Pre-transplant donor biopsy (PTDB)-based marginal-donor allocation systems to single or dual renal transplantation could increase the use of organs with Kidney Donor Profile Index (KDPI) in the highest range (e.g. >80 or >90), whose discard rate approximates 50% in the US. To test this hypothesis, we retrospectively calculated the KDPI and analyzed the outcomes of 442 marginal kidney transplants (340 single transplants: 278 with a PTDB Remuzzi score <4 [median KDPI:87; interquartile range(IQR):78-94] and 62 with a score =4 [median KDPI:87; IQR:76-93]; 102 dual transplants [median KDPI: 93; IQR:86-96]) and 248 single standard transplant controls [median KDPI:36; IQR:18-51]. PTDB-based allocation of marginal grafts led to a limited discard rate of 15% for kidneys with KDPI of 80-90 and of 37% for kidneys with a KDPI of 91-100. Although 1-year eGFRs were significantly lower in recipients of marginal kidneys (-9.3, -17.9, and -18.8ml/min, for dual transplants, single kidneys with PTDB score <4, and =4, respectively; P<0.001), graft survival (median follow-up 3.3 years) was similar between marginal and standard kidney transplants (hazard ratio: 1.20 [95% confidence interval: 0.80 to 1.79; P=0.38]). In conclusion, PTDB-based allocation allows the safe transplantation of kidneys with KDPI in the highest range that may otherwise be discarded.

Patients affected by chronic kidney disease (CKD) or end-stage renal disease (ESRD) experience a huge cardiovascular risk and cardiovascular events represent the leading causes of death. Since traditional risk factors cannot fully explain such increased cardiovascular risk, interest in non-traditional risk factors, such as hyperhomocysteinemia and folic acid and vitamin B12 metabolism impairment, is growing. Although elevated homocysteine blood levels are often seen in patients with CKD and ESRD, whether hyperhomocysteinemia represents a reliable cardiovascular and mortality risk marker or a therapeutic target in this population is still unclear. In addition, folic acid and vitamin B12 could not only be mere cofactors in the homocysteine metabolism; they may have a direct action in determining tissue damage and cardiovascular risk. The purpose of this review was to highlight homocysteine, folic acid and vitamin B12 metabolism impairment in CKD and ESRD and to summarize available evidences on hyperhomocysteinemia, folic acid and vitamin B12 as cardiovascular risk markers, therapeutic target and risk factors for CKD progression.

Vascular calcification (VC) is common in dialysis and non-dialysis chronic kidney disease (CKD) patients, even in the early stage of the disease. For this reason, it can be considered a CKD hallmark. VC contributes to cardiovascular disease (CVD) and increased mortality among CKD patients, although it has not been proven. There are more than one type of VC and every form represents a marker of systemic vascular disease and is associated with a higher prevalence of CVD in CKD patients, as shown by several clinical studies. Major risk factors for VC in CKD include: Increasing age, dialysis vintage, hyperphosphatemia (particularly in the setting of intermittent or persistent hypercalcemia), and a positive net calcium and phosphate balance. Excessive oral calcium intake, including calcium-containing phosphate binders, increases the risk for VC. Moreover, it has been demonstrated that there is less VC progression with non-calcium-containing phosphate binders. Unfortunately, until now, a specific therapy to prevent progression or to facilitate regression of VC has been found, beyond careful attention to calcium and phosphate balance.

Background: Kidney transplantation is the treatment of choice for chronic kidney disease (CKD), but in kidney transplant recipients (KTRs) cardiovascular events are the first cause of death with a functioning graft, ranging from 36 to 55%. The impact of vascular calcification (VC) on morbidity and mortality of KTRs is not appreciated enough nowadays. Summary: This review summarizes 13 important studies on VC in KTRs, comparing the results with CKD and dialysis populations. We focused on VC evaluation and use of coronary artery calcification (CAC) and aorta calcification (AoC) scores. We also evaluated the influence of traditional and non-traditional progression risk factors. Key Messages: VC strongly predicts cardiovascular events and all-cause mortality in KTRs. VC assessment is important in KTRs and based essentially on multislice computed tomography or electron beam computed tomography recognition of lesions. Quantitative measurement of CAC and AoC scores is essential for a correct definition of the calcium burden before and after kidney transplant. Progression of CAC slows down but does not halt after kidney transplant. A variable association of both traditional and non-traditional risk factors is shown. There is a strong association between baseline CAC score and CAC progression. A significant improvement in secondary hyperparathyroidism after transplantation favorably affects the progression of CAC. Low 25(OH)D₃ levels are an independent determinant of CAC progression. Diabetes is a risk factor for the presence of CAC in KTRs, but has not been independently associated with CAC progression. The data published on the use of immunosuppressive drugs as progression factors are few and inconclusive.

