Masum M. Mia and Ruud A. Ba
Objective: Myofibroblasts are causally involved in the hallmark of fibrosis, i.e. the excessive deposition of a collagen-rich extracellular matrix (ECM). So far, there are no pharmacological treatments that combat successfully fibrosis, making this pathology a major global disease burden. In preclinical models, mesenchymal stem cells attenuate fibrosis, but how these stem cells are involved remains unclear. In this study, we assessed the effect of paracrine factors of fetal and adult human stem cells on primary dermal myofibroblasts. Methods: TGFβ1-activated human adult dermal (myo) fibroblasts (two donors: age 27 and 73 years) were treated with conditioned medium collected from amniotic fluid-derived stem cells (cmAFSCs) as well as from adipose tissue derived stem cells (cmADSCs). The effects of conditioned medium on the following fibrogenic events were measured: formation of myofibroblasts, synthesis of ECM as well as cell proliferation. Results: Cell proliferation was enhanced by cmAFSCs. The main pro-fibrotic effects of TGFβ1, namely the induction of myofibroblast formation (αSMA) and collagen type I protein synthesis, were blocked to baseline levels with cmAFSCs. Similar data were obtained for the ECM-proteins tenascin C, fibronectin, and collagen type III. Furthermore, pre-existing myofibroblasts could be reversed into fibroblasts. Synthesis of lysyl hydroxylase 2, a collagen-modifying enzyme, was highly up-regulated despite the absence of the major fibrillar collagens, and it is speculated that this enzyme has also another function. The use of bFGF-neutralizing antibodies revealed that the suppression of αSMA stress fibers by cmAFSCs can be partially attributed to bFGF. Despite the fact that cmADSCs was also able to reverse pre-existing myofibroblasts into fibroblasts, its anti-fibrotic properties was less compared with cmAFSCs. Major discrepancies between mRNA levels and protein levels were observed, especially for collagen type I. Conclusions: This study describes the high anti-fibrotic potential of conditioned medium from human fetal stem cells on adult fibroblasts cultured under pro-fibrotic conditions.