Selection of viable <i>in vitro</i>-fertilized bovine embryos using time-lapse monitoring in microwell culture dishes

Abstract

Conventionally, in vitro-fertilized (IVF) bovine embryos for transfer are morphologically evaluated at day 7–8 of embryo culture. This method is, however, subjective and results in unreliable selection. We previously described a novel selection system for IVF bovine blastocysts for transfer that traces the development of individual embryos with time-lapse monitoring in our specially developed microwell culture dishes (LinKID micro25). The system can noninvasively identify prognostic factors that reflect viability after transfer. By assessing a combination of identified prognostic factors —timing of the first cleavage; number of blastomeres at the end of the first cleavage; and number of blastomeres at the onset of lag-phase, which results in temporary developmental arrest during the fourth or fifth cell cycle— the pregnancy rate was improved over using conventional morphological evaluation. Time-lapse monitoring with LinKID micro25 could facilitate objective and reliable selection of healthy IVF bovine embryos. Here, we review the novel bovine embryo selection system that allows for prediction of viability after transfer.

Live-cell imaging of nuclear–chromosomal dynamics in bovine in vitro fertilised embryos

“…It has been well documented that delayed timing of first cleavage is involved in blastocyst formation and pregnancy success 7 , 9 , 20 , 21 . We observed a relationship between delayed timing of first cleavage and ACS.…”

“…This is also true for human artificial reproductive technology (ART) 3 . Generally, assessment of bovine embryo quality is performed by morphological grading on days 7 to 8 post-insemination, as recommended by the International Embryo Transfer Society (IETS) 4 , 5 , but the pregnancy success rate of embryos judged as transferable (Code 1 or Code 2) is only 30–50% 6 , 7 .…”

“…Using time-lapse cinematography analysis in cattle, we recently found that morphokinetic indicators (MKIs) such as timing, number of blastomeres at first cleavage, and number of blastomeres at onset of the lag-phase, are useful markers for evaluating embryo viability after transfer to a recipient 7 , 9 . Therefore, using MKIs may be a better assessment method than using IETS morphological grading, in terms of reliability and objectivity of evaluation of bovine IVF embryos 9 .…”

Review: Recent advances in bovine in vitro embryo production: reproductive biotechnology history and methods

“…Therefore, cryoresistance evaluation was added as a viability test parameter (Massip and Leibo, 2002) along with many other biomarker-based methods to supplement the traditional morphological assessment (Rødgaard et al, 2015). New approaches, such as morphokinetics (Sugimura et al, 2017) and advanced genomic screening techniques, may become routine for embryo selection in a commercial IVP laboratory. In the near future, CRISPRCas-9 type-related technologies could assist in performing precise genome editing or epigenome editing for biomedical applications and bioreactors (Yum et al, 2018).…”

Consequences of assisted reproductive techniques on the embryonic epigenome in cattle

“…By the 1970s, assisted reproductive techniques (ARTs) had already started to be used in domestic animals, but IVF was not achieved in cattle until the early 1980s (Brackett et al 1982) and it would be another decade before the first ART calves (produced by IVM, IVF and in vitro culture) were born (Fukuda et al 1990). ART procedures have been under constant scrutiny since their inception with the common goal of improving the number and quality of embryos produced (Luvoni et al 1996;Sugimura et al 2017). Although most reports use specific stages of preimplantation development as the end point to determine the adequacy of the embryo, especially compared with in vivoproduced counterparts, the ultimate goal of an in vitro system for many is the production of a live and healthy calf with improved genetic potential (Hasler 2014;Sirard 2018).…”