Publications by authors named "Tilleman K"

Although the impact of gender-affirming hormone therapy (GAHT) on spermatogenesis in trans women has already been studied, data on its precise effects on the testicular environment is poor. Therefore, this study aimed to characterize, through histological and transcriptomic analysis, the spermatogonial stem cell niche of 106 trans women who underwent standardized GAHT, comprising estrogens and cyproterone acetate. A partial dedifferentiation of Sertoli cells was observed, marked by the co-expression of androgen receptor and anti-Müllerian hormone which mirrors the situation in peripubertal boys.

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  • The study investigates how genotype analysis can enhance the classification of (mosaic) aneuploid embryos that have been diagnosed through copy number analysis of a trophectoderm biopsy.
  • Results showed that genotype analysis can identify different types of aneuploidy, revealing meiotic or uniform aneuploidy in embryos with intermediate changes, and presumed mitotic or mosaic aneuploidy in those with full changes.
  • The research involved a large-scale analysis of 1560 embryos, focusing on assessing the chromosomal anomalies and their origins by integrating copy number data with genotyping.
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  • The study explored how Belgian fertility clinics approach the management of genetic risks in treatments using donor sperm.
  • An electronic survey sent to clinics revealed that while all assessed donor risks, a significant lack of consistent communication about adverse genetic events existed between clinics, donors, and recipients.
  • Findings indicated that although genetic conditions were often suspected or identified in donor sperm treatments, clinics varied in their protocols for informing affected parties and deciding on the future use of donor sperm linked to adverse events.
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Study Question: Which clinical and embryological factors should be considered to apply double embryo transfer (DET) instead of elective single embryo transfer (eSET)?

Summary Answer: No clinical or embryological factor per se justifies a recommendation of DET instead of eSET in IVF/ICSI.

What Is Known Already: DET is correlated with a higher rate of multiple pregnancy, leading to a subsequent increase in complications for both mother and babies. These complications include preterm birth, low birthweight, and other perinatal adverse outcomes.

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This commentary examines the impact of light conditions in the assisted reproductive technology (ART) laboratory, specifically considering gametes and embryo culture. While these processes traditionally occur in the absence of light within the female reproductive tract, laboratory conditions often involve exposure to varying wavelengths, intensities and light sources. Although literature reports describe potential detrimental effects of certain wavelengths of light on biological material, these findings are often based on experiments that might not reflect actual laboratory conditions.

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MicroRNAs (miRNAs), which can be carried inside extracellular vesicles (EVs), play a crucial role in regulating embryo development up to the blastocyst stage. Yet, the molecular mechanisms underlying blastocyst development and quality are largely unknown. Recently, our group identified 69 differentially expressed miRNAs in extracellular vesicles (EVs) isolated from culture medium conditioned by bovine embryos that either developed to the blastocyst stage or did not (non-blastocysts).

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Fatty acids (FA) in follicular fluid (FF) are present in an esterified form [triglycerides, cholesterol esters and phospholipids] or as non-esterified FA, which partly originate from blood. However, a comprehensive comparison of blood vs. FF FA in various lipid classes is missing.

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Research Question: What are the incidence of and indications for sperm donor restriction due to suspected/confirmed disease risk, and the future treatment choices of patients using these sperm donors?

Design: This single-centre retrospective study involved donors who had restrictions on the use of their imported spermatozoa from January 2010 to December 2019, and current or previous recipients. Indications for sperm restriction and the characteristics of patients undergoing medically assisted reproduction (MAR) treatment with these specimens at the time of restriction were collected. Differential characteristics of women who decided on whether or not to contintue the procedure were assessed.

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Background: Hormonal treatments and surgical interventions practiced with the aim to affirm gender identity in transgender and gender diverse patients may impact their future reproductive ability, family building, and family planning options. Whereas it is recommended by international guidelines to discuss the potential risks of infertility and to present fertility preservation (FP) options to transgender individuals and their families prior to initiating any of these treatments, many barriers still remain. Further, transgender and gender diverse individuals often experience barriers to accessing contraception, abortion, pre-conception care, and comprehensive perinatal care.

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Transgender healthcare is a rapidly evolving interdisciplinary field. In the last decade, there has been an unprecedented increase in the number and visibility of transgender and gender diverse (TGD) people seeking support and gender-affirming medical treatment in parallel with a significant rise in the scientific literature in this area. The World Professional Association for Transgender Health (WPATH) is an international, multidisciplinary, professional association whose mission is to promote evidence-based care, education, research, public policy, and respect in transgender health.

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Study Question: Is the cumulative live birth rate (CLBR) per oocyte collection cycle (OCC) comparable after cleavage-stage or blastocyst-stage transfer in combination with supernumerary blastocyst vitrification on Day 5 (D5) in patients with four or fewer zygotes on Day 1?

Summary Answer: The CLBR in a fresh blastocyst-transfer or cleavage-stage transfer policy followed by vitrification on D5 is comparable in patients with four or fewer zygotes.

What Is Known Already: Blastocyst transfer enhances the self-selection of the embryo and shortens the time to pregnancy in patients with normal or high ovarian response. Whether these advantages are also present in patients with a low ovarian response and/or a limited number of available zygotes is a continuous debate.

