| Backgroud and ObjectivesPrevalence rates of chronic pain were found to be 30%,which is difficult to be relieved,and harms the peoples' physical and mental health.The current drugs treatment may inevitably cause various defects, for this reason, chronic pain thus presents a challenge to both health care providers and patients understandably searching for a quick and definitive solution. Recently, studies have demonstrated the feasibility of analgesia by method of transplantation of transgeneic cells.However, which kind of cell we can be transgeneiced is undefinite. Currently, people have made a lot of rearch on bone marrow mesenchymal stem cells (BMSCs).Some studies show that BMSCs could be easily collected and isolated from autologous bone marrow, with strong amplification,no ethical problem or rejection.Under some specific conditions or circumstances,they can differentiate into many kinds of nonhematopoietic tissues. In addition, BMSCs can homing to a specific tissue, resulting in playing repair and reestablishment effects. Chronic constriction injury (CCI) model is easily to be established and has a long duration of pain.It is the most commonly used model for neuropathic pain research. This study is aimed to observe the analgesia effects of Human bone marrow mesenchymal stem cells transfected with human proenkephalin gene (hMSC-PENK) which were adminsitered by different ways in CCI rats.Methods1 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 painForty male SD rats weighing 160-180g 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 10μl, hMSC-pBABE cell suspension 10μl (2×108-3×108/μl) and hMSC-PENK cell suspension 10μl (2×108-3×10/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. Cell survival and expression of human proenkephalin were estimated by immunohistochemistry 2 weeks after operation, and the level of human proenkephalin was evaluated by Enzyme linked immunosorbent assay (ELISA). RNA was extracted from the spinal cord for determination of proenkephalin mRNA expression. In addition,the hMSC cell differentiation were detected by immunofluorescence.2 The analgesic effect of venous human bone marrow mesenchymal stem cells (hMSC) genetically modified with human proenkephalin gene (PENK) in a rat model of neuropathic painForty male SD rats weighing 160-180g in which was induced with chronic constrictive injury (CCI)successfully were randomly divided into 4 gorups (n=10 each):group A neuropathic pain (NP);B NP+NS; group C NP+hMSC-pBABE and group D NP+hMSC-PENK. Venous normal saline 10μl, hMSC-pBABE cell suspension 10μl (2×108-3×108/μl) and hMSC-PENK cell suspension 10μl (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 3,5,7,9,11 and 14 d after operation. The animals were killed on the 14th day after last PWL measurement. Cell survival and expression of human proenkephalin were estimated by immunohistochemistry 2 weeks after operation, and the level of human proenkephalin was evaluated by Enzyme linked immunosorbent assay (ELISA).In addition,And nude mice transplantation were also used to investigate hMSC-PENK tumorrigenesis.Results1 PWL was significantly decreased after operation as compared with the baseline values before operation in group B, C and D(P<0.05). Compared with A group, PWL was significantly shorter in group B, C and D,and PENK mRNA expression was significantly lower in group B and C than in group A, while compared with group B and C, PWL was significantly longer in group D and the PENK mRNA expression was significantly higher,There was no significant difference in PENK mRNA expression between group B and C. Immunohistochemistry and Elisa show that the expression of enkephalin was higher in group D than in group B and C. the hMSC cells that were labeled by Brdu could be detected in the rat spinal cord tissue 14 days after the operation. Immunofluorescence showed that expression of astrocytes and neurons was higher in transgeneic cells.2 PWL was significantly decreased after operation as compared with the baseline values before operation in group B, C and D(P<0.05). Compared with A group, PWL was significantly shorter in group B, C and D,and PENK mRNA expression was significantly lower in group B and C than in group A, while compared with group B and C, PWL was significantly longer in group D and the PENK mRNA expression was significantly higher,There was no significant difference in PENK mRNA expression between group B and C. Immunohistochemistry and Elisa show that the expression of enkephalin was higher in group D than in group B and C. the hMSC cells that were labeled by Brdu could be detected in the rat spinal cord tissue 14 days after the operation.Moreover, hMSC-PENK could not form neoplasm formation in nude mice.Conclusions1 Intratheccal human bone marrow mesenchymal stem cells genetically modified with human proenkephalin gene (hMSC-PENK) can relieve neuropathic pain in rats.2 After CCI, hMSC with intravenous administration migrate into spinal cord,which is useful in the treatment of CCI.3 hMSC-PENK could not form neoplasm formation in nude mice,so it is safe for the transplantation of transgeneic cells for analgesia. |
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