Pre-collecting lymphatic vessels form detours following obstruction of lymphatic flow and function as collecting lymphatic vessels

• Published in: PloS one 2020-01, Vol.15 (1), p.e0227814-e0227814
• Main Authors: Asano, Kimi, Nakajima, Yukari, Mukai, Kanae, Urai, Tamae, Okuwa, Mayumi, Sugama, Junko, Konya, Chizuko, Nakatani, Toshio
• Format: Article
• Language: English
• Subjects: Abdomen; Anesthesia; Animals; Antibodies; Biology and Life Sciences; Blood vessels; Enlargement; Expansion; Fluorescence; Health sciences; Identification methods; Infrared imaging; Ligation; Lymph; Lymph nodes; Lymphangiogenesis; Lymphatic system; Lymphatic Vessels - diagnostic imaging; Lymphedema; Lymphedema - diagnostic imaging; Lymphography; Male; Medical research; Medicine and Health Sciences; Mice; Mice, Inbred C57BL; Muscles; Nursing; Pharmaceuticals; Research and Analysis Methods; Supervision
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0227814

Previously, we showed that lymphatic vessels (LVs) formed detours after lymphatic obstruction, contributing to preventing lymphedema. In this study, we developed detours using lymphatic ligation in mice and we identified the detours histologically. Under anesthesia, both hindlimbs in mice were subcutaneously injected with Evans blue dye to detect LVs. We tied the right collecting LV on the abdomen that passes through the inguinal lymph node (LN) at two points. The right and left sides comprised the operation and sham operation sides, respectively. Lymphography was performed to investigate the lymph flow after lymphatic ligation until day 30, using a near-infrared fluorescence imaging system. Anti-podoplanin antibody and 5-ethynyl-2'-deoxyuridine (EdU) were used to detect LVs and lymphangiogenesis. Within 30 days, detours had developed in 62.5% of the mice. Detours observed between two ligation sites were enlarged and irregular in shape. Podoplanin+ LVs, which were located in the subcutaneous tissue of the upper panniculus carnosus muscle, connected to collecting LVs at the upper portion from the cranial ligation site and at the lower portion from the caudal ligation site. EdU+ cells were not observed in these detours. The sham operation side showed normal lymph flow and did not show enlarged pre-collecting LVs until day 30. Detours after lymphatic ligation were formed not by lymphangiogenesis but through an enlargement of pre-collecting LVs that functioned as collecting LVs after lymphatic ligation. Further studies are required to explore the developmental mechanism of the lymphatic detour for treatment and effective care of lymphedema in humans.