Article

Assisted oocyte activation is not beneficial for all patients with a suspected oocyte-related activation deficiency

Department for Reproductive Medicine, Ghent University Hospital, De Pintelaan 185, B-9000 Ghent, Belgium.
Human Reproduction (Impact Factor: 4.57). 04/2012; 27(7):1977-84. DOI: 10.1093/humrep/des097
Source: PubMed

ABSTRACT

Despite the success of ICSI, total fertilization failure (TFF) still occurs in 1-3% of all ICSI cycles. ICSI followed by assisted oocyte activation (ICSI-AOA) can restore fertilization, most efficiently in cases of sperm-related fertilization deficiency. The indication for ICSI-AOA is less obvious when the capacity of the sperm to activate oocytes is considered normal, as proved by a heterologous ICSI model, such as the mouse oocyte activation test (MOAT). In this study, we verified whether ICSI-AOA is beneficial for patients in whom an oocyte-related activation deficiency is suspected.
A prospective study was conducted including patients presenting with a history of TFF or low fertilization (LF) following conventional ICSI in our centre (in-house cases, n= 2) or elsewhere (out-house cases, n= 12). In all cases a sperm deficiency was refuted by the MOAT. In a next treatment cycle, ICSI-AOA was performed on half of the sibling metaphase II oocytes and conventional ICSI on the rest ('split ICSI-AOA cycle'). The main outcome parameters were fertilization, pregnancy and live birth rates.
Overall, ICSI-AOA was able to improve fertilization rates in couples with a suspected oocyte-related fertilization problem, with a mean fertilization rate of 74.2% following ICSI-AOA compared with 43.5% following conventional ICSI (P< 0.001). Cumulative pregnancy rate and live birth rate per cycle were 35.7 and 14.3%, respectively. Considering the out-house patients only, fertilization rates with ICSI-AOA were higher in couples with previous TFF than with conventional ICSI (P< 0.001). Interestingly, for out-house patients who had experienced low, but not zero, fertilization elsewhere, ICSI-AOA could not enhance the fertilization rate. For the two in-house patients, both suffering from previous LF following conventional ICSI, the ICSI-AOA procedure enhanced the mean fertilization rate (25 versus 75%, respectively).
For patients with a suspected oocyte-related activation deficiency, as diagnosed by a heterologuous ICSI model, the indication for ICSI-AOA still remains debatable. Our data show that ICSI-AOA is very efficient in patients with a suspected oocyte-related activation deficiency and previous TFF after conventional ICSI. In contrast, when there was a history of LF in another centre, one should be careful and test the efficiency of ICSI-AOA on half of the sibling oocytes, because ICSI-AOA is not always beneficial for patients with previous LF and a suspected oocyte-related activation deficiency. For these patients, a split ICSI-AOA cycle using sibling oocytes can help to distinguish between a molecular oocyte-related activation deficiency and a previous technical or other biological failure. Moreover, this split ICSI-AOA strategy enables us to set the appropriate strategy for future treatment cycles. Further research with larger groups of patients is now required.

