Normal Vessel Wall Research Articles

Carotid Intraplaque Hemorrhage Imaging with Quantitative Vessel Wall T1 Mapping: Technical Development and Initial Experience.

Purpose To develop a three-dimensional (3D) high-spatial-resolution time-efficient sequence for use in quantitative vessel wall T1 mapping. Materials and Methods A previously described sequence, simultaneous noncontrast angiography and intraplaque hemorrhage (SNAP) imaging, was extended by introducing 3D golden angle radial k-space sampling (GOAL-SNAP). Sliding window reconstruction was adopted to reconstruct images at different inversion delay times (different T1 contrasts) for voxelwise T1 fitting. Phantom studies were performed to test the accuracy of T1 mapping with GOAL-SNAP against a two-dimensional inversion recovery (IR) spin-echo (SE) sequence. In vivo studies were performed in six healthy volunteers (mean age, 27.8 years ± 3.0 [standard deviation]; age range, 24-32 years; five male) and five patients with atherosclerosis (mean age, 66.4 years ± 5.5; range, 60-73 years; five male) to compare T1 measurements between vessel wall sections (five per artery) with and without intraplaque hemorrhage (IPH). Statistical analyses included Pearson correlation coefficient, Bland-Altman analysis, and Wilcoxon rank-sum test with data permutation by subject. Results Phantom T1 measurements with GOAL-SNAP and IR SE sequences showed excellent correlation (R2 = 0.99), with a mean bias of -25.8 msec ± 43.6 and a mean percentage error of 4.3% ± 2.5. Minimum T1 was significantly different between sections with IPH and those without it (mean, 371 msec ± 93 vs 944 msec ± 120; P = .01). Estimated T1 of normal vessel wall and muscle were 1195 msec ± 136 and 1117 msec ± 153, respectively. Conclusion High-spatial-resolution (0.8 mm isotropic) time-efficient (5 minutes) vessel wall T1 mapping is achieved by using the GOAL-SNAP sequence. This sequence may yield more quantitative reproducible biomarkers with which to characterize IPH and monitor its progression. © RSNA, 2017.

Large coverage black-bright blood interleaved imaging sequence (LaBBI) for 3D dynamic contrast-enhanced MRI of vessel wall.

To propose a large coverage black-bright blood interleaved imaging sequence (LaBBI) for 3D dynamic contrast-enhanced MRI (DCE-MRI) of the vessel wall. LaBBI consists of a 3D black-blood stack-of-stars golden angle radial acquisition with high spatial resolution for vessel wall imaging and a 2D bright-blood Cartesian acquisition with high temporal resolution for arterial input function estimation. The two acquisitions were performed in an interleaved fashion within a single scan. Simulations, phantom experiments, and in vivo tests in three patients were performed to investigate the feasibility and performance of the proposed LaBBI. In simulation tests, the estimated Ktrans and vp by LaBBI were more accurate than conventional bright-blood DCE-MRI with lower root mean square error in all the tested conditions. In phantom test, no signal interference was found on the 2D scan in LaBBI. Pharmacokinetic analysis of the patients' data acquired by LaBBI showed that Ktrans was higher in fibrous tissue (0.0717 ± 0.0279 min-1 ), while lower in necrotic core (0.0206 ± 0.0040 min-1 ) and intraplaque hemorrhage (0.0078 ± 0.0007 min-1 ), compared with normal vessel wall (0.0273 ± 0.0052 min-1 ). The proposed LaBBI sequence, with high spatial and temporal resolution, and large coverage blood suppression, was promising to probe the perfusion properties of vessel wall lesions. Magn Reson Med 79:1334-1344, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

18-kDa translocator protein ligand 18F-FEMPA: Biodistribution and uptake into atherosclerotic plaques in mice

