Potential selection of genetically balanced spermatozoa based on the hypo-osmotic swelling test in chromosomal rearrangement carriers.

Chromosomal translocations and other balanced rearrangements, although usually associated with a normal phenotype, can lead to the transmission of an abnormal unbalanced genome to the offspring. Balanced and unbalanced spermatozoa, being indistinguishable, cannot be selected or deselected for prior to IVF and pre-implantation genetic diagnosis. Spermatozoa from 16 chromosomal rearrangement carriers were studied. After incubation in a hypo-osmotic solution (hypo-osmotic swelling test, or HOST), spermatozoa were fixed on microscope slides. The chromosomally balanced or unbalanced status corresponding to each observed class of flagellar conformation was evaluated through fluorescent in-situ hybridization (FISH). We show here a specific type of spermatozoa, with a distinct flagellar conformation that was associated with a balanced genetic content. HOST is a simple, low-cost and time-honoured procedure initially developed to distinguish immotile viable from non-viable spermatozoa. We demonstrate that it can also be used to identify genetically balanced spermatozoa in chromosomal rearrangement carriers, with a 96% decrease in the proportion of unbalanced spermatozoa after selection. This may potentially improve reproductive prognosis in affected couples if used prior to pre-implantation genetic diagnosis (PGD), and clinical utility and efficacy should be evaluated in further studies.

Nuclear volume differences between balanced and unbalanced spermatozoa in chromosomal translocation carriers.

While chromosomal translocations are usually associated with a normal phenotype, they can still cause male infertility as well as recurrent miscarriages and fetal malformations related to their transmission in an unbalanced state. The distinction between balanced and unbalanced spermatozoa on morphological criteria is still unfeasible. However, we previously showed that: i) spermatozoa with an unbalanced content have a higher rate of DNA fragmentation; and ii) that density gradient centrifugation partially separates balanced from unbalanced sperm cells. We hypothesized that a chromosomal imbalance could alter the fine spermatic nuclear architecture and consequently the condensation of DNA, thus modifying normal sperm density. Spermatic nuclear volumes in four translocation carriers were analyzed using confocal microscopy. Secondarily, FISH analysis was used to establish the segregation mode of each spermatozoon. We found the average spermatic nuclei size to be higher among unbalanced spermatozoa in all patients but one. All the unbalanced modes were associated with larger nuclei in two patients, while this was the case for the 3:1 mode only in the other two, suggesting an abnormal condensation. This could be the first step in elaborating a procedure to completely eliminate unbalanced spermatozoa from semen prior to in vitro fertilization.

Low birth defects by deselecting abnormal spermatozoa before ICSI.

Consistent evidence from meta-analysis has linked assisted conception by IVF, and particularly intracytoplasmic sperm injection (ICSI), with an increased risk of major birth defects. To compare the risk of major malformations of children born after standard ICSI and after intracytoplasmic injection of morphologically selected spermatozoa (IMSI), a prospective population-based study was conducted from 2005 to 2010. ICSI and IMSI were performed in only one assisted reproduction unit according to its classification of spermatozoa and using fresh semen. Medical data and follow up during 2 years of 1028 infants were collected. Major malformations were identified and classified by an external independent physician. The two groups were similar concerning the parents' age, treatment, number of oocytes recovered, days of transfer, gestational age and birthweight. However, major malformations were significantly lower with IMSI (6/450, 1.33%) versus ICSI (22/578, 3.80%; adjusted odds ratio 0.35, 95% confidence interval 0.14-0.87, P=0.014), mainly affecting boys (adjusted odds ratio 2.84, 95% confidence interval 1.24-6.53, P=0.009). In conclusion, the significantly decreased risk of major birth defects associated with IMSI remained decreased after multivariate adjustment and highlights the beneficial effect of sperm selection before ICSI.

Discontinuous gradient centrifugation (DGC) decreases the proportion of chromosomally unbalanced spermatozoa in chromosomal rearrangement carriers.

