Pericytes display increased CCN2 expression upon culturing

Abstract

By providing a source of alpha-smooth muscle actin (alpha-SMA)-expressing myofibroblasts, microvascular pericytes contribute to the matrix remodeling that occurs during tissue repair. However, the extent to which pericytes may contribute to the fibroblast phenotype post-repair is unknown. In this report, we test whether pericytes isolated from human placenta can in principle become fibroblast-like. Pericytes were cultured in vitro for 11 passages. The Affymetrix mRNA expression profile of passage 2 and passage 11 pericytes was compared. The expression of type I collagen, thrombospondin and fibronectin mRNAs was induced by passaging pericytes in culture. This induction of a fibroblast phenotype was paralleled by induction of connective tissue growth factor (CTGF/CCN2) and type I collagen protein expression and the fibroblast marker ASO2. These results indicate that, in principle, pericytes have the capacity to become fibroblast-like and that pericytes may contribute to the population of fibroblasts in a healed wound.

Fig. 1

Induction of CCN2, type I collagen and ASO2 protein production in pericytes passaged in vitro. Protein harvested from primary human placenta pericyes in culture for 2, 3, 4, 5, 6, 7,11 passages post-isolation (P2, P3, P4, P5, P6, P7 and P11, respectively) were subjected to Western blot analysis with anti-CCN2, anti-ASO2, anti-type I collagen, anti-α-SMA and anti-GAPDH antibodies are shown. Four different isolates of pericytes were tested. Westerns of protein extracts from human dermal fibroblasts from two different individuals are shown (F1 and F2)

Fig. 2

Change in morphology of cultured pericytes upon passaging. Phase contrast images of pericytes were taken at passage (P) 2, 5, 7 and 11. Note that cells gradually acquire a linear, fibroblast-like morphology