Postconditioning promotes the cardiac repair through balancing collagen degradation and synthesis after myocardial infarction in rats
Authors: Ning-Ping Wang
Tiji Philip
Zhang-Feng Wang
Xue-Fen Pang
Zhi-Qing Zhao
Feng Bai
Suzanna Harmouche
Journal: Basic research in cardiology (2013)
Discipline: CLINICAL MEDICINE
Keywords: Postconditioning; infarct size; cardiac repair; extracellular matrix; collagens
Affiliations: Cardiovascular Research Laboratory, Mercer University School of Medicine, Savannah, GA 31404, USA.

Abstract:  Postconditioning (Postcon) reduces infarct size. However, its role in modulation of cardiac repair after infarction is uncertain. This study tested the hypothesis that Postcon inhibits adverse cardiac repair by reducing degradation of extracellular matrix (ECM) and synthesis of collagens via modulating matrix metalloproteinase (MMP) activity and transforming growth factor (TGF) β1/Smad signaling pathway. Sprague-Dawley rats were subjected to 45 min ischemia followed by 3 h, 7 or 42 days of reperfusion, respectively. In acute studies, four cycles of 10/10 s Postcon significantly reduced infarct size, which was blocked by administration of a mitochondrial K(ATP) channel blocker, 5-hydroxydecanoate (5-HD) at reperfusion. In chronic studies, Postcon inhibited MMP activity and preserved ECM from degradation as evidenced by reduced extent of collagen-rich scar and increased mass of viable myocardium. Along with a reduction in collagen synthesis and fibrosis, Postcon significantly down-regulated expression of TGFβ1 and phospho-Smad2/3, and up-regulated Smad7 as compared to the control, consistent with a reduction in the population of α-smooth muscle actin expressing myofibroblasts within the infarcted myocardium. At 42 days of reperfusion, echocardiography showed significant improvements in left ventricular end-diastolic volume and ejection fraction. The wall thickness of the infarcted middle anterior septum in the Postcon was also significantly greater than that in the control. The beneficial effects of Postcon on cardiac repair were comparable to preconditioning and still evident after a blockade with 5-HD. These data suggest that Postcon is effective to promote cardiac repair and preserve cardiac function; protection is potentially mediated by inhibiting ECM degradation and collagen synthesis. 

Retracted: Yes

PubPeer comments:
 This article has been retracted in February 2015. The retraction notice, posted at https: link.springer.com article 10.1007%2Fs00395-015-0469-6 , reads: *The article u201cPostconditioning promotes the cardiac repair through balancing collagen degradation and synthesis after myocardial infarction in ratsu201d, Basic Res Cardiol (2013) 108:318, was retracted by the authors who regret to have used different fields of the same samples for MMP staining and western blot assay to represent two distinct groups on two occasions in Figs. 4 and 5. Some of the raw data for the earlier experiments with the use of echocardiography for Figs. 8 and 9a were not available for further analysis to exclude that also the same samples were used for two distinct groups. The authors regret the effect of this action on the work of other investigators.* , 
 For the post-mortem analysis, here is Figure 4. Contrast changed to bring out details. * Red arrows: The last three lanes in the top panel (7 day) appear to look similar * Green arrows: Lanes 5-6 and lanes 8-9 appear to look similar. Sharp vertical background transitions are visible between several lanes. ![file] , 
 Here are some similarities between lanes in Figure 5. Arrows of the same color highlight lanes that look similar. Not ruling out that there might be more similarities. ![file] , 
 For Figure 8, it indeed appears as if two panels might have been reused to represent different experiments. * Blue boxes: In the Baseline column, the Con and Pre panels appear to show an overlap. ![file] , 
 For Figure 9, it indeed appears as if multiple panels might have been reused to represent different experiments. ![file] Here is a Forensically analysis for those people who are convinced more by software tools than the human eye. ![file] ,