VEGF-C improves regeneration and lymphatic reconnection of transplanted autologous lymph node fragments: An animal model for secondary lymphedema treatment

Abstract

Secondary lymphedema occurs after for example breast cancer surgery and radiation in 20–50% of the patients. Due to the poor outcomes of surgical treatments in the past, the therapy often remains symptomatic. However, avascular transplantation of autologous lymph node fragments (LN-Tx) combined with postoperative injections of vascular endothelial growth factor-C (VEGF-C) emerges as a potential surgical therapy. In this study, adult rats underwent LN-Tx to investigate the following parameters of VEGF-C application: time point, location and dosage. Furthermore, the influences of VEGF-C on lymphatic reconnection and transplant regeneration were analyzed. The reconnection was investigated using intradermally injected blue dye and the regeneration was evaluated histologically using hematoxylin-eosin (H&E) staining and immunohistochemistry. The higher dosage enhanced the reconnection rates significantly and showed a statistical tendency of improving regeneration. An application on early postoperative days and the injection into the medial thigh improved the reconnection significantly. However, these variables did not affect the regeneration statistically. This study confirms that LN-Tx combined with lymphatic growth factor VEGF-C is a possible approach in the therapy of secondary lymphedema and shows the important role of VEGF-C application parameters.

The Venous Lymph Node Flap: Concepts, Experimental Evidence, and Potential Clinical Implications

“…Experimental research on lymph node transplantation has focused on two models: vascularized (LNF transfer) and avascularized (lymph node grafting). [14][15][16][17] The research generally agrees that in LNF transfer, nodal structure is preserved and lymphatic continuity is reestablished. In lymph node grafting, without growth factors enrichment, nodes necrose and lymphatic continuity is not reestablished.…”

“…The spread of methylene blue found from distant intradermal injections to the surgical field is a good indicator of restoration of lymphatic connections between the transplanted LNF and the lymphatics of the surrounding tissues. [14][15][16][17] Although the venous LNF model is novel, the venous flowthrough flap is not, even though the mechanism of perfusion is not clearly elucidated. 18 The key difference setting the venous LNF apart from traditional venous flaps is the identification and vascularized inclusion of a functional lymphatic unit.…”

“…The timing of 45 days was used because it is considered reliable to evaluate node viability and lymphatic flow reconnections in rats. [14][15][16][17]…”

“…This method has been validated by other studies. [14][15][16][17] The inguinal scar was reopened after 30 minutes, and the methylene blue drainage within the flap was verified.…”

Outcomes of vascularized versus non‐vascularized lymph node transplant in animal models for lymphedema. Review of the literature

“…Of the 16 studies included, only two presented both vascularized and non-vascularized groups in the same study [4,5], allowing for more consistent conclusions. The heterogeneity in the experimental lymphedema model might have an impact on the final results since in some studies the lymphedema was clinically evidenced [6,7], in other studies the model was created with removal of lymph nodes and/or lymphatic vessels [8][9][10][11][12][13][14][15] or without removal of lymph nodes [16,17].…”