Serum-dependent effects of IGF-I and insulin on proliferation and invasion of human first trimester trophoblast cell models

Abstract

Extravillous cytotrophoblasts are specialised epithelial cells of the placenta that proliferate or invade the maternal decidua. Little is known about the mechanisms that regulate these processes. Here the effects of several insulin and insulin-like growth factor-I (IGF-I) doses, either singly or in synergy with serum, on human chorionic gonadotropin-beta (hCG-beta) secretion (RIA), proliferation (cell counting, cyclin B(1) levels) and invasion [Matrigel invasion assay, secretion of matrix metalloproteinases (MMP) 2 and 9] were investigated. The choriocarcinoma cell lines BeWo, JAR and JEG-3 served as models for first trimester human trophoblasts. Both growth factors altered hCG-beta secretion and proliferation dependent on the cell line. Insulin stimulated proliferation in JAR cells and, to a lesser extent, in JEG-3 cells, and when cultured in serum-free medium, BeWo was not affected. Invasion was not affected although proMMP-2 levels in culture medium were altered under some conditions. A strong synergistic effect with serum was noted. In the presence of serum both growth factors reduced proliferation and invasion in a similar fashion. Since the cell models differ by their degree of differentiation, the data demonstrate that the effects of insulin and IGF-I strongly depend on serum and the degree of differentiation. It can be speculated that IGF-I can take on tasks of insulin in the regulation of trophoblast functions under conditions of insulinopenia.

The Human Placenta in Gestational Diabetes Mellitus

“…This may indicate a mitogenic effect of insulin on the trophoblast, predominantly at the beginning of pregnancy, whereas fetal insulin will stimulate metabolic processes within the endothelium. In fact, in vitro studies confirmed the mitogenic potency of insulin in trophoblast models (19). This may explain the biphasic growth of the placenta and fetus at around mid-gestation in type 1 and experimental diabetes (20,21).…”

Myostatin regulates glucose uptake in BeWo cells

“…Glucose uptake by BeWo cells was carried out as described (31) with a few adaptations. At 24,48,72, and 96 h after seeding, the culture media were removed, and cells were washed briefly with tyrode buffer [in mM: 135 NaCl, 5 KCl, 1.8 CaCl 2, 1 MgCl2 (6H2O), and 10 HEPES as described previously (2) with the exception of glucose; the solution was filter sterilized] to remove any residual FBS. Next, the cells were preincubated for 10 min at room temperature in 0.3 ml of warm Tyrode solution to acclimatize with the assay buffer and remove cellular glucose (14).…”

Treatment With Insulin and Its Analogs in Pregnancies Complicated by Diabetes

“…IGF-I facilitates the implantation of the human embryo in the endometrium. Disturbance of IGF-I functions could result in spontaneous miscarriage, preeclampsia, and defects of the embryo (38). It is well known that the incidence of spontaneous miscarriage because of malformations of the fetuses during early pregnancies is much higher in women with poorly controlled diabetes than in nondiabetic pregnancies.…”