Amniotic Fluid Stem Cells

The amniotic fluid or liquor amnii, was first isolated and studied during the beginning of the 20th century (Brace et al., 1989). More recently, in the 1960s and 1970s there was an increased interest in characterization and culture of the cells contained in the amniotic fluid (Huisjes HJ, 1970; Marchant GS, 1971). Nevertheless, most all of these studies were directed at using amniotic fluid, and the cells contained within, for determining the health of the fetus during development, or to provide a general characterization of the amniotic fluid. Although the discovery of stem cells, in particular bone marrow stem cells, occurred in the 1960’s, it was not until recently that the possibility of isolating stem cells from the amniotic fluid was investigated. Amniotic fluid stem cell isolation and characterization is therefore fairly recent, dating back to the early 1990’s (Torricelli et al., 1993). The study of amniotic fluid-derived stem cells (AFDSCs) has captured the attention of researchers and clinicians for several reasons. First, AFDSCs can be collected during amniocentesis and isolated from material that would be otherwise discarded. Therefore, their use is not subject to the ethical debate that surrounds the use of embryonic stem cells. Second, like other fetal derived stem cells, storage of AFDSCs is easy and achieved at minimal costs. AFDSC populations can be easily expanded, and have shown the capability of being stored over long periods of time with no adverse effects (Da Sacco et al., 2010). Furthermore, the “banking” of AFDSCs from developing fetuses, may guarantee a source of stem cells with a matching immune profile to that of the recipient. Most importantly, the extensive characterization of a specific subset of AFDSCs positive for the marker c-Kit+ (De Coppi et al., 2007), have displayed no tumor formation following transplant into an animal model, even after several months. These cells, known simply as amniotic fluid stem cells (AFSC) have been at the forefront of AFDSC research and will be discussed in depth later. Finally, as a source of stem cells collected before birth AFDSCs may become an invaluable source of stem cells for direct treatment of various genetic disorders treatable in utero (Turner CG et al., 2009). The potential applications and implications of AFDSCs in regenerative medicine and therapeutic treatments are significant, however; AFDSCs research is still in its infancy and much work is required to properly characterize AFDSCs and determine their effectiveness. In this chapter, we describe the different AFDSCs that have been isolated to date, list their characteristics, and provide an overview of the different organs in which AFDSCs have been used in vitro or in vivo to develop this stem cell population into a viable therapeutic strategy.