Conditioned Medium Obtained from Amnion-Derived Mesenchymal Stem Cell Culture Prevents Activation of Keloid Fibroblasts

Background: Mesenchymal stem cells are a valuable cell source in regenerative medicine, and conditioned medium obtained from mesenchymal stem cells reportedly inhibits inflammation. Keloids are characterized by abnormal fibrosis, caused by fibroblasts in response to inflammation. In this study, the authors evaluated whether conditioned medium obtained from amnion-derived mesenchymal stem cells suppressed activation of keloid fibroblasts. Methods: Keloid (n = 7), mature (n = 5), and normal (n = 5) fibroblasts were harvested from patients. Fibroblasts were stimulated with transforming growth factor (TGF)-beta, and the effects of conditioned medium obtained from amni-on-derived mesenchymal stem cells on cell proliferation, activation, and expression of extracellular matrix-related genes were analyzed. The effect of concentrating the conditioned medium by ultrafiltration on fibroblast activation was also analyzed. Results: Conditioned medium obtained from amnion-derived mesenchymal stem cells significantly up-regulated proliferation of mature fibroblasts but tended to suppress that of keloid fibroblasts. Conditioned medium obtained from amnion-derived mesenchymal stem cells significantly suppressed the TGF-ss-induced up-regulation of a-smooth muscle actin in keloid and normal fibroblasts and collagen I in keloid fibroblasts, but not in mature fibroblasts. The conditioned medium obtained from amnion-derived mesenchymal stem cells concentrated by ultrafiltration and the filtrate significantly suppressed TGF-ss-induced a-smooth muscle actin expression. Conclusion: Conditioned medium obtained from amnion-derived mesenchymal stem cells prevents proliferation and activation of keloid fibroblasts and is a promising keloid treatment for administration as a topical agent.