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Review

In Vitro Maturation of Oocytes Retrieved from Ovarian Tissue: Outcomes from Current Approaches and Future Perspectives

by
Chloë De Roo
* and
Kelly Tilleman
Department for Reproductive Medicine, Ghent University Hospital, 9000 Ghent, Belgium
*
Author to whom correspondence should be addressed.
J. Clin. Med. 2021, 10(20), 4680; https://doi.org/10.3390/jcm10204680
Submission received: 31 August 2021 / Revised: 29 September 2021 / Accepted: 30 September 2021 / Published: 13 October 2021
(This article belongs to the Special Issue The State of the Art in Fertility Preservation for Adults and Children)
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Abstract

:
In vitro maturation (IVM) of transvaginally aspirated immature oocytes is an effective and safe assisted reproductive treatment for predicted or high responder patients. Currently, immature oocytes are also being collected from the contralateral ovary during laparoscopy/laparotomy and even ex vivo from the excised ovary or the spent media during ovarian tissue preparation prior to ovarian cortex cryopreservation. The first live births from in vitro-matured ovarian tissue oocytes (OTO-IVM) were reported after monophasic OTO-IVM, showing the ability to achieve mature OTO-IVM oocytes. However, fertilisations rates and further embryological developmental capacity appeared impaired. The introduction of a biphasic IVM, also called capacitation (CAPA)-IVM, has been a significant improvement of the oocytes maturation protocol. However, evidence on OTO-IVM is still scarce and validation of the first results is of utmost importance to confirm reproducibility, including the follow-up of OTO-IVM children. Differences between IVM and OTO-IVM should be well understood to provide realistic expectations to patients.

1. Introduction

The potential application of in vitro maturation (IVM) of oocytes as an alternative to in vitro fertilization (IVF) of in vivo-matured oocytes has gained increasing interest in the last two decades. IVM involves the in vitro maturation of immature cumulus–oocyte complexes (COCs) collected from antral follicles, with or without follicle-stimulating hormone (FSH) priming, from the germinal vesicle (GV) stage to metaphase II (MII) [1,2,3,4]. Since the first observation in 1934 by Pincus and Enzmann [5] of rabbit oocytes capable of undergoing spontaneous in vitro maturation and fertilization, IVM has successfully been carried out in different species, with Cha et al. [6] being the first to report, in 1990, an IVM birth in humans from immature oocytes retrieved from donors [6]. The first IVM birth from the mother’s own immature oocytes followed four years later [7]. The intriguing history of IVM has been summarized in 2018 by Shirasawa et al. [8] and more recently (2020) by De Vos M et al. [9].
Although promising, the rollout of IVM was initially hampered by the reduced oocyte maturation rate of this method. Subsequent improvements were made to optimize both in vitro cytoplasmic and meiotic maturation and the developmental competence of oocytes by means of preparatory treatments in patients and optimisation of laboratory protocols. One of the procedures explored to optimize maturation rate was FSH priming before oocyte retrieval [3,9]. For this purpose, patients were prepared with a short regime of FSH and triggered with human chorionic gonadotropin (hCG) and/or gonadotropin-releasing hormone (GnRH) agonist (termed hCG-primed IVM or truncated IVF in the first case, and truncated IVF without FSH in the second case) [3,9]. Likewise, laboratory protocols were optimized from monophasic or single-step IVM to biphasic IVM or pre-IVM to support the synchrony in cytoplasmic and nuclear maturation [10]. The biphasic protocol includes a pre-maturation culture or ‘capacitation’ (CAPA) which increases oocyte maturation potential [11]. This protocol is now known as ‘CAPA-IVM’.
IVM was initially introduced in clinical practice as a safer alternative for conventional ovarian stimulation to avoid ovarian hyperstimulation syndrome (OHSS) and ovarian torsion [12,13]. Thus, IVM constitutes a promising alternative to in vitro fertilization of in vivo-matured oocytes conventional in predicted or expected high responders, such as polycystic ovary syndrome (PCOS) patients [9,13,14,15,16]. Encouraging results have been reported in these patients, with maturation rates up to 84% [17], fertilization rates up to 80% [18], clinical pregnancy rates up to 50% per cycle [19] and live birth rates up to 33% [19] as reviewed by the Cochrane library in 2018 [13]. Subsequently, IVM indications have been broadened to include fertility preservation and rare conditions where a controlled ovarian stimulation failed to result in mature oocytes, such as resistant ovary syndrome or repeated deficient oocyte maturation [16,20].
Recently, other alternatives have been introduced in IVM related to the way follicles are retrieved. Although in its initial stages COCs were collected by transvaginal follicle aspiration, new procedures include in situ follicle aspiration from the ovary or the contralateral ovary during laparoscopy/laparotomy and ex vivo aspiration either from the excised ovarian tissue (OT) or the spent media during cortex preparation for cortex cryopreservation. This latter protocol, called ovarian tissue oocyte (OTO)-IVM [21], is now increasingly being explored to maximize fertility preservation potential where the clinical application of OT transplantation may be contraindicated. Cancer patients in whom orthotopic transplantation of OT carries the risk of malignant cell contamination [22] and transgender men in whom transplantation is undesired as it restores the endogen productions of female hormones [23] are targets potentially benefiting of OTO-IVM. We have conducted a review of the outcomes achieved with OTO-IVM until today and on the current evidence on CAPA-IVM. The role of this latter protocol in women undergoing OT follicle retrieval is further discussed.

2. Materials and Methods

A literature search of PubMed was performed using search terms containing to the method of interest (e.g., in vitro maturation or IVM alone or in combination with OTO, PCOS, ex vivo, CAPA, biphasic, ovarian tissue oocyte) and reproductive outcomes (e.g., live birth, pregnancy, outcome). No date restrictions were used. Papers were selected by the authors based on completeness of the reproductive outcome and fitting within the scope of this narrative review.

3. Results

3.1. Monophasic OTO-IVM

Given that oocytes can be aspirated by ultrasound from small follicles visible on the ovary, it was reasonable to assume that upon oophorectomy these small follicles and residing oocytes would be present in the ex vivo-collected OT. This protocol, known as OTO-IVM, was first described by Revel et al. [24], who reported the collection of immature oocytes from small antral follicles during the processing of OT. Since then, other authors have used this protocol to find an additional pool of oocytes that could maximize the preservation of fertility in patients undergoing oophorectomy in the case of urgent gonadotoxic therapies. The standard procedure for cryopreservation of OT comprises removing the medulla from the ovarian cortex and cutting the cortical tissue into smaller pieces before exposing them to freezing medium followed by a slow freezing or vitrification protocol (please consult Leonel et al. 2019 for review on cryopreservation of ovarian tissue [25]) (Figure 1). The residual medulla is usually discarded, although this disposed solution contains a considerable pool of immature oocytes that can be visualized and identified as COCs when the dish is carefully inspected under a stereo microscope.
In 2011, Kristensen et al. [26] described the possibility of collecting COCs from leftover medulla. Despite this, many centers still discard the medulla during OT cryopreservation [26]. Several studies have shown OTO-IVM maturation rates of 30–40% [21,23,27,28,29,30,31,32], although maturation rates up to 68% have been reported [29,33]. While the monophasic OTO-IVM protocol is alike in these studies, three of the studies showed that higher transportation times from procurement of the tissue to the IVF laboratory, in which the tissue is exposed to low temperatures, were related to lower, although not statistically significant, maturation rates [34,35,36].
Detailed literature on embryo development from OTO-IVM oocytes, especially up to the blastocyst stage, remains scarce (Table 1). Several case reports and small cohort studies have shown that the average rate of normal fertilised OTO-IVM oocytes–as characterised by the appearance of two pronuclei (2PN)—is lower than in vivo-matured oocytes obtained by conventional ovarian stimulation, ranging from 35.2% to 65% [24,27,28,29,35,37,38,39]. This wide range could be due to differences in the patient cohorts included in these studies. As commented before, patients with oncological diagnoses have been the main focus of studies on OTO-IVM, although transgender men are a new focus. It is worth noting that transgender men included in these studies are still under testosterone treatment at the time of oophorectomy. Additionally, in these studies, either fresh- or vitrification-warmed OTO-IVM oocytes were used, which is likely to have an impact on the fertilisation rates. Embryo development data are mostly related to Day 2 or Day 3, and only two studies show results up to the blastocyst stage. In a case report, Kirillova et al. [38] described the development of three blastocysts after intracytoplasmic sperm injection (ICSI) from 33 COCs retrieved from a woman with breast cancer using fresh OTO-IVM. Lierman et al. [39], describes the development of one blastocyt after ICSI out of 1903 COCs retrieved from 83 transgender men in vitrification-warmed OTO-IVM oocytes. The development of almost all embryos was arrested in this latter study, where COCs were collected at the time of gender-affirming surgery and while patients were under testosterone treatment.
The results of these studies showed that, although the OTO-IVM oocytes were able to mature and to display a good morphological structure, their fertilisation and further embryological developmental capacities were somehow impaired. In any case, this low effectiveness has not withheld clinics to perform embryo transfers with OTO-IVM embryos and five live births have been reported so far [42,43,44] (Table 2).
In summary, the OTO-IVM protocol seems promising and has resulted in healthy babies [42,43,44]. The OTO-IVM oocytes display a good morphological structure but fertilisation and further embryological developmental capacities seemed to be impaired, as shown by the low efficacy achieved in comparison to other IVF procedures. This is probably related to the COCs IVM process.

