Stem cell-based human embryo models: current knowledge and open questions

Recently, the research field revolving around the stem cell-based modeling of the human embryo gained particular momentum when the first integrated models were designed with the aim to recapitulate the development of the entire early human conceptus. The underlying driving force to reconstruct embryo-like structures is the prospect of a more comprehensive understanding of the fundamental processes controlling early human embryogenesis including their deregulation causing reproductive failures, and the endeavor to use these embryo models for drug testing and disease modeling. Although efforts will continue to create improved models with steadily increasing fidelity to human embryogenesis, the next phase focusing on the application of human embryo models as a platform to address particular scientific questions is currently being entered. In this review, we discuss the benefits, promises and limitations associated with the use of non-integrated and integrated stem cell-based human embryo models in translational research and biomedical applications.