PDF(Pubmed)
Abstract：
The presence of cell-free DNA in spent embryo culture media (SECM) has unveiled its possible utilization for embryonic ploidy determination, opening new frontiers for the development of a non-invasive pre-implantation genetic screening technique. While a growing number of studies have shown a high concordance between genetic screening using cell-free DNA (cfDNA) and trophectoderm (TE), the mechanism pertaining to the release of cfDNA in SECM is largely unknown. This review aims to evaluate research evidence on the origin and possible mechanisms for the liberations of embryonic DNA in SECM, including findings on the self-correction abilities of embryos which might contribute to the presence of cfDNA. Several databases including EMBASE, PUBMED, and SCOPUS were used to retrieve original articles, reviews, and opinion papers. The keywords used for the search were related to the origins and release mechanism of cfDNA. cfDNA in SECM originates from embryonic cells and, at some levels, non-embryonic cells such as maternal DNA and exogenous foreign DNA. The apoptotic pathway has been demonstrated to eliminate aneuploid cells in developing mosaic embryos which might culminate to the release of cfDNA in SECM. Nonetheless, there is a recognized need for exploring other pathways such as cross-talk molecules called extracellular vesicles (EVs) made of small, round bi-layer membranes. During in vitro development, embryos physiologically and actively expel EVs containing not only protein and microRNA but also embryonic DNA, hence, potentially releasing cfDNA of embryonic origin into SECM through EVs.
摘要：
废胚胎培养基（SECM）中无细胞DNA的存在揭示了其可能用于胚胎倍性测定的可能性，为开发非侵入性植入前遗传筛查技术开辟了新的领域。虽然越来越多的研究表明，使用无细胞DNA（cfDNA）和滋养外胚层（TE）进行遗传筛查之间存在高度一致性，与SECM中cfDNA释放有关的机制在很大程度上是未知的。这篇综述旨在评估SECM中胚胎DNA释放的起源和可能机制的研究证据。包括对胚胎的自我校正能力的发现，这可能有助于cfDNA的存在。几个数据库，包括EMBASE，pubmed,和SCOPUS用于检索原始文章，reviews,和意见文件。用于搜索的关键词与cfDNA的起源和释放机制有关。SECM中的cfDNA起源于胚胎细胞，在某些层面,非胚胎细胞，如母体DNA和外源外源DNA。已证明凋亡途径消除了发育中的镶嵌胚胎中的非整倍体细胞，这可能最终导致SECM中cfDNA的释放。尽管如此，有一个公认的需要探索其他途径，如被称为细胞外囊泡（EV）的串扰分子，圆形双层膜。在体外发育过程中，胚胎在生理上积极地排出EV，不仅含有蛋白质和microRNA，而且还含有胚胎DNA，因此，可能通过EV将胚胎起源的cfDNA释放到SECM中。
