Table 1: Comparison of ES, AM and AF stem cells.

Embryonic stem cellsAmniotic epithelial cellsAmniotic mesenchymal stromal cellsAmniotic fluid cells

SourceInner cell mass of preimplantation embryoAmniotic membrane Amniotic membraneAmniotic fluid
In vitro lifespan300+ population doublings [48]14 population doublings [49]5–10 passages [50], 27 population doublings [51]55 [52] to 250+ [14] population doublings
Differentiation potential in vitro Ectodermal, mesodermal, endodermal [53]Ectodermal, mesodermal, endodermal [20]Ectodermal, mesodermal, endodermal [20]Ectodermal, mesodermal, endodermal [14]
TumorigenicityYes [54]No [15]Not knownNo [14]
Ethical issuesYesNoNoNo
Clinical trialsYes [55]Yes [56]NoNo