| Objectives:To investigate the in vivo effects and their possible mechanisms of Thalidomide and human mesenchymal stem cells on interstitial fibrosis in a unilateral ureteral obstruction rat model.Methods:(1) Forty female SD rats were divided into four groups randomly with 10 rats in each:Sham (operation, as the control) group, UUO (model) group, Thd (treated with Thalidomide,200mg/kg/d) group and Lot (treated with Lotensin, 10mg/kg/d) group. In the treated groups, the rats were intragastrically given daily Thalidomide and Lotensin from the day of surgery on to the end of the experiments respectively. While in the Sham and UUO groups, only solvent of the same volume were administered. On day 7 and 14 post-op, blood samples were drawn for renal function analysis. Then the kidneys were harvested for investigation into renal interstitial fibrosis with HE and Masson Staining, and expression of hypoxia inducible factor 1 a (HIF-1α), ColI, andα-smooth muscle actin (α-SMA) were detected with immunohistochemistry and real time quantitative PCR. (2) Human mesenchymal stem cells (HMSCs) were separated from human bone marrow and cultured, and identification and cell concentration were also carried out with flow cytometry (FCM). At the same time, thirty-six female SD rats were divided into Sham group, UUO group and HMSCs group randomly, with 12 in each.1×107 human MSCs (of concentration 1×107/0.5ml) were injected via vena cauda, by the end and on day 7 post-op of the establishment of rat model in HMSCs group, while in the Sham group and UUO group, only solvent of the same volume (i.e. serum free DMEM-LG medium) were given. On time spots of one month and two months after the administration of the first dose of HMSCs, blood samples of six rats were drawn for renal function and serum albumin analysis, then renal specimens were harvested for interstitial fibrosis inspection after HE and Masson staining, and expression of HIF-la, Coll, and a-SMA were examined with immunohistochemistry and real time quantitative PCR.Results:(1) On the time spots checked, Blood urine nitrogen (BUN) and serum creatinine (Scr) levels were higher in UUO group than in Sham group (P<0.05). The BUN and Scr levels were significantly lower in Thd group and Lot group but higher than in Sham group (P＜0.05), and the differences in BUN and Scr showed no statistical significances between Thd group and Lot group (P>0.05). (2) In Sham group, there were no significant changes in renal pathology. On each time spot, renal interstitial damages were heavier in UUO group than the others (P<0.05), and there were no significant differences between Thd group and Lot group (P>0.05). (3) With immunohistochemistry and RT-PCR, on all the time spots, there were low HIF-la and ColI expression and no a-SMA expression in Sham group; and the expression of HIF-la, ColI and a-SMA were higher in UUO group than in Sham group. The expression of ColI and a-SMA in the two chemically treated groups were lower than in UUO group (P＜0.05) but higher than in Sham group (P<0.05).The expression of. HIF-la in Thd group was lower than in UUO group (P<0.05),and that in Lot group was similar to in UUO group (P>0.05) (4) One and two months after surgery, BUN and Scr in HMSCs group were higher than in Sham group, but significantly lower than in UUO group. (5) There were no obvious changes in renal pathology in Sham group before and after surgery, but there were damages to renal interstitial tissues in UUO group and HMSCs group, and statistics showed no significant difference between these two groups. (6) The expression of HIF-la and a-SMA were lower in HMSCs group than in UUO group (P<0.05), but higher than in Sham group (P<0.05); and the expression of Coll was lower than in UUO group, but not statistically different (P>0.05).Conclusion:Thalidomide could reduce renal interstitial damages to unilateral ureteral obstructed model rats, and its possible mechanism might be related with its down-regulation of expression of HIF-1αandα-SMA and inhibition of synthesis of ColI; and HMSCs could improve renal function, with its possible mechanism by inhibiting epithelial-myofibroblast transition via down-regulating expression of HIF-1α. In this study, HMSCs showed no obvious benefit to renal interstitial damage in UUO rats.
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