An important component of tissue engineering (TE) is the supporting matrix upon which cells and tissues grow, also known as the scaffold. Scaffolds must easily integrate with host tissue and provide an excellent environment for cell growth and differentiation. Most scaffold materials are naturally derived from mammalian tissues. The amniotic membrane (AM) is considered an important potential source for scaffolding material. The AM represents the innermost layer of the placenta and is composed of a single epithelial layer, a thick basement membrane and an avascular stroma. The special structure and biological viability of the AM allows it to be an ideal candidate for creating scaffolds used in TE. Epithelial cells derived from the AM have the advantages of stem cells, yet are a more suitable source of cells for TE than stem cells. The extracellular matrix components of the basement membrane of the AM create an almost native scaffold for cell seeding in TE. In addition, the AM has other biological properties important for TE, including anti-inflammatory, anti-microbial, anti-fibrosis, anti-scarring, as well as reasonable mechanical property and low immunogenicity. In this review, the various properties of the AM are discussed in light of their potential use for TE.
The differentiation of neural cells from embryonic stem cells is influenced by several growth factors. Amniotic epithelial cells (AECs) share many of the same characteristics as embryonic stem cells, and therefore those factors may similarly affect the derivation of neural cells from AECs. In this study, we examined the differentiation of neural cells in vitro from AECs following AECs treatment with retinoic acid (RA), basic fibroblast growth factor (bFGF) as well as investigation of bFGF withdrawal on neuronal differentiation. We also studied whether blocking bone morphogenetic protein (BMP) signaling using its antagonist, noggin, affects the derivation of neuronal cells from AECs. The effects of serum on the rate of neural markers expression were also examined. Analysis of AECs derived neurons was performed at some neural markers expression level by immunocytochemistry. All cultures treated with noggin showed the higher levels of neural markers expression than noggin free cultures. Combined treatment with bFGF and RA showed the highest level of neural markers in all treatment groups with or without noggin. bFGF withdrawal did not promote expression of neural markers, while its maintenance increased the expression of these markers. Serum-free condition decreased the viability of cells but increased the rate of neural markers expression. These results show the capability of AECs to express neural cell markers and this ability is affected by some factors including serum, noggin, bFGF and RA.
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