非侵入胚胎植入前染色體篩檢： 基於胚胎膨脹程度與培養液收集之策略

Abstract

不孕症為高度開發國家面臨到的問題，最根本的原因在於晚婚與晚生育，目前主要是透過人工生殖的方式進行治療，然而挑選合適的胚胎進行植入為最重要的一步。目前最常使用的方式是根據胚胎型態學進行挑選，但是傳統的胚胎學並不能了解胚胎染色體組成，許多研究指出，早期流產很大原因在於染色體的非整倍性。目前篩選胚胎染色體的方式為胎植入前染色體篩檢Preimplantation genetic testing for aneuploidy (PGT-A)，根據滋養外胚層切下來的細胞進行分析，進而推估胚胎的染色體組成，但是切片需要高技術人員操作，以及切片衍生的鑲嵌體問題，還有是否會造成胚胎損傷等問題，都是可能的潛在風險。因此，非侵入性胚胎植入前染色體篩檢Non-invasive preimplantation genetic testing for aneuploidy (niPGT-A)被視為，可以替代PGT-A的方案之一。 本次研究從祈新婦產科診所收集了180顆胚胎進行分析，初步先確定拋棄的胚胎培養液的收集流程，在全基因放大成功率、次世代定序成功率、染色體一致率，有達到近年文獻上的標準，再以此收集流程應用在臨床的實驗流程上，結果發現培養到第五天所收集的胚胎培養液，顯示出較低的全基因放大成功率、次世代定序成功率、染色體一致率，延長培養到第六天後結果有改善。另外我們也根據胚胎的型態學結合一致率進行分析，結果顯示胚胎的膨脹程度與一致率呈現正相關，結論是胚胎的培養時間及胚胎的膨脹程度，會影響到胚胎DNA的釋出。 最後，雖然niPGT-A目前還不能取代傳統PGT-A，但可以當作一個替代方案使用，在反覆PGT-A失敗的個案，可以考慮使用，並相信後續會有更多研究投入，進一步的改善niPGT-A的使用體驗。

Infertility is a significant problem in developed countries, primarily due to late marriage and delayed childbearing. Currently, the main method of treatment is through artificial reproduction, and the most important step is selecting suitable embryos for implantation. The traditional method of selecting embryos base on morphology does not provide information about the embryo chromosomal composition. Many studies have shown that a large proportion of early miscarriages is due to chromosomal aneuploidy. Preimplantation genetic testing for aneuploidy (PGT-A) is currently used to screen embryos for chromosomal abnormalities by analyzing cells from a trophectoderm biopsy (TE). however, TE biopsy requires skilled embryologists and has potential risks, including mosaicism and potential damage to the embryos. Therefore, Non-invasive preimplantation genetic testing for aneuploidy (niPGT-A) is being considered as an alternative to PGT-A. Initially, the process of collecting spent culture medium (SBM) was confirmed to meet recent literature standards in terms of whole genome amplification (WGA) success rate, next-generation sequencing (NGS) success rate, and chromosomal concordance rate. This collection process was then applied to clinical experimental workflow. The results showed that the SBM collected on day 5 of culture had a lower WGA success rate, NGS success rate, and chromosomal concordance rate, and extending the culture to the day 6 showed improvements. Additionally, we analyzed the correlation between embryo morphology and concordance rate. The results indicated a positive correlation between embryo expansion and concordance rate. The conclusion is that the culture time and embryo expansion affect the release of embryonic DNA. Finally, although niPGT-A cannot currently replace traditional PGT-A, it can be used as an alternative. In cases of repeated PGT-A failures, niPGT-A can be considered. It is believed that more research will be invested in the future to further improve niPGT-A.