Understanding the Lymphatic System: Tissue-on-Chip Modeling.

The lymphatic vasculature plays critical roles in maintaining fluid homeostasis, transporting lipid, and facilitating immune surveillance. A growing body of work has identified lymphatic dysfunction as contributing to the severity of myriad diseases and to systemic inflammation, as well as modulating drug responses. Here, we review efforts to reconstruct lymphatic vessels in vitro toward establishing humanized, functional models to advance understanding of lymphatic biology and pathophysiology. We first review lymphatic endothelial cell biology and the biophysical lymphatic microenvironment, with a focus on features that are unique to the lymphatics and that have been used as design parameters for lymphatic-on-chip devices. We then discuss the state of the art for recapitulating lymphatic function in vitro, and we acknowledge limitations and challenges to current approaches. Finally, we discuss opportunities and the need for further development of microphysiological lymphatic systems to bridge the gap in model systems between lymphatic cell culture and animal physiology.