Fibrotic remodeling of CTEPH thrombi. (A) qPCR analysis for TGFB1 expression in CTEPH thrombus (Thr) (n = 8) and nonthrombosed pulmonary artery (PA) (n = 6). (B) qPCR analysis (n = 22) and (C) immunoblotting (n = 8) for different collagen types in CTEPH thrombus. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was chosen as a housekeeping protein. (D) Representative trichrome staining of CTEPH thrombus (scale bar, 200 µm) and magnification of the boxed area shows fibroblast-like cells (scale bar, 100 µm). (E) Merged immunofluorescence staining for α-SMA (red) and FAP (yellow) of CTEPH thrombus; single-channel images are shown on the right (scale bars, 20 µm). Data in panel A are shown as mean ± SEM. **P < .01 (unpaired Student t test).