Adeno-associated Virus 2 Mediates The Effects Of KLF7 On The Expression And Function Recovery Of Neurotrophin Receptors TrkA And TrkB After Spinal Cord Injury In Rats

Objective:To investigate the effect of adeno-associated virus 2?AAV2?mediated transcription factor Krüpple-like factor 7?KLF7?on neurotrophic factor receptor tyrosine kinase A?TrkA?,tyrosine kinase B?TrkB?and myelinated nerve fiber axons?P0?following spinal cord injury?SCI?in rats,to explicit overexpression of KLF7 restored lesion morphology and function of spinal cord injury in rat.To clarify the mechanism of KLF7promoting SCI nerve regeneration and to provide a new ideas and theoretical basis for gene therapy of spinal cord injury.Methods:60 healthy adult SD rats were used to prepare the transected spinal cord injury model and randomly divided into sham operation group?Sham?,control group?AAV2?and KLF7 treatment group?AAV2-KLF7?,n=20.Sham group was only underwent laminectomy,AAV2 group and AAV2-KLF7 group were injected into the spinal cord lesion with AAV2(2?l,1×10¹¹ viral particle/ml))and AAV2-KLF7(2?l,1×10¹¹viral particle/ml))respectively.The BBB score was observed after SCI;electrophysiology were used to evaluate nerve conduction velocity,latency and amplitude;28 days after operation,HE staining were used to observe the morphological changes of spinal cord lesions,myelinated nerve fiber axons?P0 marker?were evaluated by immunofluorescence staining KLF7,Trk A and Trk B protein were evaluated by Western bolt.Results:1.There was no significant difference in BBB score between AAV2 group and AAV2-KLF7 group from 1d to 3w after spinal cord injury?P>0.05?.The BBB score of AAV2-KLF7 group was significantly higher than that of group AAV2 in the 4w after operation?t=6.57,P<0.05?.2.The electrophysiological examination showed that compared with the sham group,the nerve conduction velocity and amplitude of AAV2 group and AAV2-KLF7 group decreased significantly,however,the latency were significantly decreased?P<0.05?,the effect of AAV2-KLF7 group was more powerful in electrophysiological parameters than AAV2 group?P<0.05?electrophysiological parameters3.HE staining showed that in the T10 segment of the spinal cord lesion,compared with the sham group?0?,percentage of lesion area of AAV2-KLF7 group?0.489+0.072?and AAV2 group?0.7490+0.055?was significantly higher,and the percentage of lesion area in AAV2-KLF7 group was decrease than AAV2 group?t=4.45,P<0.05?.4.Western blot showed that there was no KLF7 expression in sham group and AAV2group,the expression of KLF7 protein in AAV2-KLF7 group was significantly higher than that of sham group and AAV2 group?F=507.70,P<0.05?.After spinal cord injury,the expression of TrkA and Trk B protein in AAV2 group and AAV2-KLF7 group was higher than in sham group,moreover,the expression of TrkA and TrkB protein in AAV2-KLF7group was higher than in AAV2 group?Trk A:F=25.24,P<0.05;Trk B:F=24.72,P<0.05?.5.Immunofluorescence staining showed that compared with the sham group,the expression of P0 protein in AAV2 group and AAV2-KLF7 group was significantly decreased,and the expression of P0 in AAV2-KLF7 group was significantly higher than AAV2 group?F=45.52,P<0.001?.Conclusions:AAV2-KLF7 treatment can significantly promote lesion morphological changes and the recovery of motor function after spinal cord injury in rats,the mechanism may be related to KLF7 upregulating Trk A and Trk B neurotrophic signaling pathway and promoted myelinated axonal regeneration.