Electrical Stimulation Promotes The Survival And Regeneration Of Embryonic Spinal Cord Neurons Transplanted Into The Injured Distal Peripheral Nerve

Objective: Peripheral nerve injury is a common and frequent disease in clinical practice,despite through a variety of surgical treatment,the neuromuscular function recovery is still poor.,Experimental and clinical studies showed that electrical stimulation,as a kind of physical therapy,can promote axonal regeneration of peripheral nerve injury after repairation.Another animal experiment found that embryonic spinal cord derived cells transplanted into the distal injury nerve stump,can reduce chronic degenerative of target muscles,and improve muscular function after two stage nerve repair.The purpose of this study is to investigate whether electrical stimulation can improve the survival and differentiation of transplanted spinal cord cells;whether electrical stimulation can promote the regeneration of axons which outgrowth from transplanted cells;whether electrical stimulation can alleviate muscular degeneration and enhance muscular functional recovery.Method: 45 SD rats were divided randomly into 3 groups(15 rats per group).The right tibial nerve was transected to denervate gastrocnemius muscle in each rat of all the 3 groups for 1 week,and after denervation,3?l(1.0×106/?l)of GFP positive embryonic spinal cord cells were prepared for transplantation.Animals in electrical stimulation group underwent cell transplantation into the distal tibial nerve stump,and 20 HZ for 1h stimulation was administrated immediately.Treatment of animals in the ‘‘sham stimulation” group was identical to that of the stimulation group except that no stimulation was delivered.The control group had medium injected into the distal tibial nerve stump without cells and no stimulation was given.Ten weeks after experimentation,before sample drawing,EMG of gastrocnemius muscle was tested,and CMAP was recorded.Also,nerve cross-sectional area,counting of neurons,motonuerons and myelinated nerve fibers were measured to compare the difference between each group.Result: 10 weeks after transplantation,the transplanted cells in distal tibial nerve stump can survive and differentiate into neurons and motor neurons both in electrical stimulation group and sham stimulation group.More neurons and motor neurons were counted and more outgrowth axons were found in electrical stimulation group than in sham stimulation group.The number of myelinated nerve fibers were more in electrical stimulation group than in sham stimulation group.In electrical stimulation group,the range of EMG of gastrocnemius muscle was higher,and muscle atrophy and motor endplate disintegration were lighter than sham stimulation group.There were significantly no EMG amplitude,no myelinated nerve fibers and no muscle end plate in the control group.Conclusion: 1.Electrical stimulation promotes transplanted embryonic spinal cord cells to survive in the injured distal nerve stump,and differentiate into neurons and motor neurons.2.Electrical stimulation increases more axons outgrowth from the transplanted spinal cord cells and more axons were myelinated.3.More regenerative myelinated axons established function contact with target muscles,which relieve chronic muscular degenerative and improve the muscle function.