Regulation of Migration of Human Colonic Myofibroblasts

Abstract

Background and Aim: The migration of mesenchymal cells to areas of mucosal or submucosal tissue damage is an essential factor for wound healing in the intestine. Thus far, neither migration inducing factors nor signal transduction cascades involved in the migration of colonic myofibroblasts (CMF) have been studied in detail. Methods: Primary CMF were isolated from the mucosa of surgical specimens or endoscopic biopsies. Migration assays of CMF were performed in the modified 48-well Boyden chamber. Secreted growth factors were quantified by ELISA. Results: CMF secrete autocrine or paracrine migration stimulating factors. Culture supernatant of CMF collected after 24, 48, and 72 h (=conditioned media) stimulated the migration of CMF ( 48.9 - 4.5; 60.3 - 5.3 and 67.8 - 6.4 cells/hpf, respectively). Heating of conditioned media to 95°C or addition of cycloheximide during the conditioning period abolished migration. Addition of PDGF-AB (2.5-50 ng/ml) or IGF-I (10-300 ng/ml) to CMF conditioned media further increased the migration of CMF to a maximum of 177 and 160%, respectively, when compared to the migration induced by conditioned medium alone. Addition of EGF (2.5-50 ng/ml) or TGF- g 1 (1-50 pg/ml) caused an increased CMF migration up to 139 and 128%, respectively. MCP-1 (5-50 ng/ml) and bFGF (10-200 ng/ml) had no effect on CMF migration. Conclusion: The growth factors PDGF-AB, IGF-I, EGF and TGF- g 1 stimulate the migration of CMF. However, factors secreted by CMF are essential for their ability to migrate in response to these growth factors. The identification of physiologically relevant migration inducing factors may help to elucidate the network of interactions and the complex mechanisms involved in intestinal wound healing or fibrosis.