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Background Mesenchymal stem/stromal cells (MSCs) release extracellular vesicles (EVs), which shuttle proteins to recipient cells, promoting cellular repair. We hypothesized that cardiovascular risk factors may alter the pattern of proteins packed within MSC‐derived EVs, blunting their capacity to preserve the post‐stenotic kidney in pigs with metabolic syndrome (MetS) and renal artery stenosis (RAS). Methods We compared the protein cargo of EVs to their parent MSCs obtained from pigs with MetS and Lean controls. Porcine MSCs were harvested from abdominal fat after 16 weeks of Lean‐ or MetS‐diet (n=5 each), and their EVs isolated. Following LC‐MS/MS proteomics, clustering analysis was performed to identify primary functional categories of proteins enriched in Lean‐ and MetS‐EVs. In addition, MetS pigs were studied after 16 weeks of RAS untreated or treated 4 weeks earlier with a single intrarenal delivery of allogeneic labeled Lean‐ or MetS‐EVs (2.5x10^5/Kg). Lean and MetS Sham served as controls (n=6 each). Single‐kidney volume, renal blood flow (RBF), and glomerular filtration rate (GFR) were studied in‐vivo (multi‐detector CT), and tubular injury (Periodic Acid Schiff) and fibrosis (Trichrome) ex‐vivo. Results Proteomics analysis identified 6,690 and 6,790 distinct proteins in Lean‐ and MetS‐EVs, respectively. Differential expression analysis revealed that 91 proteins were upregulated in Lean‐EVs and 130 proteins in MetS‐EVs compared to their parent MSCs (FDR<0.05 and log2 fold‐change EVs/MSCs>2). Proteins enriched exclusively in Lean‐EVs modulate pathways related to the MSC reparative capacity, including cell proliferation, differentiation, and activation, as well as transforming growth factor‐β signaling (Figure 1A). Contrarily, proteins enriched only in MetS‐EVs are linked to pro‐inflammatory pathways, including acute inflammatory response, leukocyte transendothelial migration, and cytokine production (Figure 1B). Blood pressure was elevated in all MetS groups and all RAS groups develop moderate, but significant stenosis of a similar degree (Table). EVs were detected in the stenotic‐kidney 4 weeks after injection (Figure 2A). Renal volume, RBF, and GFR, which increased in MetS compared to Lean (consistent with hyperfiltration), fell in MetS+RAS, but restored in pigs treated with Lean‐EVs. Lean‐EVs also attenuated tubular injury and renal fibrosis (Figure 2B). Yet, these renoprotective effects were blunted in pigs treated with MetS‐EVs. Conclusion MetS alters the protein cargo of porcine MSC‐derived EVs, selectively packaging specific pro‐inflammatory signatures. Intrarenal delivery of Lean‐EVs attenuated renal injury and fibrosis and improved function in pigs with MetS+RAS, whereas these beneficial effects were blunted in pigs treated with MetS‐EVs. Therefore, our observations suggest that approaches to improve the therapeutic efficacy of autologous MSC‐derived EVs might be useful for patients with MetS+RAS. Support or Funding Information This study was partly supported by the National Institutes of Health grant numbers: DK104273, HL123160, DK102325, and DK106427. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .

Renovascular disease (RVD) and hypertension (HT) are cardiovascular risk factors, but if recovery of renal function can reverse cardiac dysfunction remained unclear. We hypothesized that improved stenotic kidney function would rescue myocardial microvascular (MMV) function in renovascular HT by reducing oxidative stress and inflammation. Single‐kidney hemodynamics and function and MMV permeability were assessed in pigs in vivo using CT after 6 weeks of RVD. Autologous endothelial progenitor cells (EPC) were then infused intra‐renally, and studies repeated 4 weeks later (RVD+EPC, n=7). Normal and untreated RVD (n=7 each) served as controls. Blood pressure was similarly increased in RVD and RVD+EPC pigs. Compared to normal, RVD showed elevated systemic TNF‐alpha (142.3± 3.7 vs 43.3 ± 3.5 pg/ml, p<0.001) and oxidized‐LDL, blunted glomerular filtration rate (47.9±10.1 vs 70.8 ± 4.3 ml/min, p<0.05), decreased MMV volume fraction, increased MMV permeability, and myocardial fibrosis. EPC were rarely observed in myocardium. However, RVD+EPC showed a decrease in TNF‐alpha (90.5± 2.9, p<0.01 vs RVD) and oxidized‐LDL, implying decreased inflammation and oxidative stress. Furthermore, not only renal, but also MMV function were significantly improved in RVD+EPC. In conclusion, selective improvement in renal function reduces oxidative stress and inflammation and preserves remote MMV function, underscoring functionally important cardiorenal crosstalk.

