Re-establishment of Lymphatic Drainage after Vascularized Lymph Node Transfer in a Rat Model

BACKGROUND:Vascularized lymph node transfer (VLNT) has recently received attention as a potential surgical treatment for lymphedema. Despite good results in some series, the mechanism and benefits of VLNT have yet to be fully understood. This study aimed to investigate the re-establishment of drainage into transferred lymph nodes following VLNT in a rat model. METHODS:Seven rats underwent VLNT. The operation performed on each rat consisted of two parts. First, the left groin lymph node basin with superficial epigastric vessels was harvested as a free flap. Second, the flap was re-attached in the left groin of the rat via end-to-end microvascular anastomoses. Anastomosis patency was assessed immediately post-op and at the time of animal sacrifice. The rats were evaluated for re-establishment of lymphatic flow into the transplanted nodes at 1 month intervals for at least 6 months post-op. This was accomplished non-invasively by injecting the rats in their flanks with fluorescent indocyanine green (ICG) which was detected using a PDE infrared camera. RESULTS:Anastomoses were patent in all 7 rats immediately postop. No ICG uptake was seen in the transplanted lymph node basins in the first 2 months post-op in any of the rats. In 5 of 7 rats, however, ICG uptake was demonstrated in the transplanted lymph node basin by 6 months (average 13 weeks). CONCLUSIONS:We report uptake of ICG in 5 of 7 rats at an average of 13 weeks following lymph node transplantation, consistent with the re-establishment of lymphatic drainage into the transplanted nodes.