BackgroundThe favorable effect of bone marrow mesenchymal stem cells (BMSCs) on the reconstruction of injured corneas have been reported,but the mechanism remains unclear.ObjectiveThis study was to evaluate the anti-inflammatory and antiangiogenic effect after transplantation of BMSCs in chemically burned corneas.Methods BMSCs were isolated and extracted from the bone marrow.The cells were cultured and passaged and then were seeded on the amniotic membrane.Corneal alkali injury models were created in 18 clean SD rats by sticking the filter paper containing 1 mol/L NaOH at the central cornea for 40 seconds.The rats were then randomized into 3 groups.Amniotic membrane with BMSCs or amniotic membrane without BMSCs were transplanted in 1 week after the establishment of models,and the rats without transplantation were used as the control group.The severity of corneal lesion was graded,and angiogenesis area was measured 2 weeks after the transplantation.The expression of interleukin-2 ( IL-2 ),interferon-γ(IFN-γ),IL-10 and transforming growth factor-β ( TGF-β ) were examined by ELISA,and the mRNA of the matrix metalloproteinase-2 ( MMP-2 ),vascular endothelial growth factor (VEGF),epidermal growth factor(EGF) and basic fibroblast growth factor(bFGF) were analyzed by real-time PCR.ResultsThe positive rates of the cells were 99.78％ and 99.79％ for CD90 and CD29,7.90％,1.16％ and 1.28％ for CD34,CD45 and CDllba.The cells grew well on the amniotic membrane.The corneal inflammatory score and neovascularization area were similar among the three groups ( F =0.021,P-- 0.979 ; F =0.076,P =0.927 ).However,the corneal inflammatory score was significantly reduced and neovascularization area was significantly less in the amniotic membrane group compared with the BMSCs group and control group(P=0.011,0.001 ;P=0.005,0.000).The levels of IL-2 and IFN-γ secreted by Th1 cells were decreased (P =0.000,0.002;P =0.003,0.045 ) and the levels of IL-10 and TGF-β secreted by Th2 cells were increased in the BMSCs group compared with the amniotic membrane and control group ( P =0.000,0.000 ; P =0.000,0.021 ).No significant difference was found in VEGF expression among three groups( F=4.880,P =0.056).But the mRNA of the MMP-2 and bFGF were lower in the BMSCs group than the amniotic membrane group(P=0.009,0.003 ) and control group(P＜0.01 ).Conclusions BMSCs modulate the expression of inflammatory-related and angiogenic-related cytokines and therefore play the antiinflammatory and anti-angiogenic effects in the chemically burned cornea.

OBJECTIVE: To explore the influencing factors of low back pain and the relationship of the influence of bad working posture, weight load and frequency of load and the dose-response relationship among the occupational workers of key industries in China. METHODS: A total of 57 501 employees from 15 key industries in China were selected as research subjects using stratified cluster sampling method. The occurrence of low back pain in the past one year, as well as occupational factors such as job type, labor organization and work posture were investigated by using the Chinese version Musculoskeletal Disorders Questionnaire. RESULTS: The prevalence of low back pain in the occupational population of key industries in China was 16.4%(9 448/57 501). Multivariate Logistic regression analysis showed that the risk of low back pain in females was higher than that in males(P<0.01). Married, obese, occasional and frequent smokers, and a history of lower back disease were associated with increased risk of low back pain(all P<0.05). The risk of low back pain was associated with older age, higher education level, and lower frequency of physical exercise(all P<0.01). The risk of low back pain was higher with longer working time, greater back curvature, and the high frequency of long standing and sitting position work, uncomfortable working posture, repeated operation per minute, and lifting>5 kg weight(all P<0.01). CONCLUSION: The influencing factors of low back pain in the occupational population of key industries in China include bad working posture, high frequency load, weight load and other individual factors. There is a dose-response relationship with low back posture load and frequency of load.