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One of the greatest challenges in assisted reproduction is to find the one embryo, which can develop successfully. Now, combining time lapse imaging of IVF embryos cultured for 5 days to the blastocyst stage with trophoblast biopsy, it has proved possible to correlate the rate of blastocyst formation with chromosomal abnormalities.
Such an approach should allow early and widely accessible non-invasive identification of the best embryo to place in the uterus.
The majority of embryos that fail to initiate a pregnancy do so because they have abnormal chromosomes. Unfortunately these embryos cannot be recognized by embryologists using conventional microscopy. Only biopsy of one or a few cells of the early embryo followed by preimplantation genetic screening (PGS) can establish whether the number of chromosomes is normal or not.
In their research Alison Campbell and colleagues of CARE Fertility, Nottingham, went one step further, describing the use of morphokinetic analysis to identify those embryos that have an abnormal chromosomal constitution. In that study, they cultured embryos under time lapse imaging to day 5, by which time they formed blastocysts. These were then biopsied by removing a few of the cells from the outer layer of the embryo, which will normally contribute only to the placenta. The biopsy was then analyzed for its chromosomal constitution.
The authors then related the chromosomal make up of each embryo to its morphokinetic history. They found that a proportion of embryos with chromosomal abnormalities were delayed in initiating blastocyst formation and also reached the full blastocyst stage later than did normal embryos. The authors conclude that using this approach they could avoid exposing at least a subset of the embryos to invasive biopsy procedures.
"This non-invasive model for the classification of chromosomal abnormality may be used to avoid selecting embryos with high risk of aneuploidy while selecting those with reduced risk,"
Alison Campbell, lead author
The same group has now applied this risk classification model retrospectively to examine the pregnancy outcomes in a series of unselected IVF patients without the use of PGS. A significant improvement in both implantation and live birth rates was observed when low risk embryos were transferred.
"The idea of using time-lapse imaging and morphokinetic analysis is intriguing, because having available a completely non-invasive procedure to predict which embryo is euploid or aneuploid would allow the application of this technique for virtually every assisted reproduction cycle.
The potential benefit of such an approach is obvious in view of published data on the incidence of aneuploidy even in oocytes from younger women."
Markus Montag ,Scientist, Department of Gynecological Endocrinology and Fertility Disorders, University Clinics of Heidelberg
The research was published in Reproductive BioMedicine Online on May 17, 2013.
"Recently the world of IVF has become very excited by the use of time-lapse imaging (TLI) of early human embryo development to follow the change of embryo morphology over time. The data can then be compared with the outcome after the embryos are transferred. The hope is that this morphokinetic analysis will enable reproductive specialists to predict more successfully those embryos most likely to generate pregnancies. The advantage of using morphokinetic analysis to predict outcome is its minimal invasiveness,"says Martin Johnson, Editor of Reproductive BioMedicine Online
Modelling a risk classification of aneuploidy in human embryos using non-invasive morphokinetics, by Campbell, A., Fishel, S., Bowman, N., Duffy, S., Sedler, M., Hickman, C.F.L.; Reproductive BioMedicine Online; 26, 477- 485;DOI: 10.1016/j.rbmo.2013.02.006. The article appears in Reproductive BioMedicine Online, Volume 26, Issue 5 (May 2013), published by Elsevier. Available online on ScienceDirect.
Retrospective analysis of clinical pregnancy and live birth rate for IVF embryos classified for aneuploidy risk, without PGS, demonstrates the benefit of a time-lapse imaging derived model, by Campbell, A., Fishel, S., Bowman, N., Duffy, S., Sedler, M., Thornton, S.; This article is available as an Article in Press in Reproductive Biomedicine Online (May 17, 2013), published by Elsevier. Available online on ScienceDirect on May 17.
Alison Campbell and Simon Fishel
Alison Campbell, telephone: +44(0)161 2493040, fax: +44(0)1612244283, Alison.email@example.com
Simon Fishel, Simon.firstname.lastname@example.org
About Reproductive Biomedicine Online
Reproductive BioMedicine Online covers the formation, growth and differentiation of the human embryo. It is intended to bring to public attention new research on biological and clinical research on human reproduction and the human embryo including relevant studies on animals. It is published by a group of scientists and clinicians working in these fields of study. Its audience comprises researchers, clinicians, practitioners, academics and patients.
It is an official publication of:
The American Association of Bioanalysts (AAB) http://www.aab.org
Alpha – Scientists in Reproductive Medicine, http://alphascientists.org
The American College of Embryology (ACE) http://www.embcol.org
The Global Chinese Association for Reproductive Medicine (GCARM) http://www.gcarm.com
The International Society for In Vitro Fertilization (ISIVF) http://www.isivf.com
The Mediterranean Society for Reproductive Medicine (MSRM) http://www.medreproduction.org
The Preimplantation Genetic Diagnosis International Society (PGDIS) http://www.pgdis.org
The Turkish Society of Reproductive Medicine (TSRM) http://www.tsrm.org.tr
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Original article: http://www.eurekalert.org/pub_releases/2013-05/e-bfi051613.php