Lerman, Lilach O.

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.

Background and Purpose: XO (xanthine oxidase) is a key enzyme of uric acid metabolism and is thought to contribute to oxidative pathways that promote atherosclerotic plaque progression, yet its role in plaque destabilization is not well elucidated. We hypothesized that XO is expressed in carotid plaque from symptomatic patients in association with cardiovascular risk factors. Methods: Patients were stratified by symptoms, defined as presentation with an ipsilateral cerebral ischemic event. Carotid atherosclerotic plaques were obtained from 44 patients with symptomatic plaque and 44 patients without ischemic cerebral events. Protein expression of XO was evaluated by immunohistochemical staining and the percentage of cells expressing XO and CD68 (macrophage marker) compared between the groups. Biochemical and demographic cardiometabolic risk factors of study participants also were measured. Results: Carotid atherosclerotic plaques from symptomatic patients were associated with significantly higher XO expression versus asymptomatic plaque (median [interquartile range]: 1.24 [2.09] versus 0.16 [0.34]; P <0.001) and with significantly higher circulating uric acid levels (mean±SD: 7.36±2.10 versus 5.37±1.79 mg/dL; P <0.001, respectively). In addition, XO expression in atherosclerotic carotid plaque was inversely associated with serum high-density lipoproteins cholesterol levels ( P =0.010, r =−0.30) and directly with circulating uric acid levels ( P <0.001, r =0.45). The average percentage of macrophages that expressed XO was significantly higher in symptomatic versus asymptomatic plaques (median [interquartile range]: 93.37% [25] versus 46.15% [21], respectively; P <0.001). Conclusions: XO overexpression in macrophages is associated with increased serum uric acid and low high-density lipoproteins cholesterol levels and may potentially have a mechanistic role in carotid plaque destabilization. The current study supports a potential role for uric acid synthesis pathway as a target for management of carotid atherosclerosis in humans.

AbstractRegenerative, cell-based therapy is a promising treatment option for diabetic kidney disease (DKD), which has no cure. To prepare for clinical translation, this systematic review and meta-analysis summarized the effect of cell-based interventions in DKD animal models and treatment-related factors modifying outcomes. Electronic databases were searched for original investigations applying cell-based therapy in diabetic animals with kidney endpoints (January 1998-May 2019). Weighted or standardized mean differences were estimated for kidney outcomes and pooled using random-effects models. Subgroup analyses tested treatment-related factor effects for outcomes (creatinine, urea, urine protein, fibrosis, and inflammation). In 40 studies (992 diabetic rodents), therapy included mesenchymal stem/stromal cells (MSC; 61%), umbilical cord/amniotic fluid cells (UC/AF; 15%), non-MSC (15%), and cell-derived products (13%). Tissue sources included bone marrow (BM; 65%), UC/AF (15%), adipose (9%), and others (11%). Cell-based therapy significantly improved kidney function while reducing injury markers (proteinuria, histology, fibrosis, inflammation, apoptosis, epithelial-mesenchymal-transition, oxidative stress). Preconditioning, xenotransplantation, and disease-source approaches were effective. MSC and UC/AF cells had greater effect on kidney function while cell products improved fibrosis. BM and UC/AF tissue sources more effectively improved kidney function and proteinuria vs adipose or other tissues. Cell dose, frequency, and administration route also imparted different benefits. In conclusion, cell-based interventions in diabetic animals improved kidney function and reduced injury with treatment-related factors modifying these effects. These findings may aid in development of optimal repair strategies through selective use of cells/products, tissue sources, and dose administrations to allow for successful adaptation of this novel therapeutic in human DKD.

