Despite the fact that a significant fraction of kidney graft dysfunctions observed after transplantation is due to ischemia-reperfusion injuries, there is still no clear consensus regarding optimal kidney preservation strategy. This stems directly from the fact that as of yet, the mechanisms underlying ischemia-reperfusion injury are poorly defined, and the role of each preservation parameter is not clearly outlined. In the meantime, as donor demography changes, organ quality is decreasing which directly increases the rate of poor outcome. This situation has an impact on clinical guidelines and impedes their possible harmonization in the transplant community, which has to move towards changing organ preservation paradigms: new concepts must emerge and the definition of a new range of adapted preservation method is of paramount importance. This review presents existing barriers in transplantation (e.g., temperature adjustment and adequate protocol, interest for oxygen addition during preservation, and clear procedure for organ perfusion during machine preservation), discusses the development of novel strategies to overcome them, and exposes the importance of identifying reliable biomarkers to monitor graft quality and predict short and long-term outcomes. Finally, perspectives in therapeutic strategies will also be presented, such as those based on stem cells and their derivatives and innovative models on which they would need to be properly tested.

/pdf/barriers-and-advances-in-kidney-preservation-57a5vmnpw1.pdf

Barriers and Advances in Kidney Preservation

Bio-products from stem/progenitor cells, such as extracellular vesicles, are likely a new promising approach for reprogramming resident cells in both acute and chronic kidney disease. Forty CKD patients stage III and IV (eGFR 15–60 mg/ml) have been divided into two groups; twenty patients as treatment group “A” and twenty patients as a matching placebo group “B”. Two doses of MSC-derived extracellular vesicles had been administered to patients of group “A”. Blood urea, serum creatinine, urinary albumin creatinine ratio (UACR) and estimated glomerular filtration rate (eGFR) have been used to assess kidney functions and TNF-α, TGF-β1 and IL-10 have been used to assess the amelioration of the inflammatory immune activity. Participants in group A exhibited significant improvement of eGFR, serum creatinine level, blood urea and UACR. Patients of the treatment group “A” also exhibited significant increase in plasma levels of TGF-β1, and IL-10 and significant decrease in plasma levels of TNF-α. Participants of the control group B did not show significant improvement in any of the previously mentioned parameters at any time point of the study period. Administration of cell-free cord-blood mesenchymal stem cells derived extracellular vesicles (CF-CB-MSCs-EVs) is safe and can ameliorate the inflammatory immune reaction and improve the overall kidney function in grade III-IV CKD patients.

/pdf/umbilical-cord-mesenchymal-stem-cells-derived-extracellular-23n8mgae3g.pdf

Umbilical cord mesenchymal stem cells derived extracellular vesicles can safely ameliorate the progression of chronic kidney diseases

The early and long-term effects of coronary artery ligation on the plasma and left ventricular angiotensin-converting enzyme (ACE and ACE2) activities, ACE and ACE2 mRNA levels, circulating angiotensin (Ang) levels [Ang I, Ang-(1-7), Ang-(1-9), and Ang II], and cardiac function were evaluated 1 and 8 weeks after experimental myocardial infarction in adult Sprague Dawley rats. Sham-operated rats were used as controls. Coronary artery ligation caused myocardial infarction, hypertrophy, and dysfunction 8 weeks after surgery. At week 1, circulating Ang II and Ang-(1-9) levels as well as left ventricular and plasma ACE and ACE2 activities increased in myocardial-infarcted rats as compared with controls. At 8 weeks post-myocardial infarction, circulating ACE activity, ACE mRNA levels, and Ang II levels remained higher, but plasma and left ventricular ACE2 activities and mRNA levels and circulating levels of Ang-(1-9) were lower than in controls. No changes in plasma Ang-(1-7) levels were observed at any time. Enalapril prevented cardiac hypertrophy and dysfunction as well as the changes in left ventricular ACE, left ventricular and plasmatic ACE2, and circulating levels of Ang II and Ang-(1-9) after 8 weeks postinfarction. Thus, the decrease in ACE2 expression and activity and circulating Ang-(1-9) levels in late ventricular dysfunction post-myocardial infarction were prevented with enalapril. These findings suggest that in this second arm of the renin-angiotensin system, ACE2 may act through Ang-(1-9), rather than Ang-(1-7), as a counterregulator of the first arm, where ACE catalyzes the formation of Ang II.

