Outcome of Axonal Regeneration Following Rat Sciatic Nerve Transection Treated with End-to-End Microsuture or Fibrin Seal

Abstract

Fibrin is widely used to successfully secure nerve grafts in humans; however, it is seldom used in primary nerve repair, and the few reported animal studies show a high failure rate. These disappointing results prompted a prospective study to compare a new commercially available fibrin (Tisseel Duo 500 IU Thrombin) with a previously available product (Tisseel Kit 4 IU Thrombin). The two-stage study, using the rat sciatic nerve as a model, evaluated nerve end separation under an electron microscope in the three groups. In the first stage the two types of fibrin were compared. In the second stage, the sciatic nerves of those animals originally treated with Tisseel Duo were allowed to regenerate for a total of three months after which time they were sacrificed. After perfusion with glutaraldehyde, samples were taken from three branches of the sciatic nerve 30 mm distal to the original site of injury and examined under the electron microscope. Numbers of myelinated and unmyelinated nerve fibers were recorded in addition to measuring the diameter of the myelinated fibers. These results were then compared with controls of normal rats which had regenerated for three months after a controlled crash injury, and those which had the sciatic nerve sectioned and repaired using standard microsurgical techniques. There was no statistical difference in nerve regeneration between microsurgical repair and the use of Tisseel Duo fibrin in the primary repair of transsected peripheral nerves. All three types of nerve branch showed similar patterns of regeneration in the two types of repair. We conclude that neither Tisseel Duo, containing 500 IU thrombin, nor Tisseel Kit, containing 4 IU Thrombin, fail in the primary repair of transsected peripheral nerves in our model. This study also demonstrates equally good nerve repair and regeneration using Tisseel Duo and conventional microsurgical techniques.