Estudo do balanço entre MMPs e TIMPs no parênquima renal de ratos com hipertensão renovascular após o transplante de células-tronco mesenquimais de medula óssea

Abstract

Renovascular hypertension (RH) is caused by partial occlusion of the renal artery promoting renal ischemia and subsequent activation of the renin-angiotensin-aldosterone system (RAAS), a starting point for systemic arterial hypertension. RH is a progressive disease that, when untreated, leads to chronic kidney disease (CKD). Currently, there is no specific treatment in the advanced stages of the disease, since the only alternative is dialysis and/or renal transplantation. However, due to high cost of dialysis treatments and to the lack of available organs for transplantation, there is an imminent need for the development of new therapies. Mesenchymal stem cells (MSC) are excellent candidates for cell therapy because of their ability to reduce renal damage, through the synthesis and release of cytokines and growth factors, preserving renal function. However, it is necessary to elucidate the renal parenchyma remodeling through the epithelial-mesenchymal transition (EMT) in the presence of mesenchymal stem cells. The main objective of this work was to evaluate the effects of bone marrow MSC transplantation on the expression balance of metalloproteinases -2 and -9 and the inhibitors of tissue metalloproteinases -1 and -2 (TIMP) in the left kidney of rats with RH induced by 2 kidney- 1clip model (clipping of left renal artery – 2K1C). It was also analyzed morphological and functional alterations, basal membrane integrity, TNF-α (tumor necrosis factor alpha) and TGF-β (transforming growth factor beta) contents and tissue expression of CD68 (macrophage), IL-10 (interleukin), and α-SMA (smooth muscle alpha-actin). Male Wistar rats (n = 18) were divided into three groups: Sham, 2K1C and 2K1C+MSC (received transplantation after 4 weeks of clipping surgery). After 2 weeks of transplantation (week 6) the animals were euthanized and the kidneys were collected and processed for microscopy and western blotting. The 2K1C animals presented hypertension, with increased urea, creatinine and proteinuria, while there was a reduction of total serum proteins. The kidneys of these animals showed increased fibrosis, a basement membrane disruption, increased MMP-2 and -9, TNF-α and TGF-β expression, and increased CD68, α-SMA and TNF-α staining. After 15 days of MSC transplantation, the animals showed reduction of blood pressure, urea and proteinuria, and serum proteins normalization, showing that the therapy promoted renal function reestablishment. In addition, MSC transplantation reduced the renal content of MMP-2 and -9, and TGF-β, and the α-SMA staining, while increased TIMP-1 and -2 content, contributing to basal membrane restoration, reduction of fibrosis by TEM, and renal glomeruli and tubules restoration. We also observed reduction of TNF-α expression and staining, reduction of CD68 staining, and increase of IL-10 staining. These results suggest that MSC transplantation was able to improve morphological and functional aspects caused by RH, promoting an immunomodulatory effect and renal parenchyma remodeling, preventing the progression of fibrosis through TEM in an experimental model of CKD.