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Biomedical subjects

Santiago Munné

Publications and source records attributed to Santiago Munné.

At least 19 recordsLinked to original sources
PubMed2006

Removal of 2 cells from cleavage stage embryos is likely to reduce the efficacy of chromosomal tests that are used to enhance implantation rates.

OBJECTIVE: To evaluate whether differences in results between studies that involve preimplantation genetic diagnosis for chromosome testing are affected by technology, such as the number of cells to be biopsied or by differences in study design. DESIGN: Evaluation of studies of aneuploidy testing according to the use of probes, fixation technology, error determination, and number of cells per embryo analyzed. SETTING: Preimplantation genetic diagnosis laboratories. PATIENT(S): Patients in published studies who underwent preimplantation genetic diagnosis for infertility or repeated pregnancy loss. INTERVENTION(S): As determined by each evaluated study, the number of biopsied cells and its effect on further development was evaluated by a comparison of models of embryo freezing and partial cell loss. MAIN OUTCOME MEASURE(S): Use of probes, fixation strategy, number of biopsied cells, and error rate determination of different published studies. RESULT(S): Differences in results between studies can be explained by the technology used and are not affected necessarily by differences in design and patient allocation. CONCLUSION(S): Studies that contradict the finding that aneuploidy screening improves implantation and lowers miscarriage rates all have > or =1 of the following aspects in common: (I) an excess of cells having been removed; (II) inadequate choice of probes; and (III) suboptimal fixation technology.

Abortion, Spontaneous↗
PubMed2006

Preimplantation genetic diagnosis significantly reduces pregnancy loss in infertile couples: a multicenter study.

OBJECTIVE: The inicidence of miscarriage is correlated with maternal age. The majority of miscarriages are chromosomally abnormal. The purpose of this study was to determine in a large population of infertility patients (>2000 cycles) if preimplantation genetic diagnosis (PGD) reduced the rate of spontaneous abortions. DESIGN: Multicenter retrospective controlled study. SETTING: One hundred IVF centers referring samples to a reference PGD laboratory. PATIENT(S): Infertile women. INTERVENTION(S): The spontaneous abortion rate after PGD was retrospectively compared to non-PGD cycles from the 2002 American Society for Reproductive Medicine-Society for Assisted Reproduction Technology report on IVF cycles. MAIN OUTCOME MEASURE(S): Spontaneous abortions and trisomic offspring rates. RESULT(S): The study included 2,279 cycles of PGD. The pregnancy rate per retrieval was 26.7% (average age 39.6). The mean pregnancy loss for the PGD group (0.167) was significantly lower than for the general IVF group (0.215) (P<.001). After PGD, the spontaneous abortion rate was 14.1% for ages 35-40, and 22.2% for women over 40, compared to 19.4% (P=.03) and 40.6% (P<.001), respectively, in controls. The clinical error rate of PGD (1.2%) was significantly lower than expected (4.7%) (P<.001). CONCLUSION(S): The data suggests that PGD significantly reduces the risk of spontaneous abortions in women undergoing IVF and PGD, particularly in women over 40. In addition, PGD may also reduce the risk of trisomic offspring.

Abortion, Spontaneous↗
PubMed2006

Cryopreservation of unfertilized human oocytes.

Previous investigations revealed that choline-based freezing media developed in our laboratory were superior to conventional sodium-based media for storing mouse oocytes. This paper examines the ability of the choline-based medium CJ2 and a modified form of this medium, CJ3, to cryopreserve unfertilized human oocytes. Oocytes that were consented for research and matured overnight, as well as freshly collected, donor, mature metaphase II (MII) oocytes, were cryopreserved using choline-based media and an optimized slow-cooling protocol. The results showed higher survival and fertilization rates when CJ3 supplemented with 0.2 mmol/l sucrose was used as compared with CJ2 supplemented with either 0.1 mmol/l or 0.2 mmol/l sucrose. Freshly collected oocytes were more difficult to cryopreserve than those matured in vitro. Modification of the base medium proved to be one of the key factors in obtaining survival rates over 90%. Fertilization rates, embryo development, and genetic analysis of embryos resulting from control and frozen-thawed oocytes are provided. There appears to be a high correlation between chromosomal anomalies and abnormal morphology in embryos from thawed oocytes.

