Russell A. Foulk

Trophoblast differentiation during embryo implantation and formation of the maternal-fetal interface

Trophoblasts, the specialized cells of the placenta, play a major role in implantation and formation of the maternal-fetal interface. Through an unusual differentiation process examined in this review, these fetal cells acquire properties of leukocytes and endothelial cells that enable many of their specialized functions. In recent years a great deal has been learned about the regulatory mechanisms, from transcriptional networks to oxygen tension, which control trophoblast differentiation. The challenge is to turn this information into clinically useful tests for monitoring placental function and, hence, pregnancy outcome.

Effect of Karyotype on Successful Human Embryonic Stem Cell Derivation

The success rate of human embryonic stem cell (hESC) derivation depends on both culture conditions and embryo quality and is routinely determined by morphological criteria. However, high incidence of chromosomal abnormality even in high-grade cleavage embryos from in vitro fertilization (IVF) patients suggests that the morphological grade of supernumerary embryos obtained from IVF clinics may not be a good prediction factor for successful hESC derivation. We show here that from one donor under identical derivation conditions 12 karyotypically abnormal post-bioptic embryos did not yield hESC lines, whereas two out of four normal embryos did. This suggests that the capacity of embryos to give rise to hESC line is likely to be influenced by their genetic status.

Expression of L-selectin ligand MECA-79 as a predictive marker of human uterine receptivity

Problem Patients with repeated implantation failure (RIF) represent a subgroup of couples who suffer from unexplained infertility. Human blastocysts utilize L-selectin to initiate implantation by binding to endometrial ligands composed of oligosaccharide moieties on the surface glycoproteins. The absence of these ligands could lead to recurrent implantation failure (RIF) in some of these couples.

Trophoblast Implantation Versus Tumor Invasion

The steps involved in hemochorial placentation bear a striking resemblance to tumor invasion. Interestingly, trophoblast and tumor invasion progress with very little, if any, tissue destruction, hemorrhage or necrosis. Undoubtedly, this is because the tumor cells mimic a physiologic process. The major difference between implantation (physiologic invasion) and tumor invasion (pathologic invasion) is that trophoblast invasion during implantation is spatially and temporally regulated whereas tumor cell invasion is not. The sequence of events leading to invasion is similar: it includes cellular attachment (apposition) to the host tissue, transmigration through a basal lamina, stromal infiltration, and aggressive penetration into blood vessels. The endpoints, however, differ drastically.