BackgroundRadioligands of 18-kDa translocator protein (TSPO) expressed on activated macrophages are a potential approach for imaging of inflammation in atherosclerosis. We evaluated a novel TSPO-targeted tracer 18F-FEMPA for the detection of atherosclerotic plaque inflammation in mice. Methods and resultsThe distribution kinetics of 18F-FEMPA was evaluated by in vivo PET/CT imaging. 18F-FEMPA uptake was compared in atherosclerotic (LDLR−/−ApoB100/100, n = 10) and healthy mice (C57BL/6 N, n = 7) ex vivo at twenty minutes post-injection. Biodistribution was analyzed from harvested tissue samples, and aortas were sectioned for autoradiography. Aortas of LDLR−/−ApoB100/100 mice showed large, macrophage-rich atherosclerotic plaques. In vivo, 18F-FEMPA showed rapid blood clearance but no difference in aortic uptake between atherosclerotic and healthy mice. In the mice studied ex vivo at 20 minutes post-injection, quantification of radioactivity in the whole aorta showed 1.3-fold higher 18F-FEMPA accumulation in atherosclerotic than healthy mice (P = .028). Autoradiography showed higher tracer uptake in plaque areas with high macrophage content as compared with areas of no macrophages (count densities 190 ± 54 vs 40 ± 13 PSL/mm2, P < .001), but the uptake in the plaques was not higher than in the normal vessel wall (230 ± 78 PSL/mm2). In vitro blocking showed specific accumulation in mouse and human atherosclerotic plaques. Immunohistochemistry confirmed co-localization of TSPO and macrophages. Conclusions18F-FEMPA shows rapid blood clearance and uptake in the mouse aorta. Uptake in atherosclerotic plaques correlated with the amount of macrophages, but did not exceed that in the normal vessel wall.

Abstract 7: Higher Prevalence of High-t1w-signal Plaques on the Symptomatic Side in Patient with Recent Ischemic Stroke

Introduction: Inversion-recovery prepared variable-flip-angle 3D FSE (IR-SPACE) was recently proposed as a whole-brain vessel wall MRI method to assess intracranial vessel wall (IVW) abnormalities. Compared with conventional SPACE or 2D FSE, it provides more heavily T1 weighted (T1w) contrast that, based on extensive research on carotid atherosclerosis, is highly sensitive to vulnerable atherosclerotic plaque features - intraplaque hemorrhage and inflammation. It was hypothesized that, using the new approach, the prevalence of HT 1 S plaques is higher in the symptomatic side in patients with recent anterior circulation ischemic stroke. Methods: From Oct 2015 to Aug 2016, 33 patients with ischemic stroke (&lt;14 days) and an intracranial stenosis of &gt; 50% were consecutively recruited. The MRI protocol included regular brain MRI and intracranial MRA followed by pre- and post-contrast IR-SPACE. After excluding those with nonatherosclerosis etiology (5) and uninterpretable images (3), 25 patients were available for image review by two independent blind readers. Plaques defined as eccentric wall thickening with or without luminal stenosis were first identified and were then categorized as either hyper-intense or iso-intense using adjacent normal vessel wall for reference. Results: In 25 patients, 65 plaques were identified, with 40 and 25 at the symptomatic and asymptomatic side, respectively. HT1S was shown in 32 plaques on pre-contrast IR-SPACE and in 23 plaques on post-contrast IR-SPACE on the symptomatic side, with 22 plaques in both scenarios. On the asymptomatic side, the incidence of HT1S was lower (i.e. 7 on pre-contrast, 4 on post-contrast, 1 in both). Conclusion: In the current study, IR-SPACE revealed higher prevalence of HT1S in the symptomatic side. Pre-contrast scans identified more HT1S plaques than post-contrast scans, and almost all (22/23) of these HT1S plaques shown on post-contrast images also demonstrated HT1S feature on pre-contrast images. Further classification of these HT1S plaques according to the likelihood to cause stroke will help elucidate the clinical relevance of the above findings and this analysis is underway.

Roles of Cells from the Arterial Vessel Wall in Atherosclerosis.