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    • "It has been shown that certain oocyte deficiencies, such as spindle abnormalities, might lead to lower activation and 564 F Vanden Meerschaut et al. pregnancy rates (Combelles et al., 2010). ICSI–AOA is not beneficial for all patients with a suspected oocyte-related activation deficiency (MOAT group 3) and fertilization history should be taken into account when choosing the appropriate diagnostic and therapeutic approach (Vanden Meerschaut et al., 2012). When subgroups of MOAT group 1 were examined in more detail, it became clear that pregnancy rates were very high in the globozoospermic patients and patients with moderate OAT (42–67%); only the group of patients with extreme OAT showed lower pregnancy rates after AOA (9%;Heindryckx et al., 2008). "
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    ABSTRACT: Intracytoplasmic sperm injection (ICSI) is a very efficient technique used in couples diagnosed with severe sperm abnormalities. Fortunately, in only a minority of the couples ICSI does not lead to normal fertilization, which means that, in those couples, no (or very few) embryos will be available for transfer. Failure of fertilization following conventional ICSI can be related to the oocyte or the spermatozoon. Only a few diagnostic tests are currently available to assess the reason for ICSI fertilization failure. The most often advised treatment is assisted oocyte activation (AOA), a highly specialized fertilization technique that can be added to conventional ICSI to overcome fertilization failure in those couples. Since the late 1990s, many centres have been performing AOA in this rare group of patients, with restoration of fertilization and pregnancy rates in many couples. However, until adequate scientific evidence is provided regarding its safety and efficacy, AOA cannot yet be considered an established treatment. This review tackles the mechanism of human oocyte activation and the relatively rare phenomenon of fertilization failure after ICSI. Next, we describe the current diagnostic approaches and focus on the application, efficiency and safety of AOA in human assisted reproduction.
    Preview · Article · May 2014 · Reproductive biomedicine online
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    • "Wob, ICSI using wobbler sperm; Wob-Sr, AOA by strontium chloride; Wob-E, AOA by electrical pulses; Wob-I, AOA by ionomycin, WT, wild type. technique (Heindryckx et al., 2005;Heindryckx et al., 2008;Vanden Meerschaut et al., 2012). In the mouse and the rabbit, it has been shown that a distinct pattern of calcium oscillations is crucial for successful fertilization and embryo development (Ozil, 1998;Berridge et al., 2000;Ducibella et al., 2002;Ozil et al., 2006). "
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    ABSTRACT: Study question: Does the application of three different artificial activating stimuli lead to a difference in pre- and post-implantation embryo development in the wobbler mouse, a mouse model with oocyte activation deficient round-headed sperm cells similar to human globozoospermia? Summary answer: No gross differences were found between strontium chloride, electrical pulses or ionomycin with respect to the pre- and post-implantation development in the wobbler mouse. What is known already: Fertilization failure following intra-cytoplasmic sperm injection (ICSI) occurs in 1–3% of the ICSI cycles in human assisted reproduction technology (ART) and has been successfully overcome by different artificial activating stimuli. No comparison has been made yet in terms of their efficiency and safety. Study design, size, duration: Calcium release and embryo development were compared between oocytes fertilized by wobbler and wild-type (WT) sperm following ICSI with or without three different artificial activating agents. Preimplantation development was assessed on 70 injected oocytes on average per group. On average, 10 foster mothers were used per activating group to compare post-implantation development. Participants/materials, setting, methods: We used the wobbler mouse model that possesses oocyte activation deficient round-headed sperm cells. First, the calcium release following ICSI using wobbler sperm was compared with that of WT sperm. Outcome measures were the percentage of oocytes that showed calcium release and their mean amount of calcium rises. Secondly, the pre- and post-implantation development was assessed following ICSI with wobbler sperm plus artificial oocyte activation using either: (i) strontium chloride (Wob-Sr), (ii) electrical pulses (Wob-E) or (iii) ionomycin (Wob-I). Outcome measures were the activation, cleavage and blastocyst rates and the assessment of blastocyst quality by differential staining. Following mouse embryo transfer, pregnancy and birth rates as well as mean litter sizes were examined. Finally, pups were followed up until 8 weeks of age and then mated with fertile controls to assess their fertility. Main results and the role of chance: The percentage of oocytes showing calcium rises as well as the number of calcium