Validation of the Sw71-spheroid model with primary trophoblast cells

PROBLEM

Human implantation is a limiting factor for the success of natural and IVF reproduction since about 60% of pregnancy losses occur in the peri-implantation period. The in vitro modeling of human implantation challenges the researchers in accurate recreation of the complex in vivo differentiation and function of human blastocyst in the peri-implantation period. In previous studies, we constructed Sw71-spheroid models, which like human blastocyst undergo compactization, attaches to the endometrial epithelium, invade, and migrate. The aim of this study was to validate the trophoblast Sw71-spheroid model with primary trophoblast cells, derived from healthy women in early pregnancy.

METHOD OF STUDY

We performed a direct comparison of Sw71-spheroid model with placenta-derived primary trophoblasts regarding their hybrid phenotype and HLA status, as well as the ability to generate spheroids able to migrate and invade. From the primary trophoblast cells, isolated by mild enzymatic treatment and Percoll gradient separation, were generated long-lived clones, which phenotype was assessed by FACS and immunocytochemistry.

RESULTS

Our results showed that cultured primary trophoblasts have the EVT phenotype (Vim+/CK7+/HLA-C+/HLA-G+), like Sw71 cells. In both 3D culture settings, we obtained stable, round-shaped, multilayered spheroids. Although constructed from the same number of cells, the primary trophoblast spheroids were smaller. The primary trophoblast spheroids migrate successfully, and in term of invasion are equally potent but less stable as compared to Sw71 spheroids.

CONCLUSIONS

The Sw71 cell line and cultured native trophoblast cells are interchangeable regarding their EVT phenotype (HLA-C+/HLA-G+/Vim+/CK7+). The blastocyst-like spheroids sourced by both types of cells differentiate in the same time frame and function similarly. We strongly advise the use of Sw71 spheroids as blastocyst surrogate for observation on trophectoderm differentiation and function during early human implantation.

Uterine receptivity to human embryonic implantation: histology, biomarkers, and transcriptomics

Embryonic implantation is a dynamic process of paracrine interactions between the maternal compartment and the conceptus and involves a receptive endometrium and a developmentally competent blastocyst. Herein, we review histology, clinical approaches, and the promise of transcriptomics in elucidating mechanisms underlying implantation and development of biomarkers of uterine receptivity-with an eye to diagnose and treat implantation-based disorders of miscarriage, fetal growth restriction, pre-eclampsia, and infertility.

Cytokines: Important for implantation?

PROBLEM

Cytokines are obviously very important in an established pregnancy, but what about human embryo implantation?

METHODS

Literature review.

RESULTS

We first discuss the necessity and limits of animal models, and then review the few cytokines which have been demonstrated by knock-out methods to be absolutely necessary for embryo implantation using in animal models. We then review what is known or discussed about the role of other cytokines as deduced from quantitative and/or qualitative dysregulation in animals and in humans.

CONCLUSIONS

Cytokines are indeed involved in implantation as they are in ongoing pregnancy and delivery. Relevance to infertility and recurrent pregnancy loss is discussed.

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.

METHODS

Twenty fertile women and 20 patients with RIF were tested for the presence of the L-selectin ligands by immunohistochemistry. Endometrial biopsies were obtained on the sixth day post ovulation. After fixation, they were dated according to Noyes. Immunolocalization was performed using the MECA-79 antibody which is directed against ligands of L-selectin.

RESULTS

The fertile group all showed the presence of the L-selectin ligand. Of those with RIF, five were negative for the ligand and never, despite an average of five successive embryo transfers, became pregnant. Fifteen RIF patients were positive for the L-selectin ligand, of whom ten subsequently conceived. As a screening test for RIF patients who lack the ligand, the predictive value was 100% with a sensitivity of 50% and specificity of 100%. The positive predictive value was 100% and negative predictive value is 87%.

CONCLUSIONS

L-selectin and its ligands play a vital role for early human implantation. Screening for the absence of the ligand may help many patients with RIF to avoid undergoing repeated failed treatment cycles.