3.2. Biphasic IVM

Oocyte maturation is a complex event achieving both nuclear and cytoplasmic maturation. The pathways involved in oocytes maturation have been reviewed in detail by Coticchio et al. [45]. In summary, nuclear maturation consists of chromosomal condensation, segregation and polar body extrusion, whereas cytoplasmic maturation involves redistribution of organelles and dynamic changes in cytoskeletal filaments [46]. The lower developmental capacity of in vitro-matured oocytes is related to an asynchronic cytoplasmic and nuclear maturation. In vivo, a meiotic arrest provides the necessary time for cytoplasmic maturation, which is resumed after the lutheinizing hormone (LH) surge. LH receptor activation causes the up-regulation of the epidermal growth factor (EGF)-like family [47]. Amphiregulin (AREG), the most abundant EGF-ligand is present in follicular fluids of mature follicles. AREG cannot be detected before the LH surge or before human chorionic gonodotrophin (hCG) trigger and depletion of AREG was accompanied with immaturity of the oocytes concluding that AREG is a useful marker and important modulator of oocyte maturity and competence [48]. During in vitro maturation, granulosa cell–COC communication is important. Granulosa cells secrete certain factors, amongst them C-type natriuretic peptides (CNPs). CNP plays a role as maturation inhibitor maintaining the meiotic arrest. In response to the LH surge, meiosis resumes by decreasing the expression of CNP. Decreased levels of CNP can be found in murine ovaries and human follicular fluid [49]. When immature oocytes are isolated and cultured in vitro, oocytes spontaneously resume meiosis because the inhibitory environment is lost.
The culturing of COCs in media containing these secreted CNPs has been shown to improve the efficacy of the IVM in several animal species, thus supporting the role of CNP in meiosis arrest, which is conserved among mammals. Indeed, in vitro maturation rates of COCs obtained from ex vivo goat [50] or bovine ovaries [51] were significantly increased when an extra step containing CNP was performed in combination with standard IVM. The developmental capacity of these two-step IVM oocytes was dramatically increased, resulting in higher blastocyst rates and a higher blastocyst cell content in both animal studies [50,51]. This superior developmental capacity is the result of a temporarily delay in spontaneous nuclear maturation which prolongs the time of the cytoplasmic maturation by improving the mitochondrial function [51,52]. A recent study has provided evidence on the effect of treatment of immature cattle oocytes with CNP before IVM on the patterns of mitochondrial location, increasing the mitochondrial content and decreasing reactive oxygen species (ROS) during IVM [52]. Clearly, CNP impacts the level of cAMP, which is important for maintaining the oocytes in meiotic arrest.
EGFs are important for periovulatory events, including the re-initiation of meiosis in oocytes. In vivo, the LH surge induces the release of EGF from the granulosa cells. Studies conducted in the early 1990s showed that 30 h of EGF supplementation increased the amount of MII oocytes from cumulus stripped GV oocytes from 33.9% to 64.3%. When COCs stayed intact, similar amounts of metaphase II (MII) oocytes were achieved; however, a higher fertilisation rate was noted (71.7% vs. 45.6%, p < 0.05) [53]. Thus, these studies provided evidence of the benefit of EGF supplementation on the nuclear and cytoplasmic in vitro maturation of COCs [53]. Amphiregulin or AREG, a member of the EGF member family is present in pre-ovulatory follicles and the optimal amount of AREG, determined in rhesus monkeys, showed that 10 ng/mL was more beneficial than 100 ng/mL for oocyte maturation [54]. AREG promotes the maturation of human GVs in vitro (from 36.5% to 75.5%), resulting in an increased number of normal fertilised oocytes after ICSI [55]. AREG, in the presence of gonadotrophins, appears to accelerate and facilitate germinal vesicle breakdown and MI–MII transition [54]. This can be found abundantly in follicular fluid from patients undergoing IVF [56]. Biphasic IVM of ex vivo-collected ovine COCs combing CNP in a first step followed by AREG supplementation in a second IVM step has shown to dramatically increase the blastocyst rate [57].

