Breakthrough in Studying Human Post-Implantation Development using Stem Cell Models
Scientists have made significant progress in studying human post-implantation development through the creation of embryo-like models using stem cells. The study, conducted by researchers from an undisclosed institution, addresses the limitations posed by ethical and technical challenges associated with studying intrauterine development after implantation.
Until now, there have been no models that accurately replicate the spatially organized morphogenesis of all embryonic and extra-embryonic tissues in the post-implantation human conceptus. However, inspired by recent success in creating Structured Stem cell-based Embryo Models (SEMs) in mice, the team aimed to extend these findings to humans.
The researchers utilized genetically unmodified human naïve embryonic stem cells (ESCs), cultivated in culture conditions that mimic those found in the human embryo (HENSM conditions). By doing so, they were able to create human fully integrated SEMs that closely resembled the organization of all lineages and compartments found in post-implantation human embryos, including the epiblast, hypoblast, and extra-embryonic mesoderm.
The team observed that these SEMs exhibited growth dynamics similar to key hallmarks of post-implantation embryogenesis, up to 13-14 days post-fertilization. This corresponds to Carnegie stage 6a, a critical period in human development. Notable features observed in the SEMs included the formation of the embryonic disk and bilaminar disk, the development of the amniotic cavity, and the specification of primordial germ cells.
Furthermore, the SEMs accurately replicated the formation of the yolk sac with visceral and parietal endoderm, as well as the expansion of the extra-embryonic mesoderm, which defines the chorionic cavity and connecting stalk. The trophoblast surrounding compartment in the SEMs displayed syncytium and lacunae formation, mirroring the natural development observed in human embryos.
This breakthrough in creating human SEMs holds tremendous potential for studying previously inaccessible stages of human early post-implantation development. By utilizing these models, scientists can now experimentally investigate the critical period leading up to peri-gastrulation, shedding light on the intricate processes that occur during this vital stage of human embryogenesis.
While these findings are undoubtedly groundbreaking, the research team acknowledges that further studies and validations are required to fully understand the implications and potential applications of their work. Nevertheless, this study represents a significant milestone in the field of embryonic development and opens up new possibilities for understanding and treating developmental disorders and pregnancy-related complications.