Estudo da morfofuncionalidade mitocondrial renal após transplante de células estromais mesenquimais de medula óssea em ratos com nefropatia

Abstract

Nephropathy is a chronic kidney disease (CKD) induced by renovascular hypertension (RH), which consists of partial occlusion of the renal artery, promoting renal ischemia, and followed by activation of the renin-angiotensin-aldosterone system (RAAS), a key point for increased systolic blood pressure (SBP). RH is progressive and, if there is no intervention, can progress to CKD. Several mitochondrial changes are related to different pathways that make up the pathophysiology of CKD. Currently, the only alternative treatment is dialysis and/or renal transplantation. However, the high cost of dialysis and the shortage of organs for transplantation is understandable for the need to develop new therapies. Mesenchymal stromal cells (MSC) are excellent candidates as a therapeutic alternative, largely due to their paracrine effects, which modulate the microenvironment, providing preservation of renal function. Despite advances in therapeutic potential, it is necessary to elucidate the contribution of MSC to mitochondrial dysfunction in the renal parenchyma. The objective of this work was to evaluate the effects of MSC transplantation on mitochondrial morphofunctionality in the left kidney of rats with AH induced by the 2 kidneys 1 clip model (left renal artery clipping – 2K1C). For this, male Wister rats (n=24) were divided into four groups: Sham, 2K1C, 2K1C+MSC7d and 15d (transplantation after 4 weeks of clipping surgery). After 7 and 15 days of transplantation (weeks 5 and 6) the rats were euthanized and the kidneys collected and processed for light microscopy, transmission electron microscopy and western blotting. Were evaluated: renal morphology and functional parameters, tissue expression of DRP1 and MTF2 (mitochondrial dynamic), PGC1α (mitochondrial biogenesis), UCP2 (uncoupling protein), Bax/Bcl2 (apoptosis) and mitochondrial ultrastructure. The 2K1C animals showed increase in SBP (p<0.001), creatinine (p<0.05), urea and proteinuria (p<0.0001), and reduced serum proteins (p<0.05). Clipped kidneys showed fibrosis (p<0.05), parenchymal disruption, fragmented mitochondria, increased expression DRP1 (<0.0001), MTF1-2 (p<0.05), Renin, Bax/Bcl2, and UCP2 (p<0.05, for all), in addition to the reduction of PGC1α (p<0.05). Parkin stayed low on clipped kidneys. After 7 and 15 d of MSC transplantation, the animals showed a reduction in SBP (p<0.001,7 and 15d), urea levels, proteinuria (P<0.0001; p<0.001, 7 and 15d for both), creatinine (p<0,05, 7d) and serum proteins restoration (p<0.05; p<0.001, 7 and 15d). In addition, the kidneys showed parenchymal restructuring, presence of autophagosomes, reduced fibrosis (p<0.05, 7 and 15d), DRP1 (p<0.0001,7 and 15d), MTF1, Bax/Bcl2, UCP2 (P<0.05, 7 and 15d for all), MTF2, Renin (p<0.001; p<0.05, 7 and 15d for all) and increased Parkin and PGC1α (p<0.05, 7 and 15d for both). These data suggest that MSC transplantation was able to restore morphological, ultrastructural, and functional aspects, reducing apoptosis, and recovering mitochondrial function, modulated by dynamics, mitophagy, biogenesis in a model of nephropathy.