Frauke Vanden Meerschaut

Assisted oocyte activation following ICSI fertilization failure

The capacity of intracytoplasmic sperm injection (ICSI) to permit almost any type of spermatozoa to fertilize oocytes has made it the most successful treatment for male factor infertility. Despite its high success rates, fertilization failure following ICSI still occurs in 1-3% of couples. Assisted oocyte activation (AOA) is being increasingly applied in human assisted reproduction to restore fertilization and pregnancy rates in couples with a history of ICSI fertilization failure. However, controversy still exists mainly because the artificial activating agents do not mimic precisely the initial physiological processes of mammalian oocyte activation, which has led to safety concerns. This review addresses the mechanism of human oocyte activation and the relatively rare phenomenon of fertilization failure after ICSI. Next, it describes the current diagnostic approaches and focuses on the application, efficiency and safety of AOA in human assisted reproduction.

Globozoospermia is mainly due to DPY19L2 deletion via non-allelic homologous recombination involving two recombination hotspots

To date, mutations in two genes, SPATA16 and DPY19L2, have been identified as responsible for a severe teratozoospermia, namely globozoospermia. The two initial descriptions of the DPY19L2 deletion lead to a very different rate of occurrence of this mutation among globospermic patients. In order to better estimate the contribution of DPY19L2 in globozoospermia, we screened a larger cohort including 64 globozoospermic patients. Twenty of the new patients were homozygous for the DPY19L2 deletion, and 7 were compound heterozygous for both this deletion and a point mutation. We also identified four additional mutated patients. The final mutation load in our cohort is 66.7% (36 out of 54). Out of 36 mutated patients, 69.4% are homozygous deleted, 19.4% heterozygous composite and 11.1% showed a homozygous point mutation. The mechanism underlying the deletion is a non-allelic homologous recombination (NAHR) between the flanking low-copy repeats. Here, we characterized a total of nine breakpoints for the DPY19L2 NAHR-driven deletion that clustered in two recombination hotspots, both containing direct repeat elements (AluSq2 in hotspot 1, THE1B in hotspot 2). Globozoospermia can be considered as a new genomic disorder. This study confirms that DPY19L2 is the major gene responsible for globozoospermia and enlarges the spectrum of possible mutations in the gene. This is a major finding and should contribute to the development of an efficient molecular diagnosis strategy for globozoospermia.

Neonatal and neurodevelopmental outcome of children aged 3–10 years born following assisted oocyte activation

Assisted oocyte activation (AOA) using a calcium ionophore has been used for more than a decade following intracytoplasmic sperm injection (ICSI) fertilization failure. However, since AOA does not mimic precisely the physiological fertilization process, concerns exist about its use in human assisted reproduction. This study assessed the neonatal and neurodevelopmental outcome of children aged ≥ 3 years who had been born following AOA in our centre. Twenty-one children participated in the study (81% response rate; mean age 63.6 ± 21.07 months). Neonatal data were collected via questionnaires. Neurodevelopmental outcome was tested using the Reynell Developmental Language Scales or Clinical Evaluation of Language Fundamentals, Wechsler Preschool and Primary Scale of Intelligence or Wechsler Intelligence Scale for Children, and the Movement Assessment Battery for Children III. Behaviour was scored by the Social Communication Questionnaire, the Child Behaviour Checklist and the Teachers Report Form. For all tests and questionnaires, the mean outcomes lay within the expected ranges. These are first data on the developmental outcome of AOA children. The high response rate and the robustness of the tests support the data, which are reassuring although still considered preliminary. Therefore, AOA should still be performed only in selected couples.

Effect of two assisted oocyte activation protocols used to overcome fertilization failure on the activation potential and calcium releasing pattern.

OBJECTIVE To assess the effect of two assisted oocyte activation (AOA) protocols with the use of two calcium (Ca(2+)) ionophores, ionomycin and A23187 (calcimycin), on the intracellular Ca(2+) level in mouse and human oocytes and the fertilization rates. DESIGN Comparison of two Ca(2+) ionophores, ionomycin and A23187, regarding their capacity to increase the intracellular Ca(2+) level and to support subsequent oocyte activation and development. SETTING University hospital research laboratory. PATIENT(S)/ANIMAL(S) Patients undergoing intracytoplasmic sperm injection (ICSI) treatment and B6D2F1 mice. INTERVENTION(S) Assisted oocyte activation and microinjection of mouse and human oocytes with sperm. MAIN OUTCOME MEASURE(S) Measurement of the fertilizing and Ca(2+)-releasing ability of human sperm. RESULT(S) Ionomycin was more potent than A23187 in provoking Ca(2+) increases in both mouse and human oocytes with significantly higher amplitude and area under the receiver operating characteristic curve. The oocyte activation rate was significantly higher when mouse oocytes were activated with the use of the ionomycin- rather than the A23187-based AOA protocol. Furthermore, oocyte activation rate was higher when human in vitro matured oocytes were activated with the ionomycin-based AOA protocol, but the difference did not reach statistical significance. CONCLUSION(S) In both mouse and human oocytes, the AOA protocol that used ionomycin was more efficient than the one that used A23187. Bearing in mind that mammalian fertilization is successful when the total dose of Ca(2+) released reaches a minimal threshold, the use of ionomycin for human AOA might be justified instead of the use of A23187.

