Opposing effect of amniotic membrane on angiogenesis originating from amniotic epithelial cells

There are controversies about the effects of amniotic membrane (AM) on angiogenesis. It was recently hypothesised that denuded AM (without epithelial cells) can induce angiogenesis. The results from the dorsal skinfold chamber method in an animal model and aortic ring assay showed that the epithelial side of the AM inhibits vessel sprouting and reduces capillary numbers, while the mesenchymal side of the AM increases angiogenesis. These data answered the controversies about the angiogenic capability of the AM and raised some questions about the mechanisms by which the AM affects angiogenesis. In this article, mechanism(s) by which the AM affects angiogenesis and viability state of amniotic cells and its effect on angiogenesis have been propounded.