Biomechanical and biological properties of cryopreserved canine amniotic membrane

Abstract

Amniotic membrane (AM) is the innermost fetal membrane. Due to its many known properties, human AM is a favorable corneal graft. Cryopreservation at -80ºC maintains most of biological properties. Due to shortage of supply, AM of other species are studied. The objective of this study is to explore the biomechanical and biological properties of canine AM (CAM) after cryopreservation for 7 and 30 days. CAMs were collected from healthy bitches undergoing cesarean sections. After preservation, they were tested for tensile strength by Universal Testing Machine, transparency by spectrophotometer, sterility by microbial culture, cell viability by trypan blue staining, and histological study by Hematoxylin/eosin and Masson Trichrome stain. J-shaped stress-strain curve was produced on all samples. Maximum stress, extensibility, and Young’s modulus were not statistically different. Transparency and haze were not significantly different. Some bacteria and fungi were identified on both groups. Cell viability of 7-day CAMs was significantly higher than 30-day CAMs. Collagen was found in stromal layer. The stroma of 30-day CAM was significantly flattened. This research showed that cryopreservation for 30 days did not significantly affect biomechanical properties, and only partially affect biological properties. It is suggested that cryopreserved CAM has promising properties suitable for clinical use as corneal graft.