Insulin-like growth factor-binding proteins produced by Vero cells, human oviductal cells and human endometrial cells, and the role of insulin-like growth factor-binding protein-3 in mouse embryo co-culture systems

Abstract

Co-culturing embryos on helper cells can mimic the in-vivo environment, thereby enhancing embryo development in vitro. Insulin-like growth factors (IGF) and their binding proteins (IGFBP) also enhance embryo development. To investigate the kinds of IGFBP produced by various cell monolayers and the effects of IGFBP-3 on mouse embryo co-culture systems, 2-cell ICR mouse embryos were cultured in either human tubal fluid medium alone or in the presence of Vero cells, human oviductal cells or endometrial cells. The helper cells were analysed immunohistochemically to investigate the types of IGFBP produced by various cell monolayers. The concentrations of IGF-I and IGFBP-3 in media obtained from the culture of embryos alone, cells alone or cells plus embryos were determined by radioimmunoassays. On day 7, more blastocysts hatched in the co-culture groups (73% in the Vero cell group, 76% in the endometrial cell group and 74% in the oviductal cell group) than in the control group (43%) (P < 0.0001). The results of immunohistochemistry revealed that (i) all three cell groups produced a lot of IGFBP-1, -2 and -3, but only a little of IGFBP-4 and -5; and (ii) IGFBP-1, -2, and -3 were present in blastocysts in either the presence or absence of helper cells. The IGF-I secreted by cell monolayers or embryos was undetectable (detection limit 0.83 microg/l). The IGFBP-3 concentrations in media obtained from co-cultured embryos and cells were significantly higher than in media without embryos (median values in oviductal cell culture medium, 165 versus 127 microg/l, P = 0.04; median values in endometrial cell culture medium, 277.5 versus 183.5 microg/1, P = 0. 0002; median values in Vero cell culture medium, 219 versus 120 microg/l, P = 0.011). Although IGFBP-3 concentration in the medium that contained embryos alone was undetectable by radioimmunoassay (detection limit 1.1 microg/l), immunohistochemistry demonstrated the presence of IGFBP-3 in the embryos. Co-culture in systems in which there was an increased production of IGFBP-3 led to an improved development of mouse embryos. IGFBP can improve the binding of IGF to cell surface receptors of target tissue, and thus enhance the effect of limited IGF concentrations in promoting embryo development in a co-culture system. We conclude that Vero cells, human endometrial cells and oviductal cells produce IGFBP-1, -2, -3, -4 and -5. IGFBP-3 may play a role in embryotrophic potential by either regulating the action of IGF or directly enhancing embryo development.

Activin/Nodal Signaling Switches the Terminal Fate of Human Embryonic Stem Cell-derived Trophoblasts

“…Follistatin treatment increases TE formation in bovine blastocysts, whereas follistatin knockdown or activin A treatment decreases TE formation (92,93). Inhibitors of activin/nodal signaling are expressed in human fallopian tubes (94) and rat oviductal fluid (95,96), and human oviductal cells cause blastocyst formation in mouse embryos (97)(98)(99)(100)(101). Therefore, it is likely that inhibition of activin/nodal signaling has a role in TE formation in embryos.…”

IGFs and IGF-binding proteins in the regulation of human ovarian and endometrial function

“…Embryos co-cultured with various epithelial monolayers show improved development (Lai et al 1996). In such systems, IGFBP-1, -2, -3, -4 and -5 are produced by the monolayer helper cells (human endometrial and oviductal cells).…”

“…In such systems, IGFBP-1, -2, -3, -4 and -5 are produced by the monolayer helper cells (human endometrial and oviductal cells). Of these binding proteins, IGFBP-3 is the most prominent in co-cultured human endometrial monolayers and may play a role in embryo development either by regulating IGF actions or by directly enhancing embryo development (Lai et al 1996).…”

In Vitro Development of Mouse Pronuclear Embryos to Blastocysts in Sequential Media With and Without Co-Culture of Autologous Cumulus Cells

“…Dev. 54: [385][386][387][388][389][390] 2008) t has been suggested that the co-culture system exerts its beneficial effects by negative [1][2][3][4][5] or positive conditioning [4,[6][7][8][9][10][11] of the culture media, and by embryo-to-cell contact. Negative conditioning or detoxification is the ability of the feeder cells to remove deleterious components from the culture medium whereas positive conditioning is the ability of the feeder cells to modify it by releasing some components (embryotrophic factors) into the culture medium [12,13].…”