STUDY QUESTION: Can the proportion of unbalanced spermatozoa in chromosomal rearrangement carriers be decreased through the use of discontinuous gradient centrifugation (DGC)? SUMMARY ANSWER: DGC significantly decreases the proportion of genetically unbalanced spermatozoa in chromosomal rearrangement carriers. WHAT IS KNOWN ALREADY: Chromosomal rearrangement carriers present with a certain proportion of unbalanced gametes, which can lead to miscarriages or malformations in the offspring. There is presently no known way to select the balanced spermatozoa and use them for IVF. STUDY DESIGN, SIZE, DURATION: The proportion of unbalanced spermatozoa after DGC was compared with that before DGC in 21 patients with a chromosomal rearrangement. At least 500 spermatozoa were analysed per observation. PARTICIPANTS/MATERIALS, SETTING, METHODS: Twenty-one male patients with a chromosomal rearrangement were included in this prospective study. They initially consulted for infertility, recurrent miscarriages or a history of abnormal pregnancy. The samples were split into two, with one part undergoing DGC and the other being immediately fixed. Fluorescence in situ hybridization was performed to establish the chromosome segregation pattern of each spermatozoon. MAIN RESULTS AND THE ROLE OF CHANCE: DGC significantly decreased the proportion of unbalanced spermatozoa in all but 1 of the 21 chromosomal rearrangement carriers (P < 0.05). LIMITATIONS, REASONS FOR CAUTION: Although DGC reduces the proportion of unbalanced spermatozoa in ejaculates from patients with chromosome rearrangements this elimination is only partial and some abnormal spermatozoa remain. Means to exclude these spermatozoa to ensure that only balanced ones are used in IVF remain to be discovered. The motility and morphology of the sperm before and after DGC were not measured. WIDER IMPLICATIONS OF THE FINDINGS: Used in IVF or intrauterine insemination, DGC could decrease the chance that a man carrying a chromosomal rearrangement will father an abnormal fetus.

Correlation between DNA defect and sperm-head morphology.

The utility of sperm DNA testing remains controversial. However, it may be helpful in couples with unexplained failures of multiple assisted reproductive techniques and/or recurrent abortions. This study analysed 10,400 spermatozoa of 26 patients for sperm-head morphology with high-magnification microscopy, DNA fragmentation and sperm chromatin decondensation. A significant negative correlation was demonstrated between sperm-parameters and abnormal sperm-head morphology as assessed by high magnification (score 0 according to this study's classification): concentration (r=-0.41; P=0.03), motility (r=-0.42; P=0.03), morphology (r=-0.63; P=0.0008). No correlation was found with DNA fragmentation. However, the sperm chromatin-decondensation rate of score-0 spermatozoa was twice as high as the controls (19.5% versus 10.1%; P<0.0001). This observation suggests that score-0 spermatozoa should not be selected for intracytoplasmic sperm injection.

Uterine immune profiling for increasing live birth rate: A one-to-one matched cohort study.

BACKGROUND: Embryo implantation remains the main limiting factor in IVF/ICSI program. Endometrial immune remodeling events begin before implantation and are a vital process for pregnancy, preparing future maternal immune tolerance and regulating the placentation process. METHODS: Between 2012 and 2014, 193 patients (analyzed group) enrolled in our IVF program benefitted of an endometrial immune profiling to determine if their uterus was immunologically ready to accept an embryo and, if not, the specific immune mechanisms involved. Subsequently, they had an effective embryo transfer (ET) with personalization of their treatments if an immune deregulation has been diagnosed. Each analyzed patient was paired to the closest patient included in the IVF program according to biological criteria (age, number of mature oocytes, stage and number of transferred embryo), which had no endometrial immune profiling (193 patients, non-analyzed group). FINDING: 78% of analyzed patients had a uterine immune dysregulation and therefore care personalization. Their corresponding live birth rate (LBR) was twice higher than observed in the matched control group with conventional cares (30.5% versus 16.6%, OR: 2.2 [1.27-3.83] p=0.004) with a simultaneous drastic reduction of miscarriages per initiated pregnancy (17.9% versus 43.2%, OR: 0.29 [0.12-0.71], p=0.005). 22% of analyzed patients had no dysregulation. They did not differ from their matched controls for LBR and miscarriages. CONCLUSION: Uterine immune profiling enables an integrated approach of infertility that includes endometrial immunity as a key factor in planning personalized IVF/ICSI treatments. Personalization of treatment according to the woman's uterine immune balance produced a very significantly higher LBR.

First Birth after Sperm Selection through Discontinuous Gradient Centrifugation and Artificial Insemination from a Chromosomal Translocation Carrier.

