyte activation by strontium treatment was combined with ICSI to achieve viable fertilized oocytes. Oocytes were stimulated with strontium (10 mM SrCl(2), 60 min) approximately 30 min after ICSl. Six injected oocytes were stimulated and all were then successfully fertilized. Two blastocysts were transferred into the uterus, resulting in a pregnancy and birth. A second pregnancy was achieved following implantation of two cryopreserved embryos (one blastocyst and one morula). In conclusion, strontium treatment was found to be an effective method for artificial oocyte activation in a case with a low fertilization rate after ICSI.

Complete Fertilization Failure in ICSI

Fertilization failure is one of the causes of infertility that becomes evident only after in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) have been attempted. Although the frequency of incidence of fertilization failure is low, if fertilization failure is encountered, medical treatment is usually stopped and serious psychological damage may occur to the patient.While fertilization failure in IVF can be dealt with using ICSI, there is no treatment for fertilization failure in ICSI. At present, clinical investigations are being conducted to evaluate oocyte activation in combination with ICSI to cope with fertilization failure of ICSI.

The present status of artificial oocyte activation in assisted reproductive technology

Intracytoplasmic sperm injection (ICSI) is the most effective treatment for achieving fertilization in assisted reproductive technology (ART). However, fertilization failure occurs. The incidence of fertilization failure after ICSI is 1–5%. Approximately 50% of fertilization failure cases could be attributed to the abnormality of sperm factor. As the fertilization fails after ICSI using mature sperm, round spermatids and globozoospermia, artificial oocyte activation may provide a means of improving fertilization rates in such cases. The oocyte activation treatments used in clinical research include calcium (Ca) ionophore treatment, electrostimulation and strontium treatment. In terms of the efficiency of oocyte activation, electrostimulation and Ca ionophore gave better outcomes than strontium treatment. Strontium treatment causes Ca2+ oscillations in mice, so it has been viewed favorably. However, in human oocytes calcium oscillation has not been observed. The fertilization rate after ICSI was low in the case of globozoospermia and wiht round spermatids. Some cases of pregnancy were achieved by ICSI alone and oocyte activation methods were not essential in these cases. Among the various oocyte activation methods currently used, it should be noted that issues of genetic safety have not been addressed for the combined use of these oocyte activation methods.

Human round spermatids from azoospermic men exhibit oocyte-activation and Ca2+ oscillation-inducing activities.

During mammalian fertilization, intracellular Ca2+ oscillations are important for both oocyte activation and embryonic development. As the ability of round spermatids (ROS) to induce Ca2+ oscillations and oocyte activation is different between species, we examined Ca2+ oscillation- and oocyte activation-inducing abilities of human ROS originating from patients with non-obstructive azoospermia. Human ROS from 11 non-obstructive azoospermic patients were collected during their TESE-ICSI cycles. Following injection into mature unfertilized mouse oocytes, we examined the oocyte-activating and Ca2+ oscillation-inducing activities of ROS by using Ca2+ imaging and confocal laser scanning microscopy (mouse test). In these 11 cases, clinical TESE-ICSI using mature testicular spermatozoa was successful, with the exception of one case in which only one sperm-injected oocyte was not fertilized. The mean fertilization rate was 70.1% (40-100%); the mean cleavage rate was 97.9% (46/47). Two pregnancies were established from 10 transfer cycles (PR; 20%). When the ROS from these patients were injected into mouse oocytes, the ROS from all patients induced at least some intracellular Ca2+ oscillations (25-100%). In all patients, 40 out of 82 oocytes injected with ROS exhibited normal oscillation patterns of [Ca2+]i. Human spermatogenetic cells acquired oocyte-activating and Ca2+ oscillation-inducing abilities at the round spermatid stage, an earlier stage than found for rodent cells. These data indicate that human ROS might be useful for clinical treatments of non-obstructive azoospermic patients exhibiting mature spermatozoa in biopsied specimens.

The oocyte activation and Ca2+ oscillation-inducing abilities of mouse and human dead (sonicated) spermatozoa.

