Sandra García-Herrero

Effect of sperm DNA fragmentation on pregnancy outcome depends on oocyte quality

OBJECTIVE To quantify the effect of sperm DNA fragmentation (SDF) on reproductive outcome by evaluating the most statistically significant bias factors using logistic regression. DESIGN Prospective blind observational cohort study. SETTING University affiliated private IVF unit. PATIENT(S) Two hundred ten male partners of couples undergoing in vitro fertilization (IVF) or first intracytoplasmic sperm injection (ICSI) cycles with fresh or thawed sperm with the womens own or donated oocytes. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) SDF determined before and after swim-up (n=420), odds ratio calculated of the effect of an increase of one unit of SDF on pregnancy, and stratified regression analysis performed to evaluate the confusion effect of oocyte quality, sperm origin, and the fertilization procedure. RESULT(S) The effect of SDF on pregnancy was not affected by sperm origin (fresh or thawed) or fertilization procedure when measured both before and after swim-up. When oocytes from infertile patients were employed, SDF had a statistically significant negative impact on chance of pregnancy. For every 10% increase in SDF, the probability of not achieving pregnancy increased by 1.31. When donated oocytes were employed, SDF did not have a statistically significant effect. CONCLUSION(S) The effect of SDF on the probability of pregnancy can be calculated independent of the fertilization procedure or sperm origin. Oocyte quality conditions the extent of the negative impact of SDF on pregnancy; this can be overcome when good quality oocytes are employed.

Differential transcriptomic profile in spermatozoa achieving pregnancy or not via ICSI

Basic sperm analysis is limited as a method of estimating pregnancy. This study’s objective was use of microarray technology to differentiate the gene expressions of spermatozoa that achieved pregnancy in an intracytoplasmic sperm injection (ICSI)cycle in an oocyte donation programme with those that did not achieve pregnancy. A study of nested cases and controls was designed to evaluate fresh and frozen spermatozoa from infertile males undergoing ICSI with donor oocytes. The global genome expression of pooled samples from each group (achieving pregnancy versus those that didn’t, from fresh or frozen spermatozoa)was compared using microarray analysis. The level of expression of some of the transcripts from fresh spermatozoa was shown to differ for those that achieved pregnancy versus those that didn’t. Additionally, exclusively expressed transcripts were identified for both outcome groups. Analysis of frozen spermatozoa didn’t reveal differential expression, but exclusively expressed transcripts were detected. Lists of the transcripts were systematically analysed using different databases in order to provide information about them and their relationship with male fertility. The results revealed profound differences between the expression profiles of spermatozoa that resulted in pregnancy versus those that didn’t. These differences may explain ICSI failure associated with male factor infertility.

Y chromosome microdeletions, sperm DNA fragmentation and sperm oxidative stress as causes of recurrent spontaneous abortion of unknown etiology

BACKGROUND The aim of the present study was to evaluate the implication of male factor, in terms of sperm DNA oxidation and fragmentation, and Y chromosome microdeletions in recurrent spontaneous abortion (RSA) of unknown origin in a strictly selected cohort. METHODS A prospective cohort study was carried out in a private university-affiliated setting. Three groups, each comprised of 30 males, were compared. The first was formed by healthy and fertile sperm donors (SD) with normal sperm parameters (control group), the second by men presenting severe oligozoospermia (SO) without RSA history, and the third by men from couples who had experienced idiopathic RSA. Frequency of Y chromosome microdeletions and mean sperm DNA fragmentation and oxidation were determined. RESULTS Y chromosome microdeletions were not detected in any of the males enrolled in the study. Moreover, sperm DNA oxidation measurements were not demonstrated to be relevant to RSA. Interestingly, sperm DNA fragmentation was higher in the SO group than in the RSA and the SD groups, and also higher in the RSA group compared with the SD group, but lacked an adequate predictive power to be employed as a discriminative test of RSA condition. CONCLUSIONS Sperm DNA features and Y chromosome microdeletions do not seem to be related to RSA of unknown origin. Other molecular features of sperm should be studied to determine their possible influence on RSA. Clinicaltrials.gov reference: NCT00447395.

Contribution of sperm molecular features to embryo quality and assisted reproduction success.

