The aim of this retrospective study was to compare the incidence of chromosomal abnormality in embryos from in-vitro maturation (IVM) and IVF cycles. The copy numbers of chromosomes 13, 15, 16, 18, 21, 22, X and Y were assessed with fluorescence in-situ hybridization (FISH) in single blastomeres biopsied from cleavage stage embryos. Spare embryos that were not transferred or cryopreserved were also analysed in full. IVM and IVF groups comprised six and 30 couples, with mean ± SD embryos with FISH result of 8.0 ± 4.4 and 11.7 ± 3.8, respectively. The incidence of chromosomal abnormality per FISH result was similar in IVM and IVF embryos (58.7% versus 57.4%, respectively). When embryos were categorized based on maturation time of oocytes in IVM cycles, embryos derived from oocytes that matured 48 h after collection had a higher chromosomal abnormality rate compared with embryos derived from in-vivo matured oocytes and to embryos derived from oocytes that matured in the first 24 h after collection.
Introduction
IVF has been one of the major, perhaps the most influential, breakthroughs in the practice of reproductive medicine. More than two million babies have been born with IVF treatment since the birth of Louise Brown in 1978 (Steptoe and Edwards, 1978). The technique has been improved in 30 years and pregnancy rates have reached 25–50% per started cycle (Andersen et al., 2009, Society for Assisted Reproductive Technology, 2009). The success of IVF seem to depend on, among other factors, number of oocytes available for fertilization in vitro, requiring ovarian stimulation with gonadotrophin releasing hormone analogues and gonadotrophins as an integral part of treatment. However, ovarian stimulation is not without limitations. Besides the inconvenience of daily injections, frequent monitoring scans and high cost of the medication, the risk of ovarian hyperstimulation syndrome is another problem associated with ovarian stimulation. A treatment yielding similar success without ovarian stimulation would be safer, more convenient and less expensive for couples and can be regarded as the ultimate patient friendly protocol.
The first live birth following collection of immature human oocytes in an unstimulated cycle and fertilizing them following maturation in vitro was reported by Cha et al. (1991). Similar to IVF, the technique of in-vitro maturation (IVM) has also been improved over the years and over 1000 babies have already been born (Buckett et al., 2007). IVM eliminates the need for gonadotrophin injections and associated costs and inconvenience, as well as the risk of ovarian hyperstimulation syndrome. The incidence of congenital abnormalities in infants conceived following IVM is comparable to that following natural conception or IVF (Buckett et al., 2007, Buckett et al., 2008). Despite satisfactory pregnancy rates in selected patients, overall embryo implantation rates of IVM embryos are still lower than that of conventional IVF embryos (Son et al., 2008). This fact can be considered the major obstacle before widespread use of IVM. A higher incidence of chromosomal abnormality in embryos derived from IVM oocytes may be a factor limiting the implantation potential of IVM embryos (Requena et al., 2009). However, data on chromosomal constitution of IVM embryos compared with preimplantation IVF embryos are limited.
Fluorescence in-situ hybridization (FISH) analysis is used to assess the chromosomal constitution of human cleavage stage embryos produced through assisted reproduction. The technique has been used as an adjuvant to IVF for various indications, namely diagnosis of sex chromosome-linked diseases and unbalanced translocations in preimplantation embryos, as well as a screening tool for selection of chromosomally normal embryos for transfer. Although, the technique has been regarded useful for former indications, the latter indication, preimplantation genetic screening (PGS) has been controversial. FISH has also been successfully used to assess the chromosomal complement of IVM embryos (Ao et al., 2006, Requena et al., 2009). It is controversial whether embryos from IVM cycles have a higher incidence of chromosomal abnormality limiting their implantation potential as compared with embryos from conventional IVF cycles.
The aim of the present report was to compare retrospectively the incidence of chromosomal abnormality in cleavage-stage IVM and IVF embryos derived from women of similar age undergoing a PGS cycle. Spare embryos that were not transferred or cryopreserved after treatment were also assessed.
