Human oocyte cryopreservation: new perspectives regarding oocyte survival

The success of human oocyte cryopreservation depends on morphological and biophysical factors that could influence oocyte survival after thawing. Various attempts to cryopreserve human oocytes have been performed with contrasting results. Therefore the effect of some factors, such as the presence or absence of the cumulus oophorus, the sucrose concentration in the freezing solution and the exposure time to cryoprotectants, on human oocyte survival after thawing were investigated. The oocytes were cryopreserved in 1,2-propanediol added with sucrose, using a slow-freezing-rapid-thawing programme. After thawing, the oocytes were inseminated by intracytoplasmic sperm injection (ICSI) and the outcomes of insemination and subsequent embryo development were also recorded. The post-thaw cryosurvival rate was not different for the oocytes cryopreserved with their cumuli partially removed mechanically (56%) when compared with those cryopreserved with their cumuli totally removed enzymatically (53%). On the contrary, a significantly higher survival rate was obtained when the oocytes were cryopreserved in the presence of a doubled sucrose concentration (0.2 mol/l) in the freezing solution and the survival rate was even higher when the sucrose concentration was tripled (0.3 mol/l) (60 versus 82% P < 0.001). Furthermore, a longer exposure time (from 10.5 to 15 min) to cryoprotectants, before lowering the temperature, significantly increased the oocyte survival rate (P < 0.005). Intracytoplasmic sperm injection produced a good fertilization rate (57%) of thawed oocytes and a high embryo cleavage rate (91%) and a satisfactory embryo morphology was observed (14 and 34% for grade I and grade II embryos respectively).

Micromanipulation of cryopreserved embryos and cryopreservation of micromanipulated embryos in PGD

The possibility to employ cryopreservation in Preimplantation Genetic Diagnosis (PGD) should enlarge the opportunities for research and clinical activity. For these purposes, we tried three kinds of approaches on human abnormal embryos: (1) cryopreservation of biopsied embryos; (2) biopsy of thawed embryos; and (3) biopsy of embryos derived from thawed oocytes. Our preliminary results show that: (1) biopsy of thawed embryos is feasible and FISH analysis is possible on both survived and lysed cells; (2) Optimization of freezing/thawing procedures are necessary to obtain better survival rate after thawing of biopsied embryos; (3) Biopsy and FISH are feasible on embryos derived from thawed oocytes and they could be a good way to study the chromosomal arrangement of these poorly investigated embryos.

Clinical experience and applications of oocyte cryopreservation

Oocyte cryopreservation is a viable solution for the ethical problems related to embryo storage, and the only available technique for preservation of fertility in women who have to undergo chemo- or radiotherapy. The main problems with oocyte cryopreservation are concerned with the survival rate and the fertilization rate. Recently the introduction of the intracytoplasmic sperm injection (ICSI) led to an increase in the fertilization rate. The success achieved with the first case treated encouraged us to set up a clinical trial on human oocyte cryopreservation. In the first stage of the study, 23 women with tubal infertility were enrolled. Superovulation was induced and 375 oocytes were retrieved; of these 338 oocytes were frozen. The survival rate was 59.5% and was independant of the duration of cryopreservation or the presence of cumulus. The normal fertilization rate was 64.4%, and only 7.5% of fertilizations were abnormal. A total of 90.8% of fertilized oocytes cleaved. A mean of 3.1+/-1.3 embryos per patient were transferred. Three pregnancies were achieved. In the second stage of our investigation, more patients were enrolled and similar results were observed. Sixteen pregnancies were achieved. A further stage of the investigation involved the fertilization of frozen oocytes with frozen sperm and even these resulted in a pregnancy. Our study demonstrated that pregnancies can also be achieved when frozen eggs are fertilized by testicular and epididymal sperm. As a consequence of the success of our investigations, a program of oocyte cryopreservation for oncological patients has been initiated in our centre. In our opinion, oocyte cryopreservation is, at present, a safe and efficient technique as documented by the birth of several healthy children.