Atherosclerosis has been identified as a chronic inflammatory disease of the arterial vessel wall. Accumulating evidence indicates that different cells from the tunica intima, media, adventitia, and perivascular adipose tissue not only comprise the intact and normal arterial vessel wall but also participate all in the inflammatory response of atherosclerosis via multiple intricate pathways. For instance, endothelial dysfunction has historically been considered to be the initiator of the development of atherosclerosis. The migration and proliferation of smooth muscle cells also play a pivotal role in the progression of atherosclerosis. Additionally, the fibroblasts from the adventitia and adipocytes from perivascular adipose tissue have received considerable attention given their special functions that contribute to atherosclerosis. In addition, numerous types of cytokines produced by different cells from the arterial vessel wall, including endothelium-derived relaxing factors, endothelium-derived contracting factors, tumor necrosis factors, interleukin, adhesion molecules, interferon, and adventitium-derived relaxing factors, have been implicated in atherosclerosis. Herein, we summarize the possible roles of different cells from the entire arterial vessel wall in the pathogenesis of atherosclerosis.

The JCR:LA-cp rat: a novel rodent model of cystic medial necrosis.

Although there are multiple rodent models of the metabolic syndrome, very few develop vascular complications. In contrast, the JCR:LA-cp rat develops both metabolic syndrome and early atherosclerosis in predisposed areas. However, the pathology of the normal vessel wall has not been described. We examined JCR:LA control (+/+) or cp/cp rats fed normal chow diet for 6 or 18 mo. JCR:LA-cp rats developed multiple features of advanced cystic medial necrosis including "cysts," increased collagen formation and proteoglycan deposition around cysts, apoptosis of vascular smooth muscle cells, and spotty medial calcification. These appearances began within 6 mo and were extensive by 18 mo. JCR:LA-cp rats had reduced medial cellularity, increased medial thickness, and vessel hypoxia that was most marked in the adventitia. In conclusion, the normal chow-fed JCR:LA-cp rat represents a novel rodent model of cystic medial necrosis, associated with multiple metabolic abnormalities, vascular smooth muscle cell apoptosis, and vessel hypoxia.NEW & NOTEWORTHY Triggers for cystic medial necrosis (CMN) have been difficult to study due to lack of animal models to recapitulate the pathologies seen in humans. Our study is the first description of CMN in the rat. Thus the JCR:LA-cp rat represents a useful model to investigate the underlying molecular changes leading to the development of CMN.

Leukocyte trafficking-associated vascular adhesion protein 1 is expressed and functionally active in atherosclerotic plaques.

Given the important role of inflammation and the potential association of the leukocyte trafficking-associated adhesion molecule vascular adhesion protein 1 (VAP-1) with atherosclerosis, this study examined whether functional VAP-1 is expressed in atherosclerotic lesions and, if so, whether it could be targeted by positron emission tomography (PET). First, immunohistochemistry revealed that VAP-1 localized to endothelial cells of intra-plaque neovessels in human carotid endarterectomy samples from patients with recent ischemic symptoms. In low-density lipoprotein receptor-deficient mice expressing only apolipoprotein B100 (LDLR−/−ApoB100/100), VAP-1 was expressed on endothelial cells lining inflamed atherosclerotic lesions; normal vessel walls in aortas of C57BL/6N control mice were VAP-1-negative. Second, we discovered that the focal uptake of VAP-1 targeting sialic acid-binding immunoglobulin-like lectin 9 based PET tracer [68Ga]DOTA-Siglec-9 in atherosclerotic plaques was associated with the density of activated macrophages (r = 0.58, P = 0.022). As a final point, we found that the inhibition of VAP-1 activity with small molecule LJP1586 decreased the density of macrophages in inflamed atherosclerotic plaques in mice. Our results suggest for the first time VAP-1 as a potential imaging target for inflamed atherosclerotic plaques, and corroborate VAP-1 inhibition as a therapeutic approach in the treatment of atherosclerosis.

Fibroblast Growth Factor 12 Is a Novel Regulator of Vascular Smooth Muscle Cell Plasticity and Fate.

