Decorin production by the human decidua: role in decidual cell maturation

Decidualization involves the proliferation and differentiation of fibroblast-like endometrial stromal cells into epithelioid-shaped and secretory 'decidual' cells in response to steroid hormones. Human decidual cells produce insulin-like growth factor-binding protein-1 and prolactin (PRL), two well-recognized markers of decidual cell maturation and a proteoglycan decorin (DCN). We reported that DCN restrains the human trophoblast renewal, migration, invasion and endovascular differentiation needed for uterine arterial remodeling during normal pregnancy. DCN overproduction by the decidua is associated with a hypo-invasive placenta and a serious pregnancy disorder, pre-eclampsia (PE). Furthermore, elevated maternal plasma DCN levels during the second trimester is a predictive biomarker of PE. While these paracrine roles of decidua-derived DCN on trophoblast physiology and pathology have been well-defined, it remains unknown whether DCN plays any autocrine role in decidual cell development. The objectives of this study were to examine: the kinetics of DCN production during decidualization of human endometrial stromal cells; gestational age-related changes in DCN production by the first trimester decidua; and a possible autocrine role of DCN on decidual cell maturation. We found that DCN production is enhanced during decidualization of both primary and immortalized human endometrial stromal cells in vitro and during early gestation in decidual samples tested ex vivo, and that it is important for endometrial stromal cell maturation into a decidual phenotype. Decorin-depleted human endometrial stromal cells exposed to decidualizing stimuli failed to mature fully, as evidenced by fibroblastoid morphology, reduced insulin-like growth factor-binding protein-1 and PRL expression, and reduction in cellular ploidy. We identified heart and neural crest derivatives-expressed protein 2, and progesterone receptor as potential downstream mediators of DCN effects.