Pluripotent Stem Cells from Human Amniotic Fluid and their Immunomodulatory Properties

There occur two main stem cell populations in the human amniotic fluid mesenchymal stem cells and amniotic fluid stem cells (AFSCs) which can be used as a primary in vitro material with no need for transformation/immortalization (1,2). We focused our attention on AFSCs as a novel type of stem cells sharing features common to both embryonic and adult stem cells, including phenotypic markers. AFSCs will generate all of three primary germ layers, yet will not form tumors upon implantation in vivo. AFSCs express markers associated with a pluripotent undifferentiated state, and are characterized by a high proliferation potential in vitro, with a doubling time of approximately 16–20 h. To characterize the molecular signature of these cells, we generated proteomic maps. In addition, AFSCs were found to possess remarkable immunomodulation properties. In murine models of inflammation and autoimmunity, we found that AFSCs tend to migrate to inflamed tissues where they modulate the inflammatory response. Interestingly, we have also found that sphingosine 1-phosphate (S1P) signaling is critically involved in the migration and homing ability of AFSCs to inflamed tissues. AFSCs possess S1P receptors and the enzymic machinery required for its biosynthesis and degradation. Thus modulation of the S1P signaling pathway in AFSCs might result in profound changes in AFSCs migration, as observed in vitro and in vivo.