Culturing Purifies Murine Lymph Node Lymphatic Endothelium

BACKGROUND: Lymph node (LN) lymphatic sinuses transport lymph, cells, and antigens from the periphery through the LN. The lymphatic endothelium lining these sinuses appears to be an important contributor to the lymph node immune response. It has been challenging to obtain sufficient LN lymphatic endothelial cells for investigation of their functions, as they are minor constituents of LNs. METHODS AND RESULTS: A procedure was developed to purify lymphatic endothelial cells (LEC) from murine LNs, which yields large numbers of primary LN LEC. Two-dimensional in vitro cultures of dissociated LN stromal cells initially consist of multiple cell types, and then rapidly evolve to produce pure cultures of lymphatic endothelium within a few passages. One million LEC can be harvested after 4 weeks of culture, and much larger cell numbers can be obtained by continued culturing over long periods. The LEC cultures maintain endothelial morphology and expression of LEC markers, and preserve the same slow growth characteristics over at least 20 passages. The LEC cultures readily form tubes in Matrigel at early and at late passages, resembling those formed by LEC lines. CONCLUSIONS: A simple and economical approach to obtain purified primary murine LN LEC was developed for in vitro studies of their function. The morphology, growth characteristics, and functional behavior of these cells in tube formation assays did not change between initial and long-term passages. Large numbers of these cells can be harvested after long-term passage, so that they can be studied in biochemical and biological assays.