Background: Insulin-like growth factor binding protein7 (IGFBP-7) and tissue inhibitor of metalloproteinase-2 (TIMP-2) reflect G1-cell cycle arrest and are used as biomarkers for AKI. Recent studies show that these biomarkers rise in ischemic conditions and suggest that they actually may limit the severity of AKI. We tested the hypothesis that renal vein [IGFBP-7]*[TIMP-2] correlate with reductions in renal blood flow (RBF) and post-stent single kidney (SK)-GFR changes in patients with RVD undergoing contrast-based imaging and stent revascularization Methods: Inpatient studies were performed during 150 mEq Na+ intake and ACE/ARB Rx in patients with hemodynamically severe RVD (n=29, Doppler velocity = 318 ± 100cm/sec, and eGFR= 34.7 ± 11.7 mL/ min) scheduled for renal artery stenting, and compared to essential hypertensive (EH) healthy controls (n=32). Cortical and medullary RBFs (by multidetector CT) and renal vein levels of IGFBP-7 and TIMP-2 were measured before renal artery stenting and 3 months later Results: Pre-stenting IGFBP-7 and TIMP-2 levels were elevated in RVD compared to EH (18.5±2. vs 15.7±1.5 and 97.4±23.1vs 62.7±9.2 ng/mL respectively, P <0.0001). Baseline renal vein levels of IGFBP-7 * TIMP-2 correlated inversely with pre-stent RBF (r= - 0.53, P=0.01) and directly with the change (%) in SK-GFR observed 3 months after stenting Conclusion: IGFBP-7 and TIMP-2 levels are elevated in patients with chronic RVD as a function of the baseline reduction in RBF, and associate with subsequent improvement in SK-GFR 3 months after revascularization. These data are consistent with renovascular occlusion inducing cell-cycle arrest that serves to protect kidney function.

Background: The mechanisms responsible for cardiac injury in the early stage of metabolic syndrome (MetS) remain unknown. Mitochondria are intimately associated with myofibrils, where the cytoskeleton functions as a linkage coordinator. We hypothesized that early MetS is characterized by cytoskeletal-mitochondrial disorganization, and that mitoprotection with mitochondria-targeted peptides (MTP) would preserve cytoskeletal-mitochondrial structure and attenuate myocardial injury in early swine MetS. Methods: Pigs were studied after 16wks of diet-induced MetS, MetS treated for the last 4wks with the MTP Elamipretide (0.1mg/kg SC q.d), and Lean controls (n=6 each). Cardiac function (multidetector CT) was assessed in-vivo, and mitochondrial structure (electron microscopy), the mitochondrial inner membrane phospholipid cardiolipin (mass spectrometry), cytoskeletal proteins, oxidative stress, and apoptosis ex-vivo. Results: MetS pigs developed hypertension and insulin resistance, yet cardiac function was preserved. MetS induced loss of desmin and tubulin that was paralleled by mitochondrial disorganization, decreased 18:2 cardiolipin, and increased oxidative stress and apoptosis. MTP slightly improved cardiolipin species profile, restored mitochondrial organization, and upregulated cytoskeletal proteins, attenuating apoptosis and oxidative stress. Conclusion: Early MetS leads to disorganization of the cardiomyocyte cytoskeletal- mitochondrial architecture and cardiac injury. MTP may provide a novel therapeutic potential for improving cardiac injury in early MetS, and potentially preventing future deterioration in cardiac function.

Functional renal oxygen consumption, V r O 2 is due to tubular reabsorption of sodium (T Na ) in the proximal (∼67%) and distal(∼30%) nephrons, resulting in compartments (cortex/medulla) with distinct V r O 2 /T Na relationships. A progressive drop in renal blood flow (RBF) with renal arterial stenosis (RAS), disrupts O 2 delivery, vital for reabsorption. The overall objective for the study is to determine the intra‐renal regional alterations in tissue oxygenation (P t O 2 ) and theV r O 2 /T Na relationship in acute RAS. The hypothesis is RAS is accompanied by intra‐renal regional changes in oxygenation. Unilateral acute RAS was induced in 8 pigs by an extra‐vascular balloon. RBF and P t O 2 were measured continuously with an ultrasound flow probe during baseline, RBF autoregulation and 3 sequential decreases in RBF, recovery, and furosemide administration. V r O 2 was determined using Fick arterio‐venous differences. There were concomitant decreases in V r O 2 , and P t O 2 throughout the occlusion periods. Medullary P t O 2 changes were 35% more pronounced than cortical. This study suggests medullary decreases in P t O 2 are more aggravated than cortical changes with reductions in RBF, accentuating the medulla's vulnerability to progressive RAS. Mild to moderately severe obstructions seem to preserve the tubular transport costs. Funding provided by NIH Grant (HL16496‐32), 2007 APS Porter Physiology Fellowship and the Mayo Foundation.