Vascular smooth muscle cells (VSMCs) modulate their phenotype between synthetic and contractile states in response to environmental changes; this modulation plays a crucial role in the pathogenesis of restenosis and atherosclerosis. Here, we identified fibroblast growth factor 12 (FGF12) as a novel key regulator of the VSMC phenotype switch. Using murine models and human specimens, we found that FGF12 was highly expressed in contractile VSMCs of normal vessel walls but was downregulated in synthetic VSMCs from injured and atherosclerotic vessels. In human VSMCs, FGF12 expression was inhibited at the transcriptional level by platelet-derived growth factor-BB. Gain- and loss-of-function experiments showed that FGF12 was both necessary and sufficient for inducing and maintaining the quiescent and contractile phenotypes of VSMCs. FGF12 inhibited cell proliferation through the p53 pathway and upregulated the key factors involved in VSMC lineage differentiation, such as myocardin and serum response factor. Such FGF12-induced phenotypic change was mediated by the p38 MAPK (mitogen-activated protein kinase) pathway. Moreover, FGF12 promoted the differentiation of mouse embryonic stem cells and the transdifferentiation of human dermal fibroblasts into SMC-like cells. Furthermore, adenoviral infection of FGF12 substantially decreased neointima hyperplasia in a rat carotid artery injury model. In general, FGF family members induce a synthetic VSMC phenotype. Interestingly, the present study showed the unanticipated finding that FGF12 belonging to FGF family, strongly induced the quiescent and contractile VSMC phenotypes and directly promoted VSMC lineage differentiation. These novel findings suggested that FGF12 could be a new therapeutic target for treating restenosis and atherosclerosis.

Low expression of ferroxidases is implicated in the iron retention in human atherosclerotic plaques

The effect of iron on the progress of atherosclerosis is still controversial. To explore the relationship between atherosclerotic plaques and iron metabolism and how iron is accumulated in plaque macrophages, we performed Oil red O staining to detect the lipid of the atherosclerotic plaques, enzyme-linked immunosorbent assay to detect the intracellular lipids (total cholesterol, free cholesterol) and serum hepcidin, Western-blot to examine the iron-related proteins, immunohistochemical and immunofluorescence assays to localize ferroportin 1 in macrophages. The contents of serum iron and transferrin saturation were measured. The results confrimed that atherosclerotic plaques were all lipid-rich. Compared to normal vessel wall, atherosclerotic plaques had significantly higher levels of ferritin and ferroportin 1. Strikingly, we found the much lower levels of ferroxidases ceruloplasmin and hephaestin in plaque tissue than the normal vessel, while the content of serum hepcidin, iron and transferrin saturation were similar in these two groups. The novel finding suggests that the inability of ferrous iron to be oxidized into ferric iron might be a potential mechanism for iron retention in plaques.

18F]FDG Accumulation in Early Coronary Atherosclerotic Lesions in Pigs.

ObjectiveInflammation is an important contributor to atherosclerosis progression. A glucose analogue 18F-fluorodeoxyglucose ([18F]FDG) has been used to detect atherosclerotic inflammation. However, it is not known to what extent [18F]FDG is taken up in different stages of atherosclerosis. We aimed to study the uptake of [18F]FDG to various stages of coronary plaques in a pig model.MethodsFirst, diabetes was caused by streptozotocin injections (50 mg/kg for 3 days) in farm pigs (n = 10). After 6 months on high-fat diet, pigs underwent dual-gated cardiac PET/CT to measure [18F]FDG uptake in coronary arteries. Coronary segments (n = 33) were harvested for ex vivo measurement of radioactivity and autoradiography (ARG).ResultsIntimal thickening was observed in 16 segments and atheroma type plaques in 10 segments. Compared with the normal vessel wall, ARG showed 1.7±0.7 times higher [18F]FDG accumulation in the intimal thickening and 4.1±2.3 times higher in the atheromas (P = 0.004 and P = 0.003, respectively). Ex vivo mean vessel-to-blood ratio was higher in segments with atheroma than those without atherosclerosis (2.6±1.2 vs. 1.3±0.7, P = 0.04). In vivo PET imaging showed the highest target-to-background ratio (TBR) of 2.7. However, maximum TBR was not significantly different in segments without atherosclerosis (1.1±0.5) and either intimal thickening (1.2±0.4, P = 1.0) or atheroma (1.6±0.6, P = 0.4).ConclusionsWe found increased uptake of [18F]FDG in coronary atherosclerotic lesions in a pig model. However, uptake in these early stage lesions was not detectable with in vivo PET imaging. Further studies are needed to clarify whether visible [18F]FDG uptake in coronary arteries represents more advanced, highly inflamed plaques.