Choline↗
PubMed2006

Chromosome abnormalities and their relationship to morphology and development of human embryos.

This review covers the relationship between chromosome abnormalities, morphological abnormalities and embryonic development. The baseline of chromosome abnormalities in human embryos produced by assisted reproduction is higher than 50%, regardless of maternal age. While aneuploidy increases with maternal age, abnormalities arising post-meiotically, such as mosaicism, chaoticism, polyploidy and haploidy, have similar incidence in all age groups (about 33%). Post-meiotic abnormalities do increase with dysmorphism. The most common dysmorphisms found in cleavage-stage embryos are multinucleation, fragmentation and uneven cells, among others. All dysmorphisms are associated with an increase in post-meiotic chromosome abnormalities and a decreased implantation potential. Similarly, embryos developing slowly or with arrested development have higher incidence of post-meiotic abnormalities than normally developing ones. Chromosome studies in blastocysts indicate that mosaicism is the most common abnormality but that the load of abnormal cells decreases with increasing blastocyst quality. Regardless of blastocyst quality, more than 40% of mosaics are still chromosomally abnormal and will not implant or will spontaneously abort. Because aneuploidy is not related to cleavage stage dysmorphism and trisomies can reach blastocyst stage and beyond, morphological analysis is not enough to select against chromosome abnormalities, and thus preimplantation genetic diagnosis should be recommended in patients 35 and older.

Adult↗
PubMed2006

Preimplantation genetic diagnosis significantly improves the pregnancy outcome of translocation carriers with a history of recurrent miscarriage and unsuccessful pregnancies.

Preimplantation genetic diagnosis (PGD) for translocations has been shown to significantly reduce the risk of recurrent miscarriage, but because the majority of embryos produced are unbalanced, pregnancy rate is relatively low since 20% or more cycles have no normal or balanced embryos to transfer. The purpose of this study was to evaluate whether PGD could improve pregnancy outcome in translocation carriers with a history of two or more consecutive miscarriages and no live births. PGD for translocations was offered to translocation carriers with two or more previous miscarriages (average 3.5) and no live births (0/117 pregnancies) using a combination of distal and proximal probes to the breakpoints. After PGD, only 18.3% of embryos were normal or balanced. Only 5.3% of pregnancies were lost after PGD compared with 100% before PGD (P < 0.001). The cumulative pregnancy rate was 57.6% and the cumulative ongoing pregnancy rate was 54.5% in the short period of time of 1.24 IVF cycles, or 46.3% and 43.9% respectively per cycle. In conclusion, PGD significantly reduced losses and increased the number of viable pregnancies (P < 0.001). IVF plus PGD are a faster method of conceiving a live child than natural conception, at least for translocation carriers with recurrent miscarriages and no previous live births.

Abortion, Habitual↗
PubMed2005

Preimplantation genetic diagnosis reduces pregnancy loss in women aged 35 years and older with a history of recurrent miscarriages.

OBJECTIVE: To determine whether preimplantation genetic diagnosis (PGD) and transfer of euploid embryos would decrease spontaneous abortion rates in recurrent miscarriage (RM) patients. DESIGN: Controlled clinical study. SETTING: In vitro fertilization centers and PGD reference laboratory. PATIENT(S): Recurrent-miscarriage patients with three or more prior lost pregnancies with no known etiology. INTERVENTION(S): Biopsy of a single blastomere from each day 3 embryo, followed by fluorescence in situ hybridization analysis. MAIN OUTCOME MEASURE(S): The rate of spontaneous abortions in RM subjects undergoing PGD were compared with [1] their own a priori expectations and [2] a comparison group of women undergoing PGD for advanced maternal age (> or =35 years). RESULT(S): Before PGD, RM patients had lost 87% (262/301) of their pregnancies, with an expected loss rate of 36.5%. After, they only lost 16.7% pregnancies. This difference was mostly due to reduction in pregnancy loss in the > or =35-years age subgroup, to 12% from an expected 44.5%. CONCLUSION(S): Preimplantation genetic diagnosis aneuploidy screening has a beneficial effect on pregnancy outcome in RM couples, especially those in which the woman is aged > or =35 years. Our data indicate that PGD reduces the risk of miscarriage in RM patients to baseline levels.