Background Resistive reserve ratio (RRR), or the ratio of baseline to hyperemic microvascular resistance, has prognostic implications in predicting clinical outcomes in patients with obstructive coronary artery disease. However, its value in patients with angina or ischemia with nonobstructive coronary artery disease is unknown. Methods and Results We included 1692 patients with nonobstructive coronary artery disease who underwent invasive coronary vasoreactivity testing. Abnormal coronary flow reserve (CFR, the ratio of hyperemic and baseline resting flow velocities) and RRR were defined as <2.5 and <2.62, respectively. The mortality rate was marginally higher in patients with abnormal CFR (428 patients [25%]) than those with normal CFR (38 [9%] versus 81 [6%]; P =0.08), and was significantly higher in patients with abnormal RRR (716 patients [42%]) than those with normal RRR (70 [10%] versus 49 [5%], P =0.0002) over the median follow‐up of 11.3 years. Patients with abnormal CFR had marginally lower survival than those with normal CFR (log‐rank P =0.08). In contrast, patients with abnormal RRR had significantly lower survival than those with normal RRR (log‐rank P =0.001). Abnormal RRR was associated with shorter time to death even after adjustment for other covariates (adjusted hazard ratio, 1.63; 95% CI, 1.11–2.38; P =0.01). Conclusions In patients with no obstructive coronary artery disease, RRR was superior to CFR in predicting long‐term survival. An RRR <2.62 was associated with 1.6 times increased risk of death in patients with nonobstructive coronary artery disease. Indices of coronary microcirculatory resistive reserve comprising flow‐ and pressure‐derived values may reflect underlying microvascular pathology more faithfully than flow‐alone indices like CFR.

Introduction: Previous studies in patients with Raynaud’s phenomenon (RP) have found an association between microvascular abnormalities assessed via nail fold capillaroscopy as well as macrovascular peripheral endothelial dysfunction (PED). However, the association between RP and microvascular PED is not yet established. Hypothesis: We hypothesized that patients with RP have greater microvascular PED compared to controls without RP Methods: We performed a retrospective cross-sectional analysis of patients referred to Mayo Clinic between 2006 and 2014 for routine cardiovascular evaluation, and who underwent evaluation of Reactive Hyperemia Peripheral Arterial Tonometry (index < 2 consistent with PED). Patients with RP were identified by chart review. Results: Six hundred sixty six individuals were included in this study (mean age 51.9±13.5 years, 411 (61.3%) women), 637 (95.1%) individuals did not have RP (control group), and 29 (4.3%) had secondary RP. Only 4 patients had primary RP and were excluded from the final analyses. Individuals with secondary RP had a higher frequency of microvascular PED compared to controls ( Figure ). In a multivariate analysis adjusting for age, sex, smoking status, and use of statins we found a significant association between secondary RP and microvascular PED (OR: 2.45; 95% CI 1.13-5.34; P=0.0236) that remained significant in women after stratifying by sex. In a sensitivity analysis, we compared the frequency of PED in 29 patients with secondary RP and 58 controls matched with respect to age, sex, hypertension, dyslipidemia, and diabetes mellitus. Individuals with secondary RP had a higher frequency of microvascular PED compared to the risk factor-matched controls (18/29 [62.1%] vs 18/58 [31.0%], P=0.01). Conclusions: Secondary RP is associated with microvascular PED. Early detection of microvascular PED could help identify individuals with secondary RP who are at risk for developing cardiovascular disease.

Introduction: Cardiac allograft vasculopathy (CAV) is a major determinant of long term graft survival. Endothelial progenitor cells (EPC) expressing osteocalcin (OC) have been linked to atherosclerosis. However, little is known regarding bone-forming osteoblast-lineage (OL) cells, and their role in atherosclerosis and CAV. Methods: Heart transplant patients undergoing serial Intravascular Ultrasound (IVUS) and progenitor cell studies were included in the study. OL cells, defined as cells positive for alkaline phosphatase (AP) and OC, were counted using flow cytometry on the day of baseline IVUS. A follow up IVUS was done 3 years later. Gray-scale and virtual-histology IVUS were used to evaluate vessel size, plaque burden, and plaque composition (fibrous, fibrofatty, necrotic core, calcified). Patients were divided into two groups by the median change (Δ) in necrotic core volume and plaque volume over 3 years. Results: A total of 55 patients (mean age 52±15 years, 65% males) were included. At baseline, median time after transplant was 4.2 years. Average vessel area at baseline and three years were 15.8 ±4.6 and 15.3 ±5.4 mm2, respectively (p=0.32). However, 24/55 patients (44%) had positive remodeling. The number of OL cells was positively correlated with Δvessel (r=0.36, p=0.01) and Δlumen areas. (r=0.30, p=0.02). Patients with greater Δplaque volume and Δnecrotic core volume had higher OL cell levels compared to those with below medians (Δplaque volume: 95 [30,348] vs. 30 [10, 90] OL per 100,000 counts, p=0.01; Δnecrotic core volume: 95 [22.5, 320] vs. 30 [10, 90] OL per 100,000 counts, p=0.03) (Fig. 1A and 1B). Conclusions: The number of OL cells in heart transplant patients correlates with positive vascular remodeling, accompanied by increased lumen area over 3 months. Furthermore, patients with unstable plaque features had higher OL cells, suggesting a possible role in pathologic plaque progression.

