Treatment with TGFβ-neutralizing antibody (1D11) prevents fibrosis and improves heart function in aortic banded Timp3−/− mice. A, trichrome staining of Timp3−/− hearts after 6 weeks (wk) post-AB, with or without 1D11 treatment. Scale bar, 100 μm. B, collagen volume fraction as a measure of myocardial fibrosis. C, qPCR of RNA for collagen types I and III, normalized to 18 S. D, transverse cross-sections of sham and aortic banded hearts 6 weeks after AB. E, heart function measurements performed as fractional shortening (FS) and LV end-diastolic dimension (LVEDD) in sham and 1, 3, and 6 weeks after aortic banding. F, heart weight-to-tibial length ratio (HW/TL). G, qPCR of RNA for molecular markers of hypertrophy, brain natriuretic peptide (BNP), β-myosin heavy chain (β-MHC), and α-skeletal actin in sham or aortic banded WT, Timp3−/−, and 1D11-treated hearts after 6 weeks. *, p < 0.05 compared with the 1D11-treated group. ‡, p < 0.05 compared with WT-AB.