Technical aspects of oocyte cryopreservation

Since the successful development in the mouse, the oocyte cryopreservation has been applied with varying success to a number of different species including the human. The recently reported successes in terms of pregnancies obtained by human oocyte cryopreservation are encouraging. Several studies typically reported different rates of survival (20-80%), fertilization (30-60%) and cleavage (32-100%). This variability of results throws some doubts on the usefulness of oocyte cryopreservation in IVF treatment cycles. It remains to be determined whether the relatively different success rates reported in literature, mainly in terms of survival rate, are due to methodological differences. We tried to investigate the effect of some factors on the oocyte survival rate after thawing: the presence or absence of cumulus oophorus and the exposure time of the oocytes to cryoprotectant. We suggest that a combination of several factors including both morphological and biophisical ones can affect the oocyte survival rate.

Critical evaluation of an intercalibration exercise undertaken in the framework of the MED POL biomonitoring program

The results of an intercalibration exercise among the laboratories participating in the MED POL program for monitoring biological effects of pollutants along the Mediterranean coasts are presented. Three established biomarkers, i.e. lysosomal membrane stability, metallothionein concentration and ethoxyresorufin-O-deethylase (EROD) activity, were intercalibrated. The stability of lysosomal membranes in mussels (Mytilus galloprovincialis Lam.) was assessed with a cytochemical method. The four participating laboratories were able to discriminate between control animals (membrane labilization times ranging from 21 to 35 min) and Cu-exposed animals (40 micrograms/l Cu for 3 days) (labilization times ranging from 4.5 to 7.4 min). The metallothionein concentration was evaluated in digestive gland homogenates of control mussels and of animals exposed to 200 micrograms/l Cd for 7 days. The eight participating laboratories were able to discriminate between controls and treated samples using a spectrophotometric method. The EROD activity was evaluated by 11 laboratories. All laboratories were able to discriminate between liver microsomal preparations obtained from control and from benzo-a-pyrene exposed fish (Dicentrarchus labrax), with values ranging from 0.5 to 15.88 pmol/min/mg protein in controls and from 5.41 to 165.13 pmol/min/mg protein in treated animals. Using S9 fractions, it was possible to correctly identify control and treated fish, with a variation similar to that found using microsomal fractions, albeit with an inevitable difference in specific activity. As a corollary, all laboratories involved produced comparable data and were able to identify pollutant-induced stress syndromes in sentinel organisms. Thus, intercalibration enables the use of biomarkers in large biomonitoring programs.

Human embryo development and pregnancies in an homologous granulosa cell coculture system

PURPOSE

Our purpose was to determine the effects of the coculture of embryos on human granulosa cells (GCs) in patients in the first cycle of IVF-ET treatment and in patients with repeated implantation failures and to investigate the presence of specific proteins in a 48-hr GC conditioned medium and the GC ultrastructural characteristics.

METHODS

Eighteen patients with tubal or idiopathic infertility were enrolled in this study: 7 patients (Trial 1) were in the first cycle of IVF-ET treatment and 11 patients (Trial 2) had repeated implantation failures (one to five). Embryos from each patient were cocultured randomly either on homologous granulosa cells or on a conventional culture medium.

RESULTS

At the end of the coculture period (day 5 or 6), 50% of the embryos (Trial 1) reached the blastocyst stage, with respect to 35% in Trial 2. The pregnancy rate per retrieval was 14.2 and 9%, respectively, in Trial 1 and in Trial 2. Many conditioned media showed proteins of 24-29 kDa. and some of them showed additional proteins of 90 kDa. The ultrastructural analysis of GCs showed healthy, metabolically active, protein-synthesizing, and mostly steroidogenic cells.

CONCLUSIONS

GC cultures improve embryo development but not pregnancy rates both in Trial 1 and in Trial 2.