rises per oscillating oocyte were significantly lower in the wobbler group when compared with the WT group (9.3 versus 96% and 2.1 calcium rises versus 31 calcium rises) (P , 0.001). The fertilization rate was significantly lower in the wobbler group (11.4%) when compared with the WT group (92.1%) and the artificial activation groups (strontium chloride: 99%, electrical pulses: 99% and ionomycin: 81%, respectively) (P , 0.001). Post-implantation development did not differ significantly between the WT and artificial activation groups, with pregnancy rates in favor of strontium chloride and electrical pulses. The weight of the male pups did not differ between the study groups, whereas the weight of the female pups originating from Wob-Sr embryos was significantly lower at weeks 2, 3 and 4 when compared with female pups originating from WT embryos. However, the latter difference was not observed at later time points, nor in the other artificial activating groups. All offspring mated successfully with fertile controls. Limitations, reasons for caution: Results in animal models should be extrapolated with caution to a subfertile human population. Also, ionomycin is currently the most widely used artificial oocyte activating agent in human ART. Wider implications of the findings: The low frequency of observed calcium rises and the low activation rate make the wobbler mouse a highly suitable model to study oocyte activation deficiency. Strontium chloride and electrical pulses were more efficient means to restore fertilization rates and to support pre- and post-implantation embryonic development than ionomycin. Study funding/competing interest(s): This work was supported by the Flemish foundation of Scientific Research (FWOVlaanderen) (aspirant clinical research mandate to F.V.M., fundamental clinical research mandate to P.D.S.); and Ghent University grant (KAN-BOF E/01321/01 to B.H.). The authors have no competing interests to declare.
    Preview · Article · Mar 2013 · Human Reproduction
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    • "Also, in several globozoospermic patients, such a calcium ionophore activation treatment has been previously used successfully to restore fertilization and pregnancy rates (Heindryckx et al., 2005, 2008). The latter achievements in globozoospermic patients are sound because AOA is known to be more efficient to overcome sperm-related activation deficiencies, rather than suspected oocyte-related activation deficiencies (Vanden Meerschaut et al., 2012). Descriptions of familial cases of globozoospermia led to the hypothesis of a possible genetic defect responsible for this phenotype. "
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    ABSTRACT: STUDY QUESTION: Does DPY19L2 status influence intracytoplasmic sperm injection (ICSI) outcomes with or without assisted oocyte activation (AOA)?SUMMARY ANSWERDPY19L2 mutations have no major impact on ICSI outcomes in globozoospermic patients.WHAT IS KNOWN ALREADYGlobozoospermia is a rare and severe teratozoospermia characterized by round-headed spermatozoa lacking an acrosome. Recently, it has been shown that DPY19L2 mutations can be found in a vast majority of, but not all, globozoospermic patients (66.7%). These patients suffer from primary infertility due to a sperm-related oocyte activation deficiency secondary to the absence of an acrosome that can be overcome by the application of AOA.STUDY DESIGN, SIZE, DURATIONCohort study, retrospective, 34 patients, 83 cycles.MATERIALS, SETTING, METHODS Clinical and biologic data were collected from 29 patients mutated for DPY19L2 and 5 non-mutated patients. In total, 35 ICSI cycles using AOA and 48 conventional ICSI cycles were included in the analysis. Patients were divided into groups according to whether or not they were mutated for DPY19L2 and whether or not they received AOA. MAIN RESULTS AND THE ROLE OF CHANCE: Regardless of the presence of a DPY19L2 mutation, the fertilization rates with AOA are restored to normal when compared with conventional ICSI in our cohort of globozoospermic patients. Also, when performing ICSI plus AOA, both mutated and non-mutated cases have similar positive hCG rates, ongoing pregnancy rates and live birth rates per transfer. On the contrary, the fertilization rate in globozoospermic patients using conventional ICSI is correlated with the presence of a DPY19L2 mutation, with slightly better, although still very low, fertilization rates in patients carrying a DPY19L2 mutation. Nevertheless, when performing conventional ICSI, both mutated and non-mutated cases have similar very low positive hCG rates, ongoing pregnancy rates and live birth rates per transfer.LIMITATIONSA limitation of this study is the low number of included non-mutated cases. WIDER IMPLICATIONS OF THE FINDINGS: We propose a pathway for the clinical management of globozoospermic patients depending on the phenotype that includes several diagnostic and therapeutic steps. STUDY FUNDING/COMPETING INTEREST(S): None.
    Full-text · Article · Feb 2013 · Human Reproduction
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