Human embryos produce transforming growth factors α activity and insulin-like growth factors II

To assess whether growth factors are produced by early human embryos in culture. We studied various growth factors in the culture media of human embryos (n = 6) cultured from days 3 to 8 after fertilization. Four growth factors were measured: Insulin growth factors I and II (IGF-I and IGF-II), epidermal growth factor (EGF) and transforming growth factor α (TGFα) activity. Nonconditioned INRA Menezo B2 (Biomerieux, S.A., Paris, France) culture medium contained significant levels of TGFα activity (5.2 ng/mL) and low levels of IGF-I (1.02 ng/mL) and IGF-II (2.8 ng/mL), whereas EGF was below detection of our assay. With human embryo, the culture media contained lower TGFα activity on days 3 and 4 after fertilization (2.5 ng/mL and 2.8 ng/mL, P < 0.05). From days 5 to 8 after fertilization, a significant increase in TGFα activity and IGF-II was detected (TGFα: activity: day 5: 3.7 ng/mL; day 6: 4.4 ng/mL; day 7: 6.4 ng/mL; day 8: 8.4 ng/mL) (IGF-II: day 5: 3.4 ng/mL; day 6: 3.1 ng/mL; day 7: 4.1 ng/mL; day 8: 4.2 ng/mL). Epidermal growth factor was undetectable, and IGF-I did not vary significantly. Transforming growth factor α activity and IGF-II are produced by human embryos in culture at a time when they could play a role in morula to blastocyst transformation.