Ongoing pregnancy after intracytoplasmic injection of testicular spermatozoa into cryopreserved human oocytes

Human oocyte cryopreservation has met with limited success in terms of both survival and subsequent fertilization. We recently reported the first birth of a healthy female infant after intracytoplasmic sperm injection of cryopreserved oocytes. The current report describes the first pregnancy achieved after intracytoplasmic injection of testicular sperm into cryopreserved human oocytes.

Genotoxicity biomarkers in the assessment of heavy metal effects in mussels: experimental studies

Heavy metals are stable and persistent environmental contaminants. The range of metal concentrations is generally below acute thresholds in coastal areas, where recognition of chronic sublethal effects is more relevant. Evidence of long-term adverse effects, such as cancer, due to heavy metals in marine animals comes from a number of field and experimental studies. The mechanism of metal carcinogenicity remains largely unknown, although several lines of experimental evidence suggest that a genotoxic effect may be involved. The aim of our study was to evaluate the sensitivity of genotoxicity tests, alkaline elution and micronucleus test, as biomarkers for the detection of heavy metals in mussels as the sentinel species. Experimental studies were carried out on Mytilus galloprovincialis exposed in aquarium (5 days) to different concentrations of three selected metal salts, CuCl2 (5, 10, 20, 40, 80 micrograms/l/a), CdCl2 (1.84, 18.4, 184 micrograms/l/a), and HgCl2 (32 micrograms/l/a), and to a mixture of equimolar doses of the three metals to study the results of their joint action. Metallothionein quantitation was used as a marker of metal exposure. Lysosomal membrane stability was applied to evaluate the influence of physiological status on genotoxic damage. The ranking of genotoxic potential was in decreasing order: Hg > Cu > Cd. Cu and Hg caused an increase of DNA single-strand breaks and micronuclei frequency. Cd induced a statistical increase of DNA damage, but gave negative results with the micronucleus test. A relationship between genotoxic effects and metallothionein content was observed. Reduction in lysosomal membrane stability with the increasing concentration of heavy metals was also evident.

Oocyte cryopreservation

Cryopreservation of human oocytes has been employed with little success in clinical practice, even though it may solve the legal and ethical problems linked to embryo freezing. Various attempts to cryopreserve human oocytes have mostly been unsuccessful, leading to low oocyte survival rates after thawing, and the search for an optimal protocol for oocyte cryopreservation remains elusive. A preliminary study was undertaken to evaluate some of the factors influencing the survival rate of human oocytes and the efficiency of intracytoplasmic sperm injection (ICSI) as an insemination procedure. A total of 38 women with tubal infertility were enrolled in the study. The cryopreservation procedure consisted of a slow freeze-rapid thawing technique using 1,2 propanediol and sucrose as cryoprotectants. The overall oocyte survival rate was approximately 60%. A better survival rate was obtained when the oocytes were cryopreserved in the presence of partially removed cumulus oophorus rather than in the presence of totally enzymatically removed cumulus oophorus. The cryoprotectant concentration and the equilibration time also appear to influence the oocyte survival rate. ICSI may be an efficient method of achieving a satisfactory outcome in terms of fertilization in cryopreserved human oocytes. Embryonic morphological quality does not seem to be compromised by cryopreservation. In conclusion, these data show that cryopreservation may ensure that the integrity of the human oocyte is adequate for normal fertilization and embryo development.

Follicular fluid and human granulosa cell cultures: influence on sperm kinetic parameters, hyperactivation, and acrosome reaction

OBJECTIVE

To evaluate the influence of human granulosa cell (GC) cultures and follicular fluid (FF) on sperm kinetic parameters, hyperactivation, and the acrosome reaction compared with the influence of human tubal fluid (HTF) and Ham's F-10 medium.

DESIGN

Sperm kinetic parameters, hyperactivation, and the acrosome reaction were evaluated after 6 hours of incubation in HTF, Ham's F-10 medium, FF, and GC cultures.