Section snippets
Participants
A total of eight PGS cycles were performed in eight couples undergoing IVM treatment between August 2004 and March 2008 at the McGill Reproductive Centre. Female age ranged between 32 and 43 years in these couples. The 43-year-old woman and a 31-year-old woman, who had a balanced translocation, were excluded from primary analyses. The IVM group included the six remaining women aged between 32 and 35 years. The control group comprised all couples, in which the female partner was younger than 35
Results
The mean female ages were 33 ± 1.6 and 32 ± 2.9 years in couples undergoing IVM–PGS and IVF–PGS, respectively. In the IVM–PGS group, 3/6 had a history of recurrent miscarriage (50%) and 2/6 had recurrent implantation failure (33%). In the IVF–PGS group, 10/30 had a history of recurrent miscarriage (33%) and 17/30 had recurrent implantation failure (57%). The remaining four patients had either a long history of infertility or had experienced miscarriages or IVF failures but the numbers were not high
Discussion
This retrospective study aimed to compare chromosomal abnormality rates between embryos produced in IVM and IVF cycles and to further assess any differences in chromosomal constitution of these embryos. The overall incidence of chromosomal abnormality was similar between IVM and IVF embryos.
The chromosomal abnormality rate observed in IVF embryos in the control group is slightly higher than that in previously published prospective studies involving women of similar age groups (Blockeel et al.,
Acknowledgments
The authors wish to thank the patients and all the embryologists, physicians and the nurses at the McGill Reproductive Centre for their co-operation.
Assisted reproductive technology and intrauterine inseminations in Europe, 2005: results generated from European registers by ESHRE: ESHRE. The European IVF Monitoring Programme (EIM), for the European Society of Human Reproduction and Embryology (ESHRE)
Human Reproduction
(2009)
A. Ao et al.
First successful pregnancy outcome after preimplantation genetic diagnosis for aneuploidy screening in embryos generated from natural-cycle in vitro fertilization combined with an in vitro maturation procedure
Fertility and Sterility
(2006)
E. Baart et al.
Preimplantation genetic screening reveals a high incidence of aneuploidy and mosaicism in embryos from young women undergoing IVF
Are blastocysts derived from in-vitro-matured metaphase I (MI) oocytes less likely to produce usable embryos for transfer compared with those derived from in-vivo-matured oocytes in cycles undergoing preimplantation genetic testing (PGT)?
The primary outcome was usable blastocyst rate, which was compared between blastocysts derived from in-vitro-matured MI oocytes after ovarian stimulation and from in-vivo-matured oocytes. Logistic regression analysis using generalized estimating equations was used to control for confounders in the analysis of factors that may influence the chance of a blastocyst being usable and in the comparison of embryological outcomes. Student's t-test, Mann–Whitney U test, chi-squared tests or Fisher's exact tests were used to compare clinical and pregnancy outcomes.
A total of 1810 injected metaphase II (MII) oocytes from 154 PGT cycles involving 154 couples were included in this study. A total of 1577 MII oocytes were in-vivo-matured and 233 were in-vitro-matured MI oocytes. The usable blastocyst rate was similar between the in-vitro-matured MI oocyte group and the in-vivo-matured oocyte group (adjusted RR 0.97, 95% CI 0.40 to 2.34). Three live births were achieved using usable blastocysts derived from in-vitro-matured MI oocytes.
If in-vitro-matured MI oocytes can be fertilized and develop into blastocysts, their ability to provide usable embryos for transfer is similar compared with those developed from in-vivo-matured oocytes. These blastocysts could be considered valuable for women with few viable embryos in assisted reproductive technology cycles.
Does rescue in-vitro maturation (IVM) in the presence or absence of cumulus cells, affect the progress of meiosis I, compared with oocytes that mature in vivo?
This prospective study was conducted in a university-affiliated fertility centre. Ninety-five young oocyte donors (mean age 25.57 ± 4.47) with a normal karyotype and no known fertility problems were included. A total of 390 oocytes (116 mature metaphase II [MII] and 274 immature oocytes) were analysed. The immature oocytes underwent rescue IVM in the presence of cumulus cells (CC; IVM+CC; n = 137) or without them (IVM-CC; n = 137), and IVM rate was calculated. Chromosome copy number analysis using next-generation sequencing (NGS) was performed on all rescue IVM oocytes reaching MII as well as those that were mature at the time of initial denudation (in-vivo-matured oocytes [IVO]).
Maturation rates were similar in IVM+CC and IVM-CC oocytes (62.8 versus 71.5%, P = 0.16). Conclusive cytogenetic results were obtained from 65 MII oocytes from the IVM+CC group, 87 from the IVM-CC group, and 99 from the IVO group. Oocyte euploidy rates for the three groups were similar, at 75.4%, 83.9% and 80.8%, respectively (P = 0.42).