Introduction: CD34+ progenitor cells play a role in vascular repair and plaque stability. However, their role in cardiac allograft vasculopathy (CAV), vessel remodeling, and changes in plaque morphology is incompletely understood. Hypothesis: We hypothesized that decreased levels of baseline CD34+ progenitor cells would be associated with Intravascular Ultrasound (IVUS)-defined vulnerable plaque characteristics and CAV progression. Methods: In heart transplant patients undergoing annual IVUS, CD34+ cells were counted in peripheral blood using flow cytometry, on the same day as baseline IVUS. Gray-scale and virtual-histology IVUS were used to evaluate vessel size, plaque burden, and plaque composition (fibrous, fibrofatty, necrotic core, calcific). Positive remodeling was defined as expansion of external elastic membrane area on follow-up. Patients were divided into two groups by the median of the change (Δ) in necrotic core volume over the subsequent 3 years. Results: A total of 55 patients (mean age 52±15 years, 65% males) were included. Median time after transplant was 4.2 years at baseline. Average vessel area at baseline and three years were 15.8±4.6 and 15.3±5.4 mm, respectively (p=0.32). Twenty-four patients (44%) who showed positive remodeling at follow-up, compared to those who did not, had lower levels of baseline CD34+ progenitor cells (absolute count per 100,000 counts, 980 [690, 1460]) vs. 665 [438, 1015], p=0.02) (Fig. 1A). Patients with greater than median (>1.96 mm3) Δnecrotic core volume, as compared to those with below median Δ, also had lower baseline CD34+ cells (705 [483, 998] vs. 1180 [660, 1620] per 100,000 counts, p=0.04) (Fig. 1B). Conclusions: Lower levels of CD34+ progenitor cells are associated with long-term positive coronary vascular remodeling and increased plaque necrotic core volume in patients who underwent allograft heart transplant. This study supports the notion that circulating CD34+ progenitor cells play a role in CAV.

Introduction: Coronary microvascular dysfunction (CMD) is prevalent in symptomatic patients with no obstructive coronary artery disease. We postulated that exercise capacity and cardiac output augmentation in response to exercise are linked to coronary microvascular function in this patient population. Methods: Fifty-one consecutive patients with unexplained cardiac exertion symptoms, non-obstructive coronary artery disease on angiography (<50% stenosis), and normal left ventricular ejection fraction (>50%) who underwent concurrent clinically indicated coronary reactivity testing and invasive cardiopulmonary exercise testing (CPEX) were included. Microvascular function was assessed by coronary flow reserve (CFR; hyperemic/resting flow) in response to intracoronary adenosine injection. Cardiac output (CO) was calculated at rest and peak exercise using Fick’s formula. CO limitation was defined as a measured (peak CO - resting CO) <80% than the expected [6*absolute ΔVO 2 (Peak VO 2 -Rest VO 2 ) increase in CO in L/min]. The relationship between CFR, maximal exercise capacity, and CO augmentation at peak exercise was explored. Results: Patients were 56.6±10.5 years old and 73% were females. CFR had a modest positive correlation with measured increase in CO (r=0.42; P=0.003) ( Fig 1A ), and with maximal ergometric exercise capacity [in Watts/Kg] (Pearson’s r=0.33, P=0.02) ( Fig 1B ). Patients with, vs. without impaired cardiac limitations during exercise, had significantly lower CFR levels (2.6±0.5 vs 3.1±0.7; P=0.01) ( Fig 2 ). Conclusion: Impaired coronary microvascular function is associated with lower peak exercise capacity and reduced cardiac output augmentation in response to exercise, underscoring the functional ramification of CMD in symptomatic patients.