Chondromodulin-I maintains cardiac valvular function by preventing angiogenesis

Area of Science:

• Cardiovascular Biology
• Molecular Mechanisms of Disease
• Vascular Biology

Background:

• Cardiac valves are normally avascular, but this characteristic is lost in valvular heart diseases (VHDs).
• Chondromodulin-I, an antiangiogenic factor found in cartilage, is highly expressed in healthy cardiac valves.

Purpose of the Study:

• To investigate the molecular mechanisms of valvular avascularity.
• To determine the correlation between chondromodulin-I, angiogenesis, and VHD.

Main Methods:

• Gene targeting of chondromodulin-I in aged mice to assess effects on cardiac valves.
• In vitro studies using conditioned medium from valvular interstitial cells and endothelial cells.
• Analysis of human VHD samples for chondromodulin-I, VEGF-A, neovascularization, and calcification.

Main Results:

• Chondromodulin-I deficiency in mice led to increased VEGF-A, angiogenesis, lipid deposition, and calcification in cardiac valves, mimicking early aortic stenosis.
• Valvular interstitial cells inhibited endothelial cell function and induced apoptosis, with partial reversal by chondromodulin-I knockdown.
• Human VHD samples showed reduced chondromodulin-I and increased VEGF-A, neovascularization, and calcification.

Conclusions:

• Chondromodulin-I plays a critical role in maintaining normal cardiac valve function by suppressing angiogenesis.
• Downregulation of chondromodulin-I and subsequent angiogenesis are implicated in the pathogenesis of VHD.