Infarct size as a percentage of LV mass was reduced by MSCs ( -18.9 % ; 95 % CI , -30.4 to -7.4 ; within-group , P = .004 ) but not by BMCs ( -7.0 % ; 95 % CI , -15.7 % to 1.7 % ; within-group , P = .11 ) or placebo ( -5.2 % ; 95 % CI , -16.8 % to 6.5 % ; within-group , P = .36 ) .