The short and long of noncoding sequences in the control of vascular cell phenotypes.

The two principal cell types of importance for normal vessel wall physiology are smooth muscle cells and endothelial cells. Much progress has been made over the past 20years in the discovery and function of transcription factors that coordinate proper differentiation of these cells and the maintenance of vascular homeostasis. More recently, the converging fields of bioinformatics, genomics, and next generation sequencing have accelerated discoveries in a number of classes of noncoding sequences, including transcription factor binding sites (TFBS), microRNA genes, and long noncoding RNA genes, each of which mediates vascular cell differentiation through a variety of mechanisms. Alterations in the nucleotide sequence of key TFBS or deviations in transcription of noncoding RNA genes likely have adverse effects on normal vascular cell phenotype and function. Here, the subject of noncoding sequences that influence smooth muscle cell or endothelial cell phenotype will be summarized as will future directions to further advance our understanding of the increasingly complex molecular circuitry governing normal vascular cell differentiation and how such information might be harnessed to combat vascular diseases.

The role of autophagy in vascular biology.

There is increasing interest in the role of autophagic flux in maintaining normal vessel wall biology and a growing suspicion that autophagic dysregulation may be a common pathway through which vascular aging and associated pathologies develop. Within endothelial and smooth muscle cells, diverse but important triggers that range from oxidized lipids to β-amyloid seem to stimulate autophagosome formation potently. In addition, emerging evidence links autophagy to a wide array of vascular processes ranging from angiogenesis to calcification of the vessel wall. Alterations in autophagic flux are also increasingly being implicated in disease processes that include both atherosclerosis and pulmonary hypertension. Finally, recent insights point toward an important role of autophagy in the paracrine regulation of vasoactive substances from the endothelium. Here, we review the progress in understanding how autophagy can contribute to vascular biology and the emerging strategies to target this process for therapeutic benefit.

Elevated Concentration of Interferon-Inducible Protein of 10 kD (IP-10) Is Associated With Coronary Atherosclerosis.

Several studies have shown that various chemokines are more highly expressed in atherosclerotic plaques than in normal vessel walls. In the present study, we investigated the relationship between coronary atherosclerosis and noteworthy chemokines, including interferon-inducible protein of 10 kD (IP-10); monocyte chemoattractant protein 1 (MCP-1); regulated on activation, normal T-cell expressed and secreted (RANTES); and high-sensitivity C-reactive protein (hsCRP), an established marker of atherosclerotic disease. We studied 28 patients who underwent coronary angiography because of suspected coronary artery disease (CAD). CAD was defined as stenosis of more than 50% of the vessel diameter on coronary angiograms. Blood samples were obtained both from the aorta and the coronary sinus (CS) just before coronary angiography. Relative to CAD (-) patients, those who were CAD (+) tended to have higher plasma concentrations of IP-10 in the aorta, as well as significantly higher transcoronary concentration gradients of circulating IP-10. There were no significant differences between the two groups in aortic plasma concentrations or transcoronary concentration gradients of MCP-1, RANTES, and hsCRP. Furthermore, both the aortic plasma concentrations and transcoronary concentration gradients of IP-10 correlated with the Gensini score (r = 0.58 and r = 0.63, respectively, P < 0.01), while the plasma MCP-1, RANTES, and serum hsCRP concentrations did not. This study suggests that IP-10 is a good surrogate marker of coronary atherosclerosis.

CRISPR-Cas9 genome editing of a single regulatory element nearly abolishes target gene expression in mice--brief report.

