Basement membrane components stimulate epithelialization of intestinal defects in vivo

Subepithelial tissues have an important role in the structure and function of the intestinal epithelium. Basement membrane components (BMC) stimulate epithelial cell migration and differentiation in vitro. The aim of this study was to determine the effect of BMC and/or interstitial tissue collagen (type I) on the in vivo intestinal regenerative response to intestinal patching. Twenty rabbits had two 2 x 5 cm ileal defects patched with the serosal surface of adjacent caecum. Group 1 (n = 5) were controls; group 2 (n = 5), group 3 (n = 5) and group 4 (n = 5) had collagen, collagen plus BMC, and BMC respectively applied to the distal patched defect. Animals were killed at 7 d and evaluated grossly for epithelialization and contraction of the defects. Epithelial coverage was greatest in the distal patch of group 4 animals (62 +/- 9%) and was significantly greater than the group 4 proximal patch and control values (43 +/- 7 and 40 +/- 14%, P less than 0.05). Contraction was similar in all groups (38 +/- 5 to 45 +/- 5%). Crypt cell production rate, villus height, and disaccharidase activities were similar in all groups. BMC stimulated epithelialization via a local mechanism since only the distal patch was affected. Type I collagen did not stimulate epithelialization and inhibited the effect of BMC. Since crypt cell production rate was similar in all groups, the enhanced epithelialization seen with BMC is primarily due to increased cell migration.