ABSTRACT
Objective To investigate the analgesic effect of intrathecal(IT)human bone marrow mesenchymal stem cells(hMSC)genetically modified with human proenkephalin gene(PENK)in a rat model of neuropathic pain.Methods Forty male SD rats weighing 160-180 g in which IT catheters were successfully implanted without complication were randomly divided into 4 gorups(n = 10 each): group A normal control;group B neuropathic pain(NP);group C NP + hMSC-pBABE and group D NP + hMSC-PENK.Neuropathic pain was induced with chronic constrictive injury(CCI).Four loose ligatures were placed on the main stem of sciatic nerve with 4-0 chronic catgut.IT normal saline 10 μl,hMSC-pBABE cell suspension 10 μl(2 × 108-3 × 108/μl)and hMSCPENK cell suspension 10 μl(2 × 108-3 × 108/μl)were injected in group B,C and D respectively on the 3rd day after operation.Paw-withdrawal latency(PWL)to noxious thermal stimulation was measured before(baseline)and at 3,5,7,9 and 14 d after operation.The animals were killed on the 14th day after last PWL measurement.RNA was extracted from the spinal cord for determination of proenkephalin mRNA expression.Results PWL was significantly decreased after operation as compared with the baseline values before operation in group B,C and D.PWL was significantly longer at 7,9,14 d after operation in group D than in group B and C but there was no significant difference in PWL after operation between group B and C.PENK mRNA expression was significantly lower in group B and C than in group A,but was significantly higher in group D than in group B and C.There was no significant difference in PENK mRNA expression between group B and C.Conclusion Intratheccal human bone marrow mesenchymal stem cells genetically modified with human proenkephalin gene can relieve neuropathic pain in rats.