Biomechanical Characterization of Human Amniotic Membrane Preparations for Ocular Surface Reconstruction

Abstract

Purpose: To investigate the tensile and elastic properties of both commercially available and experimental human amniotic membrane preparations. Method: Nine preparations of human amniotic membrane were studied. The four dry preparations were untreated (nonirradiated, n = 20), and gamma (n = 25), low-dose (AmbioDry^®, Okto Ophtho Inc., Costa Mesa, Calif., USA, n = 20) and high-dose (n = 20) electron beam sterilized. The same dry membranes were moistened with balanced salt solution (n = 20, 34, 20 and 20, respectively). The ninth group consisted of thawed medium-frozen amniotic membrane (AmnioGraft^®, Bio-Tissue Inc., Miami, Fla., USA, n = 20). The membranes were cut into thin strips, loaded on a gram range load sensor, and stretched incrementally to the point of rupture. The modulus of elasticity, displacement until rupture and maximum tolerated stress were recorded and compared. Results: The dry preparations exhibited higher moduli of elasticity when compared with the moist samples, with the low-dose electron beam-irradiated samples having the greatest mean modulus of elasticity overall and maintaining a high modulus of elasticity as a moist sample (p < 0.05). Moist nonirradiated preparations and thawed medium-frozen preparations stretched the farthest before rupture and experienced the greatest mean stresses at the point of rupture. While 3 of 4 membranes had greater stretch when moistened as compared to their dry counterparts, there was no difference in the membrane stiffness between dry and moistened low-dose electron beam-irradiated samples (p > 0.8). Conclusions: Low-dose electron beam-irradiated amnion appeared to maintain desirable elastic characteristics in transition from a dry to rehydrated state and may thus provide an easy-to-manipulate transplant tissue for ocular surface reconstruction. Moist nonirradiated and thawed medium-frozen tissues, however, may provide surgical advantages as they required greater forces to rupture.

Human Amniotic Membrane as a Delivery Matrix for Articular Cartilage Repair

“…Chuck et al 36 reported that the mechanical characterization of HAM was very weak; however, in our study, we measured the tensile strength of HAM (rolled into an 8 mm diameter cylinder) to be 1331 AE 179 N (data not shown). We think the two results could not be directly compared because the methods of analysis methods were different, including the condition of used HAM (wet and fresh HAM was used in our study) and its thickness (100-200 mm in our study).…”

Fibrin-glue assisted multilayered amniotic membrane transplantation in surgical management of pediatric corneal limbal dermoid: a novel approach

“…Indications of amniotic membrane transplantation for treatment of ocular surface diseases have ranged from cicatricial ocular surface disorders such as Stevens–Johnson syndrome, alkali burn, bullous or band keratopathy, ocular cicatricial pemphigoid to pterygium and conjunctival tumors [21, 22]. Fresh or preserved amniotic membrane has been shown to promote epithelization, reduce inflammation, prevent neovascularization and suppress recurrent subconjunctival fibrosis following symblepharon lysis [21–23] Furthermore, amniotic membrane is known to differentiate into conjunctival epithelial cells [24]. Additionally, recent advances in the use of fibrin glue in conjunction with amniotic membrane transplantation has significantly enhanced the application of tissues adhesives in ocular surface reconstruction [25, 26].…”

The behavior of aged regenerated Bombyx mori silk fibroin solutions studied by 1H NMR and rheology

“…However, as the AM is a human-derived tissue, it is a potential vector for transferring infectious disease [11]. Other drawbacks of using this biological material have also been reported [12][13][14]. Therefore, the search for alternative materials is increasingly important.…”