Morphology of lymphatic regeneration in rat incision wound healing in comparison with vascular regeneration

In the wound healing process, angiogenesis is involved in the recovery of vasculature, and its process has been investigated. On the other hand, the reconstruction of lymphatic vessels in the injured subcutaneous tissue has not been studied in detail. We studied the recovery of lymphatic vessels using podoplanin immunohistochemistry in the paraffine section microscopy of the rat skin incision wound. Our result indicates a novel finding that subcutaneous tissue of the incised skin area does not show any recovery of lymphatic vessels up to 84 days after the skin incision. As the wound area shrunk, the surrounding subcutaneous tissue covered with the normal skin epithelial cells approached toward the center of the wound, and the lymphatic vessels in the surrounding tissue gradually reached the incision wound area. On the other hand, the regeneration of the vasculature occurred within the wound area as assessed by CD31 and von Willebrand Factor (vWF) immunohistochemistry. This difference was confirmed by the morphometric quantification of podoplanin- or vWF-positive vessels. Our results show that there is a clear difference in the recovery pattern of vascular and lymphatic vessels in the skin wound healing process.