Abortion, Habitual↗
PubMed2005

Self-correction of chromosomally abnormal embryos in culture and implications for stem cell production.

OBJECTIVE: To ascertain whether embryos classified by preimplantation genetic diagnosis (PGD) for infertility as abnormal and then plated to obtain stem cells would self-correct partially or totally in culture, producing disomic stem cells. DESIGN: Prospective study to determine the chromosome status of embryos on day 3 and 6, as well as cultured cells derived from inner cell masses from the same embryos when cultured up to day 12. SETTING: Research laboratory. PATIENT(S): Patients undergoing PGD of aneuploidy. INTERVENTION(S): Of 142 embryos classified by PGD for aneuploidy as abnormal, 50 were cultured to the blastocyst stage. At that stage a fraction of the embryos underwent trophectoderm biopsy to reconfirm the PGD diagnosis. After further co-culture with feeders up to day 12, 34 embryos attached to the feeder cells. Of those, 24 were analyzed by fluorescence in situ hybridization (FISH) and the rest for the expression of Oct-4, SSEA-3, SSEA-4, TRA1-60, and TRA1-80. MAIN OUTCOME MEASURE(S): Disomic cells obtained from trisomic embryos. RESULT(S): Analysis by FISH of day-12 cultures showed that 7 were totally normal, 6 were mostly abnormal, and 11 had experienced some chromosome normalization, having between 21% and 88% normal cells. Day-12 culture was positive for Oct-4 expression by reverse transcriptase polymerase chain reaction analysis and for SSEA-3, SSEA-4, TRA1-60, and TRA1-80 by immunocytochemistry. CONCLUSION(S): Chromosome self-normalization occurs in a significant proportion of chromosomally abnormal embryos, possibly because of the loss of a chromosome in trisomic cells after blastocyst stage. Thus chromosomally abnormal embryos are a potential source of disomic stem cells. Not all chromosomally abnormal embryos self-corrected. Abnormal stem cells that might be derived could be used as models to study the effect of chromosomal abnormalities on human development.

Chromosome Aberrations↗
PubMed2005

Genetic testing of embryos: a critical need for data.

Preimplantation genetic diagnosis (PGD), the genetic testing of embryos developed through IVF is one of the fastest growing techniques in reproductive medicine and IVF. Some suggest that PGD will become part of every IVF cycle in the future. The growing popularity of PGD has highlighted the fact that there are no comprehensive data available about the use of PGD, its accuracy, or the health outcomes of babies born following PGD. For patients, practitioners, and policymakers alike, such information is critical. To address the gaps in knowledge, a working group of the leading experts in the development and practice of PGD and IVF has begun to design a database to collect information about PGD as practised in the United States.

Databases, Factual↗
PubMed2005

Cryopreservation of biopsied cleavage stage human embryos.

The aim was to develop a method to optimize cryopreservation of biopsied multi-celled human embryos. Human day 3 embryos that were donated to research, along with those found to be chromosomally abnormal after blastomere biopsy and fluorescence in-situ hyridization (FISH), were cryopreserved using a slow-freezing protocol in either standard embryo cryopreservation solution [embryo transfer freezing medium (ETFM), a conventional sodium-based medium] or CJ3 (a choline-based, sodium-free medium). After thawing, the number of intact cells was recorded and the previously biopsied embryos were re-analysed using FISH. Biopsied embryos had a lower proportion of intact blastomeres after cryopreservation as compared with intact embryos. However, a significantly (P < 0.05) higher proportion of blastomeres from intact and biopsied embryos cryopreserved in CJ3 (84.1 and 80.1% respectively) survived after thaw than those in ETFM (73.6 and 50.5% respectively). The proportion of aneuploid and mosaic embryos was not statistically different between the two groups. In addition, the frequency of lost cells by aneuploid and mosaic embryos was similar. This study describes a new method that improves the survival of cryopreserved biopsied embryos, and shows that it may also be beneficial for the storage of intact human multi-celled embryos.

