Modulation of peripheral nerve regeneration: A tissue-engineering approach. The role of amnion tube nerve conduit across a 1-centimeter nerve gap

A new type of a biodegradable nerve graft conduit material, the amnion tube , has been developed in our laboratory. To test the tube in the peripheral nerve regeneration process, it was initially applied across a l-cm sciatic nerve gap in rats and was compared with other nerve conduit materials. We u sed male Sprague-Dawley rats as our animal model. The experiment included 6 6 rats that were randomly assigned into five groups: autograft (n = 17), am nion tube (n = 19), silicone tube (n = 20), no repair (n = ti), and sham gr oup (n = 3). The process of peripheral nerve regeneration was evaluated at 2, 4, 10, and 17 weeks following injury, and repair by using morphologic an d functional assessments of the outcome of nerve regeneration in each anima l. Nerve regeneration across the amnion tube nerve conduit was comparable w ith that seen in autograft and superior to that of the silicone group. a un iform nerve tissue was seen filling and crossing the amnion conduit, and th e regenerated nerve from the proximal stump reached the distal end and was undifferentiated from the normal nerve tissues. At 4 months, the amnion tub e biodegraded and no longer could be identified and differentiated from the nerve tissues. The amnion tube animal group showed a number of axons very close to that in the nerve autograft group (37,157 versus 33,054). Function al recovery at a 2- to 4-week interval was significantly statistically high er only in the amnion tube animal group (p = 0.01). However, the improvemen t disappear ed between 10 and 17 weeks. In conclusion, the amnion tube is a potential ideal nerve conduit material secondary to its unique characteristics: it contains important neurotropic factors, is biodegradable, provokes a very weak immune response, is semifle xible, is readily available, and is easily manufactured into different size s and diameters.