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Chronic kidney disease (CKD) is an important health problem worldwide. Hyperactivity of the renin-angiotensin-aldosterone system (RAAS) directly contributes to CKD progression, leading to tissue fibrosis and renal function loss. RAAS inhibitors, are the most employed drugs to the management of CKD progression, inducing effective proteinuria reduction. However, it results in only partial renoprotection. In this context, the administration of mesenchymal stem cells (mSC) to control inflammation, renal fibrosis and CKD progression has shown promising results in studies with animal models of CKD. The beneficial effects achieved by mSC administration likely derive from the paracrine effect of signaling factors, released by these cells through the secretion of extracellular vesicles (EV). The aim of this study was to analyze the renoprotective effects of EVs derived from mSC, associated to the oral treatment with Losartan, in rats subjected to a severe CKD model.
mSCs were isolated from the perigonadal adipose tissue of male Wistar rats, cultured until P4 and characterized by flow cytometry and in vitro differentiation. After 24 hours of fetal bovine serum (FBS) deprivation, cell culture medium was collected and subjected to ultracentrifugation to obtain an EVs pellet. CKD was induced through the surgical ligation of 2 of the 3 branches of the left renal artery, followed by the total nephrectomy of the right kidney. Fifteen days after surgery, the animals subjected to CKD model were stratified into 3 groups, with very similar mean values of body weight (BW), systolic blood pressure (SBP), and 24 h urinary protein excretion (UPE). The animals in the CKD group were kept untreated. CKD+LOS animals received 50mg/kg/day of Losartan, diluted in drinking water. CKD+LOS+EV animals received the same oral treatment, associated to a single renal subcapsular application of EV derived from 2 million of mSC. Additional sham-operated rats were used as controls. All animals were followed until 30 days after CKD induction, when SBP, UPE, serum creatinine (SCr) and urea (BUN), glomerulosclerosis (GS), interstitial fibrosis (INT), renal cortical interstitial proliferation (PCNA) and the infiltration by macrophages (CD68) were determined. Differences among groups were analyzed by one-way ANOVA.
The association of a single subcapsular injection of EV derived from mSC to the oral treatment with Losartan, significantly improved the effects of this antihypertensive drug. CKD+LOS+EV animals exhibited normal SBP, in spite of having only 1/6 of functioning renal mass. Moreover, the combined treatment significantly reduced UAE and diminished de percentage of glomerulosclerosis, compared to Losartan alone. Detailed results are presented as Mean ± SE in the attached table. p<0.05 vs. a: Sham, b: CKD, c: CKD + LOS.
Our preliminary results show that EV from mSC exert additional renoprotective effects when associated to Losartan, especially regarding SBP control and reduction of proteinuria. These findings suggest that EV therapy could be employed as a therapeutic additive together with the traditional RAAS blockade, to better halt the progression of CKD.