Dissect Human Primordial Germ Cell Development Using Stem Cell Models - Project Summary Primordial germ cells (PGCs), the precursors of eggs and sperm, are essential for human reproduction. A comprehensive understanding of the molecular mechanisms underlying specification, maturation and migration of human primordial germ cells (hPGCs) is critical for advancing infertility treatments, regenerative medicine, and potential therapies for genetic disorders. Most of our current knowledge on mammalian germline biology is derived from studies using laboratory mice. However, due to the unique transcriptional networks and developmental pathways of hPGCs, the knowledge from other species cannot be directly extrapolated. Moreover, PGCs emerge during the earliest stage of embryogenesis, undergoing complex morphogenesis and migration, which presents significant technical challenges for in vivo tracking and study. The overarching objective of my research is to develop stem cell-based modeling systems that closely recapitulate the landmarks of human embryonic developmental processes, and to apply these systems to elucidate the fundamental mechanisms governing human development. Notably, over the past few years, I developed a stem cell-based microfluidic human embryoid model that faithfully recapitulates the early development of human embryonic sac in a highly controllable and scalable fashion, wherein the emergence of hPGCs mirrors the molecular signatures and developmental trajectories observed in vivo. I also recently devised a novel method for deriving hPGC-like cells (hPGCLCs) using an embryonic-like culture system. This method significantly simplifies hPGCLC induction protocols and provides insights into how the native cellular microenvironment facilitates hPGC specification. The research objectives for this five-year project are to integrate approaches from developmental and stem cell biology, microengineering, genome editing, and bioinformatics to uncover the fundamental mechanisms driving early hPGC specification and migration. Specifically, 1) leveraging the microfluidic embryoid platform, we will generate a novel lineage reporter line to perform lineage tracing assays on hPGCLCs. Through single-cell RNA sequencing and functional genetic studies, we aim to elucidate the origin and lineage trajectory of hPGCs. 2) We will establish a PGC-hindgut co-development model to investigate the maturation and migration of hPGCs after specification. We anticipate this model will yield insights into the mechanisms governing hPGC migration and the cellular crosstalk between hPGCs and the hindgut. 3) Using the embryoid and PGC-hindgut co-development models, we will systematically dissect the roles of Wnt signaling in hPGC lineage commitment and migration. Successful completion of this project will deepen our knowledge of human germline biology and facilitate future research on hereditary diseases and reproductive medicine.
