Analysis of mtDNA variant segregation during early human embryonic development: a tool for successful NARP preimplantation diagnosis.

BACKGROUND: Diseases arising from mitochondrial DNA (mtDNA) mutations are usually serious pleiotropic disorders with maternal inheritance. Owing to the high recurrence risk in the progeny of carrier females, "at-risk" couples often ask for prenatal diagnosis. However, reliability of such practices remains under debate. Preimplantation diagnosis (PGD), a theoretical alternative to conventional prenatal diagnosis, requires that the mutant load measured in a single cell from an eight cell embryo accurately reflects the overall heteroplasmy of the whole embryo, but this is not known to be the case. OBJECTIVE: To investigate the segregation of an mtDNA length polymorphism in blastomeres of 15 control embryos from four unrelated couples, the NARP mutation in blastomeres of three embryos from a carrier of this mutation. RESULTS: Variability of the mtDNA polymorphism heteroplasmy among blastomeres from each embryo was limited, ranging from zero to 19%, with a mean of 7%. PGD for the neurogenic ataxia retinitis pigmentosa (NARP) mtDNA mutation (8993T-->G) was therefore carried out in the carrier mother of an affected child. One of three embryos was shown to carry 100% of mutant mtDNA species while the remaining two were mutation-free. These two embryos were transferred, resulting in a singleton pregnancy with delivery of a healthy child. CONCLUSIONS: This PGD, the first reported for a mtDNA mutation, illustrates the skewed meiotic segregation of the NARP mtDNA mutation in early human development. However, discrepancies between the segregation patterns of the NARP mutation and the HV2 polymorphism indicate that a particular mtDNA nucleotide variant might differentially influenced the mtDNA segregation, precluding any assumption on feasibility of PGD for other mtDNA mutations.

[The follicular flushing duplicate the pregnancy rate on semi natural cycle IVF]. / Le rinçage folliculaire lors des prélèvements ovocytaires double le taux de grossesses en fécondation in vitro en cycle semi-naturel.

OBJECTIVE: To evaluate the importance of follicular flushing on semi natural cycle IVF. MATERIAL AND METHODS: We have compared prospectively the reproductive potential of oocytes obtained from follicular fluid (LF, N = 79) to those obtained from follicular flushing (R, N = 47) in 146 oocyte pick ups. RESULTS: The group LF and R were similar with regard to fertilization rate (79.7 versus 88.1%, respectively), percentage of superior grade embryos (28.8 versus 37.8%) and implantation rate (24.1 versus 44.1%). CONCLUSION: The practice of follicular flushing on semi natural IVF cycle improves the pregnancy rate. The oocytes obtained by follicular flushing had the same reproductive potential than those obtained on follicular fluid.

[Preimplantation genetic diagnosis (PGD): results from a Parisian center]. / Indications et résultats du diagnostic pré-implantatoire (DPI).

OBJECTIVE: To report the results of preimplantation genetic diagnosis (PGD) cycles performed in our unit from 2000 to 2004. Materials and methods. One hundred and seventy-one couples were enrolled in the PGD program over this period. The collected oocytes were inseminated by intracytoplasmic sperm injection (ICSI). The resulting embryos were biopsied on the third day of development and the genetic analysis was performed on the same day. Embryo transfers were carried out on the fourth day. RESULTS: The 416 stimulation cycles started yielded 280 oocyte pick-ups, 3506 oocytes retrieved, of which 2966 were suitable for ICSI. Among the 1982 embryos obtained, 1337 embryos were biopsied and genetic diagnosis was performed for 1083 (81%) of them. 381 embryos were transferred during the course of 189 transfer procedures. There were 51 clinical and 46 ongoing (35 single, 11 twin) pregnancies. In addition, 25 frozen embryo replacement cycles were initiated, leading to 6 embryo transfers and 1 ongoing pregnancy. A total of 58 unaffected children were born. CONCLUSION: PGD has gained a place among the choices offered to couples at risk of transmission of a serious and incurable genetic disease. It might be a realistic alternative to prenatal diagnosis for patients carrier of chromosomal rearrangements, single gene defects, X-linked disesases or mitochondrial DNA disorders.

[Extending preimplantation genetic diagnosis to HLA typing: the Paris experience]. / Le diagnostic préimplantatoire couplé au typage HLA: l'expérience parisienne.