Biopsy↗
PubMed2005

Negligible interchromosomal effect in embryos of Robertsonian translocation carriers.

It has been suggested that translocations, and perhaps other chromosome rearrangements, disturb meiotic disjunction of chromosome pairs not involved in the translocation, resulting in non-disjunction in those chromosomes (interchromosomal effect) and predisposition to trisomy offspring. Other reports have suggested an increased risk of mosaicism and chaotic embryos in translocation carriers. This study was designed to determine if such interchromosomal effects are producing significantly more chromosome abnormalities than those expected from unbalanced gametes. For that purpose, two groups of PGD patients were compared, Robertsonian translocation carriers (RBT) and carriers of X-linked diseases (XLI), of similar age. Both groups were analysed by FISH with similar DNA probes. The results indicate that overall, the higher rate of chromosome abnormalities in the RBT group was solely due to unbalanced gametes and not to an interchromosomal effect or higher incidence of mosaicism. If unbalanced and normal were combined, this proportion was 53% in XLI and 59% in RBT. However, when specific RBT translocations were studied, only a slight increase in embryos with aneuploidy for chromosome 22 was found for the t(13;14) translocation carriers, while a higher rate of post-zygotic abnormalities was observed in the more rare RBT. In conclusion, the overall rate of non-translocation related abnormalities was not increased in the RBT group compared with the control group, but a slight interchromosomal effect may exist, as some Robertsonian translocations may be more prone to produce mosaic and chaotic embryos.

Adult↗
PubMed2005

Fluorescence in situ hybridization and spectral imaging analysis of human oocytes and first polar bodies.

We investigated the frequencies of abnormalities involving either chromosome 1, 16, 18, or 21 in failed-fertilized human oocytes. Although abnormalities involving chromosome 16 showed an age-dependent increase, results for the other chromosomes did not show statistically significant differences among the three age groups, <35 years, 35-39 years, and >39 years. The scoring of four chromosomes is likely to underestimate the true rate of aneuploid cells. Therefore, for a pilot study investigating a more-comprehensive analysis of oocytes and their corresponding first polar bodies, we developed a novel eight-probe chromosome enumeration scheme using fluorescence in situ hybridization and spectral imaging analysis.

Adult↗
PubMed2005

Nonviable human pre-implantation embryos as a source of stem cells for research and potential therapy.

Human embryonic stem cells are derived from the inner cell mass of the human blastocyst. Presumably normal (frozen/thawed) human preimplantation embryos that remain unused following assisted reproduction procedures have provided the main source of blastocysts for stem cell derivation. Alternatively, embryos have been generated from gametes donated for the unique purpose of in vitro fertilization, blastocyst culture, and stem cell isolation. This article describes two previously published methods--and the background to those methods--that allow the use of nonviable embryos excluded from transfer and cryopreservation as a source of stem cells. The first method is based on the observation that some blastomeres from embryos with abnormal division during the first 3-5 d in culture can continue very limited development in isolation. When aggregated in a chimaeric form, some of these blastomeres can contribute to the formation of normally organized blastocysts. Blastocysts so obtained provide a route to embryonic stem cells from otherwise nonviable embryos. Thus the inner cell masses of blastocysts obtained from trisomic embryos were placed on feeder cells and cultured for seven additional days, following which the resulting cell colonies were examined for chromosome content. The second method concerns embryos diagnosed with specific chromosome abnormalities many of which are incompatible with life. Some of these aneuploidies do not preclude development to the blastocyst stage in culture. A proportion of these cells were found to be disomic and the cultures were shown to express OCT-4, a molecular marker for pluripotent cells. This apparent correction of the trisomic state in some cells within the colonies suggests that embryos with cromosomal abnormalities incompatible with life may be another source of human embryonic stem cells.

