Human amniotic epithelial cells(hAEC) are located in the inner layer of the amniotic membrane and surrounded by human amniotic mesenchymal cells(hAMC) and an extracellular matrix. hAEC has a typical epithelial celllike morphology and an ultra-structure, whereas hAMC exhibits mixed epithelial–mesenchymal, ultrastructural features. These amniotic derived stem cells can express octamer 4, Nanog, redox regulator 1, sex determination region of Y chromosome-related high mobility group-box 2, and other stem cell markers, which may indicate a higher multi-lineage differentiation potential than adult stem cells. In vitro osteoblastic culture can promote the bone alkaline phosphatase level, osteoblast marker expression(such as type 1 collagen and osteocalcin), and extracellular mineralization in hAEC and hAMC. A recent study have shown that amniotic epithelial cells implanted into an animal bone defect can undergo rapid osteogenic differentiation and survive for 45 d with the continuous formation of a new bone in the transplantation site. As a transitional class between embryonic and adult stem cells with special stem cell-like characteristics, hAEC possesses potential applications in research and maxillofacial bone regeneration; thus, researchers believe that hAEC is worthwhile to study.
