Study On Chemotactic Peripheral Nerve Regeneration On Different Injury And Repair Models Of Rat Femoral Nerve

With the development economy, especially because of the increasingpopularity of private cars in China, there has been a significant rise at theincidence rate of peripheral nerve injuries. Now that with the application ofmicrosurgical equepments and techniques, the surgical accuracy ofneurorrhaphy has reached a platue that can not be further refined, yetcomplete functional recovery after nerve injury has never been achieved. This made it necessary to study biological mechanisms of nerve regeneration, inorder to find a way to gain satisfying recovery from peripheral nerve injury.The theory of selective regeneration of peripheral nerves which was termedas chemotaxis by Cajal et al in the beginning of the last century has providedus with new methods to cure peripheral nerve injury. The theory of chemotaxisreminds us that, in order to achieve full recovery from nerve injury, it is not onlyrequired to gain full regeneration of nerves, but also that these regeneratedaxons should arrive at their original target tissues and organs. that is say, theaxon regerated from motor nerves should grow into their motor nervecounterparts at the other end of the nerve stump.Also there have been much research about selective nerve regenerationand it is already widely accepted, but there is still much dispute to be solved.The current study puts efforts to built experimental models on the study ofchemotaxis, and makes further investigation to its mechanisms as well as itspossible applications in clinics.Methods:1.Make crush injuries on the femoral nerve of healthy male SD rats.8weeks after the surgery, a series of observational, histochemical as well aselectrophysiological assessments were applied to test the chemotacticregeneration of injured femoral nerves.2. Make assessments on the nerve repair after rat femoral nerve crush andfreezing injury by the means of retrograde labeling and electrophysiologicalobservations on different time points after injury and evaluate the chemotacticregeneration of nerves at the injury site.3. Make two different shapes of PPC conduits by electrospinning techniqueand use them to repair4mm rat femoral nerve defect. Evaluate thechemotactic regeneration of femoral nerve by means of retrograde labelingand electrophysiological methods.Results:1. Kinetic functions of the rat’s leg at the injury site was significantly hindered, latent phase prolonged, amplitude declined. Only the neuronsstained red can be found in the anterior spinal medulla of healthy rats, whilered, green as well as orange colored neurons can be found in the injured rats.2. Rats in both crush and freezing injury groups achieved fine regenerationof nerve8weeks after the femoral injury. The number of neurons stained redin the anterior spinal medulla increases gradually. Although there is not asmuch neurons stained red can be found in the anterior spinal medulla offreezing injury rats than crush injury rats, but the proportion of red stainedneurons is higher and there is no significant difference between groups byelectrophysiological terms.3. Kinetic functions of the rat’s leg at the injury site was significantlyhindered in nerve defect rats bridged by Y type nerve guidance channels. Yconduit repair group NO1showed better signs of recovery that group NO2bythe terms of both retrograde labeling and electrophysiological assessment.Conclusions:1. Besides histological, direct observational as well as electrophysiologicalterms, retrograde labeling can also be an effective way to assess nerveregeneration recovery of peripheral nerves in rats.2. Once perineurial structure is intact, axons can gain more accurateregeneration regardless of longer nerve injury.3. The early bifurcation in Y type nerve conduits can ensure betterchemotactic regenerations of axons in femoral nerve defects.