Comparison of avascular lymph node fragment transplantation techniques to optimize lymphangiogenesis in the minipig model.

BACKGROUND: Secondary lymphoedema is a challenging pandemic. This condition may arise after oncologic resection of tumor-draining lymph nodes and/or radiation. Plastic-surgical procedures for lymphoedema comprise transplantation of vascularized lymph node flaps, which are, however, technically challenging and difficult to implement on a global level due to the scarcity of microsurgery facilities in some countries. To improve this situation, comparative research in valid animal models is needed. METHODS: A total of 33 minipigs were subjected to lymphatic resection in the hind limbs. This large animal model was used in a first phase to compare different lymph node fragmentation methods and assess lymphatic regeneration after avascular transplantation. In a second phase, several stimulants were tested for their effect on lymphatic regeneration after fragment transplantation. In a third phase, animals additionally received irradiation of the groin. In this novel animal model, autologous avascular lymph node fragment transplantation was complemented by peripheral injections of vascular endothelial growth factor-C (VEGF-C). Finally, regeneration rates were quantified in relative numbers (percentage) in the irradiated tissue. RESULTS: In the first phase, transversal lymph node fragmentation under preservation of the nodal capsule showed the best percentage of regeneration (62.5%). Peripheral intradermal administration of VEGF-C enhanced lymph node fragment regeneration (70.8%) better than injections of tetanus toxoid (41.6%) or Streptococcus suis (62.5%). Lymph node fragment regeneration also occurred in an irradiated porcine model of lymphadenectomy under VEGF-C administration (66.6%). CONCLUSIONS: The present findings provide a pre-clinical proof-of-concept for a possible simplification strategy for current operative procedures of autologous lymph node transplantation.Level of evidence : Not gradable.

Testicular yolk sac tumor and impaired spermatogenesis in a Holstein Friesian calf.

Yolk sac tumors are testicular germ-cell tumors of the non-seminoma type. In cattle, this neoplasm is very rare and to date has only been described three times. In human males, it usually occurs in infants and children. Immunohistochemistry provides solid criteria for diagnostics. Especially present pathognomonic Schiller-Duval bodies are helpful for identification. In this report, a 32-day-old Holstein Friesian calf presented with a highly enlarged right testis. Sonographic examination was performed and blood samples were taken to measure testosterone and estrogen levels. Furthermore, the testis was surgically removed and macroscopically, histologically, and immunohistochemically examined which lead to the diagnosis of testicular yolk sac tumor. The second testis was descended until the age of nine months and histology revealed impaired spermatogenesis. This report provides the first sonographic images of bovine testicular yolk sac tumor as well as the first information about hormone levels in calves with this neoplasm. It also shows the importance to combine anamnesis, histomorphological, and immunohistochemical findings in order to diagnose yolk sac tumors when pathognomonic structures are not present.

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

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.