MICROSCOPY Vol.43▶No.2 2008
â– Feature Articles: Re-evaluation of fibroblasts and fibroblast-like cells: newer aspects

Contraction of fibroblasts, and myofibroblasts

Keisuke Ina, Hirokazu Kitamura and Yoshihisa Fujikura

Abstract: Myofibroblasts, which emerged in the tubulointerstitium of diabetic nephropathy, were called activated fibroblasts and gave rise to accumulation of extracellular matrices including collagen fibers, i.e. fibrosis. Also, it has been considered due to the morphological characteristics that they caused cell contraction following by contraction of fibrosis tissue, and they were regarded to be an intermediate type of cell between a fibroblast and a smooth muscle cell. Myofibroblasts have been demonstrated to emerge via transdifferentiation that specific cells such as fibroblasts expressed αSMA (αsmooth muscle actin) by exposure to TGF-β1. Significance of αSMA expression which was the major morphological feature of myofibroblasts was examined in the in vitro study using renal fibroblasts. It was revealed that expression of αSMA was not always necessary for contraction since fibroblasts formed stress fibers and contracted without expression of αSMA, and αSMA expression evoked contraction. Also, the intracellular signaling pathway of αSMA expression was distinct from that of contraction.

Key words: fibroblast, myofibroblast, α smooth muscle actin, fibrosis, diabetic nephropathy