MEASUREMENT OF THE OXIDATIVE PROFILE OF SPENT CULTURE MEDIA AS A NON-INVASIVE BIOMARKER OF LIFE BIRTH POTENTIAL.

To assess whether the measurement of the oxidative status of spent embryo culture media by Thermochemiluminiscence (TCL) technology is a relevant biomarker of Life birth (LB) outcome in IVF treatments. We analyzed the spent culture media from 112 transferred blastocysts from 105 ICSI treatments performed during two consecutive years. Embryos were cultured in an EmbryoScope® time-lapse system (Vitrolife), in individual wells with single-step Gems® culture media (Genea Biomedx) and selected by morphology and morphokinetics. 14μl of spent media were analyzed in the Fertissimo TCL AnalyzerTM (Carmel Diagnostics, Israel), which quantifies the oxidative status of the sample by counting the photons emitted per second (cps) after a heat-catalyzed oxidative reaction. Photon counting is normalized by a smoothing algorithm and summarized in the parameters H1sm, H2sm, H3sm (cps after 55s, 155s and 255s of heating respectively) and an overall TCL Score. TCL parameters were compared between embryos that reached life birth (LB+, n=30) and those that did not (LB-, n=82), using ANOVA tests. LB rates were calculated per TCL quartiles and compared by χ2 test. The contribution of oxidation parameters to LB outcome was quantified by multivariate logistic regression (MLR). TCL values of the culture media from LB+ embryos were significantly higher than those from LB- embryos: H1sm= 92.90 LB+ vs 80.88 LB- (P=0.011); H2sm= 93.73 LB+ vs 83.18 LB- (P=0.024); H3sm=103.16 LB+ vs 92.19 LB- (P=0.022); TCL Score= 95.53 LB+ vs 84.29 LB- (P=0.015). MLR models for LB prediction were built including the different TCL parameters and other relevant variables: oocyte age, patient BMI and morphological classification by ASEBIR criteria of the embryos. H1sm resulted the most significant parameter, with an odds ratio of 1.024 (95%CI: 1.003-1.045; P=0.025), confirming that embryos with higher values are more likely to achieve LB. A division by quartiles showed that embryos which spent media had H1sm ≥ 93 cps had significantly higher LB rate than those with lower values: (H1sm≥ 93): 42.9% LB+, (80.9< H1sm≤ 92.9): 25%LB+, (69.9< H1sm≤ 80.9): 32.1%LB+, (H1sm≤ 69.9): 7.10% LB+; P=0.022. The culture media of LB+ embryos were more oxidized than those of LB- embryos by the end of the incubation. A MLR confirmed that higher TCL levels are a valid non-invasive biomarker of LB potential, and independent of other parameters that affect said outcome. The analysis of the oxidative status of the spent culture media might constitute a valid additional criterion for improving embryo selection.