TIMP3 and heart failure: In the present work we examined the effect of exogenous HMGB1 in a murine model of heart failure and found that HMGB1 intramyocardial injection improved left ventricular (LV) function and remodelling; these effects were associated with cardiac regeneration, increased collagenolytic activity, miR-206 overexpression and miR-206 -mediated inhibition of tissue inhibitor of metalloproteinase 3 (TIMP-3).