Amniotic fluid stem cell features supporting their putative role in fetal cell microchimerism

Abstract

Since the discovery in 2003 that fetal stem cells float in the amniotic fluid, a major question still remains unanswered. So far, the in vivo biological relevance of amniotic fluid stem cells (AFSCs) is unclear. Also already since many years, it is evident that fetal stem cells with putative regenerative potential exist in the circulation of pregnant women. To support the hypothesis that these two stem cell entities share a common origin, AFSCs would have to harbour a variety of specific features. Several of these properties, including anchorage-independent growth, high differentiation potential, fine-tuned apoptotic disposal and the absence of a malignant transformation potential, have already been demonstrated for AFSCs. Here we discuss that additional features, such as migration, invasion, extravasation or the potential to translocate from the amniotic fluid to the maternal circulation, should be tested to further support the theory that AFSCs might be involved in fetal cell microchimerism during pregnancy.