Abnormality Of Mesenchymal Stem Cells (MSCs) In Patients With Lupus And Experimental Study Of Umbilical Cord MSCs Transplantation In Lupus Mice

ObjectiveTo explore the morphological character of bone marrow-derived mesenchymal stem cells (MSCs) in patients with systemic lupus erythematosus(SLE).To investigate the potential therapeutic effect and the possible mechanisms of human umbilical cord mesenchymal stem cells (UC-MSCs) transplantation in the MRL/lpr mice.MethodsBone marrow MSCs were isolated from two SLE patients and two healthy controls. Ultrastructural morphology was investigated using transmission electron microscope (TEM). Expression of actin and vinculin were assessed using laser Confocal microscopy (LCM). Twenty four 18-week-old female MRL/lpr mice were divided into 3 groups as following : the group 1(G1) had been treated with 0.5ml Phosphate buffer saline(PBS) as control,the group 2(G2)had been transplanted with 1×10~6 human UC- MSCs through caudal vein, and the group 3 (G3)had been transplanted with 1×10~6 UC- MSCs for three times via the caudal vein. Twenty-four hours proteinuria and bodyweights were assessed every two weeks. The levels of serum anti-ds-DNA antibody, urine and serum monocyte chemoattractant protein-1 (MCP-1) were measured using enzyme linked immunosorbent assay (ELISA) . The histopathology of the kidney, lung and sialaden was observed via immunohistochemical staining. Renal MCP-1, high mobility group box protein-1(HMGB-1), and matrix metalloproteinases-2 (MMP-2) and spleen (Foxp3) gene and protein expression were detecteded by quantitation real time polymerase chain reaction and western blot, respectively. Kidney MCP-1 and HMGB-1, MMP-2 expressions were assessed using immunohistochemistry. The percentage of CD4+ Foxp3+ T cell in spleen and lymph nodes was analyzed by flow cytometry. The kidney cell apoptosis was detected using TUNEL method.ResultsMSCs in patients with SLE have signs of aging: lots of autophagosomes, dense F-actin arranged disorderly at the edge of cytoplasm, dense vinculin arranged disorderly in the cytoplasm. In comparison to mice which received saline alone, mice received three weekly UC-MSCs showed marked reduction of 24h proteinuria, decrease in serum creatinine, and lower anti-ds-DNA antibody level with reduction of renal injury such as crescent formation. Less but significant decreases in these parameters were also observed in mice received single infusion. In comparison to control ground mice, UC-MSCs significantly reduced the extent of interstitial pneumonitis and sialadenitis in the MRL/lpr mice. Expression of HMGB-1 mRNA was positively correlated with the level of serum anti ds-DNA antibodies (r=0.469, P=0.021) and the 24 hours proteinuria (r=0.766, P=0.000). Marked inhibition of expression of MCP-1, HMGB-1 and MMP-2 were observed in the mice treated with UC-MSCs. The G2and G3 MRL/lpr mice had higher percentages of CD4+ Foxp3+ T cells in spleen and lower in lymphoid nodes as compared with controls (P<0.01).The expressions of Foxp3 protein and mRNA of spleen in G2 and G3 were both significantly higher than those in G1 (P<0.05).There was also a significantly difference between G2 and G3(P<0.05). The percentage of apoptotic cells in both the peritubular and perivascular infiltrating cells was also higher in G2 and G3 than in the control group. Besides, in both G2 and G3 mice, the number of apoptotic cells in glomerular mesangium increased significantly, as compared with that in G1 group(P<0.05).ConclusionsThe change of ultrastructure and cytoskeleton may explain why the MSCs from SLE patient showed an abnormal ability of cell expansion in vitro. These findings indicate that UC- MSCs has pleiotropic therapeutic effects on lupus nephritis, pneumonitis, and sialadenitis, suggesting a potential application of UC-MSCs in the treatment of human lupus. High expression of HMGB-1 may contribute to the pathogenesis of lupus nephritis in MRL/lpr mice. By upregulating Treg population and inducing inflammatory cell apoptosis, inhibition of MCP-1, HMGB-1, or MMP-2 may account for some of the therapeutic mechanisms of UC-MSCs in treating MRL/lpr mice.