Introduction. Balanced chromosomal carriers, though usually healthy, are confronted with recurrent spontaneous abortions and malformations in the offspring. Those are related to the transmission of an abnormal, chromosomally unbalanced genotype. We evidenced that the proportion of unbalanced spermatozoa can be significantly decreased through a sperm preparation process called discontinuous gradient centrifugation (DGC). We therefore started offering intrauterine inseminations with this procedure to couples with a male translocation carriers. Case Presentation. We report the case of a 37-year-old man carrying a t(3;10)(q25;p13) reciprocal translocation. He and his partner had had trouble conceiving for ten years and had four spontaneous abortions. DGC in this patient decreased the proportion of unbalanced spermatozoa from 63.6% to 52.3%. They were therefore offered intrauterine insemination with DGC, which eventually led to the birth of a healthy female child carrying the paternal translocation. Conclusion. We showed that translocation carriers could be offered intrauterine inseminations with DGC. Before this, the only two options were natural conception with prenatal diagnosis and termination of chromosomally unbalanced fetuses or preimplantation genetic diagnosis, which is a much heavier and costly procedure. We are currently offering this option through a multicentric program in France, and this is the first birth originating from it.

Sperm fluorescence in situ hybridization study in nine men carrying a Robertsonian or a reciprocal translocation: relationship between segregation modes and high-magnification sperm morphology examination.

OBJECTIVE: To evaluate whether observation of spermatozoa at × 6,100 magnification can distinguish between those with and without a balanced chromosomal content. DESIGN: Retrospective research study. SETTING: Genetics laboratory of a university hospital and in vitro fertilization center. PATIENT(S): Six men carrying a reciprocal translocation and three men with a Robertsonian translocation. INTERVENTION(S): Sperm fluorescence in situ hybridization (FISH) with a specific set of three probes for each translocation for determining chromosomal content, performed on both unselected spermatozoa and on spermatozoa selected at × 6,100 magnification according to the Cassuto-Barak classification. MAIN OUTCOME MEASURE(S): Chromosomal content in unselected and selected spermatozoa. RESULT(S): Chromosomal translocations lead to gametes carrying either a balanced or an unbalanced karyotype in offspring and consequently to changes in chromosome position within sperm nucleus and potentially in nuclear morphology. In the unselected spermatozoa, the rate of chromosomally balanced nuclei ranged from 37.1% to 52.6% and from 70% to 88.6% in reciprocal and Robertsonian translocations, respectively, which is in agreement with published data. In selected spermatozoa, there was no statistically significant difference between the rates of segregation modes when compared with their frequencies in unselected sperm cells. CONCLUSION(S): The observation of spermatozoa at high-magnification in translocation carriers cannot be used to select sperm cells with a balanced chromosomal content.

A new real-time morphology classification for human spermatozoa: a link for fertilization and improved embryo quality.

OBJECTIVE: To understand the correlation between normalcy of the sperm, fertilization, and early embryo development, and to establish a detailed classification scoring scale for the individual spermatozoon with the highest predictive fertilizing potential in real time during intracytoplasmic sperm injection (ICSI). DESIGN: A retrospective and analysis. SETTING: Laboratory Drouot. PATIENT(S): 27 couples with male factor infertility referred for ICSI treatment. INTERVENTION(S): Before ICSI, motile spermatozoa were scored after aspiration. MAIN OUTCOME MEASURE(S): Oocyte fertilization, embryo development and morphology, outcome of scored motile injected spermatozoa. RESULT(S): Our suggested formula is (Normal head score = 2) + (Lack of vacuole score = 3) + (Normal base score = 1) = (Total score = 6) for a morphologic "normal top" spermatozoon, calculated with the major criteria affecting the outcome of ICSI. We take into account the normalcy of head size and shape, the base of the head, and the lack of vacuoles. Our scoring of three classes of injected spermatozoa revealed a statistically significant difference in fertilization rate: 39 out of 46 (84%), 94 out of 128 (73%), and 27 out of 44 (61%), respectively. Our examination of the contribution of maternal age in correlation to sperm score revealed a distinction between oocytes originating from women younger than 30 years and oocytes from women aged 30 years and older. CONCLUSION(S): Our suggested classification provides allows the best spermatozoon to be chosen for ICSI, particularly for oocytes from women aged 30 years and older.