【转帖】胚胎筛选新技术可提高试管婴儿成功率

小丫

2013-05-21
* [7 s: s0 ^- p" d' C1 g
. k% {) M) o8 Y: o$ t6 J: h胚胎异常是体外受精最终失败的主要原因之一。英国研究人员开发出一种可筛查胚胎质量的新技术，有望提高试管婴儿的成功率。

! z7 E; k/ ]# M" [; D5 ~/ K英国《生殖生物医学在线》杂志刊登这项新成果说，胚胎出现非整倍性变异（即染色体数目错误）等，是体外受精和胚胎移植后最终流产或产下不健康婴儿的重要原因。一家名为“卡利生育组织”的机构发现，这种问题胚胎在早期发育时有两个节点会表现出异常，即从致密期胚胎形成微小的囊，以及囊开始充满液体两个阶段。

% B1 v5 I$ y. w( Q( \研究人员根据这一特性，开发出一套为胚胎健康程度评级的计算机程序，可将早期胚胎染色体异常的风险分为三等。研究人员在实验中评估了88个胚胎的健康风险，结果在被评为“健康风险低”的一组中，有61%最终产下健康婴儿，而被评为高风险的一组则全部失败。
研究人员说，此前只能在体外受精开始后通过细胞数量和形状来判断胚胎的健康程度，而新技术通过对胚胎质量的早期筛查，有望将体外受精并成功生育的概率提高至约78%，成功率比当前同类辅助生育技术高约3倍。（来源：新华社 刘石磊）
# o& _- o+ Z3 @& f
6 w1 ?. v* f& j; G( h! eRetrospective analysis of outcomes after IVF using an aneuploidy risk model derived from time-lapse imaging without PGS
: h4 L# \- {5 f) @# {
- Y8 D6 }2 {- N. O5 L. CTime-lapse imaging of human preimplantation IVF embryos has enabled objective algorithms based on novel observations of development (morphokinetics) to be used for clinical selection of embryos. Embryo aneuploidy, a major cause of IVF failure, has been correlated with specific morphokinetic variables used previously to develop an aneuploidy risk classification model. The purpose of this study was to evaluate the effectiveness and potential impact of this model for unselected IVF patients without biopsy and preimplantation genetic screening (PGS). Embryo outcomes – no implantation, fetal heart beat (FHB) and live birth (LB) – of 88 transferred blastocysts were compared according to calculated aneuploidy risk classes (low, medium, high). A significant difference was seen for FHB (P<0.0001) and LB (P<0.01) rates between embryos classified as low and medium risk. Within the low-risk class, relative increases of 74% and 56%, compared with rates for all blastocysts, were observed for FHB and LB respectively. The area under the receiver operating characteristic curve was 0.75 for FHB and 0.74 for LB. This study demonstrates the clinical relevance of the aneuploidy risk classification model and introduces a novel, non-invasive method of embryo selection to yield higher implantation and live birth rates without PGS. The largest single cause of failure of the human embryo to implant, and of early miscarriage, is aneuploidy (errors in numbers of chromosomes of the early (preimplantation) human embryo). More than half of human embryos are believed to be affected by aneuploidy and many must be unwittingly transferred following IVF, resulting in failed implantation, miscarriage or the birth of a baby with a related disorder. It is not possible for embryologists in IVF laboratories to identify aneuploid embryos under the microscope; however, our studies with time-lapse incubation in conjunction with preimplantation genetic screening (PGS) of IVF embryos have allowed us to develop and publish a model that rates each embryo based on its developmental patterns (morphokinetics) as being at low, medium or high risk of aneuploidy. PGS, whilst very effective, requires expensive technology and expertise, is not widely available and requires the embryo to undergo biopsy (removal of cell(s)). In this study, we tested the aneuploidy risk classification model on embryos with a known outcome and, importantly, on those embryos resulting in a live birth. This demonstrated how the model has the potential to greatly enhance IVF outcome without biopsy and PGS. By using such unique, non-invasive and specifically designed embryo selection models, we can now make more informed choices in order to select the most viable embryo to transfer, with the lowest risk of aneuploidy. Selection of an embryo classified as low risk has improved the relative chance of a live birth by 56% over conventional embryo selection.