Fig. 7: Survivin-enriched exosomes derived from Flk-1⁺ progenitors prevent diabetic embryopathy and the exosome inhibitor induces NTDs.

a Exosomes (Exo) derived from Flk-1⁺ progenitors of E8.5 embryos. Exosomes (bright round dots) were directly detected by the NanoSight (#NS300, Malvern Panalytical). b Survivin protein expression in Flk-1⁺ progenitor exosomes from Survivin transgenic (Tg) and Wild-Type (WT) E8.5 embryos. c Labeled exosomes (green) from Flk-1⁺ progenitors but not C17.2 neural stem cells were up-taken by C17.2 neural stem cells labeled by nestin staining (Red). Cell nuclei were stained with DAPI (blue). Bars = 15 μm. d Flk-1⁺ progenitor exosomes (green) via in utero amniotic microinjections were specifically up-taken by neuroepithelial cells of E8.0 embryos. e–g Survivin protein (e), cleaved caspase 8 and caspase 3 (f) and TUNEL-positive apoptotic cells (red). g after 36 h exosome microinjections into E8.0 embryos. Bars = 30 μm and 1 μm, for the top panel and the low panel, respectively. h Numbers of normal and NTD embryos after exosome injections. Mock: mock vehicle (Veh) injections. n was indicated in Table S3. i, j Exosome profile (i), exosome numbers and CD63 expression (j) in E8.5 embryos after the exosome inhibitor GW4869 injections. k Numbers of normal and NTD embryos after exosome injections (L) one-time measurement of GW4869 concentrations in E8.5 embryos. m Morphology of embryos. Bars = 100 μm and 50 μm, for the top panel and the low panel, respectively. n is a schematic diagram depicting the communication of Survivin-containing exosomes across germ layers, regulated by DNA hypermethylation of FGF2. Cells experiments were repeated three times (n = 3). Experiments were performed using three embryos from three different dam per group (n = 3). * indicates significant difference compared to other groups (P < 0.05). ND nondiabetic, DM diabetes mellitus, WT wild type, Veh vehicle.