Effect of exosomes derived from MiR-133b-modified ADSCs on the recovery of neurological function after SCI.

OBJECTIVE: To investigate the recovery effect of exosomes derived from micro ribonucleic acid (miR)-133b-modified adipose-derived stem cells (ADSCs) on neurological function after spinal cord injury (SCI) and its mechanism. MATERIALS AND METHODS: The SCI model of rats was used and divided into the following 5 groups: sham-operation group, 4 d SCI group, phosphate-buffered saline (PBS) group, miR-control group and miR-133b group. At 96 h after operation, rats were euthanatized, and spinal tissues were removed. Next, the level of miR-133b was detected via reverse transcription-polymerase chain reaction (RT-PCR), and the expression of RhoA protein was measured via Western blotting. Moreover, expressions of proteins associated with the axon regeneration pathway, including phosphorylated-cAMP-response element binding protein (p-CREB), CREB, phosphorylated-signal transducer and activator of transcription 3 (p-STAT3) and STAT3, along with expressions of neurofilament (NF), growth associated protein 43 (GAP43), glial fibrillary acidic protein (GFAP) and myelin basic protein (MBP), were tested by Western blotting and immunofluorescence staining. RESULTS: The miR-133b mimics significantly upregulated the expression of miR-133b in adipose-derived stem cells (ADSCs), compared to blank group (p<0.05). The expression of miR-133b was significantly decreased in 4 d SCI group compared with that in sham-operation group (p<0.001). The RhoA expression was statistically increased in 4 d SCI group compared with that in sham-operation group (p<0.001), and it was partially impaired by using miR-133b compared with that in 4 d SCI group (p<0.001). Expressions of NF, GAP43, GFAP and MBP were remarkably higher in 4 d SCI group than those in sham-operation group (p<0.01), and they were also significantly increased in miR-133b group than those in 4 d SCI group (p<0.01). Besides, our data showed a significant increase of p-CREB/CREB, p-STAT3/STAT3, NF, GAP-43, GFAP and MBP in miR-133b group compared to those in 4 d SCI group, with statistical reduction of RhoA (p<0.05). CONCLUSIONS: We showed that exosomes derived from miR-133b-modified ADSCs can significantly promote the recovery of neurological function of SCI animals through affecting the signaling pathway related to axon regeneration and expressions of NF, GAP-43, GFAP and MBP.

Symptoms and signs in workers exposed predominantly to xylenes.

Surveys were conducted in factories in China where workers were engaged in the production of rubber boots or plastic-coated wire or in printing work, and were exposed to xylene vapors. Based on the data on exposure as monitored by personal diffusive sampling, 175 xylene-exposed workers (107 men and 68 women) were selected as those (1) who underwent all examinations and (2) for whom the sum of the three xylene isomers accounted for 70% or more of the total exposure (on a ppm basis). The intensity of exposure was such that the sum of the three isomer concentrations was 14 ppm as a geometric mean and 21 ppm as an arithmetic mean. As controls, 241 nonexposed workers (116 men and 125 women) were recruited either from the same factories or from factories in the same regions. There was an increased prevalence of subjective symptoms in the exposed workers which were apparently related to the effects on the central nervous system and to the local effects on the eyes, the nose, and the throat, although dose-dependency of the symptoms was evident in only a limited number of cases, possibly because the intensity of exposure was rather low. It was further observed that the findings of hematology and serum biochemistry in respect of liver and kidney functions were generally negative, showing that xylenes are not toxic to the hematopoietic organs, the liver, or the kidney.