RESUMO
OBJECTIVE: To explore the inhibitory effect of transforming growth factor-beta (TGF-ß) gene modified human amniotic mesenchymal stem cells on rejection after xenotransplantation of peripheral nerves. MATERIALS AND METHODS: In this study, 6 placentas collected in our hospital were selected as the source of human amniotic mesenchymal stem cells. A total of 60 C57BL/6 experimental mice (mouse sciatic nerves were removed before the experiment) were taken as research objects. Mice were randomly divided into experimental group 1, experimental group 2 and experimental group 3 (xenogenous peripheral nerves were introduced to all experimental groups), and a control group (autologous peripheral nerves were introduced). Among them, TGF-ß gene modified (overexpression) human amniotic mesenchymal stem cells were introduced to experimental group 1; TGF-ß gene modified (inhibition) human amniotic mesenchymal stem cells were introduced to experimental group 2; normal human amniotic mesenchymal stem cells were introduced to experimental group 3; and autologous sciatic nerves were introduced to control group. The messenger ribonucleic acid (mRNA) and protein expressions of the TGF-ß in different human amniotic mesenchymal stem cells were detected by quantitative polymerase chain reaction (qPCR) and Western blotting, respectively. Mouse sciatic nerve function in each group after 2 weeks of procedures was detected via the CatWalk system. Expression level of interleukin-22 (IL-22) in the peripheral tissues of transplanted nerves and blood was detected using immunohistochemistry and enzyme-linked immunosorbent assay (ELISA). Its mRNA level was examined via fluorescence quantitative PCR. RESULTS: TGF-ß1 was highly expressed in mice of experimental group 1, but lowly expressed in experimental group 2 relative to that of experimental group 3 (p<0.05). CatWalk test results revealed that the main indexes in experimental group 1 were superior to those in other groups, while the main indexes in experimental group 2 were inferior to those in other groups. According to immunohistochemistry and ELISA results, there were significant differences in the expression level of IL-22 in mice of different treatment groups (p<0.05). IL-22 level was the lowest in control group [(5.05±0.15) pg/mL], followed by that in experimental group 1 [(6.52±0.24) pg/mL], and it was the highest in experimental group 2 [(9.47±0.31) pg/mL]. CONCLUSIONS: Human amniotic mesenchymal stem cells overexpressing TGF-ß can inhibit rejection after xenotransplantation of peripheral nerves.