Antigens, Differentiation↗
PubMed2004

Reliability of comparative genomic hybridization to detect chromosome abnormalities in first polar bodies and metaphase II oocytes.

BACKGROUND: Preimplantation Genetic Diagnosis (PGD) using FISH to analyze up to nine chromosomes to discard chromosomally abnormal embryos has resulted in an increase of pregnancy rates in certain groups of patients. However, the number of chromosomes that can be analyzed is a clear limitation. We evaluate the reliability of using comparative genomic hybridization (CGH) to detect the whole set of chromosomes, as an alternative to PGD using FISH. METHODS AND RESULTS: We have analysed by CGH both, first polar bodies (1PBs) and metaphase II (MII) oocytes from 30 oocytes donated by 24 women. The aneuploidy rate was 48%. Considering two maternal age groups, a higher number of chromosome abnormalities were detected in the older group of oocytes (23% versus 75%, P < 0.02). About 33% of the 1PB-MII oocyte doublets diagnosed as aneuploid by CGH would have been misdiagnosed as normal if FISH with nine chromosome probes had been used. CONCLUSION: We demonstrate the reliability of 1PB analysis by CGH, to detect almost any chromosome abnormality in oocytes as well as unbalanced segregations of maternal translocations in a time frame compatible with regular in vitro fertilization (IVF). The selection of euploid oocytes could help to increase implantation and pregnancy rates of patients undergoing IVF treatment.

Adult↗
PubMed2004

PGD analysis for aneuploidy in a patient heterozygous for a polymorphism of chromosome 16 (16qh-).

OBJECTIVES: Detection and study of a polymorphism of chromosome 16qh in preimplantational embryos as well as in peripheral blood from the carrier. METHODS: A polymorphism of chromosome 16 (16qh-) was detected in PGD analysis for aneuploidy using a probe for the centromeric region of chromosome 16. The lack of pericentromeric heterochromatin in one of the chromosomes 16 could lead to misdiagnosis in PGD. PGD analysis using telomeric probes for this chromosome was performed to confirm the polymorphism as well as to avoid misdiagnosis in embryo blastomeres. FISH in lymphocyte metaphases was used to detect the carrier. RESULTS: Telomeric probes allowed detection of a polymorphism for the centromeric region of chromosome 16. FISH with centromeric and telomeric probes in lymphocyte metaphases of the parents showed that the patient was the carrier of the polymorphism. CONCLUSION: It is highly recommended that telomeric probes for chromosome 16 be used in preimplantation genetic diagnosis when a high frequency of monosomy for chromosome 16 is observed after regular aneuploidy analysis.

Adult↗
PubMed2004

Increased rate of aneuploid embryos in young women with previous aneuploid conceptions.

OBJECTIVES: To determine whether a history of a previous aneuploid conception increases the rate of aneuploidy among women having preimplantation diagnosis (PGD). METHODS: Preimplantation embryos were tested for aneuploidy using FISH probes specific for chromosomes 13,15,16,17,18,21,22,X and Y. Using logistic regression to control for maternal age, we compared the rates of aneuploidy and other chromosome errors in 344 embryos from women having PGD because of a history of a previous aneuploid conception, 363 embryos from 42 women having PGD because of X-linked disorders and 1158 embryos from 135 women having PGD because of repeated in vitro fertilization failure. RESULTS: The frequency of aneuploidy differed significantly among patient groups for women younger than 35 (p = 0.003) but not for women older than 35. In women < 35, the rate of detected aneuploidy was 37.4% in the Aneuploid group, 20.9% in the X-linked group and 27.0% in the RIF group. (p = 0.0003 when the control groups are combined). The frequency of other chromosome abnormalities, as well as pregnancy and implantation rates, did not differ significantly among patient groups. CONCLUSIONS: This study suggests that a history of a trisomic pregnancy, whether or not it was a viable trisomy, is associated with an increased risk of another aneuploid conception at conception.

Adult↗