Interest in the role of extracellular vesicles in various diseases including cancer has been increasing. Extracellular vesicles include microvesicles, exosomes, apoptotic bodies, and argosomes, and are classified by size, content, synthesis, and function. Currently, the best characterized are exosomes and microvesicles. Exosomes are small vesicles (40-100 nm) involved in intercellular communication regardless of the distance between them. They are found in various biological fluids such as plasma, serum, and breast milk, and are formed from multivesicular bodies through the inward budding of the endosome membrane. Microvesicles are 100-1000 nm vesicles released from the cell by the outward budding of the plasma membrane. The therapeutic potential of extracellular vesicles is very broad, with applications including a route of drug delivery and as biomarkers for diagnosis. Extracellular vesicles extracted from stem cells may be used for treatment of many diseases including kidney diseases. This review highlights mechanisms of synthesis and function, and the potential uses of well-characterized extracellular vesicles, mainly exosomes, with a special focus on renal functions and diseases.

This study evaluated the effects of bone marrow-derived mesenchymal stem cells (BMSCs) or their conditioned medium (CM) on the repair and prevention of Acute Kidney Injury (AKI) induced by gentamicin (G). Animals received daily injections of G up to 20 days. On the 10th day, injections of BMSCs, CM, CM+trypsin, CM+RNase or exosome-like microvesicles extracted from the CM were administered. In the prevention groups, the animals received the BMSCs 24 h before or on the 5th day of G treatment. Creatinine (Cr), urea (U), FENa and cytokines were quantified. The kidneys were evaluated using hematoxylin/eosin staining and immunohystochemistry. The levels of Cr, U and FENa increased during all the periods of G treatment. The BMSC transplantation, its CM or exosome injections inhibited the increase in Cr, U, FENa, necrosis, apoptosis and also increased cell proliferation. The pro-inflammatory cytokines decreased while the anti-inflammatory cytokines increased compared to G. When the CM or its exosomes were incubated with RNase (but not trypsin), these effects were blunted. The Y chromosome was not observed in the 24-h prevention group, but it persisted in the kidney for all of the periods analyzed, suggesting that the injury is necessary for the docking and maintenance of BMSCs in the kidney. In conclusion, the BMSCs and CM minimized the G-induced renal damage through paracrine effects, most likely through the RNA carried by the exosome-like microvesicles. The use of the CM from BMSCs can be a potential therapeutic tool for this type of nephrotoxicity, allowing for the avoidance of cell transplantations.

Stroke is the most common cause of motor disabilities and is a major cause of mortality worldwide. Adult stem cells have been shown to be effective against neuronal degeneration through mechanisms that include both the recovery of neurotransmitter activity and a decrease in apoptosis and oxidative stress. We chose the lineage stroke-prone spontaneously hypertensive rat (SHRSP) as a model for stem cell therapy. SHRSP rats can develop such severe hypertension that they generally suffer a stroke at approximately 1 year of age. The aim of this study was to evaluate whether mesenchymal stem cells (MSCs) decrease apoptotic death and oxidative stress in existing SHRSP brain tissue. The results of qRT-PCR assays showed higher levels of the antiapoptotic Bcl-2 gene in the MSC-treated animals, compared with untreated. Our study also showed that superoxide, apoptotic cells, and by-products of lipid peroxidation decreased in MSC-treated SHRSP to levels similar those found in the animal controls, Wistar Kyoto rats. In addition, we saw a repair of morphological damage at the hippocampal region after MSC transplantation. These data suggest that MSCs have neuroprotective and antioxidant potential in stroke-prone spontaneously hypertensive rats.

The therapeutic potential of mesenchymal stem cells (MSCs) and their conditioned medium (MSC-CM) has been extensively studied. MSCs can repair tissue, reduce local inflammation, and modulate the immune response. Persistent renal tubular interstitial inflammation results in fibrosis and leads to chronic kidney disease (CKD). Unilateral ureteral obstruction (UUO) is a very well-accepted renal fibrosis model. In this study, we evaluated factors influenced by the administration of MSCs or MSC-CM in the UUO model. MSCs extracted from rat bone marrow were cultivated in vitro and characterized by flow cytometry and cellular differentiation. Eight groups of female rats were used in experiments (n = 7, each), including Sham, UUO, UUO + MSC (obstruction + MSC), and UUO + CM (obstruction + MSC-CM) for 7 days of obstruction and Sham, UUO, UUO + MSC, and UUO + CM for 14 days of obstruction. The MSCs or MSC-CM was administered via the abdominal vena cava after total ligation of the left ureter. After 7 or 14 days, rats were euthanized, and serum and obstructed kidney samples were collected. MSCs or MSC-CM decreased the expression of molecules, such as Col1a1, α-SMA, and TNF-α. We also observed reductions in the levels of caspase 3, α-SMA, and PCNA in treated animals by immunohistochemistry. Our results suggest that the intravenous administration of MSCs or MSC-CM improves fibrosis progression and factors involved in apoptosis, inflammation, cell proliferation, and epithelial-mesenchymal transition in Wistar rats subjected to UUO, indicating a potential tool for preventing CKD.

SummaryThe objective of this study was to evaluate the frequency of CD4 1 T cell subsets in peripheral blood mononuclear cells (PBMC), urine and renal tissue from patients with lupus nephritis (LN). PBMC and urinary cells were collected from 17 patients with active LN, 20 disease controls (DC) with primary glomerulonephritis and 10 healthy controls (HC) and were analysed by flow cytometry with markers for T helper type 1 (Th1), Th2, Th17 and regulatory T cells (T reg ) cells. T cell subsets were assessed by immunohistochemistry from LN biopsy specimens from 12 LN patients. T cell subtypes in PBMC were re-evaluated at 6 months of therapy. CD4 1 T cells were decreased in PBMC in LN compared with DC and HC (P 5 0Á0001). No differences were observed in urinary CD4 1 T cell subsets between LN and DC. The frequency of urinary Th17 cells was higher in patients with non-proliferative than in proliferative LN (P 5 0Á041). CD3 1 and T-box 21 (T 1 bet ) cells were found in glomeruli and interstitium of LN patients, while forkhead box protein 3 (FoxP3), retinoid-related orphan receptor gamma (ROR-g) and GATA binding protein 3 (GATA-3) were present only in glomeruli. Th1 cells in PBMC were correlated negatively with urinary Th1 cells (Rho 5 -0Á531; P 5 0Á028) and with T bet in renal interstitium (Rho 5 -0Á782; P 5 0Á004). At 6 months, LN patients showed an increase in Th17 cells in PBMC. In conclusion, the inverse association between Th1 cells from PBMC and urinary/renal tissue indicate a role for Th1 in LN pathophysiology. Urinary Th17 cells were associated with less severe LN, and Th17 increased in PBMC during therapy. Urinary CD4 1 T cells were not different between LN and DC.