Effects of epithelial cells on amniotic membrane angiogenic properties using rat aortic ring assay

 Introduction:There are controversial reports about angiogenesis of the amniotic membrane after transplantationas cornea substitute. Inducing or inhibitory effects of amniotic epithelial cells on angiogenesis of the amniotic membrane were evaluated in this in vitro study. Materials and Methods:The scraped and non-scraped amniotic membranes were cultured in 12-wells plates in two positions of epithelial side up and mesenchymal side up. In order to evaluate angiogenesis, rat aortic rings were placed on the cultured amniotic membranes. Results were reported as presence or absence of angiogenesis within 7 days. Results:When the amniotic membrane was intact, no formation of capillary like structures or angiogenesis was seen on both sides of the amniotic membrane. In contrast, after removing the amniotic epithelial cells, infiltration of fibroblastic cells from rat aortic ring was seen on both epithelial and mesenchymal sides of amniotic membrane after 2 days. Afterward, the cells started directional out-growth and initiated formation of capillary like structures up to day 7. Conclusion:This study showed that epithelial cells have a key role in angiogenic or anti-angiogenic properties of the amniotic membrane. In addition, acellular amniotic membrane (without epithelial cells) is a proper substrate for angiogenesis and neovascularization. These dual effects on angiogenesis make the amniotic membrane useful in several clinical situations