Summary
Published in Bioactive Materials (2022), this peer-reviewed study used 3D Petri Dish® micro-molds to form scaffold-free 3D microtissues. Full citation: Guo, Yaru, et al. Matrix stiffness modulates tip cell formation through the p-PXN-Rac1-YAP signaling axis
Matrix stiffness modulates tip cell formation through the p-PXN-Rac1-YAP signaling axis
Research Overview
Angiogenesis begins when endothelial tip cells sprout from existing vessels, yet how matrix mechanics govern tip-cell formation had been largely overlooked. This study found elevated CD31 expression in the stiffened outer layer of hepatocellular carcinoma compared with surrounding soft tissue, and showed that stiffened matrix promoted sprouting from endothelial spheroids and upregulated tip-cell genes in vitro.
Tip cells were themselves stiffer, with more organized actin and greater YAP nuclear translocation than stalk and phalanx cells. Substrate stiffness regulated FAK and Paxillin phosphorylation at focal adhesions, driving Rac1 from inactive to active — a mechanotransduction chain from matrix to tip-cell identity.
Key Discoveries
- Stiffened matrix increased sprouting from endothelial spheroids and tip-cell gene expression
- Tip cells were stiffer, more actin-organized, and showed greater YAP nuclear transfer than stalk/phalanx cells
- Stiffness acted through FAK/Paxillin phosphorylation and Rac1 activation at focal adhesions
