Lymphedema development and lymphatic function following lymph node excision in sheep.

BACKGROUND

Our objective was to develop an animal model of postsurgical lymphedema that would permit quantitation of edema and lymphatic function after the removal of a single popliteal lymph node in sheep.

METHODS

As a measure of lymph transport, (125)I-human serum albumin was injected into prenodal vessels at 8, 12 and 16 weeks after nodal excision, and plasma levels of the protein tracer were used to calculate the transport rate of the tracer to blood (percent injected per hour). Edema was quantified from the circumferential measurement of the hind limbs.

CONCLUSIONS

Following nodal excision, the limbs became progressively more edematous up to 3 days after nodectomy. After this, the swelling decreased but had not resolved even at 16 weeks after surgery. Compared with control limbs (17.2 +/- 0.6; n = 7), lymphatic function was depressed at 8 weeks after surgery (10.6 +/- 1.5; n = 7). At 12 (14.4 +/- 1.0; n = 7) and 16 weeks (13.9 +/- 1.0; n = 6), regeneration of lymphatic vessels at the excision site helped to restore about 80% of lymphatic capacity. These techniques may be helpful in understanding the pathophysiology associated with cancer-related postsurgical lymphedema and may facilitate the development of new strategies to treat or prevent this condition.