SETTING

Infertility and In Vitro Fertilization Centre, Reproductive Endocrinology Unit, Institute of Obstetrics and Gynaecology.

PATIENT(S)

Sixteen normal semen samples.

INTERVENTION(S)

Sperm kinetic parameters and hyperactivation were analyzed using an automated videomicrography system, the acrosome reaction was performed using a triple-stain technique, and progesterone and 17OH-progesterone levels were measured with the use of commercially available kits.

MAIN OUTCOME MEASURE(S)

Sperm kinetic parameters, hyperactivation, acrosome reaction.

RESULT(S)

The percentage of motile sperm, the mean curvilinear velocity, and the mean of the maximum amplitude of lateral head movement were increased significantly after 6 hours of incubation in FF or GC cultures compared with incubation in HTF or Ham's F-10 medium, whereas the mean linearity was decreased significantly. Follicular fluid and GC cultures significantly increased hyperactivation and the acrosome reaction compared with the values obtained using HTF and Ham's F-10 medium. Progesterone and 17OH-progesterone levels were increased significantly after incubation in FF and GC cultures compared with HTF and Ham's F-10 medium.

CONCLUSION(S)

Follicular fluid and GC cultures increase sperm motility parameters, hyperactivation, and the acrosome reaction. This effect may be related to GC detoxification of the microenvironement or GC secretion of peptides, glycoproteins, growth factors (insulin-like growth factors 1 and 2), or steroids (progesterone and 17OH-progesterone).

Birth of a healthy female after intracytoplasmic sperm injection of cryopreserved human oocytes

OBJECTIVE

To describe the first birth achieved after intracytoplasmic sperm injection (ICSI) of cryopreserved human oocytes.

DESIGN

Case report.

SETTING

University of Bologna Hospital, Department of Obstetrics and Gynecology, Reproductive Endocrinology Unit, IVF and Infertility Center.

PATIENT(S)

One patient undergoing IVF.

INTERVENTION(S)

Transvaginal ultrasound-guided oocyte retrieval followed by oocyte freezing. Artificial preparation of the endometrium with E2 and P, oocyte thawing, and ICSI.

RESULT(S)

Four of 12 cryopreserved oocytes survived; using ICSI, 2 underwent normal fertilization but only 1 cleaved. One good-quality 4-cell embryo was transferred. A single gestation was confirmed by ultrasound at the 7th week. Amniocentesis was performed at the 16th week and demonstrated a normal female karyotype of 46,XX. After a normal pregnancy, a healthy female infant was born at the 38th week of gestation.

CONCLUSION(S)

The combination of ICSI and oocyte cryopreservation is a new tool in assisted reproductive technology.

Births after transcervical gamete intrafallopian transfer with a falloposcopic delivery system

OBJECTIVE

To evaluate the safety and efficiency of a new delivery system to perform transcervical GIFT.

DESIGN

Evaluation of pregnancy rate (PR), miscarriage rate, ectopic pregnancy rate, and delivery rate.

SETTING

Institute of Obstetrics and Gynecology, Reproductive Endocrinology Unit, Infertility and IVF Center.

PATIENT(S)

Twenty-five patients with patent tubes documented by laparoscopy plus falloposcopy.

INTERVENTION(S)

Superovulation was induced with GnRH analogue and FSH. Under laparoscopic control, transcervical cannulation of the tube was done using a linear everting catheter incorporating direct falloposcopic vision of the tubal lumen. Two lengths of everting catheter (3 and 6 cm) were used providing either isthmic-ampullary or midampullary placement of the inoculum. A comparison was done in terms of ease of access and transfer, falloposcopic observations, and PRs between the groups.

MAIN OUTCOME MEASURE(S)

Efficacy was established by evaluating the PR, miscarriage rate, ectopic pregnancy rate, and delivery rate.

