Immunohistochemical long-term evaluation of laminin expression in microvascular anastomoses of the carotid artery in the Wistar rat

Introduction: The main risk of complications of free-flap tissue transfer is from the microvascular anastomoses. The anastomoses are threatened by thrombosis, aneurysm and vascular insufficiency. Laminin is associated with the basement membrane complex and plays an essential role in vascular tissue organization, wound healing and supports mechanical properties of vessels. A long-term animal experiment was used to obtain new information on the distribution of laminin in anastomoses. Methods: Seventy Wistar rats, seven groups of 10 animals each, were operated upon. A 4mm long segment of common carotid artery was removed and reinserted. After various periods (from directly postoperative to 6 months later), the common carotid arteries, including the bifurcation, were isolated after cardiovascular perfusion. Carotid arteries were embedded and cross-sections stained using an immunohistochemical anti-laminin-antibody. Two anastomoses with four sutures each were examined by using this technique to evaluate histomorphology and intensity of anti-laminin staining. Results: Compression, shift and dehiscence were often seen following vessel apposition. A loss of laminin expression was observed in the media in cases of compression and shift after 6 months. The grade of expression of laminin in anastomoses was dependent on the extent of injury. Conclusions: The application of antibodies to identify the laminin distribution was valuable for studying vascular healing. A well-performed microvascular anastomosis is clinically important not only for the acute phase following the operation, but also long term. Further antibody studies could be used in follow-up studies of vascular prostheses. (C) 2004 European Association for Cranio-Maxillofacial Surgery.