Optimal Mechanical Stretch Promotes TSP-1 Expression Through Akt and GSK-3β/β-Catenin Signaling Pathways in Keloid Formation.

Background and Aims: The formation of keloids is influenced by mechanical stretch. Thrombospondin-1 (TSP-1) is identified as a tension-sensitive protein. However, the relationship between TSP-1 and keloid formation induced by mechanical stretch remains unknown. Methods: A simple customized mechanical stretch device was used for the application of homogeneous equibiaxial stretch (HES). Using Western blot and RT-PCR, the optimal stretch strength and duration were determined. Regarding the functional changes induced by stretch in keloid fibroblasts (Kfbs), cell function assays were used. The relationship between TSP-1 expression and stretch-induced scar formation in human and animal models was investigated using immunohistochemistry. The knockdown of TSP-1 in fibroblasts served as a reverse test. Results: Optimal HES (oHES) could be achieved with four rotations of the screws on our mechanical stretch device, resulting in a significant increase in vimentin, Col I, and fibronectin expression in Kfbs on Day 5. Additionally, oHES significantly promoted cell proliferation and migration. oHES resulted in the upregulation of TSP-1 expression in both in vitro and in vivo experimental settings. The inhibition of TSP-1 may attenuate oHES-induced keloid formation through the Akt and GSK-3β/β-catenin signaling pathways. Conclusion: The results confirmed that oHES promoted keloid formation by increasing Col I expression through TSP-1-mediated Akt and GSK-3β/β-catenin signaling pathways.