Language development of children born following intracytoplasmic sperm injection (ICSI) combined with assisted oocyte activation (AOA)

BACKGROUND The effect of assisted reproduction technology (ART) on language development is still unclear. Moreover, different techniques are introduced at rapid pace and are not always accompanied by extensive follow-up programmes. AIMS To investigate the language development of 3-10-year-old children born following ART using intracytoplasmic sperm injection (ICSI) combined with assisted oocyte activation (AOA), which is a highly specialized technique applied in cases with a history of fertilization failure following conventional ICSI. Secondly, a comparison is made between the language development of singletons and twins. METHODS & PROCEDURES Twenty children, six boys and 14 girls, born following ICSI combined with AOA and older than 3 years were included in the study. The mean age of the children was 5;4 years (range = 3;1-10;4 years; SD = 1;8 years). Expressive and receptive language development were assessed using the Clinical Evaluation of Language Fundamentals (CELF-IV-NL) for children older than 5 years and the Reynell Developmental Language Scales (RTOS) for children younger than or equal to 5 years. OUTCOMES & RESULTS The mean total score for language ability (in percentiles) was 56.8 (SD = 33.6), which corresponds to normal language skills. Significantly higher scores were found for AOA singletons compared with twins. For the general language, none of the children scored within the clinical zone for language disability corresponding with a percentile lower than 5. CONCLUSION & IMPLICATIONS This study presents the first data concerning language outcome in 3-10-year-old children born following AOA. General language scores of the AOA children in this study are located within the normal ranges. The language development of singletons was significantly better compared with twins. Although the results are reassuring for language development, in future long-term follow-up studies in this population are necessary.

Sperm involved in recurrent partial hydatidiform moles cannot induce the normal pattern of calcium oscillations

OBJECTIVE To assess the Ca2+-releasing ability of sperm involved in partial hydatidiform moles. DESIGN Analysis of the activating and Ca2+-releasing ability of human sperm. SETTING University hospital research laboratory. PATIENT(S) Patients undergoing intracytoplasmic sperm injection (ICSI) treatment. INTERVENTION(S) Microinjection of mouse and human oocytes with sperm. MAIN OUTCOME MEASURE(S) Measurement of the fertilizing and Ca2+-releasing ability of human sperm. RESULT(S) The mouse oocyte Ca2+ analysis showed that only 19.0% (4/21) of the mouse oocytes injected with sperm involved in molar pregnancies exhibited a normal pattern of Ca2+ oscillations versus 63.2% (36/57) of those injected with control sperm. Further, 83.3% (15/18) of donated in vitro-matured human oocytes injected with deficient sperm did not exhibit any Ca2+ release, while 76.9% (10/13) failed to show normal pronuclear development. Yet the sperm oocyte activation factor phospholipase C zeta (PLCζ) was present in the majority (96.6%, n=113) of the analyzed sperm at a normal expression level. Eventually, fertilization failure was overcome with assisted oocyte activation in subsequent therapeutic ICSI cycles, which led to normal deliveries. CONCLUSION(S) Sperm that previously provoked recurrent partial hydatidiform mole pregnancies due to dispermic fertilization is not able to activate human oocytes or trigger the normal pattern of Ca2+ oscillations in mouse and human oocytes in vitro.

Anonieme donatie van gameten: de maatstaf?

Het aantal patienten dat de laatste jaren een beroep doet op geassisteerde voortplantingstechnieken stijgt. Ook de vraag naar donorgameten groeit. In Belgie is momenteel bij wet de anonimiteit van de donor de regel. Niet-anonieme donatie is enkel toegestaan indien zowel de donor als de ontvanger hierin toestemmen. Dit is niet overal in de wereld het geval en anonimiteit bij donatie van gameten wordt niet langer als vanzelfsprekend beschouwd. Enkele vooraanstaande ethische commissies sluiten de mogelijkheid van contact tussen donoren en nakomelingen niet langer uit en openden het debat hieromtrent. Dit artikel geeft een overzicht van de argumenten voor en tegen de anonieme donatie van gameten. In de literatuur is nagegaan of onderzoek hieromtrent reeds werd verricht. Tot slot wordt gesteld dat, in het belang van alle betrokken partijen, een sfeer van openheid moet kunnen gecreeerd worden, waarbinnen ieder voor zichzelf een geinformeerde en gegronde keuze kan maken tot welke informatie hij/zij toegang wenst voor zichzelf en/of voor zijn/haar nakomelingen en familie.