MRE is a noninvasive novel MRI modality that detects changes in tissue viscoelastic properties by imaging shear wave propagation. Renal artery stenosis (RAS) induces kidney fibrosis, yet we have previously shown that concomitant reductions in renal perfusion pressure mask an increase in cortical stiffness. We hypothesized that due to its lower vascular volume and turgor, change es in medullary elasticity in RAS would be detectable by MRE. MRE 3D elastograms were obtained in pigs after 10 weeks of RAS or matched controls (n=6 per group), and contrast‐enhanced computed tomography images obtained in the same pigs guided selection of MRE medullary regions of interest (Fig 1). Trichrome staining was used for computer‐aided quantification of medullary fibrosis ex‐vivo. The renal medulla was significantly more fibrotic (5.96±0.19 vs. 1.82±0.49%, p<0.001) and stiffer (10.9±0.84 vs. 7.88±0.26 kPa, p<0.05) in RAS compared to controls (Fig 1 and 2). The histological degree of medullary fibrosis directly correlated with MRE‐derived stiffness (R 2 =0.55, p<0.05, Fig 3). This study therefore suggests that renal medullary MRE may be useful for detection of chronic kidney fibrosis in RAS. Grant Funding Source: NIH DK73608, HL77131 , HL085307 , and EB001981

Significance Statement Renal artery stenosis (RAS) engenders stenotic-kidney ischemia, dysfunction, and injury, but whether these are mediated by cellular senescence has not been elucidated. INK-ATTAC transgenic mice, high-resolution imaging, and unbiased single-cell RNA sequencing of murine kidneys demonstrated cellular senescence as an important mechanism of progressive injury to epithelial/stromal cells within poststenotic kidneys. Both p16-specific and broad quercetin/dasatinib interventions to blunt senescence improved renal function and structure, underscoring the central role of senescence in the pathogenesis. Furthermore, this mechanism was conserved in human subjects with RAS. These observations reveal new mechanisms that contribute to the pathogenesis of chronic ischemic renal injury, and support the development of senolytic therapy to reduce senescent cell burden and delay renal injury. Background Peripheral vascular diseases may induce chronic ischemia and cellular injury distal to the arterial obstruction. Cellular senescence involves proliferation arrest in response to stress, which can damage neighboring cells. Renal artery stenosis (RAS) induces stenotic-kidney dysfunction and injury, but whether these arise from cellular senescenceand their temporal pattern remain unknown. Methods Chronic renal ischemia was induced in transgenic INK-ATTAC and wild type C57BL/6 mice by unilateral RAS, and kidney function ( in vivo micro-MRI) and tissue damage were assessed. Mouse healthy and stenotic kidneys were analyzed using unbiased single-cell RNA-sequencing. To demonstrate translational relevance, cellular senescence was studied in human stenotic kidneys. Results Using intraperitoneal AP20187 injections starting 1, 2, or 4 weeks after RAS, selective clearance of cells highly expressing p16 Ink4a attenuated cellular senescence and improved stenotic-kidney function; however, starting treatment immediately after RAS induction was unsuccessful. Broader clearance of senescent cells, using the oral senolytic combination dasatinib and quercetin, in C57BL/6 RAS mice was more effective in clearing cells positive for p21 ( Cdkn1a ) and alleviating renal dysfunction and damage. Unbiased, single-cell RNA sequencing in freshly dissociated cells from healthy and stenotic mouse kidneys identified stenotic-kidney epithelial cells undergoing both mesenchymal transition and senescence. As in mice, injured human stenotic kidneys exhibited cellular senescence, suggesting this process is conserved. Conclusions Maladaptive tubular cell senescence, involving upregulated p16 ( Cdkn2a ), p19 ( Cdkn2d ), and p21 ( Cdkn1a ) expression, is associated with renal dysfunction and injury in chronic ischemia. These findings support development of senolytic strategies to delay chronic ischemic renal injury.

