Z. Liu1, P. P. Parikh1, H. Shao1, Y. Li1, R. Prokupets1, S. Liu1, O. C. Velazquez1 1University Of Miami,Surgery,Miami, FL, USA
Introduction: Wounds heal in coordination of a myriad of types of cells, including keratinocytes, inflammatory cells, endothelial cells and fibroblasts. Fibroblasts play pivotal roles in supporting wound healing and tissue remodeling by producing extracellular matrix proteins (ECM) and regulatory soluble factors, providing structural scaffolding and contracting the wound. However, the molecular mechanisms that determine the function of fibroblasts in wound healing remain unknown. Here, we uncover the Notch1 signaling pathway as a molecular determinant that controls the function of fibroblasts in wound healing and angiogenesis.
Methods: To explore the role of Notch1 signaling in regulating function of fibroblasts in wound healing and neovascularization, we generated two new mouse lines in which Notch1 signaling is specifically activated (Gain-Of-Function, GOF) or inactivated (Loss-Of-Function, LOF) in fibroblasts, respectively. A 6-mm skin wound was created on mouse dorsal skin by punch biopsy (n=6/group). Wound healing rates were evaluated based on daily photography. Wound tissue angiogenesis was assessed by Dil-LDL perfusion and confocal microscopy.
Results: Using novel mouse models, we demonstrated that Notch1 pathway activity could determine the function of fibroblasts in wound healing and angiogenesis. Notch1 activation in fibroblasts significantly inhibited wound angiogenesis (~40%, P<0.05) and wound closure rate (~30%, P<0.05). However, inactivation of Notch1 signaling in fibroblasts did not promote angiogenesis and wound healing, likely because the basal level of Notch1 activity in fibroblasts is already very low, lower Notch1 activity by deletion of Notch1 would not be expected to add additional effect.
Conclusion: These findings identify the Notch1 signaling pathway as a molecular determinant that regulates the function of fibroblasts in wound healing and angiogenesis, unveiling Notch1 pathway as a potential target for therapeutic intervention in delayed wound healing and/or vascular diseases.