3.3. Biphasic IVM in Human

The proof of concept for the biphasic IVM protocol in animal studies, which showed its potential for maturing COCs collected ex vivo from unstimulated ovaries [50,51,52,54], encouraged its use in humans [10]. Table 3 summarises the studies conducted using CAPA-IVM vs. monophasic IVM in humans. Detailed information of the laboratory protocol and the media used are provided in these papers. In summary, monophasic IVM was carried out in IVM medium (IVM system, Medicult, Origio), supplemented with 75 mIU/mL HP-hMG (Menopur), 100 mIU/mL hCG (Pregnyl) and 10 mg/mL human serum albumin (HSA). Cumulus complexes were cultured for 30 h in groups of 10 COCs per well in 500 µL IVM medium with oil overlay at 37 °C, 6% CO2 in air. Biphasic IVM was performed in two steps: the first step contained IVM medium (IVM system, Medicult, Origio), supplemented with 1 mIU/mL rFSH (Puregon), 5 ng/mL insulin, 10 nM estradiol, 10 mg/mL HSA and 25 nM CNP (Tocris Bioscience; Abdingdon, UK). COCs were cultured in groups of 10 in 500 µL of this medium under oil for 24 h at 37 °C, 6% CO2 in air. Following this 24 h incubation, COCs were washed and transferred to the 2nd step, containing Medicult IVM medium supplemented with 5 ng/mL insulin, 10 nM estradiol, 100 ng/mL human recombinant Amphiregulin (rhAREG, Tocris Biosciences) and 100 mIU/mL rFSH, and incubated for 30 h under the same conditions.
This biphasic technique was first used in the patient cohort most intensively studied in, and benefiting from, IVM: PCOS patients. Biphasic IVM was initially clinically performed following the so-called ‘mild stimulation IVF’, in which a short treatment of gonadotropins is performed prior to ultrasound-guided oocyte aspiration [10]. This approach has been shown to improve oocyte maturation (up to 70%), resulting in higher fertilisation rates (up to the 2PN rate of in vivo-matured oocytes) and yielding higher amounts of embryos and blastocysts (up to 23% blastocyst rate) compared to the monophasic protocol [11]. A pilot study conducted in Belgium translated the CAPA-IVM protocol derived from animal studies to human. The results of this study were subsequently confirmed in a prospective study conducted by Sánchez et al. [58] in Vietnam. The report of the first 20 babies born showed that the protocol was efficacious and safe in short-term follow-up [59]. As shown in Table 3, this protocol has allowed higher amounts of in vitro-matured oocytes, higher fertilisation rates after ICSI and higher blastocyst rates to be achieved compared to the monophasic protocol [11,38,58,59]. Sánchez et al. [58] have recently reported the birth of healthy children using CAPA-IVM. DNA methylation studies and analysis of imprinting genes showed no differences in embryos derived from CAPA-IVM and ovarian stimulation adding more evidence on the safety of the protocol [60].
The basis for clinical application of CAPA-IVM mostly stems from evidence of COCs collected through ultrasound-guided aspiration from ovary after mild ovarian stimulation. Although animal studies have provided evidence on the possibility of using this protocol in unstimulated ovaries, this path has only recently been explored in humans [38]. A first human pilot study using CAPA-IVM in COCs retrieved ex vivo from unstimulated ovaries showed an improvement in maturation and developmental capacity of the OTO-IVM oocytes compared to the monophasic protocol, thus providing a proof of concept for using CAPA-OTO-IVM in humans [38] (Table 3). This new path opens future possibilities for making the most of OTO-IVM in COCs retrieved in patients where oophorectomy has to be performed.
Table
Table 3. Human studies comparing monophasic IVM vs. biphasic IVM.
Table 3. Human studies comparing monophasic IVM vs. biphasic IVM.
Study TypeMethodologyResultsReference
Prospective pilot study
n = 15 PCOS patients
age mean ± SD 28.9 ± 3.9 years
Single center		Stimulation: 3 days HP-hMG (225 IU, 225 IU, 150 IU)
(+2 days if applicable)
COC retrieved via aspiration
Sibling oocyte study:
Monophasic IVM (n = 264 COCs)
vs. biphasic IVM (n = 117 COCs)		COCs collected via ultrasound-guided in situ ovarian aspiration
Monophasic vs. biphasic IVM:
Maturation rate: 48% vs. 70% (p < 0.001)
Fertilization rate: 62% vs. 82% (p < 0.001)
Yield good quality embryos day 3: 23% vs. 43% (p < 0.001)
Blastocyst rate: 14% vs. 23% (p < 0.05)		Sanchez F. et al., 2017 [11]
Prospective pilot study
n = 40 PCOS patients
Single center		Stimulation: 3 doses of 150 IU rFSH (no HCG trigger)
COC retrieved via aspiration
Sibling oocyte study:
Monophasic IVM:
(n = 20 patients; age: mean ± SD 28.8 ± 2.9 years;
n = 238 COCs)
vs biphasic IVM
(n = 20 patients, age: mean ± SD 29.1 ± 3.4 y; n = 305 COCs)		COCs collected via ultrasound-guided in situ ovarian aspiration
Monophasic vs. biphasic IVM:
Maturation rate: 48% vs. 62% (p < 0.05)
Fertilization rate was similar
Yield good quality embryos day 3: 24% vs. 38% (p < 0.05)
Blastocyst rate: 14% vs. 23% (p < 0.05)
1.8x higher amounts of usable embryos per patient:
2.2% vs. 4.2% (p < 0.001) 		Sanchez F. et al., 2019 [58]
Prospective pilot study
n = 80 PCOS patients
Single center		Stimulation: 3 doses of gonadotropins
(2.5days; ~377 IU used) (no HCG trigger)
COC retrieved via aspiration
Sibling oocyte study:
Monophasic IVM:
(n = 40 patients; age: mean ± SD 28.1 ± 3.1 years;
n = 16.5 COCs/patient)
vs biphasic IVM:
(n = 40 patients; age: mean ± SD 28.5 ± 3.4 years;
n = 17.5 COCs/patient)		COCs collected via ultrasound-guided in situ ovarian aspiration
Monophasic vs. biphasic IVM:
Maturation rate: 49% vs. 63.6% (p < 0.001)
Fertilization rate similar
Yield good quality embryos day 3: 26.8% vs. 30%
Vitrified embryos after fresh ET: 1.3 ± 1.9 vs. 2.5 ± 2.5 (p < 0.05)
Clinical pregnancy rate: 37.5% vs. 60% (NS; p = 0.06)
19 babies born after biphasic IVM
no serious adverse events or reactions found
Normal physical appearances were found in the newborn babies
Detailed follow-up of the babies is being conducted.		Vuong L. et al., 2020 [59]
Prospective pilot study
n = 10 patients (mean ± SE 29.40 ± 1.76 years;
Range: 16–36 years) with
gynecological malignancies
Single center		Stimulation: 3 doses of 150 IU rFSH (no HCG trigger)
COC retrieved via aspiration
Sibling oocyte study:
Monophasic OTO-IVM (n = 96 COCs) vs. biphasic OTO-IVM (n = 105 COCs)		COC identification via microscopic evaluation after tissue
manipulation
Monophasic OTO-IVM vs. biphasic OTO-IVM:
Maturation rate: 35% vs. 56% (p < 0.05)
Fertilization rate: 68.4% vs. 80% (p < 0.001)
Yield good quality embryos day 3: 24% vs. 38%Blastocyst rate: 0% vs. 16%
1.8x higher amounts of usable embryos per patient:
2.2% vs. 4.2% (p < 0.001) 		Kirillova A. et al., 2021 [38]
Polycystic ovary syndrome (PCOS); highly purified-human menopausal gonadotropin (HP-hMG); ovarian tissue oocyte in vitro maturation (OTO-IVM); recombinant follicle-stimulating hormone r(FSH); human chorionic gonadotropin (HCG); cumulus–oocyte complex (COC); standard deviation (SD).