The results suggest that culture of germinal vesicle and metaphase I oocytes in the presence of cumulus cells does not improve rates of IVM. In general, the process of rescue IVM does not appear to alter the frequency of oocytes with a normal chromosome copy number.
In vivo, oocyte maturation involves an intimate dialogue, possible due to the gap junctions, between the oocyte and cumulus cells, which surround it. Studies show higher rates of maturation and embryonic cleavage when oocytes are cultured with their cumulus cells, and conversely, a delay in embryonic development and an increased rate of embryonic fragmentation have been observed when culture is carried out without CC [21,23,24]. Cumulus cells are thought to be involved in the reduction of reactive oxygen species (ROS) during oocyte metabolism, and their absence shows decreased levels of amino acids and antioxidants [25].
In stimulated IVF-ICSI cycles, follicles at different stages of maturation can be aspirated during oocyte pickup. Nowadays, only mature oocytes (metaphase 2 stage) are used and immature oocytes (germinal vesicle and metaphase 1 stages), which are judged unfit for fertilization, are non-used at day 0. In our IVF center, the rate of immature oocytes recovered is around 25%. A significant number of this precious resource is therefore non-used every day in IVF laboratories. The objective of our study was to evaluate the competence of our in vitro maturation autologous coculture method on the maturation and developmental potential of immature oocytes obtained from stimulated IVF-ICSI cycles, in order to obtain additional embryos for the couple as a rescue system to increase the changes of cumulative pregnancy.
This is a prospective study, carried out in the Reproductive Medicine and Biology Unit of the Amiens-Picardy University Hospital (France). It was included 14 couples, managed in IVF-ICSI in our center, from January to March 2020. Thirty-eight oocytes, identified as immature after cumulus-oocyte complexes (COC) stripping for ICSI, were placed in our in vitro maturation medium with the addition of autologous cumulus cells. Oocytes that had reached the metaphase II stage after a maximum of 36 hours of maturation were microinjected. The fertilization and embryonic development potential of the in vitro matured oocytes were compared to those of 148 in vivo matured “siblings” oocytes from the same oocyte retrieval, and then also compared to those of 127 in vivo matured oocytes from different patients (control group).
Maturation rate, fertilization rate, early cleavage rate and developmental activity to blastulation rate.
Embryo quality at cleavage and blastocyst stages, blastulation rate, and useful blastulation rate.
No significant difference was found in the main and secondary criteria of the study compared to the “siblings” in vivo matured oocytes from the same oocyte retrieval. However, a significant difference was obtained on the rate of early cleavage and useful blastulation when our cohort was compared to mature in vivo oocytes from different patients (control group).
This study has shown that after incubation in our in vitro maturation autologous cumulus cell co-culture with cumulus-oocyte cells, immature oocytes recovered during stimulated cycles can give rise to competent oocytes, i.e., capable of being fertilized, of cleaving, and of developing into embryos up to the blastocyst stage. Our study therefore seems to be in the direction of a favorable use of these immature oocytes obtained after stimulated IVF-ICSI cycles. The continuation of this study by including a larger number of oocytes is necessary in order to evaluate the real contribution of this technique in routine.
2023, Handbook of Current and Novel Protocols for the Treatment of Infertility
Immature oocyte collection followed by in vitro maturation (IVM) is the procedure of choice for infertile patients and for fertility preservation as another type of assisted reproductive technologies (ARTs). This chapter introduces laboratory process of oocytes obtained in different types of human IVM cycles. It starts by summarizing in vivo oocyte maturation mechanism. It then explains the practical laboratory process in human IVM cycles such as oocyte identification, evaluation of oocyte maturity at collection in IVM cycles-associated hCG priming, immature oocyte maturation media, in vitro culture time, insemination method, embryo culture and transfer, and cryopreservation of IVM oocytes and embryos. By the end of the chapter, several of the challenging aspects to introduce IVM into the routine laboratory are explained.
In an experimental model of parthenogenetic activation by the chemical stimulus of immature oocytes, Imesch et al. (106) reported a satisfactory developmental potential regarding the survival rate and response to parthenogenetic activation, but more than half of the activated oocytes were arrested at the pronucleus stage, and only 1 embryo was able to reach the blastocyst stage. Finally, in patients with infertility, IVM has also been associated with increased oocyte aneuploidy rates compared with those obtained after controlled ovarian stimulation (107, 108). The reasons for this suboptimal oocyte quality remain poorly understood, but they might involve suboptimal culture conditions and/or the incapacity of oocytes to continue the oogenesis process.
