Role of senescent fibroblasts on alkali-induced corneal neovascularization

Cellular senescence acts as a potent regulator of tumor suppression and fibrosis limitation; however, its contribution and crosstalk with neovascularization during normal wound healing has not been examined. Here, we explored the role of senescent fibroblasts on neovascularization with a mouse model of alkali-induced corneal wound healing. Senescent cells accumulated in corneal stroma from day 7 to 27 after alkali burn and peaked on day 14, which was consistent with the development of corneal neovascularization (CNV). In vitro and in vivo assays confirmed that the senescent cells were derived primarily from activated corneal fibroblasts. Furthermore, senescent corneal fibroblasts exhibited enhanced synthesis and secretion of extracellular matrix-degrading enzymes (matrix metalloproteinases 2, 3, and 14 and tissue- and urokinase-type plasminogen activators) and angiogenic factors (vascular endothelial growth factor) and decreased expression of anti-angiogenic factors (pigment epithelium-derived factor and thrombospondins), which supported the proliferation, migration, and promotion of tube formation of vascular endothelial cells. Intrastromal injection of premature senescent fibroblasts induced CNV earlier than that of normal fibroblasts, while matrix metalloproteinase inhibitors blocked the early onset of senescent cell-induced CNV. Therefore, senescent fibroblasts promoted the alkali-induced CNV partially via the enhanced secretion of matrix metalloproteases.