4. Discussion

Several studies reporting ongoing pregnancies and live births after OTO-IVM have provided evidence on the potential of this methodology for the optimization of fertility potential. The first live births from OTO-IVM embryos were reported using the monophasic protocol, which clearly showed the ability of this protocol to achieve mature OTO-IVM oocytes. However, fertilisation rates and further embryological developmental capacities of the resulting oocytes seemed to be impaired.
The introduction of the biphasic IVM (or CAPA-IVM) protocol, where nuclear and cytoplasmatic maturation is enhanced, has been an important step forward in the COCs maturation protocol. In CAPA-IVM, the meiosis of immature COCs was arrested using CNP in the capacitation medium before moving COCs into a meiosis-promoting medium, which contains AREG in order to achieve both nuclear and cytoplasmic maturation. When trying to transpose the CAPA-IVM protocol to OTO, it should be noted that evidence supporting this methodology (and IVM in general) stems from highly respondent patients (PCOS patients) in whom COCs had been retrieved by in situ ovarian transvaginal aspiration. This is important, since overall maturation rates after OTO-IVM have shown to be lower than after IVM [24,27,28,29,35,37,38,39]. Besides this, other important aspects are to be taken into account to have realistic expectations when considering CAPA-IVM for OTO.
First, the differences in collection methods lead to COCs retrieved from a different follicle size. While COCs collected by transvaginal follicle aspiration are obtained from larger and, hence, more mature follicles, COCs retrieved ex vivo from an excised OT or spent media during cortex preparation come from very small, thus more immature, follicles. This results in a higher IVM rate in the first case, some adjustments to the IVM laboratory protocol will eventually be required.
Secondly, patient cohorts where OTO-IVM has been studied are particularly heterogeneous, comprising mainly oncological patients, but more recently also transgender men. OT cryopreservation has become standard of care for fertility preservation in pre-pubertal girls. This population is highly heterogeneous in terms of hormonal profile and ovarian constitution [27]. It has been hypothesized that pre-pubertal ovaries need a maturation phase to obtain optimal follicle function [27,61,62], which would imply the difficulty of harvesting COC in vitro or obtaining COC at all, these will show low maturity (18–33%) [27,32,63]. When performing COC retrieval after gender confirmation testosterone treatment, OTO-IVM showed that transgender men have lower developmental ability compared with cancer patients [39]. This may indicate that long-term testosterone treatment has an adverse effect on the development of oocytes [39]. For this reason, prior OT cryopreservation testosterone withdrawal can be recommended.
Thirdly, conversely to IVM, patient cohorts where OTO-IVM has been studied are heterogenous, these are comprised of mainly oncological patients, but more recently also transgender men. OTO-IVM has shown low developmental capacity in transgender men when compared to oncologic patients when COC retrieval is performed after gender-affirming testosterone treatment [39]. This might indicate a deleterious effect of prolonged testosterone treatment on the development competence of oocytes [39]. For this reason, testosterone withdrawal prior to the cryopreservation of OT is recommended. OT cryopreservation has become the standard of care for fertility preservation in prepubertal girls. This population is highly heterogeneous in terms of hormonal profile and ovarian constitution [27]. It has been hypothesized that prepubertal ovaries need a maturation phase to obtain optimal follicle function [27,61,62], which would imply the impossibility of harvesting COCs ex vivo or, if COCs could be obtained, whether these would present with lower maturation capacity (18–33%) [27,32,63].
Figure 2 aims to provide objective information about the effectiveness of current IVM methods and chances, so that shared, informed decisions can be made.
Biphasic IVM has been clinically performed with so-called ‘mild stimulation IVF’ (i.e., with a short treatment of gonadotropins prior to ultrasound-guided oocyte aspiration), as this approach has shown to improve oocyte maturation rates, fertilisation rates and to result in higher amounts of embryos and blastocysts. A proof of concept for using biphasic OTO-IVM [38] provides new options for patients needing urgent fertility preservation. FSH priming is not always feasible or safe when the timeframe needed is impossible or when FSH priming appears to be unsafe given the underlying diagnosis.
The analysis and follow-up of newborn children after OTO-IVM from immature oocytes from PCOS patients has provided evidence of the safety of this protocol [9,59,64]. It remains unknown if this evidence in enough to guarantee the safety of OTO-IVM. In this context, some concerns have been expressed regarding possible epigenetic risks for IVM children [9]. Despite promising initial reports, evidence on OTO-IVM is still scarce and validation of the first results is of utmost importance. A multicentric study confirming the reproducibility is necessary to validate the technique and outcomes in larger cohorts. Special attention should be given to the efficacy in the different patient populations using this approach. A correct follow-up of OTO-IVM children is mandatory, including the (epi)genetic safety of this laboratory protocol.

5. Conclusions

OTO-IVM seems promising to optimize fertility potential, with several reports providing evidence of ongoing pregnancies and live births. IVM protocols have been studied in predicted or expected high responders. Success rates after OTO-IVM are not comparable to the latter, mostly due to differences in COC collection methods and in the patient populations used for these methodologies. These differences should be well understood in order to advise patients correctly and to stimulate research to introduce laboratory protocol adjustments. Although promising, evidence on OTO-IVM is still scarce and validation of the first results is of utmost importance to confirm reproducibility, including the follow-up of OTO-IVM children.

Author Contributions

Conceptualization, C.D.R. and K.T.; methodology, K.T.; writing—original draft preparation, C.D.R. and K.T.; writing—review and editing, C.D.R. and K.T. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Acknowledgments

