Thrombospondin 1 synthesis and function in wound repair.

Thrombospondin 1 (TSP1) is a multifunctional extracellular matrix molecule that belongs to a family of homologous glycoproteins. TSP1 can be produced by many cell types that are involved in wound repair, including keratinocytes, fibroblasts, endothelial cells, and macrophages. To investigate the kinetics of TSP1 synthesis in wounds, mRNA from murine full thickness excisional dermal wounds was analyzed. TSP1 mRNA was undetectable in normal skin but was present in early wounds. After day 1, TSP1 mRNA levels within wounds slowly decreased, returning to undectable day 10. In situ hybridization revealed that the primary source of the TSP1 mRNA within wounds was macrophage-like cells in the inflammatory infiltrate. To explore the function of TSP1 production in sites of injury, wounds were treated with antisense TSP1 oligomers. Antisense-treated wounds contained 55 to 66% less TSP1-positive macrophages than control and exhibited a marked delay in repair. This delay included a decreased rate of re-epithelialization as well as a delay in dermal reorganization. The results suggest that TSP1 production by macrophages facilitates the repair process and provide evidence that TSP1 production is an important component of optimal wound healing.