title: Absence of type VI collagen paradoxically improves cardiac function, structure, and remodeling after myocardial infarction.
abstract: BACKGROUND
  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 post-MI wound healing would alter cardiac function and remodeling in the days to weeks after injury.
  
  
  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 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.
authors.affiliation: Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Luther
authors.forename: Charles K
authors.initials: CK
authors.lastname: Thodeti
authors.forename: Patricia E
authors.initials: PE
authors.lastname: Shamhart
authors.forename: Ravi K
authors.initials: RK
authors.lastname: Adapala
authors.forename: Cheryl
authors.initials: C
authors.lastname: Hodnichak
authors.forename: Dorothee
authors.initials: D
authors.lastname: Weihrauch
authors.forename: Paolo
authors.initials: P
authors.lastname: Bonaldo
authors.forename: William M
authors.initials: WM
authors.lastname: Chilian
authors.forename: J Gary
authors.initials: JG
authors.lastname: Meszaros
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D024142:Collagen Type VI / Q000235:genetics* / Q000378:metabolism*; D004195:Disease Models, Animal; D004452:Echocardiography; D005109:Extracellular Matrix / Q000378:metabolism / Q000473:pathology; D005355:Fibrosis / Q000235:genetics / Q000473:pathology / Q000503:physiopathology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009203:Myocardial Infarction / Q000000981:diagnostic imaging / Q000235:genetics* / Q000503:physiopathology*; D032383:Myocytes, Cardiac / Q000473:pathology / Q000502:physiology; D020257:Ventricular Remodeling / Q000502:physiology*
chemical_list: C540085:Col6a1 protein, mouse; D024142:Collagen Type VI