The authors thank Beatriz Viejo, for her assistance in writing and editing the manuscript.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Edwards, R. Maturation in vitro of human ovarian oocytes. Lancet 1965, 286, 926–929. [Google Scholar] [CrossRef]
  2. Cross, P.C.; Brinster, R.L. In vitro development of mouse oocytes. Biol. Reprod. 1970, 3, 298–307. [Google Scholar] [CrossRef] [Green Version]
  3. Wynn, P.; Picton, H.M.; Krapez, J.A.; Rutherford, A.J.; Balen, A.H.; Gosden, R.G. Pretreatment with follicle stimulating hormone promotes the numbers of human oocytes reaching metaphase II by in-vitro maturation. Hum. Reprod. 1998, 13, 3132–3138. [Google Scholar] [CrossRef] [Green Version]
  4. De Vos, M.; Smitz, J.; Thompson, J.G.; Gilchrist, R.B. The definition of IVM is clear—Variations need defining. Hum. Reprod. 2016, 31, 2411–2415. [Google Scholar] [CrossRef] [Green Version]
  5. Pincus, G.; Enzmann, E.V. Can mammalian eggs undergo normal development in vitro? Proc. Natl. Acad. Sci. USA 1934, 20, 121–122. [Google Scholar] [CrossRef] [Green Version]
  6. Cha, K.Y.; Koo, J.J.; Ko, J.J.; Choi, D.H.; Han, S.Y.; Yoon, T.K. Pregnancy after in vitro fertilization of human follicular oocytes collected from nonstimulated cycles, their culture in vitro and their transfer in a donor oocyte program. Fertil. Steril. 1991, 55, 109–113. [Google Scholar] [CrossRef]
  7. Trounson, A.; Wood, C.; Kausche, A. In vitro maturation and the fertilization and developmental competence of oocytes recovered from untreated polycystic ovarian patients. Fertil. Steril. 1994, 62, 353–362. [Google Scholar] [CrossRef]
  8. Shirasawa, H.; Terada, Y. In vitro maturation of human immature oocytes for fertility preservation and research material. Reprod. Med. Biol. 2017, 16, 258–267. [Google Scholar] [CrossRef] [PubMed]
  9. De Vos, M.; Grynberg, M.; Ho, T.M.; Yuan, Y.; Albertini, D.F.; Gilchrist, R.B. Perspectives on the development and future of oocyte IVM in clinical practice. J. Assist. Reprod. Genet. 2021, 38, 1265–1280. [Google Scholar] [CrossRef] [PubMed]
  10. Gilchrist, R.B.; Luciano, A.M.; Richani, D.; Zeng, H.T.; Wang, X.; de Vos, M.; Sugimura, S.; Smitz, J.; Richard, F.J.; Thompson, J.G. Oocyte maturation and quality: Role of cyclic nucleotides. Reproduction 2016, 152, R143–R157. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  11. Sánchez, F.; Lolicato, F.; Romero, S.; de Vos, M.; van Ranst, H.; Verheyen, G.; Anckaert, E.; Smitz, J. An improved IVM method for cumulus-oocyte complexes from small follicles in polycystic ovary syndrome patients enhances oocyte competence and embryo yield. Hum. Reprod. 2017, 32, 2056–2068. [Google Scholar] [CrossRef]
  12. Vesztergom, D.; Segers, I.; Mostinckx, L.; Blockeel, C.; de Vos, M. Live births after in vitro maturation of oocytes in women who had suffered adnexal torsion and unilateral oophorectomy following conventional ovarian stimulation. J. Assist. Reprod. Genet. 2021, 38, 1–7. [Google Scholar] [CrossRef]
  13. Siristatidis, C.S.; Maheshwari, A.; Vaidakis, D.; Bhattacharya, S. In vitro maturation in subfertile women with polycystic ovarian syndrome undergoing assisted reproduction. Cochrane Database Syst. Rev. 2018, 2018, CD006606. [Google Scholar] [CrossRef]
  14. Child, T.J.; Abdul-Jalil, A.K.; Gulekli, B.; Tan, S.L. In vitro maturation and fertilization of oocytes from unstimulated normal ovaries, polycystic ovaries, and women with polycystic ovary syndrome. Fertil. Steril. 2001, 76, 936–942. [Google Scholar] [CrossRef]
  15. Söderström-Anttila, V.; Mäkinen, S.; Tuuri, T.; Suikkari, A.-M. Favourable pregnancy results with insemination of in vitro matured oocytes from unstimulated patients. Hum. Reprod. 2005, 20, 1534–1540. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  16. Galvão, A.; Segers, I.; Smitz, J.; Tournaye, H.; de Vos, M. In vitro maturation (IVM) of oocytes in patients with resistant ovary syndrome and in patients with repeated deficient oocyte maturation. J. Assist. Reprod. Genet. 2018, 35, 2161–2171. [Google Scholar] [CrossRef] [PubMed]
  17. Chian, R.; Buckett, W.; Tulandi, T.; Tan, S. Prospective randomized study of human chorionic gonadotrophin priming before immature oocyte retrieval from unstimulated women with polycystic ovarian syndrome. Hum. Reprod. 2000, 15, 165–170. [Google Scholar] [CrossRef]
  18. Ge, H.-S.; Huang, X.-F.; Zhang, W.; Zhao, J.-Z.; Lin, J.-J.; Zhou, W. Exposure to human chorionic gonadotropin during in vitro maturation does not improve the maturation rate and developmental potential of immature oocytes from patients with polycystic ovary syndrome. Fertil. Steril. 2008, 89, 98–103. [Google Scholar] [CrossRef] [PubMed]
  19. Holzer, H.E.G.; Scharf, E.; Chian, R.-C.; Demirtas, E.; Buckett, W.; Tan, S.L. In vitro maturation of oocytes collected from unstimulated ovaries for oocyte donation. Fertil. Steril. 2007, 88, 62–67. [Google Scholar] [CrossRef]
  20. Huang, J.Y.; Chian, R.-C.; Tan, S.L. Ovarian hyperstimulation syndrome prevention strategies: In vitro maturation. Semin. Reprod. Med. 2010, 28, 519–531. [Google Scholar] [CrossRef]
  21. Kedem, A.; Yerushalmi, G.M.; Brengauz, M.; Raanani, H.; Orvieto, R.; Hourvitz, A.; Meirow, D. Outcome of immature oocytes collection of 119 cancer patients during ovarian tissue harvesting for fertility preservation. J. Assist. Reprod. Genet. 2018, 35, 851–856. [Google Scholar] [CrossRef]
  22. Meirow, D.; Hardan, I.; Dor, J.; Fridman, E.; Elizur, S.; Ra’Anani, H.; Slyusarevsky, E.; Amariglio, N.; Schiff, E.; Rechavi, G.; et al. Searching for evidence of disease and malignant cell contamination in ovarian tissue stored from hematologic cancer patients. Hum. Reprod. 2008, 23, 1007–1013. [Google Scholar] [CrossRef]
  23. De Roo, C.; Lierman, S.; Tilleman, K.; Peynshaert, K.; Braeckmans, K.; Caanen, M.; Lambalk, C.; Weyers, S.; T’Sjoen, G.; Cornelissen, R.; et al. Ovarian tissue cryopreservation in female-to-male transgender persons: Insights in ovarian histology and physiology after prolonged androgen treatment. Reprod. Biomed. Online 2017, 34, 557–566. [Google Scholar] [CrossRef] [Green Version]
  24. Revel, A.; Safran, A.; Benshushan, A.; Shushan, A.; Laufer, N.; Simon, A. In vitro maturation and fertilization of oocytes from an intact ovary of a surgically treated patient with endometrial carcinoma: Case report. Hum. Reprod. 2004, 19, 1608–1611. [Google Scholar] [CrossRef] [PubMed]
  25. Leonel, E.C.R.; Corral, A.; Risco, R.; Camboni, A.; Taboga, S.R.; Kilbride, P.; Vazquez, M.; Morris, J.; Dolmans, M.-M.; Amorim, C.A. Stepped vitrification technique for human ovarian tissue cryopreservation. Sci. Rep. 2019, 9, 1–12. [Google Scholar] [CrossRef]
  26. Kristensen, S.G.; Rasmussen, A.; Byskov, A.G.; Andersen, C.Y. Isolation of pre-antral follicles from human ovarian medulla tissue. Hum. Reprod. 2011, 26, 157–166. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  27. Segers, I.; Mateizel, I.; van Moer, E.; Smitz, J.; Tournaye, H.; Verheyen, G.; de Vos, M. In vitro maturation (IVM) of oocytes recovered from ovariectomy specimens in the laboratory: A promising “ex vivo” method of oocyte cryopreservation resulting in the first report of an ongoing pregnancy in Europe. J. Assist. Reprod. Genet. 2015, 32, 1221–1231. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  28. Hourvitz, A.; Yerushalmi, G.; Maman, E.; Raanani, H.; Elizur, S.; Brengauz, M.; Orvieto, R.; Dor, J.; Meirow, D. Combination of ovarian tissue harvesting and immature oocyte collection for fertility preservation increases preservation yield. Reprod. Biomed. Online 2015, 31, 497–505. [Google Scholar] [CrossRef] [Green Version]
