Lymphatic Reconnection and Restoration of Lymphatic Flow by Nonvascularized Lymph Node Transplantation: Real-Time Fluorescence Imaging Using Indocyanine Green and Fluorescein Isothiocyanate–Dextran

BACKGROUND: Lymph node transplantation is being increasingly recognized as a method of reconstruction of the lymphatic system for the treatment of lymphedema. However, the mechanisms regulating the connections between the lymphatic vessels and the lymph nodes remain poorly understood. The objective of this study was to examine whether removal of a popliteal lymph node (PLN) could result in rerouting of lymph flow and whether a single transplanted nonvascularized lymph node could reconnect with a lymphatic vessel and restore lymph flow. METHODS AND RESULTS: Thirty-six mice were allocated to undergo resection of a PLN alone (group 1) or a transplanted lymph node after resection of a PLN (group 2). Changes in lymph flow were observed using indocyanine green dye. The ability of the transplanted lymph node to reconnect with the lymphatic vessels was examined by fluorescein isothiocyanate (FITC)-dextran and immunohistochemical staining. In group 1, the flow of lymph was redirected to an inguinal lymph node (ILN) in 8 of 18 mice and continued to drain to the PLN in 10 mice. In group 2, the lymph continued to drain normally after removal of the PLN, and was also directed to an ILN in two mice. FITC-dextran demonstrated continuity of the transplanted PLN and the lymphatic vessels. Immunohistochemical staining showed that T cell and B cell populations in the transplanted lymph node were preserved. CONCLUSION: Lymphatic flow was rerouted after lymph node resection. A transplanted lymph node can be made viable with normal lymph flow by reconnecting the transplanted lymph node to a lymphatic vessel.