Extracellular matrix of human amnion manufactured into tubes as conduits for peripheral nerve regeneration

Abstract

The human amnion consists of the epithelial cell layer and underlying connective tissue. After removing the epithelial cells, the resulting acellular connective tissue matrix was manufactured into thin dry sheets called amnion matrix sheets. The sheets were further processed into tubes, amnion matrix tubes (AMTs), of varying diameters, with the walls of varying numbers of amnion matrix sheets with or without a gelatin coating. The AMTs were implanted into rat sciatic nerves. Regenerating nerves extended in bundles through tubes of 1-2 mm in diameter and further elongated into host distal nerves 1-3 weeks after implantation. Morphometrical analysis of the regenerated nerve cable at the middle of each amnion matrix tube 3 weeks after implantation was performed. The average numbers of myelinated axons were almost the same (ca. 80-112/10(4) microm(2)) in AMTs of 1-2 mm in diameter, as in the normal sciatic nerve (ca. 95/10(4) microm(2)). No myelinated fibers were found in AMTs composed of multiple thin tubes of 0.2 mm in diameter. The myelinated axons were thinner in implanted tubes than those in the normal sciatic nerve. The rate of occurrences of myelinated axons less than 4 microm in diameter was significantly higher in the AMTs, whereas axons in the normal sciatic nerve were diverse in distribution, with the highest population at 8-12 microm in diameter. Reinnervation to the gastrocnemius muscle was demonstrated electrophysiologically 9 months after implantation. It was concluded that the extracellular matrix sheet from the human amnion is an effective conduit material for peripheral nerve regeneration.

Amniotic membrane as a potent source of stem cells and a matrix for engineering heart tissue

“…The aforementioned authors introduced the use of AM in ophthalmic surgery in experimental model and described the ability of AM to enhance wound healing, and epithelisation, noting an increase in the use of AM as a biomaterial in surgeries in recent decades. Similar data were submitted by other authors over the following years (Table 1) [15,[18][19][20][21][22][23][24][25].…”

Scaffolding in tissue engineering: general approaches and tissue-specific considerations

“…Decellularized ECM can also be used for non-homologous functions when it is used for a purpose different from which it fulfills in its native state, or in a location of the body where such structural function does not normally occur. Examples are to use small intestinal submucosa (SIS) for vascular graft, tendon, dura mater, skin and other tissues [7,8,38,49,101] and to use amnion membrane for peripheral nerve regeneration [77]. The major advantage of this scaffolding approach is the most close-to-nature mechanical and biological properties of the decellularized ECM.…”

Properties of the amniotic membrane for potential use in tissue engineering

“…Several experimental studies have been performed using the AM as a scaffold. It has been reported that the ECM of the human amnion is an effective conduit for peripheral nerve regeneration and that the AM is a biodegradable scaffold with unique biochemical and mechanical characteristic for nerve regeneration (Mohammad et al, 2000;Mligiliche et al, 2002). It has also been demonstrated that denuded AM can be utilized as a feeder layer for some stem cells and may be used for neuronal differentiation (Miyamoto et al, 2004;Ueno et al, 2006;Meng et al, 2007).…”