  29. Park, C.W.; Lee, S.H.; Yang, K.M.; Lee, I.H.; Lim, K.T.; Lee, K.H.; Kim, T.J. Cryopreservation of in vitro matured oocytes after ex vivo oocyte retrieval from gynecologic cancer patients undergoing radical surgery. Clin. Exp. Reprod. Med. 2016, 43, 119–125. [Google Scholar] [CrossRef] [Green Version]
  30. Yin, H.; Jiang, H.; Kristensen, S.G.; Andersen, C.Y. Vitrification of in vitro matured oocytes collected from surplus ovarian medulla tissue resulting from fertility preservation of ovarian cortex tissue. J. Assist. Reprod. Genet. 2016, 33, 741–746. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  31. Lierman, S.; Tilleman, K.; Braeckmans, K.; Peynshaert, K.; Weyers, S.; T’Sjoen, G.; de Sutter, P. Fertility preservation for trans men: Frozen-thawed in vitro matured oocytes collected at the time of ovarian tissue processing exhibit normal meiotic spindles. J. Assist. Reprod. Genet. 2017, 34, 1449–1456. [Google Scholar] [CrossRef]
  32. Fasano, G.; Moffa, F.; Dechène, J.; Englert, Y.; Demeestere, I. Vitrification of in vitro matured oocytes collected from antral follicles at the time of ovarian tissue cryopreservation. Reprod. Biol. Endocrinol. 2011, 9, 150. [Google Scholar] [CrossRef] [Green Version]
  33. Walls, M.L.; Douglas, K.; Ryan, J.P.; Tan, J.; Hart, R. In-vitro maturation and cryopreservation of oocytes at the time of oophorectomy. Gynecol. Oncol. Rep. 2015, 13, 79–81. [Google Scholar] [CrossRef] [PubMed]
  34. Wilken-Jensen, H.N.; Kristensen, S.G.; Jeppesen, J.V.; Andersen, C.Y. Developmental competence of oocytes isolated from surplus medulla tissue in connection with cryopreservation of ovarian tissue for fertility preservation. Acta Obstet. Gynecol. Scand. 2014, 93, 32–37. [Google Scholar] [CrossRef] [PubMed]
  35. Fasano, G.; Dechène, J.; Antonacci, R.; Biramane, J.; Vannin, A.-S.; van Langendonckt, A.; Devreker, F.; Demeestere, I. Outcomes of immature oocytes collected from ovarian tissue for cryopreservation in adult and prepubertal patients. Reprod. Biomed. Online 2017, 34, 575–582. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  36. Nikiforov, D.; Junping, C.; Cadenas, J.; Shukla, V.; Blanshard, R.; Pors, S.E.; Kristensen, S.G.; Macklon, K.T.; Colmorn, L.; Ernst, E.; et al. Improving the maturation rate of human oocytes collected ex vivo during the cryopreservation of ovarian tissue. J. Assist. Reprod. Genet. 2020, 37, 891–904. [Google Scholar] [CrossRef] [PubMed]
  37. Karimi-Zarchi, M.; Mohsenzadeh, M.; Khalili, M.A.; Tabibnejad, N.; Yari, N.; Agha-Rahimi, A. Embryo cryopreservation following in-vitro maturation for fertility preservation in a woman with Mullerian adenosarcoma: A case report. J. Hum. Reprod. Sci. 2017, 10, 138–141. [Google Scholar] [CrossRef] [PubMed]
  38. Kirillova, A.; Bunyaeva, E.; van Ranst, H.; Khabas, G.; Farmakovskaya, M.; Kamaletdinov, N.; Nazarenko, T.; Abubakirov, A.; Sukhikh, G.; Smitz, J.E.J. Improved maturation competence of ovarian tissue oocytes using a biphasic in vitro maturation system for patients with gynecological malignancy: A study on sibling oocytes. J. Assist. Reprod. Genet. 2021, 38, 1–10. [Google Scholar] [CrossRef] [PubMed]
  39. Lierman, S.; Tolpe, A.; de Croo, I.; de Gheselle, S.; Defreyne, J.; Baetens, M.; Dheedene, A.; Colman, R.; Menten, B.; T’Sjoen, G.; et al. Low feasibility of in vitro matured oocytes originating from cumulus complexes found during ovarian tissue preparation at the moment of gender confirmation surgery and during testosterone treatment for fertility preservation in transgender men. Fertil. Steril. 2021, 116, 1068–1076. [Google Scholar] [CrossRef]
  40. Fadini, R.; Renzini, M.M.; Guarnieri, T.; Canto, M.D.; de Ponti, E.; Sutcliffe, A.; Shevlin, M.; Comi, R.; Coticchio, G. Comparison of the obstetric and perinatal outcomes of children conceived from in vitro or in vivo matured oocytes in in vitro maturation treatments with births from conventional ICSI cycles. Hum. Reprod. 2012, 27, 3601–3608. [Google Scholar] [CrossRef] [Green Version]
  41. Dietrich, J.E.; Jauckus, J.; Hoffmann, S.; Liebenthron, J.; Capp, E.; Strowitzki, T.; Germeyer, A. In vitro maturation of immature oocytes from ovarian tissue prior to shipment to a cryobank. Arch. Gynecol. Obstet. 2020, 302, 1019–1024. [Google Scholar] [CrossRef] [PubMed]
  42. Prasath, E.B.; Chan, M.L.H.; Wong, W.H.W.; Lim, C.J.W.; Tharmalingam, M.D.; Hendricks, M.; Loh, S.F.; Chia, Y.N. First pregnancy and live birth resulting from cryopreserved embryos obtained from in vitro matured oocytes after oophorectomy in an ovarian cancer patient. Hum. Reprod. 2014, 29, 276–278. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  43. Uzelac, P.S.; Delaney, A.A.; Christensen, G.L.; Bohler, H.C.; Nakajima, S.T. Live birth following in vitro maturation of oocytes retrieved from extracorporeal ovarian tissue aspiration and embryo cryopreservation for 5 years. Fertil. Steril. 2015, 104, 1258–1260. [Google Scholar] [CrossRef] [PubMed]
  44. Segers, I.; Bardhi, E.; Mateizel, I.; van Moer, E.; Schots, R.; Verheyen, G.; Tournaye, H.; de Vos, M. Live births following fertility preservation using in-vitro maturation of ovarian tissue oocytes. Hum. Reprod. 2020, 35, 2026–2036. [Google Scholar] [CrossRef] [PubMed]
  45. Coticchio, G.; Canto, M.D.; Renzini, M.M.; Guglielmo, M.C.; Brambillasca, F.; Turchi, D.; Novara, P.V.; Fadini, R. Oocyte maturation: Gamete-somatic cells interactions, meiotic resumption, cytoskeletal dynamics and cytoplasmic reorganization. Hum. Reprod. Updat. 2015, 21, 427–454. [Google Scholar] [CrossRef] [Green Version]
  46. Ferreira, E.; Vireque, A.; Adona, P.; Meirelles, F.; Ferriani, R.; Navarro, P. Cytoplasmic maturation of bovine oocytes: Structural and biochemical modifications and acquisition of developmental competence. Theriogenology 2009, 71, 836–848. [Google Scholar] [CrossRef] [PubMed]
  47. Ashkenazi, H.; Cao, X.; Motola, S.; Popliker, M.; Conti, M.; Tsafriri, A. Epidermal growth factor family members: Endogenous mediators of the ovulatory response. Endocrinology 2005, 146, 77–84. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  48. Zamah, A.M.; Hsieh, M.; Chen, J.; Vigne, J.L.; Rosen, M.P.; Cedars, M.I.; Conti, M. Human oocyte maturation is dependent on LH-stimulated accumulation of the epidermal growth factor-like growth factor, amphiregulin†. Hum. Reprod. 2010, 25, 2569–2578. [Google Scholar] [CrossRef] [Green Version]
  49. Kawamura, K.; Cheng, Y.; Kawamura, N.; Takae, S.; Okada, A.; Kawagoe, Y.; Mulders, S.; Terada, Y.; Hsueh, A.J. Pre-ovulatory LH/hCG surge decreases C-type natriuretic peptide secretion by ovarian granulosa cells to promote meiotic resumption of pre-ovulatory oocytes. Hum. Reprod. 2011, 26, 3094–3101. [Google Scholar] [CrossRef] [Green Version]
  50. Zhang, J.; Wei, Q.; Cai, J.; Zhao, X.; Ma, B. Effect of C-type natriuretic peptide on maturation and developmental competence of goat oocytes matured in vitro. PLoS ONE 2015, 10, e0132318. [Google Scholar] [CrossRef]