Chronic kidney disease-mineral and bone disorder (CKD-MBD) is common in kidney transplant recipients (KTRs), where secondary hyperparathyroidism (HPTH) and post-transplantation bone disease (PTBD) are potential effectors of both graft and vascular aging. Reduced 25(OH)D levels are highly prevalent in KTRs. Experimental and clinical evidence support the direct involvement of deranged vitamin D metabolism in CKD-MBD among KTRs. This review analyzes the pathophysiology of vitamin D derangement in KTRs and its fall out on patient and graft outcome, highlighting the roles of both nutritional and active vitamin D compounds to treat PTBD, cardiovascular disease (CVD) and graft dysfunction. Fibroblast growth factor-23-parathyroid hormone (PTH)-vitamin D axis, immunosuppressive therapy and previous bone status have been associated with PTBD. Although several studies reported reduced PTH levels in KTRs receiving nutritional vitamin D, its effects on bone mineral density (BMD) remain controversial. Active vitamin D reduced PTH levels and increased BMD after transplantation, but paricalcitol treatment was not accompanied by benefits on osteopenia. Vitamin D is considered protective against CVD due to the widespread pleiotropic effects, but data among KTRs remain scanty. Although vitamin deficiency is associated with lower glomerular filtration rate (GFR) and faster estimated GFR decline and data on the anti-proteinuric effects of vitamin D receptor activation (VDRA) in KTRs sound encouraging, reports on related improvement on graft survival are still lacking. Clinical data support the efficacy of VDRA against HPTH and show promising evidence of VDRA's effect in counteracting post-transplant proteinuria. New insights are mandatory to establish if the improvement of surrogate outcomes will translate into better patient and graft outcome.

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Core tip: Mesenchymal stem cells (MSCs) may have an important therapeutic potential in acute kidney injury management. A body of evidence has demonstrated that MSCs act through a paracrine/endocrine secretion of soluble factors and microvesicles. We summarize preclinical studies and ongoing clinical trials that evaluate the role of MSCs in restoring kidney function. We critically explain the current concerns about the use of MSCs and microvesicles that limit their applications in clinical trials. Then, we propose the future directions that could lead to extend MSCs use in humans.Bianchi F, Sala E, Donadei C, Capelli I, La Manna G. reperfusion injury (IRI) is a major cause of AKI, and it is characterized by acute tubular injury and rapid renal dysfunction, generally caused by ischemic or toxic insults [1][2][3] . The kidney undergoing IRI presents an extensive and complex inflammatory/oxidative stress response, that may result in fibroblast proliferation and excessive deposition of extracellular matrix and has been recognized as a major contributor to end-stage kidney disease [4] . Although many efforts have been made to deal with this problem, such as new drugs and modern dialysis techniques, innovative interventions beyond supportive therapy are not available yet [5] ; therefore, a potent therapeutic intervention for ischemia AKI is imperative. In recent years, a promising approach to manage renal IRI is the use of mesenchymal stem cells (MSCs). Their use in treating different kind of diseases as immunological, vascular, cardiac and renal diseases has been extensively explored [6,7] . MSCs can be isolated from various sources, such as bone marrow or adipose tissue, but other organs have their own niches of MSC-like cells, such as the kidney. Besides their broad distribution in the body and an easy isolation, the interest in MSC was originally raised by their capacity to differentiate into other cell types, suggesting that they could be a source of healthy cells to repair/replace injured tissue [8] .There is evidence from both in vitro studies and animal models of AKI that MSCs can promote regenerative responses in the injured kidney, leading to tissue repair and improvement of renal function [9][10][11] . These beneficial effects have been initially ascribed to the trans-differentiation of MSCs into organ specific cells. However, at least in the kidney, this is a very rare event and the kidneyprotective effects of MSCs have been attributed mainly to paracrine mechanisms [12] . This review will focus on the application of cell therapy in AKI, and it will summarize the recent preclinical and clinical results about the use of MSCs in renal IRI (Figure 1). THERAPEUTIC POTENTIAL OF MESENCHYMAL STEM CELLSMesenchymal stem cells are undifferentiated adult stem cells derived from mesodermal embryonic layer that can differentiate into a broad range of different mesenchymal tissues, including cartilage, bone, muscle, stroma, fat, tendon, and other connective tissues [13] . These cells have been originally isolated f...

Donation after circulatory death (DCD) is a potential source of reducing organ demand. In Italy, DCD requires a 20-min no-touch period that prolongs warm ischemia and increases delayed graft function (DGF) risk and graft loss. We report here our preliminary experience of sequential use of normothermic regional perfusion (NRP), as standard procedure, and hypothermic oxygenated perfusion (HOPE), as an experimental technique of organ preservation, in 10 kidney transplants (KT) from five DCD Maastricht III with extensive functional warm ischemia time (fWIT) up to 325 min. During NRP, renal function tests were evaluated to accept organs which were retrieved according to standard fashion with biopsy. While waiting for pathology and cross-match results, organs were preserved with HOPE through pressure- and temperature-controlled arterial pulsatile flow. All grafts with Karpinski score ≤4 were used for conventional single KT with mean cold ischemia time of 584 ± 167 min and mean fWIT of 151 ± 132 min. At the end of HOPE, lactate levels increased significantly in all cases with DGF (P = 0.0095), which were 3/10 (30%). No primary nonfunctions were recorded, and all patients had sCr < 1.5 mg/dl at 6-month post-KT. NRP and HOPE for DCD may overcome fWIT limits safely, and lactate during HOPE predicts DGF.