In this article we review the cellular and molecular mechanisms of
gastric ulcer healing. A
gastric ulcer (GU) is a deep defect in the gastric wall penetrating through the entire mucosa and the muscularis mucosae. GU healing is a regeneration process that encompasses cell dedifferentiation, proliferation, migration, re-epithelialization, formation of granulation tissue, angiogenesis, vasculogenesis, interactions between various cells and the matrix, and tissue remodeling, all resulting in
scar formation. All these events are controlled by
cytokines and
growth factors (e.g.,
EGF, TGFα, IGF-1, HGF, bFGF, TGFβ,
NGF,
VEGF,
angiopoietins) and
transcription factors activated by tissue injury. These
growth factors bind to their receptors and trigger cell proliferation, migration, and survival pathways through Ras, MAPK, PI3K/Akt, PLC-γ, and Rho/Rac/actin signaling. The triggers for the activation of these
growth factors are tissue injury and
hypoxia.
EGF, its
receptor, IGF-1, HGF, and COX-2 are important for epithelial cell proliferation, migration, re-epithelialization, and gastric gland reconstruction.
VEGF,
angiopoietins, bFGF, and
NGF are crucial for blood vessel regeneration in GU
scars. The
serum response factor (SRF) is essential for
VEGF-induced angiogenesis, re-epithelialization, and blood vessel and muscle restoration. Local
therapy with
cDNA of human recombinant VEGF165 in combination with angiopoietin1, or with the
NGF protein, dramatically accelerates GU healing and improves the quality of mucosal restoration within
ulcer scars. The future directions for accelerating and improving healing include local gene and
protein therapies with
growth factors, their combinations, and the use of stem cells and tissue engineering.