Objective To observe the effect of electroacupuncture(EA)combined with transplantation of Schwann cells(SCs)on limb locomotor

myelin sheath repair and expression of CD4 and CD8 in compressed spinal cord injury(CSCI)rats

so as to explore its mechanisms underlying improvement of CSCI.Methods A total of 45 female SD rats were randomly divided into normal control

model

EA

Schwann cell(SC)transplantation

and EA+SC transplantation groups(n=9 rats in each group).The CSCI model was established by laminectomy at T12—L2 and clip compression.Rats of the SC transplantation group accepted injection of the cultured SC suspension(2×106/6!L)into the central

upper and lower sites of the injured spinal cord(5 mm in depth)7—8 days after CSCI modeling.EA(2 Hz)was applied to bilateral"Zusanli"(ST36)and"Sanyinjiao"(SP6)for10 min

once daily and 6 days a week for 3 weeks.The Basso

Beattie and Bresnahan locomotor rating scale(BBB scale)was used to evaluate the function state of CSCI.Morphological changes of the regional injured tissue were observed under light microscope after H.E.staining.The myelin sheath repair state and survival of SCs were detected by Luxol fast blue(LFB)staining and immunofluorescence histochemistry

and the expression of CD4

CD8 and P0 of the injured spinal cord was detected by Western blot.Results Compared with the normal control group

the BBB scores at the time-points of 0 d

and 1

2

and3 weeks were significantly decreased in the model group(P<0.001)

and those of the EA+SC transplantation group at the 2 nd and 3 rd week were significantly higher than those of the model group(P<0.05).No significant changes of BBB scores were found after EA and SC transplantation relevant to the model group(P>0.05).LFB staining showed a disordered arrangement of the nerve fibers in the white matter

myelinociasis and obvious decrease of the medullated fibers in the model group

and these situations were relatively milder in both EA and SC transplantation groups and obviously milder in the EA+SC transplantation group.H.E.staining displayed that the structure of the injured region of the spinal cord was incomplete

accompanied with a large number of defect cavities and neuronal karyopyknosis in the model group

while the structure was relatively clear

with an increase of the normal neurons and fewer neuronal karyopyknosis in the EA+SC transplantation group.Compared with the normal control group

MBP in the model group was significantly decreased(P<0.001)

and P0 was significantly increased(P<0.001).Compared with the model group

the expressions of MBP and P0 were significantly increased in the EA

SC transplantation

and EA+SC transplantation groups(P<0.01

P<0.001)

and was significantly higher in the EA+SC transplantation group than in both EA and SC transplantation groups(P<0.001).The average immunofluorescence intensity of Hoechst33342-labeled SCs was significantly higher in the EA+SC transplantation group than in the SC transplantation group(P<0.05).After CSCI

the expression levels of spinal CD4

CD8 and P0 proteins had no significant changes in comparison with the normal control group(P>0.05)

while after the intervention and in comparison with the model group

the expression levels of P0 protein were significantly increased in the EA

SC transplantation and EA+SC transplantation groups(P<0.05)

and was significantly higher in the EA+SC transplantation group than in both EA and SC transplantation groups(P<0.05).The expression levels of CD4 and CD8 proteins were significantly lower in the EA+SC transplantation group than in the SC transplantation group(P<0.05).Conclusion EA+SCs transplantation can improve the locomotor function in CSCI rats

which may be related to its effects in increasing the survival of transplanted SCs to promote the remyelination and in reducing the immune rejecting reaction.