RESULT(S)

The PR was 28% (with no differences between the lengths of everting catheters). No ectopic pregnancies occurred. The abortion rate was 28.6% and the delivery rate was 20%. Neither tubal perforation nor other complications occurred during the procedure.

CONCLUSION(S)

Falloposcopic GIFT is safe and efficient and may be a less invasive alternative than laparoscopic transfer.

Chronobiologic evolution of luteinizing hormone secretion in adolescence: developmental patterns and speculations on the onset of the polycystic ovary syndrome

OBJECTIVE

To investigate the long-term evolution of the LH circadian profile in adolescent women with anovulatory cycles and normal or elevated LH levels in the first evaluation.

DESIGN

Prospective controlled clinical study.

SETTING

Reproductive endocrinology unit of an academic medical center.

PATIENT(S)

Twelve healthy anovulatory adolescent girls aged 12 to 17 years (5 subjects with high plasma LH level and 7 subjects with normal LH level) and four ovulatory subjects as controls.

INTERVENTION(S)

Blood samples were drawn every 20 minutes for 24 hours beginning at 10:00 A.M. at early and late gynecologic ages.

MAIN OUTCOME MEASURE(S)

Luteinizing hormone, FSH, E2, T, androstenedione, ovarian volume.

RESULT(S)

In the first evaluation, the highest plasma LH levels and greatest pulse amplitude were found early in the morning in the normal-LH group and late in the afternoon in the high-LH group. Controls did not display any significant circadian variation in LH secretion. The second evaluation revealed ovulatory cycles in six of seven subjects (85.7%) in the normal-LH group with the disappearance of the circadian rhythm. Two of five (40%) patients with high LH in the first evaluation became ovulatory with a significant decrease of mean LH levels and the disappearance of the circadian rhythm. Girls of both groups who remained anovulatory still displayed the accentuated circadian profiles that were seen at the first evaluation.

CONCLUSION(S)

An accentuated 24-hour LH periodicity is typical of puberty but disappears in adulthood. The persistence of these rhythms in persistently anovulatory adolescents may indicate a maturational arrest. In particular, the persistence of the high LH circadian profile with the highest values during the day is very similar to that found in polycystic ovary syndrome.

The effect of leuprorelin on steroidogenesis of human preovulatory granulosa cells in vitro

PURPOSE

LHRH analogues are commonly used in in vitro fertilization protocols to induce hypogonadotropic hypogonadism. The aim of our study was to evaluate the action of the LHRH agonist leuprorelin on the E2 steroidogenesis of human preovulatory granulosa cells.

RESULTS

FSH causes a significant increase in E2 production which is double that of the basal condition (P < 0.01). At concentrations of 1, 10, and 100 ng/ml, leuprorelin does not produce any modification with respect to the basal condition during the 24- or 72-hr culture period. The FSH, added at different analogue concentrations, produces a significant increase in E2 production as compared to the basal condition (P < 0.05) and the E2 production percentage is similar to the values obtained with FSH alone during the 24- or 72-hr culture period.

CONCLUSIONS

Leuprorelin has no effect on the in vitro E2 production at any concentration. The treatment with different doses of leuprorelin does not suppress FSH-stimulated E2 production. Our findings suggest that human granulosa cells are not acutely sensitive to a direct action on E2 steroidogenesis by LHRH analogues.

Longitudinal change of sonographic ovarian aspects and endocrine parameters in irregular cycles of adolescence