Preimplantation genetic diagnosis (PGD) consists in the genetic analysis of one or two cells. These cells (blastomeres) are sampled from embryos, obtained by in vitro fertilization, at the third day of development. Since 1998, the bioethical laws (1994) and their decrees restricted PGD practices in France, strictly to the avoidance of the birth of a child affected with a genetic defect. In parallel, works on blood cord transplantation, taken at the birth of a compatible HLA sibling, showed very encouraging results, particularly for the treatment of Fanconi anemia. In 2001, Verlinsky et al., have reported the first PGD for Fanconi anaemia combined with HLA typing, allowing the birth of a healthy child, HLA-identical with his affected sister. The "designer baby" concept was born. The French law, which allowed PGD under specific conditions, i.e. when the genetic defect has been characterized in one parent at least, recently extended PGD to HLA typing when embryos are at risk of a genetic disorder. Article L.2131-4-1 (August 2004) allows the practice of HLA typing for PGD embryos when an elder sibling is affected with a genetic disorder and need stem cell transplantation. The HLA-matched offspring resulting from PGD can give cord blood at birth to supply the necessary therapy. This double selection give rise to serious ethical problems, but technical difficulties and legal restrictions will probably limit the development of such a procedure.

A dynamic in vivo model of epithelial-to-mesenchymal transitions in circulating tumor cells and metastases of breast cancer.

Epithelial-to-mesenchymal transition (EMT) processes endow epithelial cells with enhanced migratory/invasive properties and are therefore likely to contribute to tumor invasion and metastatic spread. Because of the difficulty in following EMT processes in human tumors, we have developed and characterized an animal model with transplantable human breast tumor cells (MDA-MB-468) uniquely showing spontaneous EMT events to occur. Using vimentin as a marker of EMT, heterogeneity was revealed in the primary MDA-MB-468 xenografts with vimentin-negative and vimentin-positive areas, as also observed on clinical human invasive breast tumor specimens. Reverse transcriptase-PCR after microdissection of these populations from the xenografts revealed EMT traits in the vimentin-positive zones characterized by enhanced 'mesenchymal gene' expression (Snail, Slug and fibroblast-specific protein-1) and diminished expression of epithelial molecules (E-cadherin, ZO-3 and JAM-A). Circulating tumor cells (CTCs) were detected in the blood as soon as 8 days after s.c. injection, and lung metastases developed in all animals injected as examined by in vivo imaging analyses and histology. High levels of vimentin RNA were detected in CTCs by reverse transcriptase-quantitative PCR as well as, to a lesser extent, Snail and Slug RNA. Von Willebrand Factor/vimentin double immunostainings further showed that tumor cells in vascular tumoral emboli all expressed vimentin. Tumoral emboli in the lungs also expressed vimentin whereas macrometastases displayed heterogenous vimentin expression, as seen in the primary xenografts. In conclusion, our data uniquely demonstrate in an in vivo context that EMT occurs in the primary tumors, and associates with an enhanced ability to intravasate and generate CTCs. They further suggest that mesenchymal-to-epithelial phenomena occur in secondary organs, facilitating the metastatic growth.

[Non-obstructive azoospermia: option of the testicular sperm extraction performed on the day of oocyte retrieval]. / Azoospermie non obstructive: intérêt du prélèvement testiculaire synchrone du recueil ovocytaire.

OBJECTIVE: Analyzing the results and validating the procedure of testicular sperm extraction (TESE) performed on the day of oocyte retrieval in non obstructive azoospermia (NOA) patients. PATIENTS AND METHODS: Sixty TESE were performed on the day of oocyte retrieval (dOR), in 52 NOA men. Patients were sorted into three groups according to the results of the surgical procedure: 1: sperm recovery with possible sperm freezing (n=20); 2: sperm recovery without freezing (n=27); 3: "negative" biopsy (n=13). ICSI outcomes in the two groups with sperm recovery were compared to those of ICSI performed with frozen-thawed sperm obtained from TESE performed (n=13). RESULTS: The rate of positive sperm retrieval was 78%. While the overall clinical pregnancy rate was 50%, no difference in the fertilization, implantation and clinical pregnancy rates was found in the two groups with positive sperm retrieval as compared to frozen-thawed sperm group. Twelve pregnancies were obtained in patients without further sperm cryopreservation. CONCLUSION: After TESE in NOA men, cryopreserved sperm produced comparable results with freshly obtained sperm. However, TESE performed on dOR can offer the opportunity, in patients with rare sperm that might not survive freeze-thaw, to have a possible fresh embryo transfer. Couples should be counselled regarding the possibility of oocyte retrieval without sperm for ICSI.

