Absence of Type VI Collagen Paradoxically Improves Cardiac Function, Structure, and Remodeling After Myocardial Infarction
Rationale: We previously reported that type VI collagen deposition increases in the infarcted myocardium in vivo. To date, a specific role for this nonfibrillar collagen has not been explored in the setting of myocardial-infarction (MI).
Objective: To determine whether deletion of type VI collagen in an in vivo model of wound healing after MI would alter cardiac function and remodeling in the days to weeks after injury.
Methods and Results: Wild-type and Col6a1−/− mice were subjected to MI, followed by serial echocardiographic and histological assessments. At 8 weeks after MI, infarct size was significantly reduced, ejection fraction was significantly preserved (43.9%±3.3% versus 29.1%±4.3% for wild-type), and left ventricular chamber dilation was attenuated in the Col6a1−/− MI group (25.8%±7.9% increase versus 62.6%±16.5% for wild-type). The improvement in cardiac remodeling was evident as early as 10 days after MI in the Col6a1−/− mice. Myocyte apoptosis within the infarcted zones was initially greater in the Col6a1−/− group 3 days after MI, but by day 14 this was significantly reduced. Collagen deposition also was reduced in the infarcted and remote areas of the Col6a1−/− hearts. The reductions in chronic myocyte apoptosis and fibrosis are critical events leading to improved long-term remodeling and functional outcomes.
Conclusions: These unexpected results demonstrate for the first time to our knowledge that deletion of type VI collagen in this knockout model plays a critical protective role after MI by limiting infarct size, chronic apoptosis, aberrant remodeling, and fibrosis, leading to preservation of cardiac function.
- cell matrix
- myocardial infarction remodeling
- nonfibrillar collagen
- Received July 15, 2011.
- Revision received February 9, 2012.
- Accepted February 9, 2012.
- © 2012 American Heart Association, Inc.