Abstract
INTRODUCTION / AIMS Chronic kidney disease (CKD) is a progressive, debilitating condition of high lethality, which prevalence have been increasing considerably in recent decades. CKD can be triggered by many different factors, such as genetic predisposition, systemic hypertension, diabetes mellitus and autoimmune diseases. It is characterized by the gradual loss of renal function, leading to kidney failure and the need for renal replacement therapy for the maintenance of life. Regardless of the etiology of CKD, the establishment of local renal inflammation, with leucocyte recruitment, cell proliferation, extracellular matrix accumulation, glomerular and tubulointerstitial fibrosis, contribute significantly to its establishment and evolution. Due to its known pathophysiology, the primary aim when clinically treating CKD is to slow the progression of renal function loss and the advance of inflammation. However, until the present moment, there is no efficient pharmacological treatment to completely arrest the aggravation of renal inflammation and, specially, renal fibrosis. This motivates the scientific community to develop experimental research in order to test new therapeutic approaches to stunt renal fibrosis. In this context, experimental application of mesenchymal stem cells (mSC) as a treatment to control renal inflammation have been showing promising results in studies with animal models of CKD. The aim of the present study was to analyze the renoprotective effects of subcapsular application of Adipose Tissue-derived mSC (ASC), in rats submitted to 5/6 nephrectomy, after the establishment of the disease (15 days after CKD induction), in order to more closely resemble the clinical settings in humans.
METHODS ASC were obtained from gonadal adipose tissue from healthy male Wistar rats. These cells were cultured until P4 when characterization by flow cytometry and in vitro differentiation were performed. Male Wistar rats underwent 5/6 nephrectomy and were followed for 15 days until the complete establishment of CKD (group CKD 15d). At this time, animals underwent a new surgery in which they received a subcapsular injection of 2x106 ASC diluted in 10 μL of sterile PBS (group CKD + ASC 30d), or only 10 μL of sterile PBS (group CKD 30d). Sham-operated rats, euthanized at day 15 (Sham 15d) and 30 (Sham 30d) were used as controls. Survival rate, body weight (BW), 24h urinary protein (24h UPE) and albumin (24h UAE) excretion serum creatinine (SCr) and blood urea nitrogen (BUN) concentration, percentage (GS%) and index (GSI) of glomerulosclerosis, tubulointerstitial fibrosis (INT%) and renal infiltration by macrophages (CD68) were studied at 15 and 30 days after 5/6 nephrectomy. Our results are presented as Mean ± SE. Differences among groups were analyzed by one-way ANOVA.
RESULTS ASC injection significantly improved the survival rate of CKD + ASC 30d animals, compared to the observed in the untreated group. Moreover, ASC treatment markedly reduced protein and albumin urinary excretion, prevented the development of glomerulosclerosis, both the percentage of sclerotic glomeruli and the index of glomerular damage, numerically reduced interstitial fibrosis and significantly avoided renal inflammation by halting the progression of renal cortical macrophage infiltration.
CONCLUSIONS According to our results, subcapsular ASC application promoted considerable renoprotection in the 5/6 renal ablation model, even after the complete establishment of severe CKD, suggesting that experimental therapy with these cells could be associated to the current pharmacological treatments employed to detain the progression of CKD.
Figure
Effects of maternal thyroid hormone deficiency on differentiation of mesenchymal stem cells in CSF-exposed neonatal Wistar rats
