Endogenous Epicardial Regenerative Response Figure 2. Comparison of the expression pattern of Wt1 and Cre in the healthy and infarcted heart. In the ventricles of control (A–C) Wt1Cre mouse cTnI mRNA is expressed in all cardiomyocytes (A), whereas neither Wt1 (B) nor Cre (C) mRNA are detected in the ventricles. One day after LAD ligation (post-MI) (D–F), the expression level of cTnI mRNA has dropped below detection in the infarcted zone and is expressed at a lower level in the cardiomyocytes of the border zone than in remote healthy myocardium (D). At one day post-MI both Wt1 and Cre (E & F) are not detected. Three days post-MI (G–O), the expression of both Wt1 (H L) and Cre (I, N) are found in the epicardial cells covering the border of the PLOS ONE | www.plosone.org 5 September 2012 | Volume 7 | Issue 9 | e44692