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Background: Advanced maternal age and obesity are associated with impaired female fertility. Moreover, fatty acids (FA) in follicular fluid (FF) play important roles in oocyte maturation and embryo development. However, the effects of body mass index (BMI), age, and FF FA composition on embryo development between days 3 and 5 and blastocyst stage on day 5 are still unclear.

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Background: Hypospadias affects around 1/200 newborn males. Intrauterine testicular dysfunction may underlie a subset of cases. The long-term endocrine and reproductive outcomes in these men remain largely unknown.

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Study Question: Is it possible to develop a comprehensive pipeline for all-in-one preimplantation genetic testing (PGT), also suitable for parents-only haplotyping and, for the first time, third-party reproduction?

Summary Answer: Optimized reduced representation sequencing (RRS) by GENType, along with a novel analysis platform (Hopla), enables cheap, accurate and comprehensive PGT of blastocysts, even without the inclusion of additional family members or both biological parents for genome-wide embryo haplotyping.

What Is Known Already: Several haplotyping strategies have proven to be effective for comprehensive PGT. However, these methods often rely on microarray technology, whole-genome sequencing (WGS) or a combination of strategies, hindering sample throughput and cost-efficiency.

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Research Question: Lack of guidance on the frequency of Chlamydia trachomatis screening in non-partner donors has led to heterogeneous testing protocols. C. trachomatis was checked in sperm donations unscreened for C.

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SignificanceHatching from the zona pellucida is a prerequisite for embryo implantation and is less likely to occur in vitro for reasons unknown. Extracellular vesicles (EVs) are secreted by the embryo into the culture medium. Yet the role that embryonic EVs and their cargo microRNAs (miRNAs) play in blastocyst hatching has not been elucidated, partially due to the difficulties of isolating them from low amounts of culture medium.

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Study Question: What information and support should be offered to donors, intended parents and donor-conceived people, in general and in consideration of the availability of direct-to-consumer genetic testing and matching services?

Summary Answer: For donors, intended parents and donor-conceived offspring, recommendations are made that cover information needs and informed consent, psychosocial implications and disclosure.

What Is Known Already: Trends indicate that the use of donor-assisted conception is growing and guidance is needed to help these recipients/intended parents, the donors and offspring, navigate the rapidly changing environment in which donor-assisted conception takes place.

Study Design Size Duration: A working group (WG) collaborated on writing recommendations based, where available, on evidence collected from a literature search and expert opinion.

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Objective: To assess the best-performing machine learning (ML) model and features to predict euploidy in human embryos.

Design: Retrospective cohort analysis.

Setting: Department for reproductive medicine in a university hospital.

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Study Question: What is the recommended management for medically assisted reproduction (MAR) in patients with a viral infection or disease, based on the best available evidence in the literature?

Summary Answer: The ESHRE guideline on MAR in patients with a viral infection/disease makes 78 recommendations on prevention of horizontal and vertical transmission before, during and after MAR, and the impact on its outcomes, and these also include recommendations regarding laboratory safety on the processing and storage of gametes and embryos testing positive for viral infections.

What Is Known Already: The development of new and improved anti-viral medications has resulted in improved life expectancy and quality of life for patients with viral infections/diseases. Patients of reproductive age are increasingly exploring their options for family creation.

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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.

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Study Question: Is it possible to define a set of performance indicators (PIs) for clinical work in ART, which can create competency profiles for clinicians and for specific clinical process steps?

Summary Answer: The current paper recommends six PIs to be used for monitoring clinical work in ovarian stimulation for ART, embryo transfer, and pregnancy achievement: cycle cancellation rate (before oocyte pick-up (OPU)) (%CCR), rate of cycles with moderate/severe ovarian hyperstimulation syndrome (OHSS) (%mosOHSS), the proportion of mature (MII) oocytes at ICSI (%MII), complication rate after OPU (%CoOPU), clinical pregnancy rate (%CPR), and multiple pregnancy rate (%MPR).

What Is Known Already: PIs are objective measures for evaluating critical healthcare domains. In 2017, ART laboratory key PIs (KPIs) were defined.

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Objective: To study the feasibility of in vitro maturation of ovarian tissue oocytes for fertility preservation in transgender men on testosterone treatment.

Design: Cross-sectional study SETTING: University hospital PATIENT(S): Eighty-three transgender men enrolled from November 2015 to January 2019 INTERVENTION(S): In vitro maturation of cumulus-oocyte complexes (COCs) harvested at the time of gender confirmation surgery, and fertilization through intracytoplasmic sperm injection.

Main Outcome Measure(s): In vitro maturation, fertilization, and blastulation rates; comparison of morphokinetics with vitrified-warmed oocytes; and analysis of the genetic profiles of embryos.

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We aimed to assess the feasibility of passive slow freezing (PSF using Mr. Frosty container, Nalgene) as an alternative to controlled slow rate freezing (CSF using (Freezal™, Air liquide)) for human ovarian tissue (OT) cryopreservation. Validation studies needed were determined after assessing the risk associated (EuroGTP-II ART tool) and were conducted in 66 OT samples from 10 transgender men aged 23.

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Extracellular RNAs present in biofluids have emerged as potential biomarkers for disease. Where most studies focus on blood-derived fluids, other biofluids may be more informative. We present an atlas of messenger, circular, and small RNA transcriptomes of a comprehensive collection of 20 human biofluids.

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