  51. Zhang, T.; Zhang, C.; Fan, X.; Li, R.; Zhang, J. Effect of C-type natriuretic peptide pretreatment on in vitro bovine oocyte maturation. In Vitro Cell. Dev. Biol. Anim. 2017, 53, 199–206. [Google Scholar] [CrossRef]
  52. Jia, Z.; Yang, X.; Liu, K. Treatment of cattle oocytes with C-type natriuretic peptide before in vitro maturation enhances oocyte mitochondrial function. Anim. Reprod. Sci. 2021, 225, 106685. [Google Scholar] [CrossRef]
  53. Goud, P.T.; Goud, A.P.; Qian, C.; Laverge, H.; van der Elst, J.; de Sutter, P.; Dhont, M. In-vitro maturation of human germinal vesicle stage oocytes: Role of cumulus cells and epidermal growth factor in the culture medium. Hum. Reprod. 1998, 13, 1638–1644. [Google Scholar] [CrossRef] [Green Version]
  54. Peluffo, M.C.; Ting, A.Y.; Zamah, A.M.; Conti, M.; Stouffer, R.L.; Zelinski, M.; Hennebold, J.D. Amphiregulin promotes the maturation of oocytes isolated from the small antral follicles of the rhesus macaque. Hum. Reprod. 2012, 27, 2430–2437. [Google Scholar] [CrossRef] [Green Version]
  55. Ben-Ami, I.; Komsky, A.; Bern, O.; Kasterstein, E.; Komarovsky, D.; Ron-El, R. In vitro maturation of human germinal vesicle-stage oocytes: Role of epidermal growth factor-like growth factors in the culture medium. Hum. Reprod. 2011, 26, 76–81. [Google Scholar] [CrossRef] [Green Version]
  56. Inoue, Y.; Miyamoto, S.; Fukami, T.; Shirota, K.; Yotsumoto, F.; Kawarabayashi, T. Amphiregulin is much more abundantly expressed than transforming growth factor-alpha and epidermal growth factor in human follicular fluid obtained from patients undergoing in vitro fertilization–embryo transfer. Fertil. Steril. 2009, 91, 1035–1041. [Google Scholar] [CrossRef]
  57. Heydarnejad, A.; Ostadhosseini, S.; Varnosfaderani, S.R.; Jafarpour, F.; Moghimi, A.; Nasr-Esfahani, M.H. Supplementation of maturation medium with CoQ10 enhances developmental competence of ovine oocytes through improvement of mitochondrial function. Mol. Reprod. Dev. 2019, 86, 812–824. [Google Scholar] [CrossRef]
  58. Sánchez, F.; Le, A.H.; Ho, V.N.A.; Romero, S.; van Ranst, H.; de Vos, M.; Gilchrist, R.B.; Ho, T.M.; Vuong, L.N.; Smitz, J. Biphasic in vitro maturation (CAPA-IVM) specifically improves the developmental capacity of oocytes from small antral follicles. J. Assist. Reprod. Genet. 2019, 36, 2135–2144. [Google Scholar] [CrossRef] [PubMed]
  59. Vuong, L.N.; Ho, V.N.A.; Ho, T.M.; Dang, V.Q.; Phung, T.H.; Giang, N.H.; Le, A.H.; Pham, T.D.; Wang, R.; Smitz, J.; et al. In-vitro maturation of oocytes versus conventional IVF in women with infertility and a high antral follicle count: A randomized non-inferiority controlled trial. Hum. Reprod. 2020, 35, 2537–2547. [Google Scholar] [CrossRef] [PubMed]
  60. Saenz-De-Juano, M.; Ivanova, E.; Romero, S.; Lolicato, F.; Sánchez, F.; van Ranst, H.; Krueger, F.; Segonds-Pichon, A.; de Vos, M.; Andrews, S.; et al. DNA methylation and mRNA expression of imprinted genes in blastocysts derived from an improved in vitro maturation method for oocytes from small antral follicles in polycystic ovary syndrome patients. Hum. Reprod. 2019, 34, 1640–1649. [Google Scholar] [CrossRef] [PubMed]
  61. Anderson, R.A.; McLaughlin, M.; Wallace, W.H.B.; Albertini, D.F.; Telfer, E. The immature human ovary shows loss of abnormal follicles and increasing follicle developmental competence through childhood and adolescence. Hum. Reprod. 2014, 29, 97–106. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  62. Hambridge, H.L.; Mumford, S.; Mattison, D.; Ye, A.; Pollack, A.; Bloom, M.; Mendola, P.; Lynch, K.L.; Wactawski-Wende, J.; Schisterman, E. The influence of sporadic anovulation on hormone levels in ovulatory cycles. Hum. Reprod. 2013, 28, 1687–1694. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  63. Revel, A.; Revel-Vilk, S.; Aizenman, E.; Porat-Katz, A.; Safran, A.; Ben-Meir, A.; Weintraub, M.; Shapira, M.; Achache, H.; Laufer, N. At what age can human oocytes be obtained? Fertil. Steril. 2009, 92, 458–463. [Google Scholar] [CrossRef] [PubMed]
  64. Strowitzki, T.; Bruckner, T.; Roesner, S. Maternal and neonatal outcome and children’s development after medically assisted reproduction with in-vitro matured oocytes—A systematic review and meta-analysis. Hum. Reprod. Updat. 2021, 27, 460–473. [Google Scholar] [CrossRef] [PubMed]
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Figure 1. Ovarian tissue preparation for cryopreservation: (a) Bisection of the ovary; (b) Bisected ovary with antral follicles displayed in the medulla; (c) Cortical tissue of which the medulla is removed; (d) Cortical tissue pieces ready for cryopreservation; (e) Residual medulla after it has been mechanically scraped from the cortical tissue; (f) Microscopic view of the Petri dish (e) showing cumulus–oocyte complexes.
Figure 1. Ovarian tissue preparation for cryopreservation: (a) Bisection of the ovary; (b) Bisected ovary with antral follicles displayed in the medulla; (c) Cortical tissue of which the medulla is removed; (d) Cortical tissue pieces ready for cryopreservation; (e) Residual medulla after it has been mechanically scraped from the cortical tissue; (f) Microscopic view of the Petri dish (e) showing cumulus–oocyte complexes.
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Figure 2. Overview of success ratios achieved with current IVM methods [11,13,27,28,35,38,42,43,44,58,59].
Figure 2. Overview of success ratios achieved with current IVM methods [11,13,27,28,35,38,42,43,44,58,59].
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Table
Table 1. Embryological and reproductive outcomes of human monophasic OTO-IVM.
Table 1. Embryological and reproductive outcomes of human monophasic OTO-IVM.
Study Type MethodologyResultsReference
Case report43 years old patient
Endometrial carcinoma
Removal of polycystic ovary 10,000 IU HCG, 36 h prior to surgery,
no FSH priming		Follicle aspiration from the ovary ex vivo (17 gauge needle)
17x oocytes retrieved, of which already 2x MII
3x MII after 24 h OTO-IVM; 1x 2PN after ICSI
7x MII after 48 h OTO-IVM; 3x 2PN after ICSI
40% 2PN rate; 4x day 3 embryos cryopreserved (2x ≥ 6 cell)		Revel A. et al., 2004 [24]
Case report38 years old patient
Ovarian adenocarcinoma		Follicle aspiration from the ovary in situ (26 gauge needle)
during surgery
3x COCs identified
2x MII after 30 h OTO-IVM; vitrification
After warming, 1x 2PN after ICSI
50% 2PN rate; 1x day 2 embryo (2 cell); no pregnancy after ET		Fadini R. et al., 2012 [40]
Cohort study255 patients (mean ± SE 22.3 ± 1.26 years, range 10–40 years), different types of IVM
56 patients underwent OTO-IVM
Hodgkin (n = 15), hematological cancer (n = 8), sarcoma (n = 11), breast cancer (n = 4), cervix cancer (n = 6), other (n = 12)		Follicle aspiration from the ovary ex vivo using needles
and medium was analyzed microscopic after manipulation of
the tissue
6.95 ± 0.83 COCs identified (mean ± SE)
In 2.47 ± 0.43 MII after 48 h OTO-IVM; vitrification or ICSI on fresh oocytes
10/16 2PN after ICSI
62.5% 2PN rate; 1.67 ± 0.56 embryos cryopreserved		Hourvitz A. et al., 2015 [28]
Cohort study 19 patients (mean ± SD 30.6 ± 3.84 years, range 26–36 years)
