Constructing a 3D in Vitro Embryo Implantation Model

Implantation failure remains an unsolved obstacle in reproductive medicine and is a major cause of infertility. An in vitro model was established to mimic the events in the uterine wall during the implantation process. To that aim, endometrial cells were seeded into alginate macro-porous scaffolds and cultured under sequential hormonal treatment, mimicking the typical menstrual cycle. Two endometrial cell lines, either RL95-2 or HEC-1A, were used, displaying receptive and non-receptive endometrial properties, respectively. Cell constructs were evaluated for E-cadherin mRNA expression levels by qPCR and for E-cadherin protein expression by specific immuno-staining and Western blot. JAR spheroids, utilized as embryo-like tissue models, were seeded on 3-week old cell constructs and their attachment to the 3D tissue model was examined to test endometrial tissue receptivity. Cultivation under 3D conditions within macro-porous alginate scaffolds enabled long-term endometrial culture for at least 3 weeks under hormonal treatment. E-cadherin mRNA expression was significantly higher in the 3-week old RL-95 cell constructs compared to HEC-1A cell constructs. Attachment of JAR spheroids to 3-week old RL95-2 culture was confirmed, whereas no such attachment was evident in HEC-1A. Moreover, transfecting HEC-1A cells with Estrogen receptor a restored JAR spheroid attachment. This 3D model provides insight into the regulatory mechanism of the implantation process and enables examining potential novel therapeutic strategies for repeated implantation failure.