Myotonic dystrophy: does it affect ovarian follicular status and responsiveness to controlled ovarian stimulation?

BACKGROUND: Myotonic dystrophy (MD) is characterized by myotonia, multisystemic lesions and hypogonadism. In women, the relationship between MD and infertility remains controversial. This study investigated the ovarian status and response to controlled ovarian stimulation (COS) in MD women entering our preimplantation genetic diagnosis programme. METHODS: We elected to compare MD patients with X-linked disorders (XLD) carriers, given that XLD have not been shown to affect ovarian status. On the one hand, we analysed all the cycles performed and, on the other hand, we conducted a subanalysis based on only first cycles. RESULTS: MD and XLD groups were similar with regard to women's ages, day 3 parameters, number of oocytes retrieved, embryos obtained and prevalence of top quality embryos. The day of HCG was significantly delayed and the prevalence of poor quality embryos was higher in the MD group. The subanalysis on first cycles only also showed significantly fewer mature follicles on the day of HCG in MD population. Implantation and pregnancy rates were similar in both groups; however, no pregnancy occurred at the first cycle in MD (0 out of 4), whereas 77% of pregnancies (10/13) occurred at the first attempt in XLD carriers. CONCLUSIONS: These results indicate that the responsiveness to COS was moderately hindered in MD women as compared to controls. Reassuring data about implantation and pregnancy rates support the feasibility of PGD in selected mildly affected MD women.

A randomized double-blind controlled study on the efficacy of laser zona pellucida thinning on live birth rates in cases of advanced female age.

BACKGROUND: It is conceivable that defective embryo hatching plays a part in the mechanisms involved in the decrease of embryo implantation rates with advancing age. In an effort to test this hypothesis, we tested the effectiveness of assisted hatching (AH) in women > or =37 years of age. METHODS: We prospectively studied 103 IVF-embryo transfer patients undergoing 103 embryo transfers. All of them were > or =37 years of age and had <3 previous IVF-embryo transfer attempts. Laser-AH of transferred embryos was either performed (AH group, n = 49) or not (control group, n = 54) according to randomized and double-blind methodology. Primary outcome was live birth rate. RESULTS: Population characteristics were comparable in AH and control groups as well as the mean number of embryos transferred (2.7 +/- 0.6 versus 2.7 +/- 0.6) and the prevalence of top quality embryos transferred (65 versus 59%, respectively). We failed to find any statistically significant difference between AH and control groups with regard to implantation (16.1 versus 16.7%, respectively) and live birth rates (22.4 versus 29.6%, respectively). CONCLUSION: The present study indicates that AH does not improve IVF-embryo transfer outcome in women aged > or =37 years.

Multiple displacement amplification improves PGD for fragile X syndrome.

We report an improvement in the PGD test for fragile X syndrome (FXS). Recently, multiple displacement amplification (MDA) has been reported to yield large amounts of DNA from single cells. Taking into account this technique, we developed a new PGD test for FXS, enabling combined analysis of linked polymorphic markers with the study of the non-expanded CGG repeat. Single cell amplification efficiency was first assessed on single lymphocytes. Amplification rate of the different markers ranged from 85 to 95% with an allele drop-out (ADO) rate comprised between 7 and 34%. Using this test, eight PGD cycles were carried out for six couples, and 37 embryos were analysed after preliminary MDA. Amplification rate was increased by this technique from 41 to 66% so that embryos with no results were rarer (14 versus 45% without MDA). Reliability of the test was considerably improved by combining direct with indirect genetic analysis. Furthermore, in cases of fully expanded alleles too large to be amplified by PCR, this test gives an internal amplification control. Embryonic transfers were carried out in all but one PGD cycles. One biochemical and one clinical pregnancy resulted, and a healthy child was born. This single diagnosis procedure could be suitable to most patients carrying FXS.