Pregnancy

Decidual Heparanase Activity Is Increased During Pregnancy in the Baboon (Papio anubis) and in In Vitro Decidualization of Human Stromal Cells

Abstract
Implantation is a complex process involving interactions between the embryo and the uterus. Adhesion, remodeling of the maternal vasculature and de 40 cidualization are crucial events necessary for successful implantation to occur. Heparanase (HPSE), an endo-beta-D-glucuronidase, cleaves heparan sulfate at specific sites leading to release of growth factors that may be involved in decidualization and remodeling of the maternal vasculature. HPSE also can function as a cell adhesion molecule. The aim of this study was to determine the expression of HPSE in uteri of 45 non-pregnant and pregnant baboon as well as in human stromal fibroblasts decidualized in vitro. We examined the localization and expression of HPSE using immunohistochemistry, Western blotting, reverse transcriptase (RT)-PCR and activity assays. In non-pregnant baboon uteri, HPSE expression was localized to the apical surface of the glandular epithelia and in glandular secretions. However, in pregnant baboon uteri, HPSE was localized primarily in decidua. Uteri 50 obtained at mid-pregnancy had higher heparanase activity compared to the non-pregnant uteri. A slight increase in HPSE expression was observed in human stromal fibroblasts decidualized in vitro. HPSE and HPSE2 mRNA transcripts were present in both decidualized tissue and cells. Increases in heparanase activity in the decidua from pregnant baboon uteri compared to tissue from non-pregnant animals and in human stromal fibroblasts decidualized in vitro suggest that 55 HPSE plays a role in extracellular matrix remodeling and in increasing heparin-binding growth factor release during embryo implantation.

Key words: Implantation • in vitro human decidualization • primate