From hyperplasia to neoplasia and invasion: angiogenesis in the colorectal adenoma-carcinoma model

Fibrocollagen-covered prosthesis for a noncircumferential segmental tracheal replacement

OBJECTIVE

Fibrocollagen-covered polyester meshes can be used as possible substitutions for tracheal segments if they become integrated into the tissue without complications. The aim of this study was to assess a fibrocollagen-covered polyester prosthesis to be used as a substitution for a tracheal segment.

METHODS

We performed a blind, randomized experimental assay. Adult Wistar rats were assigned to one of 2 groups. Prostheses were made by implanting polyester tubing in a group of animals to cover them with homologous collagen. They were implanted as substitutions of tracheal segments in the experimental group after creating a defect in the anterior wall of the trachea. Clinical, histomorphologic, and immunohistochemical assessments were made at 4 different time points.

RESULTS

The experimental group presented some respiratory distress signs during the first 7 to 10 days, such as stertors, hissing, and low motor activity. After this initial period, the symptoms subsided progressively and disappeared at the end of the first month. These respiratory symptoms caused no mortality. Initially undifferentiated monolayer cells predominated on the implant's surface, but during the last 2 months, the proportion of epithelial and ciliated cells was similar to that seen in control animals. Types I, III, and V collagen fibers were identified around the mesh. The intraluminal area of the tracheas with prostheses and prosthesis thickness were larger during the 4 months of the experiment. The increase in thickness was due to angiogenesis without evidence of fibrosis or chronic inflammation.

CONCLUSIONS

Polyester-collagen prostheses used as substitutions of tracheal segments in rats enabled the proliferation of normal respiratory epithelium and maintained tracheal function without collapse, inflammatory reaction, or secondary stenosis.

Interstitial cell cyclooxygenase-2 expression is associated with increased angiogenesis in human sporadic colorectal adenomas

Cyclooxygenase (COX)-2 plays an important role in intestinal tumorigenesis and angiogenesis in animal models. In superficial areas of human sporadic colorectal adenomas, COX-2 is expressed predominantly by interstitial macrophages, in close proximity to microvessels. The aim of this study was to investigate the association between microvessel density (MVD) and COX-2 expression in human sporadic colorectal adenomas. Immunohistochemistry and immunofluorescence for CD31 and COX-2 were performed on a well-characterized series of human sporadic colorectal adenomas (n = 37). The mean MVD and COX-2 expression level (scored 0-3) in superficial and deep interstitial cells of adenomas were assessed by two independent observers. Superficial MVD was increased in COX-2-positive adenomas, compared with COX-2-negative adenomas (p = 0.037). There was a significant correlation between superficial MVD and increasing superficial interstitial cell COX-2 expression score (p = 0.048). COX-2-expressing interstitial cells aggregated in areas of high MVD. No relationship was evident between MVD and COX-2 expression in either deep interstitial cells or epithelial cells. Multivariate analysis demonstrated that only adenoma size (p = 0.005) was a significant independent predictor of MVD. COX-2 protein expression by superficial interstitial cells in human sporadic colorectal adenomas is associated with increased angiogenesis. Promotion of angiogenesis may play a role in the pro-tumourigenic activity of COX-2 during growth of human colorectal adenomas.