[Biomechanic and biological activity assessment of concavity-convex amniotic membrane]

This paper conducted research on biomechanical characteristics and biological activity of concavity-convex amniotic membrane (CCAM) and discussed its superiority as ocular surface repair material. Folding and compression with vacuum of fresh amniotic membrane were used to prepare CCAM. After cutting the striga of CCAM, sixteen CCAM tissue section were chosen at random to test their tensile strength using electronic universal testing machine. The bilayer amniotic membrane (BAM), the double-deck amniotic membrane (DAM) and the monolayer amniotic membrane (MAM) were as controls. The test parameters included yield strength, tensile strength, elongation at break, elastic modulus and so on. The cytokines of fresh amniotic membrane (FAM), MAM and CCAM were analyzed by radioimmunoassay method. The CCAM was obviously thicker than MAM and DAM. After 15 min in PBS, the CCAM tissue can recover the normal shape. The tensile strength and the elongation at break of CCAM were higher than those of the MAM and the DAM (P < 0.05). The elastic modulus of the CCAM was smaller than that of the MAM and the DAM (P < 0.05). The content of 10 cytokines [epidermal growth factor (EGF), fibroblast growth factor (FGF), b-fibroblast growth factor b-FGF, hepatocyte growth factor (HGF), transforming growth factor-beta (TGF-beta), insulin-like growth factor (IGF), platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), nerve growth factor (NGF), brain-derived nellrotrophic factor (BDNF), ciliary neurotrophic factor (CNTF)] of CCAM decreased significantly compared with the FAM and increased significantly compared with MAM and DAM in 6 cytokines (EGF, FGF, HGF, TGF-betap, PDGF, NGF; P < 0.05). The CCAM composites is thinner and has higher cytokine content than MAM, and better biomechanical properties than the MAM and the DAM, showing the superiority as ocular surface repair material.