In ICSI procedures, it is well known that the selection of viable (live) spermatozoa and certain types of immobilization prior to injection is very important for obtaining successful results, but unfortunately there are rare situations when only immotile spermatozoa are available (such as in severe asthenozoospermia or necrozoospermia). In such cases, failure of oocyte activation after ICSI often occurs and may be due to the lack of SOAF (sperm-borne oocyte activating factor) activity. In order to investigate the SOAF activities of dead spermatozoa, mouse and human spermatozoa were immobilized (killed by sonication), maintained in THF medium for varying time intervals (up to 72 h) and then injected into mature unfertilized mouse oocytes. Injected mouse oocytes were examined for their activation, development into blastocysts and Ca2+ responses by imaging and confocal laser scanning microscope. The rates of oocyte activation, blastocyst development and normal patterns of Ca2+ oscillation from the killed-sperm-injected oocytes decreased gradually in accordance with the maintenance interval between sonication and injection. For injection with mouse sonicated spermatozoa, the rate of normal Ca2+ oscillations declined first (after a 3 h maintenance interval) and then blastocyst development was gradually obstructed (after approx. 10 h). The oocyte activation-inducing ability of dead spermatozoa was maintained for a relatively long period, but began to decline after 20 h. The activation rates and Ca2+ response of the oocytes that were injected with human sonicated spermatozoa decreased earlier than those injected with mouse spermatozoa. Although the oocyte activation-inducing ability was maintained for a relatively long time after the death of the spermatozoa, embryo development into blastocysts and the rate of normal Ca2+ oscillations declined after a short maintenance interval between sonication and injection. The Ca2+ response seemed to be the most sensitive indicator for the evaluating the SOAF activity of dead (killed) spermatozoa.

Chromosomal analysis of mouse spermatozoa following physical and chemical treatments that are effective in inactivating HIV.

Human immunodeficiency virus (HIV) can be inactivated by heating at 56 degrees C for 30 min, treating with 50% ethanol at room temperature for 10 min, or treating with 2% sodium hypochlorite solution (NaClO) at room temperature for 60 min. Using a mouse model, we evaluated the risk of generating chromosome damage in spermatozoa following these treatments. The spermatozoa were all dead after the treatments. Although 41.3% of oocytes injected with ethanol-treated spermatozoa successfully activated, none of the oocytes injected with heated or NaClO-treated spermatozoa activated. When artificial stimulation with strontium was used, the fertilization of oocytes with heated or ethanol-treated spermatozoa was completely rescued. Sperm nuclei treated with NaClO neither decondensed nor developed to a male pronucleus. The incidences of structural chromosome aberrations in 1-cell zygotes derived from the heated spermatozoa (45.6%) and ethanol-treated spermatozoa (91.2%) were significantly higher than those in the matched controls (5.5% and 10.5%, respectively). Further study is needed to develop a methodology for the protection of spermatozoa against chromosome damage or the separation of damaged spermatozoa before intracytoplasmic sperm injection.

Abstracts of Symposium

S OF SYMPOSIUM “progress in ART and Future Reproductive Medicine”

Relationship between Semenogelins bound to human sperm and other semen parameters and pregnancy outcomes

