Morphological and Biomechanical Characterization of Amniotic Membranes Across Species: Equine, Canine, Porcine, Ovine, and Human Samples—A Pilot Study

INTRODUCTION: The use of amniotic membrane (AM) has become well established in the treatment of ocular surface disorders in both humans and animals. However, comparative studies of AM from different species remain scarce. OBJECTIVE: To compare the thickness and biomechanical properties of equine, canine, porcine, and ovine AMs with those of human AM. METHODS: Placentas were collected, and AMs were manually separated from the chorion. All AM samples were cryopreserved in a 1:1 solution of Dulbecco's Modified Eagle's Medium (DMEM) and glycerin at -80°C for 60 days. After thawing, samples underwent thickness, histological, and biomechanical analyses. RESULTS: Porcine and canine AMs had an average thickness of 0.054 mm, while ovine AM averaged 0.017 mm. Equine and human AMs had average thicknesses of 0.070 and 0.068 mm, respectively. The key mechanical properties evaluated were maximum tensile force (in Newtons) and stiffness (N/mm), derived from the force-displacement curve. Equine AM exhibited the highest mean maximum tensile force (5.21 N), followed by human (2.17 N), ovine (1.35 N), canine (1.34 N), and porcine (0.52 N). Equine AM also demonstrated the highest mean stiffness (0.91 N/mm), followed by human (0.51 N/mm), ovine (0.46 N/mm), canine (0.27 N/mm), and porcine (0.15 N/mm). CONCLUSION: Equine AM closely resembles human AM in terms of thickness and mechanical behavior. Moreover, equine AM demonstrated superior biomechanical performance, suggesting its potential as a robust alternative biomaterial for ocular surface reconstruction.