/pdf/enalapril-attenuates-downregulation-of-angiotensin-1slh52vnao.pdf

Enalapril Attenuates Downregulation of Angiotensin-Converting Enzyme 2 in the Late Phase of Ventricular Dysfunction in Myocardial Infarcted Rat

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 10(th) 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 5(th) 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.

/pdf/bone-marrow-derived-mesenchymal-stem-cells-repaired-but-did-sjrqkqftdv.pdf

Bone marrow-derived mesenchymal stem cells repaired but did not prevent gentamicin-induced acute kidney injury through paracrine effects in rats.

Exosomes, which are one of the smallest extracellular vesicles released from cells, have been shown to carry different nucleic acids, including microRNAs (miRNAs). miRNAs significantly regulate cell growth and metabolism by posttranscriptional inhibition of gene expression. The rapidly changing understanding of exosomes' formation and function in delivering miRNAs from cell to cell has prompted us to review current knowledge in exosomal miRNA secretion mechanisms as well as possible therapeutic applications for personalized medicine.

https://www.mdpi.com/1422-0067/17/12/2028/pdf

Exosomes as miRNA Carriers: Formation–Function–Future

End-stage renal disease (ESRD) requires for its treatment permanent dialysis or kidney transplantation (KT). KT is the best clinical treatment, however, the early function of the allograft varies depending on multiple factors associated with cold ischemia time (CIT) and the allograft rejection process. It is known that serum creatinine is an insensitive and late marker for predicting graft recovery after KT, mainly in patients with delayed graft function (DGF). Neutrophil gelatinase-associated lipocalin (NGAL) is produced in the distal nephron and it is one of the most promising novel biomarkers for acute kidney injury (AKI) and chronic kidney disease (CKD). NGAL has been proposed to be a predictor of organ recovery from DGF after KT from donors after cardiac death. Because nonrenal diseases can also induce NGAL, more information is necessary to validate the sensitivity and specificity of urine and plasma NGAL in clinical samples. The exosomes are vesicles released into the urine from the kidney epithelium and they have been proposed as better source to explore as biomarker of renal dysfunction. The molecular composition of the urinary exosomes could be representative of the physiological or physiopathologic condition of the urinary system. We propose that determination of NGAL in urinary exosomes is a better predictor of kidney dysfunction after KT than other urinary fractions. We analyzed 15 kidney allograft recipients, with a mean age of 36 years (range, 16-60 years) and 75% were male: 11 living donors (LD) and 4 deceased donors (DD). The average length of CIT was 14 hours in DD and less than 1 hour in LD. Three patient developed DGF. Using Western blot analysis, NGAL was detectable in the cellular and exosomal fraction of the urine. The exosomes expressed higher levels of NGAL than the cellular fraction. The expression of NGAL was observed from the first day after transplantation. In the cellular fraction of the urine, no significant differences of NGAL were observed between the patients. However, the median of NGAL expression in the exosomes fraction was significantly higher in DD patient, from the first day after KT (P < .05). Moreover, we noticed that NGAL expression in exosomes remained elevated in the patients with DGF compared with non-DGF patients (P < .05). Considering the highest abundance of NGAL in the urinary exosomes and its correlation with DGF patients, we suggest the exosomal fraction as a more sensitive substrate to evaluate early biomarkers of DGF after KT.

Urinary Exosomes as a Source of Kidney Dysfunction Biomarker in Renal Transplantation

Cardiac hypertrophy is one of the main ways in which cardiomyocytes respond to mechanical and neurohormonal stimuli. It enables myocytes to increase their work output, which improves cardiac pump function. However, this compensatory mechanism can become overwhelmed by biomechanical stress, thereby resulting in heart failure, which is associated with high morbidity and mortality. The complex molecular processes that lead to cardiomyocyte growth involve membrane receptors, second messengers, and transcription factors. The common final pathway of all these intracellular substances is gene expression, whose variations are being revealed in increasing detail. The genetic response is characterized by the re-expression of fetal genes, an event which is regarded as the molecular marker of pathologic cardiac hypertrophy, and which is absent in normal physiologic cardiac growth. The possibility of stopping or reversing pathologic cardiac hypertrophy and, thereby, slowing the development of heart failure is a topic of considerable clinical interest and a large amount of relevant data has accumulated. The purpose of this review was to provide a schematic overview of current knowledge about the molecular pathogenesis of cardiomyocyte hypertrophy, with special emphasis on new research topics and investigations.

