Canon, E. | bioRxiv Science

bioRxiv2026

Bovine in vitro blastocysts with distinct morphokinetic patterns show transcriptomic differences at genome activation

Bovine embryo in vitro production (IVP) is characterised by low efficiency and variable outcomes. Monitoring early embryonic development by videomicroscopy revealed substantial morphokinetic heterogeneity in the first four embryonic cycles (EC, conventionally referred to as the 2-, 4-, 8- and 16-cell stages). Morphokinetic analysis offers a promising approach to characterize divergent developmental trajectories and provide a better understanding of underlying molecular mechanisms. We developed a Random Forest classification system (Bovine Embryo Analyser based on Morphokinetics: BEAM) to predict embryo phenotype. It is based on morphokinetic variables collected from the 1st to the 4th EC and predicts four blastocyst categories (EHB: Early Hatching Blastocyst, HB: Hatching Blastocyst, SSB: Subtle Developmental Shift Blastocyst, ADB: Arrhythmic Development Blastocyst). Classification performance on an independent dataset was good (F1 score = 0.59; Accuracy = 0.78), indicating that the BEAM can be useful for embryo development studies. The BEAM was further applied to embryos submitted to 4.3 days of culture and having completed the 4th EC (16-32 cells). RNA sequencing was performed on sixteen samples (4 x 8 pooled embryos/category). The ADB category was significantly enriched in transcripts involved in the regulation of transcriptional activity compared to the EHB category. In addition, in the ADB category, 22.7% (n = 185/816) of the upregulated genes were of maternal origin while only 6.2% were of embryonic origin (n = 54/816). In conclusion, despite being at a comparable developmental stage and transcriptionally competent, the ADB category showed delayed maternal transcript degradation suggesting delayed transition to embryonic transcriptional autonomy. Illustrated Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=138 SRC="FIGDIR/small/733532v1_ufig1.gif" ALT="Figure 1"> View larger version (45K): org.highwire.dtl.DTLVardef@13a0958org.highwire.dtl.DTLVardef@13b88a1org.highwire.dtl.DTLVardef@18707c9org.highwire.dtl.DTLVardef@105759_HPS_FORMAT_FIGEXP M_FIG C_FIG Summary SentenceIn vitro produced bovine embryo morphokinetic patterns allow prediction of four blastocyst categories (up to the 4th embryonic cycle) and are associated with distinct transcriptomic profiles at embryonic genome activation in competent embryos.

Developmental Biology↗

bioRxiv2019

Antimetastatic dsRNA mimics identified by live imaging of pathogenic neolymphangiogenesis

The crosstalk between cancer cells and the lymphatic vasculature has long been proposed to define competency for metastasis. Nevertheless, the discovery of selective blockers of lymphovascular niches has been compromised by the paucity of experimental systems for whole-body analyses of tumor progression. Here we present immunocompetent and immunodeficient mouse models for live imaging of melanoma-induced neolymphangiogenesis (driven by Vegfr3) as a cost-effective platform for drug screening in vivo. Spatio-temporal analyses in autochthonous melanomas and patient-derived xenografts identified double stranded RNA mimics (dsRNA nanoplexes) as potent repressors of lymphangiogenesis and metastasis. Mechanistically, dsRNA nanoplexes were found to suppress lymphangiogenic drivers in both tumor cells and their associated lymphatic vasculature (via MIDKINE and Vegfr3, respectively). This dual inhibitory action, driven by type I interferon, was not shared by FDA-approved antimelanoma treatments or by lymphangiogenic blockers in clinical testing. These results underscore the power of Vegfr3-lymphoreporters for pharmacological testing in otherwise aggressive cancers. RELEVANCEAlthough tumor-induced lymphangiogenesis has long been associated with metastasis, selective targeting of this process has been compromised by the paucity of experimental platforms for whole-body imaging of tumor progression and drug response. Here we present animal models engineered for spatio-temporal analyses of neolymphangiogenesis in clinically relevant autochthonous melanomas and patient-derived xenografts, and identify a unique action of double stranded-RNA nanoplexes as potent repressors of lymphatic dissemination and metastatic relapse.

cancer biology↗