Perivascular cells regulate endothelial membrane type-1 matrix metalloproteinase activity.

Area of Science:

• Endothelial cell biology
• Extracellular matrix remodeling
• Angiogenesis research

Background:

• Endothelial cells initiate blood vessel formation during angiogenesis.
• Matrix metalloproteinases (MMPs) are crucial for extracellular matrix degradation in angiogenesis.
• Membrane type-1 matrix metalloproteinase (MT1-MMP) plays a key role in pro-MMP-2 activation.

Purpose of the Study:

• To investigate the role of MT1-MMP in endothelial cells during angiogenesis.
• To determine how perivascular cells influence endothelial cell MMP activity.
• To elucidate the mechanisms by which supporting cells regulate endothelial MMPs.

Main Methods:

• Culture of human umbilical vein endothelial cells (HUVECs) with angiogenic stimuli.
• Assessment of MT1-MMP expression and activity.
• Pro-MMP-2 activation assays using inhibitors and antibodies.
• Coculture experiments with smooth muscle cells (SMC) and pericytes (PC).
• Analysis of tissue inhibitor of metalloproteinases (TIMP) expression.

Main Results:

• Angiogenic stimuli upregulated MT1-MMP in HUVECs.
• MT1-MMP was identified as the primary mediator of pro-MMP-2 activation in HUVECs.
• Coculture with SMCs or PCs suppressed HUVEC pro-MMP-2 activation.
• This suppression was linked to TIMP-2 in SMC-conditioned media.
• Perivascular cells inhibited HUVEC MT1-MMP activity via TIMP-3 expression.

Conclusions:

• Perivascular cells modulate endothelial cell MT1-MMP function through selective TIMP expression.
• This regulation by supporting cells is critical for controlling MMP activity in angiogenesis.
• The interplay between endothelial cells and perivascular cells is vital for maintaining blood vessel architecture and neovascularization.