Myofibroblast involvement in renal interstitial fibrosis

Interstitial fibrosis is a final common pathway for many, if not all forms of end-stage renal disease. Although the kidney contains several cell types that are capable of collagen biosynthesis, most in vitro and in vivo studies suggest that fibroblasts generate the principal interstitial matrix collagens. Recent studies have defined a role for myofibroblasts (cells with features of both fibroblasts and smooth muscle cells) in progressive renal interstitial fibrosis. Renal myofibroblasts are hyperproliferative and up-regulated matrix producers, consistent with them being 'activated' fibroblasts. Interstitial myofibroblasts also share a number of anatomical, phenotypic and biosynthetic features with the glomerular mesangial cell. The interstitium consists of a complex mixture of inflammatory and fibrogenic mediators. The fibroblast response to this microenvironment includes chemotaxis, proliferation and increased synthetic activity. However, the derivation and fate of the fibroblast/myofibroblast during scarring remains unclear, with migration, proliferation, differentiation and cell death all likely to determine cell number.