We longitudinally studied clinical endocrine and ultrasound parameters of the ovaries in 73 healthy adolescents having persistent menstrual irregularities. After the first examination, they were reexamined after a variable period ranging from 2 to 7 y. During the first examination, three basic features of the ovaries were observed: homogeneous (36%), multifollicular (23%), and polycystic (41%). Polycystic ovaries were most frequent, and they generally exceeded the normal adult range. During the last examination, in the entire group of irregular adolescents, homogeneous ovaries decreased (-14%), polycystic ovaries increased (+18%), and a further higher number of subjects exceeded the normal adult range (+10%). The subjects with enlarged ovaries had the highest values of LH, testosterone, and androstenedione. Fourteen subjects out of 46 (30%), with normal ovarian volume in the first examination, registered an ovarian enlargement in the last examination, exceeding the normal range. Moreover, a change from the homogeneous or multifollicular structure to the polycystic one was observed. Twenty-one subjects out of 27 (78%) with enlarged ovaries in the first examination confirmed the high ovarian volume and the unchanged structure in the last examination, whereas six subjects (22%) showed ovaries within the normal adult range; the polycystic structure was substantially confirmed. These results indicate the following. 1) Homogeneous, multifollicular, and polycystic ovaries can usually be found in the postmenarcheal period. 2) Enlarged ovaries, polycystic structure, hyperandrogenemia, and high LH values are strongly linked, and they are frequent in irregular cycles even in the absence of signs of hyperandrogenism. These characteristics may all persist or in various aggregations become a permanent feature. 3) Only a few subjects may lose ovarian enlargement and show a change in the polycystic structure; however, they frequently maintain hyperandrogenemia. 4) During the postmenarcheal period, normal ovarian characteristics may suddenly change, and the ovaries may take on a polycystic structure and increase in volume. Moreover, some endocrine parameters may reach pathologic levels.

High dose intravenous immune globulins and plasma exchange in Guillain-Barré Syndrome

We report the effects of treatment with plasma-exchange (PE) and intravenous immune globulins (IVIg) in 36 out of 50 patients with Guillain-Barré syndrome (GBS) recruited by an incidence study in the Emilia-Romagna region of Italy. Comparison of the patients treated with PE and IVIg showed no significant differences in terms of effectiveness in improving the clinical course of GBS: at one month, respectively 11.1% and 25% had recovered, and 55.5% and 58.3% had improved by at least one grade. These results are in agreement with those of the Dutch GBS trial. No relapses were observed in either group. Moreover, our results showed no difference in clinical outcome at 1 and 3 months between the patients receiving only one therapy and those receiving two; a second cycle of therapy did not seem to improve the clinical course of the disease significantly. We conclude that PE and IVIg are both safe and effective therapies for GBS.

Gamete intrafallopian transfer: prospective randomized comparison between hysteroscopic and laparoscopic transfer techniques

OBJECTIVE

To test the efficiency and overall acceptability of hysteroscopic GIFT when compared with laparoscopic GIFT.

DESIGN

We performed a randomized comparison between these techniques as regards pregnancy rate (PR), implantation rate, miscarriage rate, and ectopic pregnancy rate (ectopic PR).

SETTING

All patients were enrolled for GIFT procedures in our Reproductive Medicine Unit.

PATIENTS

We enrolled 133 patients showing documented tubal patency at a previous diagnostic laparoscopy.

INTERVENTIONS

Gonadotropin-releasing hormone analog and FSH were administered to induce superovulation in all patients, who were then randomized for hysteroscopic GIFT or laparoscopic GIFT. Laparoscopic GIFT was performed under general anesthesia while, during hysteroscopic GIFT, oocyte retrievals were transvaginal ultrasound guided and transfers were performed by cannulating tubal ostia after hysteroscopic visualization.

MAIN OUTCOME MEASURE

The efficacy was evaluated comparing PR, implantation rate, miscarriage rate, and ectopic PR.

RESULTS

Pregnancy rate and implantation rate of hysteroscopic GIFT procedures (29.8% and 9%, respectively) are not significantly different from those obtained with laparoscopic GIFT (43.3% and 14%).

CONCLUSIONS

Hysteroscopic GIFT is safe and easy and quick to perform. Moreover, it does not require hospital admission, general anesthesia, or the operating theater, reducing costs and assuring advantages in terms of low psychophysical involvement and repeatability.