Semen analysis, as stated by the World Health Organization, is the only accepted tool to assess male fertility. However its predictive value to assess male capacity to initiate a pregnancy is limited. With the introduction of IVF (especially via intracytoplasmic sperm injection), infertility caused by diminished sperm production is frequently solved, but knowledge of sperm physiology remains very poor. Moreover, a percentage of males with apparently normal semen are unable to impregnate healthy women. Therefore, improvements in the diagnostic tools to assess male fertility potential are necessary. The aim of this review is to describe sperm molecular factors implicated in male fertility, demonstrated by their role in sperm physiology, the molecular differences found between fertile and infertile males, or by their influence on the results obtained in assisted reproduction treatments in terms of embryo quality and pregnancy achievement. From a search and objective evaluation of the currently available evidence, it is concluded that there is no unique factor able to predict male fertility, but several molecular factors are involved in sperm function and can potentially be considered as fertility markers. In this context, a complex molecular tool designed to analyse a battery of parameters seems to be necessary.

New Tools for Embryo Selection: Comprehensive Chromosome Screening by Array Comparative Genomic Hybridization

The objective of this study was to evaluate the usefulness of comprehensive chromosome screening (CCS) using array comparative genomic hybridization (aCGH). The study included 1420 CCS cycles for recurrent miscarriage (n = 203); repetitive implantation failure (n = 188); severe male factor (n = 116); previous trisomic pregnancy (n = 33); and advanced maternal age (n = 880). CCS was performed in cycles with fresh oocytes and embryos (n = 774); mixed cycles with fresh and vitrified oocytes (n = 320); mixed cycles with fresh and vitrified day-2 embryos (n = 235); and mixed cycles with fresh and vitrified day-3 embryos (n = 91). Day-3 embryo biopsy was performed and analyzed by aCGH followed by day-5 embryo transfer. Consistent implantation (range: 40.5–54.2%) and pregnancy rates per transfer (range: 46.0–62.9%) were obtained for all the indications and independently of the origin of the oocytes or embryos. However, a lower delivery rate per cycle was achieved in women aged over 40 years (18.1%) due to the higher percentage of aneuploid embryos (85.3%) and lower number of cycles with at least one euploid embryo available per transfer (40.3%). We concluded that aneuploidy is one of the major factors which affect embryo implantation.

Assessment of sperm using mRNA microarray technology

The aim of this work is to review the need for new diagnostic tools for sperm, the relevance of sperm mRNA in reproductive success, and the potential of a state-of-the-art microarray-based diagnostic tool for improving reproductive results.

Ontological evaluation of transcriptional differences between sperm of infertile males and fertile donors using microarray analysis

PurposeTo catalogue Gene Ontology terms in the sperm of infertile human males vs. donors of proven fertility by analyzing five samples from each of the two groups (five aliquots from fresh sperm and five post-swim-up).MethodsMicroarray technology was employed to study the mRNA profile of both fresh and post-swim-up pooled samples from infertile males and donors.ResultsGenes that were differentially expressed in the two populations and expressed in only one of two were analyzed to determine the gene products in terms of their associated Gene Ontology terms. Each group presented a different number and pattern of Gene Ontology terms.ConclusionsWe found differences in Gene Ontology terms between the two groups. These differences could potentially be employed to establish markers of fertility success and to identify cellular processes and complex systems related with male infertility.

BACs-on-Beads technology: a reliable test for rapid detection of aneuploidies and microdeletions in prenatal diagnosis.

The risk of fetal aneuploidies is usually estimated based on high resolution ultrasound combined with biochemical determination of criterion in maternal blood, with invasive procedures offered to the population at risk. The purpose of this study was to investigate the effectiveness of a new rapid aneuploidy screening test on amniotic fluid (AF) or chorionic villus (CV) samples based on BACs-on-Beads (BoBs) technology and to compare the results with classical karyotyping by Giemsa banding (G-banding) of cultured cells in metaphase as the gold standard technique. The prenatal-BoBs kit was used to study aneuploidies involving chromosomes 13, 18, 21, X, and Y as well as nine microdeletion syndromes in 321 AF and 43 CV samples. G-banding of metaphase cultured cells was performed concomitantly for all prenatal samples. A microarray-based comparative genomic hybridization (aCGH) was also carried out in a subset of samples. Prenatal-BoBs results were widely confirmed by classical karyotyping. Only six karyotype findings were not identified by Prenatal-BoBs, all of them due to the known limitations of the technique. In summary, the BACs-on-Beads technology was an accurate, robust, and efficient method for the rapid diagnosis of common aneuploidies and microdeletion syndromes in prenatal samples.

Antioxidants in ICSI

Male factor infertility can be caused by reasons, either related or not with total sperm production. Among causes of male infertility in cases of normal sperm count and motility, oxidative stress is one of the most relevant processes influencing fertility in vivo or in assisted reproduction treatments’ results. This chapter provides the most updated information regarding the oxidative stress situation in sperm and the relevance of antioxidants use in intracytoplasmic sperm injection results.