Human lymphatic organoids reconstruct convergent developmental routes to functional lymphatic vessels
The lymphatic vasculature maintains fluid balance, regulates immune surveillance, and supports tissue repair, yet how human lymphatic vessels arise and acquire specialized functions remains poorly understood. Here, guided by single-cell and spatial analyses of human embryos, we found that both lateral plate and paraxial mesoderm converge on venous endothelial intermediates with cardinal vein-like characteristics prior to lymphatic specification. Informed by these developmental trajectories, we generated three-dimensional lymphatic organoids from human pluripotent stem cells through two distinct mesodermal routes. The organoids formed capillary-like vascular networks with emerging button-like junctions and distinct endothelial and stromal programs. The lymphatic organoids were transcriptionally benchmarked to human fetal lymphatic endothelium. The organoids supported immune-cell interactions and antigen accumulation and, following transplantation, exhibited interstitial tracer uptake and transport. These findings establish a platform for investigating how distinct developmental origins shape human lymphatic specification, vascular organization, and function, with applications to lymphatic disease modeling and tissue repair.