Breast cancer (n = 5), BRCA (n = 1), arteriovenous malformation (n = 1), systemic lupus erythematosus (n = 1), immature teratoma of tuba (n = 1)		COC identification via microscopic evaluation after tissue
manipulation
10.8 ± 2.5 COCs identified (mean ± SEM)
4.6 ± 1.2 MII after 24 h or 40 h OTO-IVM
3.5 ± 1.0 2PN after ICSI
65 ± 11% 2PN rate
2.9 ± 0.6 embryos day 3 vitrified		Segers I. et al., 2015 [27]
Case series report6 patients (mean 29 years, range 19–39 years)
Endometrial (n = 2), ovarian (n = 3), double primary endometrial and ovarian cancer (n = 1)		Follicle aspiration from the ovary ex vivo (18 gauge needle)
53x COCs identified (mean 10.6 per patient)
36x MII after 48 h OTO-IVM;
Vitrification of 28 MII oocytes for 4 patients,
5x embryos vitrified for 1 patient after ICSI on fresh OTO-IVM
oocytes (8x MII injected); 62.5% 2PN rate 		Park C.W. et al., 2016 [29]
Cross sectional study136 patients (mean ± SD 27.6 ± 5.6 years)
Different oncological indications (n = 120), hematological benign (n = 8), immunological disorders (n = 8)		Follicle aspiration from the ovary ex vivo, discarded
tissue filtered through a cell strainer and microscopic evaluation
559x COCs subjected to OTO-IVM
145x MII after 24 h or 48 h OTO-IVM;
Vitrification of 139x MII oocytes for 72 patients,
7x 2PN vitrified for 1 patient after ICSI on fresh OTO-IVM oocytes (12x MII injected in 5 patients); 58.3% 2PN rate
9x MII vitrification-warmed, 2x MII intact after warming, 1x embryo (low quality day 2); biochemical pregnancy after ET		Fasano G. et al., 2017 [35]
Case report37 years old patient
Mullerian adenocarcinoma
Ovarian wedge resection (2 × 2 cm)		Follicle aspiration from the ovary ex vivo (20 gauge needle)
3x COCs identified
2x MII after 48 h OTO-IVM;
2x 2PN after ICSI; 100% 2PN rate
2x embryos (grade B and C day 3) vitrified		Mohsenzadeh M. et al., 2017 [37]
Cohort study 18 patients (mean ± SD 27.3 ± 4.8 years range 20–34 years)Oocyte aspiration from the ovary ex vivo
25x COCs identified
12x MII after 36 h OTO-IVM
5x embryos cryopreserved after ICSI
5x embryos for ET in different patients: no pregnancies after ET		Kedem et al., 2018 [21]
Case report30 years old patient
Breast cancer
Ovarian wedge resection (2 × 2 cm)		Follicle aspiration from the ovary ex vivo (21 gauge needle),
remaining fluid after manipulation underwent microscopic
evaluation
33x COCs identified
11x MII after 48 h OTO-IVM;
6x 2PN after ICSI; 54.5% 2PN rate
6x cleavage embryos (day 3), 3 blastocysts (euploid) vitrified 		Kirillova A. et al., 2020 [38]
Prospectiveobservational study12 patients (mean ± SD 27.3. ± 4.8 years range 20–34 years)
Breast cancer (n = 6), B-cell lymphoma (n = 1), Hodgkin lymphoma (n = 2), cervical embryonal rhabdomyosarcoma (n = 1), pleiomorphic xanthoastrocytoma (n = 1), Ewing’s sarcoma (n = 1)
Unilateral ovarian resection		Follicle aspiration from the ovary ex vivo (21 gauge needle),
remaining fluid after manipulation underwent microscopic evaluation
37x COCs identified
14x MII after 24 h OTO-IVM;
8x MII were vitrified
4x 2PN vitrified for 3 patients after ICSI on fresh OTO-IVM oocytes (6x MII injected in 3 patients); 66.6% 2PN rate 		Dietrich J. et al., 2020 [41]
Cross sectional study83 patients (median; min-max: 20 years (17.6–38.4 years)
Transgender patients
Bilateral oophorectomy at the time of gender
affirming surgery under testosterone treatment		COC identification via microscopic evaluation after tissue
manipulation
1903x COCs identified
453x MII after 48 h OTO-IVM;
410x MII were vitrified, 208x MII warmed
48x 2PN (from 151 warmed intact) after ICSI with 1 sperm donor 34.5% 2PN rate
25x embryos day 3, 1x blastocyst day 5 (4BB) (euploid)
44x embryos arrested (91.7%) 		Lierman S. et al., 2021 [39]
1 Only data from patients with embryologic developmental outcomes are summarized in the table; oocyte–ovarian tissue oocyte in vitro maturation (OTO-IVM); human chorionic gonadotropin (HCG); follicle-stimulating hormone (FSH); cumulus–oocyte complex (COC); intracytoplasmic sperm injection (ICSI); standard error (SE); standard error of the mean (SEM); standard deviation (SD); metaphase 2 oocyte (MII); normally fertilized zygote showing 2 pronuclei (2PN).
Table
Table 2. Live births from monophasic OTO-IVM.
Table 2. Live births from monophasic OTO-IVM.
Study Type MethodologyResults Reference
Case report21 years old patient
Oophorectomy for bilateral large pelvic masses,
peritoneal disease and ascites and raised serum CA125 of 1.279 U/mL
left salpingo-ophorectomy at day 5 of the menstrual cycle		Follicle aspiration from the ex vivo ovary (18 gauge needle),
No data on COCs collection, number of MII oocytes or embryo development.
24 h OTO-IVM performed
3x day 2 embryos cryopreserved by slow rate freezing.
2x embryos thawed, ET in artificial frozen-embryo transfer cycle
Outcome: Healthy male singleton, 2.580 g		Prasasth. et al., 2014 [42]
Case report23 years old patient
8 cm complex mass in the solitary left ovary
Left salpingo-oophorectomy		Oocyte aspiration from a healthy piece of ovarian tissue (2 × 3 cm)
10x COCs identified
4x MII after 24 h OTO-IVM
4x 2PN after ICSI, 3x 2PN were cryopreserved by slow freezing
3x 2PN were thawed, DET (cleavage stage embryos)
Outcome: Healthy male singleton, 3.883 g		Uzelac et al., 2015 [43]
Cohort study 112 patients (mean ± SD 29.8. ± 5.05 years range 23–36 years)
Breast cancer (n = 9), Hodgkin lymphoma (n = 2), arterio-venous malformation of the uterus (n = 1)		COC identification via microscopic evaluation after tissue
manipulation
157x COCs identified
51x MII after 28 h or 40 h OTO-IVM
24x MII vitrified
37x fresh OTO-IVM MII ICSI: 21x 2PN (56% 2PN rate)
15x embryos day 3 (good quality) vitrified
Outcomes:
7x embryos warmed for 5 patients; 2 healthy female singletons (2.660 g and 3.860 g) for 2 patients
12x vitrification-warmed oocytes used for 2 patients; 1 healthy male singleton, 3.150 g 		Segers et al., 2020 [44]
1 Only data from patients having embryo transfer are summarized in the table. The live birth reported by of Kedem et al. [21] has not been included since the paper described data from different types of IVM (not only OTO-IVM) and the live birth reported resulted from a PCOS patient where the IVM oocytes were aspirated from the ovary in situ. Cumulus–oocyte complex (COC); metaphase 2 oocyte (MII); oocyte–ovarian tissue oocyte in vitro maturation (OTO-IVM); embryo transfer (ET); normally fertilized zygote showing 2 pronuclei (2PN); dual embryo transfer (DET).
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De Roo, C.; Tilleman, K. In Vitro Maturation of Oocytes Retrieved from Ovarian Tissue: Outcomes from Current Approaches and Future Perspectives. J. Clin. Med. 2021, 10, 4680. https://doi.org/10.3390/jcm10204680

AMA Style

De Roo C, Tilleman K. In Vitro Maturation of Oocytes Retrieved from Ovarian Tissue: Outcomes from Current Approaches and Future Perspectives. Journal of Clinical Medicine. 2021; 10(20):4680. https://doi.org/10.3390/jcm10204680

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De Roo, Chloë, and Kelly Tilleman. 2021. "In Vitro Maturation of Oocytes Retrieved from Ovarian Tissue: Outcomes from Current Approaches and Future Perspectives" Journal of Clinical Medicine 10, no. 20: 4680. https://doi.org/10.3390/jcm10204680

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