Figure 5.

Foxd1 progenitor–derived pericytes and Coll-GFP⁺ resident fibroblasts exhibit morphologic and behavioral differences in two-dimensional culture. (A) Fluorescence images of primary cultures of the Foxd1 progenitor–derived cells (pericytes) permanently expressing tdTomato, isolated from Foxd1-Cre; tdTR mice (left). Foxd1 progenitor–derived cells exhibit long foot processes characteristic of pericytes in vitro (arrow). Immunostaining of tdTomato⁺ cells in vitro demonstrates colabeling of PDGFRβ in tdTomato⁺ cells, whereas only some tdTomato⁺ cells colabel with NG2 (right). (B) Coll-GFP⁺ fibroblasts from Coll-GFP^Tg mice at passage 2 show a distinctly different morphology from Foxd1 progenitor–derived pericytes. (C) tdTomato⁺ pericytes isolated from Foxd1-Cre;tdTR mice activate αSMA (green) protein expression and stress fiber formation in response to TGFβ stimulation in vitro after 24 hours. (D) Foxd1 progenitor–derived pericytes (tdTomato⁺, Coll-GFP⁻) isolated from Foxd1-Cre; tdTR; Coll-GFP^Tg mice shown after two passages in culture. Foxd1-derived pericytes show persistent expression of red fate marker (left, red) in vitro. Nearly all Foxd1 progenitor–derived pericytes activate high levels of Coll-GFP (middle, green) in vitro (bars = 50 μm). (E and F) Coll-GFP⁺ fibroblasts show increased migration compared with pericytes in response to TGFβ (1 ng/ml), PDGF-BB (50 ng/ml), and PDGF-AA (30 ng/ml) at 24 hours control: serum free (mean ± SEM, n = 3, *P < 0.05 fibroblast vs. pericyte). (G and H) PDGF-BB treatment increased proliferation in Coll-GFP⁺ fibroblasts compared with control (serum-free) at 72 hours, but not in pericytes. Proliferation measured by BrdU ELISA reported as absorbance relative to control. (mean ± SEM, n = 3, *P < 0.05 vs. control).