Human Peritoneal Adhesions Show Evidence of Tissue Remodeling and Markers of Angiogenesis

Purpose This study was designed to investigate the vascular structure and angiogenic activity of human peritoneal adhesions. Methods Adhesions were collected from patients undergoing laparotomy (n = 32). Histologic features were documented and the distribution of mature and immature vascular markers were determined by immunolocalization and quantified by image analysis. The three-dimensional organization of blood vessels was investigated by confocal microscopy. Expression of vascular endothelial growth factor A, its receptor flk-1, and proliferating cell nuclear antigen were assessed by immunohistochemistry as indicators of angiogenic activity. Results Adhesions were found to be vascularized structures comprising bundles of collagen, interspersed with varying amounts of adipose tissue. Functional blood vessels expressed recognized vascular markers (vWF, CD34, α-SMA, and CD105) and formed a branching network similar to that of the peritoneum. Those adhesions expressing vascular endothelial growth factor A and its receptor showed significantly higher numbers of immature vessels as defined by expression of CD105. Omental adhesions (n = 16) contained significantly more adipose tissue (P < 0.05) and displayed a higher microvessel density (P < 0.01) but lower cellularity (P < 0.05) compared with nonomental adhesions (n = 16). Conclusions All adhesions contained functional blood vessels and most showed evidence of cell proliferation. The presence of vascular endothelial growth factor A and its receptor in human adhesions suggests ongoing angiogenic activity. This study demonstrates that adhesions are vascular structures with evidence of tissue remodeling and suggests potential for new prevention strategies involving antiangiogenic therapies. Presented in part at the Tripartite Colorectal Meeting, Dublin, Ireland, July 5 to 7, 2005. Supported by the Royal College of Surgeons of England, Shire Pharmaceuticals, Medical Research Council, and Christie Hospital Surgical Research Fund.