Percutaneous transluminal renal angioplasty and stenting (PTRS) for RVH may not revert the secondary cardiac dysfunction and remodeling. In experimental RVH, infusion of the tetrapeptide Bendavia (that inhibits mitochondrial permeability transition pore opening) during PTRS attenuated stenotic kidney inflammatory injury and improved its function. We hypothesized that adjunct Bendavia during PTRS would also attenuate cardiac remodeling after reversal of RVH. RVH was induced in 18 pigs, of which 6 were sham treated (RVH) and 12 underwent PTRS plus a 4h IV infusion of Bendavia (0.05 mg/kg) or vehicle (n=6, each); 6 normal pigs served as controls. Cardiac oxygenation and function were assessed 4 wks later by blood oxygen level‐dependent (BOLD)‐MRI and CT, and tissue studies performed. PTRS normalized blood pressure (Table). Systolic function was unchanged. Apoptotic activity (caspase‐3), hypoxia (BOLD‐R2*), inflammation (TNF‐α, IL‐6), and fibrosis (trichrome) remained elevated and diastolic function (E/A) impaired in PTRS+Vehicle, but all improved in PTRS+Bendavia (Figure). Thus, novel cardioprotective properties of Bendavia enhance cardiac recovery after reversal of experimental RVH, and may provide a novel therapeutic option.

Renal artery stenosis (RAS) may lead to hypertension and renal injury. Reversibility of renal tubular dysfunction in RAS upon revascularization is unclear. We tested the hypothesis that percutaneous transluminal renal angioplasty (PTRA) would restore tubular function assessed as medullary oxygenation response to furosemide, a diuretic that inhibits medullary tubular transport. This was studied in 16 pigs after 6 wks of RAS, using blood oxygen level dependent magnetic resonance imaging (BOLD MRI) before and after furosemide. Renal blood flow (RBF) and glomerular filtration rate (GFR) were determined with multidetector computed tomography. Pigs were then randomized for PTRA or sham (n=8 each) and studied again 4 wks later; 8 normal pigs served as controls. Results Stenotic kidney RBF, GFR, and BOLD MRI responses were reduced in RAS shams (Figure). PTRA decreased the degree of stenosis (11±7 vs. 71±5% in untreated RAS) and blood pressure (108±3 vs. 130±9 mmHg, p<0.05). Renal and tubular function were improved in RAS+PTRA, although not to normal (Figure). Non‐stenotic kidneys showed no change in tubular function. Therefore, tubular solute transport‐related oxygen consumption can be partially restored and detected by BOLD MRI 4 wks after PTRA in post stenotic swine kidneys. This noninvasive method may be useful to assess the functional status of kidneys in RAS patients. Supported by NIH, HL085307.

Abstract Aims Circulating progenitor cells (CPCs) play a role in vascular repair and plaque stability, while osteocalcin (OC) expressing CPCs have been linked to unstable plaque and adverse cardiovascular outcomes. However, their role in cardiac allograft vasculopathy (CAV) has not been elucidated. This cohort study aimed to investigate the contribution of CPCs on CAV progression and cardiovascular events after heart transplantation. Methods and results A total of 80 heart transplant patients (mean age 55 ± 14 years, 72% male) undergoing annual intravascular ultrasound (IVUS) had fresh CPCs marked by CD34, CD133, and OC counted in peripheral blood using flow cytometry, on the same day as baseline IVUS. CAV progression was assessed by IVUS as the change (Δ) in plaque volume divided by segment length (PV/SL), adjusted for the time between IVUS measurements [median 3.0, interquartile range (2.8–3.1) years] and was defined as ΔPV/SL that is above the median ΔPV/SL of study population. Major adverse cardiac events (MACEs) were defined as any incident of revascularization, myocardial infarction, heart failure admission, re-transplantation, stroke, and death. Patients with higher CD34+CD133+ CPCs had a decreased risk of CAV progression [odds ratio 0.58, 95% confidence interval (CI) (0.37–0.92), P = 0.01] and MACE [hazard ratio (HR) 0.79, 95% CI (0.66–0.99), P = 0.05] during a median (interquartile range) follow-up of 8.0 years (7.2–8.3). Contrarily, higher OC+ cell counts were associated with an increased risk of MACE [HR 1.26, 95% CI (1.03–1.57), P = 0.02]. Conclusions Lower levels of CD34+CD133+ CPCs are associated with plaque progression and adverse long-term outcomes in patients who underwent allograft heart transplantation. In contrast, higher circulating OC+ levels are associated with adverse long-term outcomes. Thus, CPCs might play a role in amelioration of transplant vasculopathy, while OC expression by these cells might play a role in progression.