The development of oncofertility over the past decade has renewed the interest in in vitro maturation (IVM) because of the specificity of some oncologic situations that may prevent the feasibility of controlled ovarian hyperstimulation. Immature cumulus-oocyte complexes can be recovered from the small antral follicles in any phase of the menstrual cycle within a very short time frame, offering the possibility of vitrifying mature oocytes or embryos after IVM in urgent situations or when stimulation is contraindicated. Cumulus-oocyte complexes and immature oocytes can be harvested either transvaginally or directly in the laboratory from extracorporeal ovarian tissue. Although IVM is no longer considered experimental as a result of safety studies, it relies on the extremely complex process of oocyte maturation. Despite some live births obtained after IVM in the context of fertility preservation, the lower developmental competence of in vitro–matured oocytes demonstrates the need to improve IVM culture systems. Recent advances in IVM systems may improve oocyte competence after IVM, thus tending to reduce the gap between IVM and ovarian stimulation outcomes. Moreover, to optimize the chances of conception in cancer survivors, the combination of IVM and ovarian tissue cryopreservation is the preferred option when ovarian stimulation cannot be performed.
To investigate the obstetrical, neonatal, and long-term outcomes of in vitro maturation (IVM) compared with conventional in vitro fertilization (IVF) in women with polycystic ovarian syndrome (PCOS).
Matched retrospective case-control study.
University fertility clinic.
One hundred eighty-four patients undergoing IVM were compared with 366 patients undergoing conventional IVF. All had PCOS and were matched for patient age, gestational age at birth, and the number of fetuses.
None.
Obstetrics, neonatal outcomes, and childhood medical problems and development.
Women's mean age at oocytes retrieval was 32.6 ± 2.9 years. Children's mean age was 7.5 ± 2.3 years. There were no differences in the frequency of obstetrical and neonatal outcomes between the two groups. No difference was found in birth weights between the two groups. The incidence of congenital anomalies was similar between the groups (4.3% in IVM group vs. 4.1% in IVF group). No significant difference was observed between the two groups in the frequency and duration of hospitalization during childhood. Growth developmental status of both groups was within normal range.
In a matched setting between IVM and IVF babies born from women with PCOS, no significant increased risk associated with IVM was been identified after a mean follow-up of 7.5 years.
Medidas obstétricas, neonatales y a largo plazo de niños concebidos a partir de ovocitos madurados in vitro
Investigar las medidas obstétricas, neonatales y a largo plazo de la maduración in vitro (IVM) comparada con la fecundación in vitro convencional (IVF) en mujeres con síndrome de ovario poliquístico (PCOS).
Estudio retrospectivo caso-control emparejado.
Clínica de fertilidad universitaria.
Ciento ochenta y cuatro pacientes que realizaron IVM fueron comparadas con 366 que realizaron IVF convencional. Todas tenían PCOS y fueron emparejadas según edad de la paciente, edad gestacional al nacimiento y número de fetos.
Ninguna.
Medidas obstétricas, neonatales y problemas médicos y de desarrollo en la infancia.
La edad media de las mujeres en el momento de la obtención de ovocitos fue 32.6 ± 2.9 años. La edad media de los niños fue 7.5 ± 2.3 años. No hubo diferencias en la frecuencia de las medidas obstétricas y neonatales entre ambos grupos. No se encontró ninguna diferencia en los pesos al nacer entre los dos grupos. La incidencia de anomalías congénitas fue similar entre los grupos (4.3% en el grupo de IVM vs. 4.1% en el grupo de IVF). No se observó diferencia significativa entre los dos grupos en la frecuencia y duración de hospitalización durante la infancia. El estatus del crecimiento evolutivo de ambos grupos estuvo dentro de límites normales.
En un contexto similar entre bebés IVM e IVF nacidos de mujeres con PCOS, no se identificó un aumento significativo del riesgo asociado con la IVM después de un seguimiento medio de 7,5 años.
Dr Baris Ata received his medical degree from Istanbul School of Medicine in 1998. After his residency training in obstetrics and gynaecology, he attended a certification programme on infertility and assisted reproduction at American Hospital of Istanbul. He is currently a clinical fellow in reproductive endocrinology and infertility at McGill University and simultaneously attending a Masters degree programme on clinical trials at London School of Hygiene and Tropical Medicine. His major areas of interest are clinical infertility and assisted reproduction.
