The Effect And Mechanism Of Bone Marrow Mesenchymal Stem Cells Transplantation On Acute Lung Injury Induced By Silica Dust

Objective:To study the effect and mechanism of BMSC transplantation on acute lung injury indced by silica dust.Methods:Sixty mice were randomly divided into three groups including control group,silica group and BMSC transplantation group.Tracheal exposure method was used to establish the experiment animal model,Mice of control group were given 20 ?L of 0.90% sodium chloride solution by intratracheal injection.Mice of silica group and BMSC transplantation group were first received 20 ?L of silica dust suspension(250 g/L mass concentration)by intratracheal injection;followed by 100 ?L of 0.90% sodium chloride solution or 100 ?L of BMSC suspension(cell density 5×109/L)by tail vein infusion 6 hours later.Mice were regular fed and euthanized on the thirth day,Observed lung changes among three groups mice.Wright-Giemsa staining was used for staining cells in BALF for counting.The level of cytokines in serum and BALF was detected by enzyme linked immunosorbent assay.Real-time quantitative polymerase chain reaction was used to detect the mRNA relative expression level of above cytokines in the lung tissues.FCM was used to measure the percentage of macrophage in BALF.Immunohistochemical detected macrophages count in the lung tissues.Western blots detected IL-1?,Caspase-1 protein level in the lung tissues.Using transwell system co-cultured macrophages and BMSC,The interleukin-1?level in macrophages cultural supernatant was detected by enzyme linked immunosorbent assay.Western blots detected IL-1?,Caspase-1 protein level in macrophages.Results:The lung surface of control group and BMSC transplantation group mice was smooth,while the lung surface of silica group mice appeared obvious swelling and hyperemia.Histopathology examination showed there was no damage found in the lung tissue of control group and BMSC transplantation group,alveolar cavity size was uniform and complete,alveolar structure were complete.But We observed there were plenty of inflammatory cells infiltration and aggregation in the lung tissue of silica group mice,inflammatory exudate in alveolar cavity,alveolar was collapsed.The lung coefficient of silica group was higher than that of control group(P<0.05);the lung coefficient of BMSC transplantation group was lower than that of silica group(P<0.05).Wright-Giemsa staining result show that the number of total cells and macrophages in BALF in silica group was higher than that of control group and above cell number of BMSC transplantation was lower than that of silica group(P<0.05).The level of interleukin-1? and interleukin-6 in serum and BALF in silica group were higer than those of control group(P<0.05),above two indices in BMSC transplantation group compared to the silica group was significant lower(P<0.05).The interleukin-1? and interleukin-6 mRNA relative expression in silica group were higer compared to BMSC transplantation group(P<0.05).above two indices in BMSC transplantation group compared to the silica group was lower(P<0.05).The FCM result show that the percentage of macrophages in silica group was higher than that in control group(P<0.05),while BMSC transplantation group was lower compared to silica group(P<0.05).we observed there were a lot of macrophages in lung tissue of silica group,while there were a few of macrophages in BMSC transplantation group.The CCL-3level in BALF of silica group was higer than that in control group(P<0.05),while BMSC transplantation group compared to the silica group was significant lower(P<0.05).The interleukin-1? and Caspase-1 protein expression in BALF of silica group were rising than those in control group,above two indeces in BMSC transplantation group compared to the silica group was down,But pro-interleukin-1? and pro-Caspase-1 level in lung tissue had no difference among three groups.The vitro experiment result show that macrophagessecrete interleukin-1? was rising after different concentrations of silica dust affected,co-culture with BMSC interleukin-1? expression decreased(P<0.05).The level of interleukin-1? and caspase-1 was in accordance with result in vivo experiment.Conclusion:1.BMSC transplantation could alleviate acute lung injury.2.The mechanism may be that BMSC through acting on NLRP3 inflammasome of macrophage and supressing IL-1?expression.