Time-lapse cleavage rating predicts human embryo viability.

Chronology of three consecutive mitotic events in human pre-implantation embryos was examined by time-lapse imaging. In zygotes producing well-formed and pregnancy-yielding expanded blastocysts, uniform time-patterning of cleavage clusters (c) and interphases (i) was revealed: i2=11+/-1, i3=15+/-1, i4=23+/-1 h / c2=15+/-5, c3=40+/-10, c4=55+/-15 min. Oppositely, shortened or prolonged durations of one or more cell cycles were strongly predictive of poor implantation and development. Furthermore, trichotomic mitosis was discovered in 17 % of cases - zygotes cleaved into 3 blastomeres and 2-cell embryos into 5-6 cells (instead of normal 2 and 4). During conventional clinical assessment, such embryos are indistinguishable from normal, often considered just-in-course of the next cell cycle. Only detailed time-lapse monitoring paced at 10-minute intervals had proven all these embryos to be absolutely unviable, even in rare cases when they reduced their hypercellularity to normal cell counts via cell-cell fusion. Overall, we demonstrate that time-lapse embryo cleavage rating (ECR) as a standalone diagnostic procedure allows for effective identification of viable early embryos with 90 % specificity, while elimination of good-looking but unviable embryos can be assumed with a specificity of 100 %. Thus, making this non-invasive and contactless approach worth of addition to routine embryo screening in clinical IVF programs.

[Non-invasive monitoring of the timing of early embryo cleavages--objectively measurable predictor of human embryo viability]. / Neinvazívne meranie dlzky bunkového cyklu v prvých dnoch embryonálneho vývoja--objektívne meratel'ný ukazovatel' zivotaschopnosti l'udských embryí.

OBJECTIVE: The evaluation of the developmental abilities of human embryos according to the timing of their early mitotic cleavages. DESIGN: Retrospective study. SETTING: Prague Fertility Centre and Institute for Care of Mother and Child, CAR, Prague. METHODS: The embryos obtained in IVF program were used for further observations and subjected to automated time-lapse monitoring (PrimoVision, Cryo-Innovation, 1 picture/10 min, intermittent white-light illumination) under standard cultivation conditions (37.0 degrees C, 5% CO2 in humid air). Image sequences were digitally recorded for later use. For intravital spindle detection we used polaryzing microscopy (Oosight, Research Instruments) and Hoechst 33342 fluorescent dye for intravital chromatin visualization. A total number of 180 human embryos which gave a vital pregnancies (FHB, fetal heart beat) were analysed retrospectively for timing of early cleavages. In our study, the exact timing of the four interphases (IP) and synchrony of sister cell divisions (ID, interval division) occurring after fertilization were identified and manually recorded. Interphases: IP1 was defined as the period from fertilization till 2 cell stage. IP2 between 2 and 3 cells stages, IP3 between 3 and 5 and IP4 between 5 and 9 cells embryo. INTERVAL DIVISION: ID2 was recorded as a time interval between 3 and 4 cells, ID3 between 5 and 8 cells and ID4 between 9 and 16 cells stage embryos. RESULTS: In the embryos giving viable pregnancies, the durations of IP1 was 20-26 hrs. IP2 was 10-12 hrs, IP3 was 14-16 hrs and IP4 was 20-26 hrs. In these embryos, the sister blastomeres cleaved in a very synchronous manner. The duration of ID1 was recorded to varry from 120 to 210 min. ID2 from 20 to 60 min., ID3 from 120 to 240 min. and ID4 from 230 to 360 min. CONCLUSION: The viable embryos cleave in a very similar time pattern which can be defined and applied as referencial value. Non-invasive monitoring of the timing of early embryo cleavages can be used as an objectively measurable predictor of human embryo.