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[Bone marrow mesenchymal stem cells modulated the inflammatory response by regulating the expression of IL-4 and RAGE products in the rats with MODS].

OBJECTIVE
To investigate the underlying mechanism of bone marrow mesenchymal stem cells (BMSC) modulating the inflammatory response during the multiple organ dysfunction syndrome (MODS), especially the expression of inflammatory cytokines, which will provide new theoretical and experimental basis of MODS in clinic.


METHODS
BMSC of Sprague-Dawley (SD) rat (female, 4 weeks) was extracted and cultivated, and the 4th passage were used in experimental study. According to the random number table, 60 female SD rats were divided into three groups (n = 20 per group): sham group, MODS group, BMSC group. MODS model in rats was induced by lipopolysaccaride (LPS, 1 mg/kg) via femoral vein injection. Sham group was injected with the sterile phosphate buffer saline (PBS) in the same volume. BMSC group, in which BMSC infusion was started at 2 hours after 0.5 mL LPS stimulation (1×106/cells) through the tail vein. The survival rate was observed after 72 hours in each group. Abdominal aortic blood was collected for routine blood and biochemical examination at 72 hours after operation. Protein microarray was used to detect the related 34 inflammatory cytokines. Signal ratio was defined as the differentially expressed factors when it was more than 2.0 or less than 0.5. And enzyme linked immunosorbent assay (ELISA) was be applied to validate the significant inflammation factor. Meanwhile, the heart, kidney, intestine tissue was harvested, then their pathological changes were observed by hematoxylin eosin (HE) staining.


RESULTS
20, 12, 16 rats lived in sham group, MODS group and BMSC group respectively at 72 hours after operation. Compared with the sham group, the indicators (routine blood, liver and kidney function, myocardial enzyme) were apparently unusual, and the heart, kidney, intestine tissue were injured obviously in the MODS group. After BMSC administration, the organ function was improved and tissue damaged was alleviated significantly. Protein microarray showed that interleukin-4 (IL-4) and receptor for advanced glycation end products (RAGE) were significantly different in 34 goal cytokines. The signal ratio change of IL-4 was 0.397, 1.124, 2.826 respectively, and the signal ratio of RAGE was 6.197, 1.552, 0.250, respectively in MODS/sham group, BMSC/sham group, BMSC/MODS group. ELISA validated the result that the expression level of IL-4 decreased significantly (ng/L: 3.59±1.21 vs. 29.10±5.78) and the expression level of RAGE increased significantly (ng/L: 1.09±0.04 vs. 0.11±0.03) in MODS group as compared with sham group (both P < 0.05). Compared with the MODS group, the level of IL-4 was obviously higher than that in BMSC group (ng/L: 9.59±2.21 vs. 3.59±1.21, P < 0.01), and RAGE decreased significantly (ng/L: 0.29±0.07 vs. 1.09±0.04, P < 0.05).


CONCLUSIONS
BMSC administration can regulate the expression of IL-4 and RAGE in the rats subjected to MODS. Moreover, BMSC can promote the restoration of tissue and organ function, thus improve the survival rate. BMSC may be the target in cell therapy for the inflammatory disease.