Expression of gene for EIIIA- and EIIIB- fibronectin, fetal types of fibronectin, during gastric ulcer healing in rats.

Fibronectin (FN) is important for wound healing via cell proliferation, adhesion, differentiation, and matrix formation. Fetal types of FN mRNA, which include the region of EIIIA or EIIIB, are well expressed during embryonic development and wound healing. This study was done to investigate the mRNA expression of full-length FN, EIIIA- and EIIIB-FN, and the localization of FN in the gastric tissues during ulcer healing with northern blot analysis and immunohistochemical technique. Gastric ulcers in rats were produced by acetic acid. EIIIA- and EIIIB-FN mRNA were not detected in normal gastric tissues, but were expressed in the ulcerated tissues throughout the healing phase. However, on day 60 (in the scarred phase), the EIIIA- and EIIIB-FN mRNA had disappeared. The levels of full-length FN mRNA were increased from day 3 to 32 compared with the control levels, and decreased to the control levels on day 60. Full-length FN was predominantly localized at the mesenchyme around the infiltrating inflammatory cells in the granulation tissues and the basement membranes of the nonproliferating epithelial cells, which were regenerated at the ulcer margin. Thus, fetal gene transcripts of FN suggest the important role of fetal FN in gastric ulcer healing, mainly via the migration of mesenchymal and epithelial cells.