BackgroundSemenogelins (SEMGs) are major components of human seminal vesicle secretions. Due to SEMG’s sperm-motility inhibitor, a significant negative correlation between sperm motility and the proportion of SEMG-bound spermatozoa (SEMG+) was found in asthenozoospermic patients. SEMGs also show intrinsic inhibitory capability for sperm capacitation; however, studies on actual clinical specimens have not been conducted.MethodsTo reveal the relationship between SEMGs and the fertilizing capacity of sperm from male infertile patients who are not restricted to asthenozoospermia, we measured the proportion of SEMG+ in the spermatozoa of 142 male infertile patients. The pregnancy outcomes in partners of these patients were retrospectively analyzed using questionnaires.ResultsAmong examined semen parameters, only the total SEMG-unbound sperm count showed a tendency to be different between the spontaneous pregnancy or intra-uterine-insemination-pregnancy groups and in-vitro-fertilization- or intracytoplasmic-sperm-injection-pregnancy groups. It was elevated in the former group, which includes patients who used in vivo fertilization.ConclusionsThe total SEMG-unbound sperm count would be a relevant parameter for in vivo fertilization. This result suggests that SEMGs inhibit ectopic capacitation before sperm reach the fertilization site and that the number of total SEMG-unbound sperm is a parameter directly linked to the possibility of in vivo fertilization.RésuméContexteLes séménogélines (SEMG) sont des composantes principales des sécrétions des vésicules séminales humaines. En raison de la présence sur SEMG d’un inhibiteur de la mobilité des spermatozoïdes, une corrélation significative a été rapportée entre la mobilité des spermatozoïdes et le pourcentage de spermatozoïdes liés à SEMG chez des patients asthénozoospermiques. Les SEMG possèdent aussi une capacité intrinsèque d’inhibition de la capacitation; aucune étude n’a cependant été réalisée sur des échantillons de sperme utilisés en pratique clinique quotidienne.Matériel et méthodesDe façon à mettre en évidence une relation entre les SEMG et la capacité fécondante de spermatozoïdes d’hommes inféconds qui ne soient pas seulement des patients asthénozoospermiques, nous avons mesuré la proportion de spermatozoïdes SEMG+ (liés à SEMG) chez 142 patients inféconds. L’issue des grossesses chez les partenaires de ces patients a été rétrospectivement analysée à partir de questionnaires.RésultatsParmi les paramètres spermatiques analysés, seul le nombre total de spermatozoïdes non liées à SEMG montre une tendance à être différent entre le groupe de grossesses obtenues spontanément ou par insémination intra-utérine et le groupe de grossesses obtenues par fécondation in vitro ou injection intra-cytoplasmique d’un spermatozoïde. Ce nombre total était élevé dans le premier groupe qui incluait des patients utilisant une fécondation in vivo.ConclusionsLe nombre total de spermatozoïdes non liés à SEMG pourrait être un paramètre pertinent pour la fécondation in vivo. Ces résultats suggèrent que les SEMG inhibent la capacitation ectopique avant que les spermatozoïdes n’atteignent le site de fécondation, et que le nombre total de spermatozoïdes non liés à SEMG est. un paramètre directement lié à la possibilité de fécondation in vivo.Mots-clésProtéine plasmatique séminale, Infécondité masculine, Séménogélines, IIU, FIV, ICSI, Issues de grossesses

Issues of ICSI as a Procedure

Abstract: It seems that ICSI is well investigated basically and clinically, as more than 20 years have passed from the first report of success in humans ICSI. However, the study is still insufficient in practice. We need discussion about the unknown points in ICSI procedure, for example the in vitro ageing of retrieved oocytes, non-physiological treatment removing the cumulus cells from COC by hyaluronidase, the method of selection of good sperm, the method of immobilization of sperm, the effect of polyvinylpyrrolidone and acrosome enzyme that are brought in the oocyte. We must practice good treatments for oocytes and embryos. It is important that we continue carrying out that it is thought to be right scientifically and theoretically in ICSI procedure to improve quality of ICSI. It leads to improvement of the quality of ART and seems to be the mission of a stuff engaged in reproductive medicine.

Relationship between Assessment of Sperm Nuclear Qualities and Embryo Development In Vitro

ABSTRACT Concept of the fertilizing ability of human spermatozoa has been drastically changed since intracytoplasmic sperm injection (ICSI) played an important role of modern reproductive medicine. Recent studies on the qualities of sperm nucleus revealed that the fertilization and embryo development in vitro should be related to the structure of sperm nuclear chromatin, especially in case of ICSI procedure. It has been suggested that oocytes injected with sperm nuclei with poor S-S bonds have more developmental potency than that with S-S rich sperm nuclei. Moreover, it has been pointed out from the assessment of DNA fragmentation that oocytes injected with genetically impaired nuclei have little potency to develop beyond 8 cell stage embryo. Hereafter, the more definitive assessments of sperm nuclear chromatin should be needed to select the best nuclei for ICSI procedure.