Cardiac Hypertrophy: Molecular and Cellular Events

CKD (chronic kidney disease) has become a public health problem. The therapeutic approaches have been able to reduce proteinuria, but have not been successful in limiting disease progression. In this setting, cell therapies associated with regenerative effects are attracting increasing interest. We evaluated the effect of MSC (mesenchymal stem cells) on the progression of CKD and the expression of molecular biomarkers associated with regenerative effects. Adult male Sprague–Dawley rats subjected to 5/6 NPX (nephrectomy) received a single intravenous infusion of 0.5×10 6 MSC or culture medium. A sham group subjected to the same injection was used as the control. Rats were killed 5 weeks after MSC infusion. Dye tracking of MSC was followed by immunofluorescence analysis. Kidney function was evaluated using plasma creatinine. Structural damage was evaluated by H&E (haematoxylin and eosin) staining, ED-1 abundance (macrophages) and interstitial α-SMA (α-smooth muscle actin). Repairing processes were evaluated by functional and structural analyses and angiogenic/epitheliogenic protein expression. MSC could be detected in kidney tissues from NPX animals treated with intravenous cell infusion. This group presented a marked reduction in plasma creatinine levels and damage markers ED-1 and α-SMA ( P

http://www.westlaboratory.org/wp-content/uploads/2011/05/Smith-101912-MSC-injection-ameliorates-chronic-renal-failure-in-a-rat-modell.pdf

Mesenchymal stem cell injection ameliorates chronic renal failure in a rat model.

La hipertrofia cardiaca constituye una de las principales formas de respuesta del cardiomiocito a estimulos mecanicos y neurohormonales y permite al miocito generar mayor trabajo, con aumento de la funcion de la bomba cardiaca. Esta accion compensadora, sin embargo, se ve en algun momento sobrepasada por el estres biomecanico, lo que da lugar al cuadro de insuficiencia cardiaca, que causa una gran morbilidad y mortalidad. En los complejos procesos moleculares que llevan al crecimiento del miocito cardiaco intervienen receptors de membrana, segundos mensajeros y factores de transcripcion. La via final comun en que convergen estos agentes intracelulares es la expresion genica, cuyos cambios estan siendo caracterizados cada vez con mas detalle. Esta modificacion genica se caracteriza por la reexpresion de genes fetales, evento considerado como el marcador molecular de hipertrofia patologica, ausente en condiciones de crecimiento ventricular fisiologico. La posibilidad de detener o revertir la hipertrofia patologica y, asi, detener la evolucion hacia insuficiencia cardiaca, ha generado un considerable interes y mucha informacion al respecto. El objetivo de la presente revision es mostrar esquematicamente el conocimiento actual de la patogenia molecular de la hipertrofia patologica del cardiomiocito, con enfasis en los nuevos interrogantes y lineas de investigacion.

/pdf/hipertrofia-cardiaca-eventos-moleculares-y-celulares-2fo5focg4w.pdf

Hipertrofia cardiaca: eventos moleculares y celulares

Therapeutic approaches for CKD (chronic kidney disease) have been able to reduce proteinuria, but not diminish the disease progression. We have demonstrated beneficial effects by injection of BM (bone marrow)-derived MSCs (mesenchymal stem cells) from healthy donors in a rat model with CKD. However, it has recently been reported that BM-MSCs derived from uraemic patients failed to confer functional protection in a similar model. This suggests that autologous BM-MSCs are not suitable for the treatment of CKD. In the present study, we have explored the potential of MSCs derived from adipose tissue (AD-MSCs) as an alternative source of MSCs for the treatment of CKD. We have isolated AD-MSCs and evaluated their effect on the progression of CKD. Adult male SD (Sprague–Dawley) rats subjected to 5/6 NPX (nephrectomy) received a single intravenous infusion of 0.5×10 6 AD-MSCs or MSC culture medium alone. The therapeutic effect was evaluated by plasma creatinine measurement, structural analysis and angiogenic/epitheliogenic protein expression. AD-MSCs were detected in kidney tissues from NPX animals. This group had a significant reduction in plasma creatinine levels and a lower expression of damage markers ED-1 and α-SMA (α-smooth muscle actin) ( P

Juan Carreno

Papers

Urinary Exosomes as a Source of Kidney Dysfunction Biomarker in Renal Transplantation

Cardiac Hypertrophy: Molecular and Cellular Events

Mesenchymal stem cell injection ameliorates chronic renal failure in a rat model.

Hipertrofia cardiaca: eventos moleculares y celulares

Human mesenchymal stem cells derived from adipose tissue reduce functional and tissue damage in a rat model of chronic renal failure