To ascertain the importance of a single regulatory element in the control of Cnn1 expression using CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9) genome editing. The CRISPR/Cas9 system was used to produce 3 of 18 founder mice carrying point mutations in an intronic CArG box of the smooth muscle cell-restricted Cnn1 gene. Each founder was bred for germline transmission of the mutant CArG box and littermate interbreeding to generate homozygous mutant (Cnn1(ΔCArG/ΔCArG)) mice. Quantitative reverse transcription polymerase chain reaction, Western blotting, and confocal immunofluorescence microscopy showed dramatic reductions in Cnn1 mRNA and CNN1 protein expression in Cnn1(ΔCArG/ΔCArG) mice with no change in other smooth muscle cell-restricted genes and little evidence of off-target edits elsewhere in the genome. In vivo chromatin immunoprecipitation assay revealed a sharp decrease in binding of serum response factor to the mutant CArG box. Loss of CNN1 expression was coincident with an increase in Ki-67 positive cells in the normal vessel wall. CRISPR/Cas9 genome editing of a single CArG box nearly abolishes Cnn1 expression in vivo and evokes increases in smooth muscle cell DNA synthesis. This facile genome editing system paves the way for a new generation of studies designed to test the importance of individual regulatory elements in living animals, including regulatory variants in conserved sequence blocks linked to human disease.

Abstract 15108: Imaging Coronary Atherosclerosis Using [18F]FDG PET-CT: Validation Study in Pigs

Introduction: Positron emission tomography (PET) with 18F-fluorodeoxyglucose ([18F]FDG) can be used to detect atherosclerotic plaque inflammation. The degree of [18F]FDG uptake in different stages of coronary atherosclerosis remains largely unknown. Thus, we studied the amount of [18F]FDG uptake and feasibility of its in vivo quantification by combination of PET and computed tomography angiography (CTA) in a pig model of atherosclerosis. Methods: In order to induce coronary atherosclerosis, diabetes was caused by streptozotocin injections in farm pigs (n=10). After 6 months on high-fat diet, pigs underwent dual gated cardiac PET and CTA to measure [18F]FDG uptake in the proximal segments of coronary arteries as maximal target to background ratio (TBR = [18F]FDG uptake normalized to blood pool). Proximal coronary segments (n=33) were harvested for ex vivo measurement of radioactivity and for histology and measurement of tracer uptake into the vessel wall by autoradiography (ARG). Results: The pigs were hyperglycemic (12.3±4.7 mmol/L) and hypercholesterolemic (12.7±5.1 mmol/L) at the end of the study. The coronary arteries showed intimal thickening (n=16 segments) and atheroma (n=10 segments). Compared with the normal vessel wall, ARG showed 1.7±0.7 times higher accumulation of [18F]FDG in intimal thickening and 4.1±2.3 in atheroma (p=0.004 and p=0.003, respectively). Ex vivo mean vessel to blood ratio of segments with atheroma was higher than non-atherosclerotic segments (2.6±1.2 vs. 1.3±0.7, p=0.04). In vivo PET imaging showed the highest TBR of 2.7. However, maximal TBR was not significantly different in segments without atherosclerosis (1.1±0.5) and either intimal thickening (1.2±0.4, p=1.0) or atheroma (1.6±0.6, p=0.4) and no correlation was seen between the segmental TBR measured by in vivo PET-CT and [18F]FDG uptake measured by either biodistribution or autoradiography. Conclusions: We found increased [18F]FDG uptake in atherosclerotic lesions. However, quantification of [18F]FDG uptake in these relatively small and early stage atherosclerotic lesions by dual gated PET and CTA was not feasible. Further studies are needed to clarify feasibility of this approach in more advanced and highly inflamed atherosclerotic coronary plaques.

Vasa vasorum in normal and diseased arteries.

The vasa vasorum are a specialized microvasculature that play a major role in normal vessel wall biology and pathology. Under physiological conditions, the adventitial vasa vasorum take up molecules that are transmitted from the blood to the adventitia by mass transport through the arterial wall. The adventitia is the primary early site for vessel wall response to arterial injury that occurs on the luminal side. The vasa vasorum expand in response to the injury, which alters vessel homeostasis. This review focuses on the impact the vasa vasorum expansion has on development of vascular pathology, particularly neointima development and growth of atherosclerotic plaque. The adventitia, the outermost layer of the vessel wall, has received considerable attention in recent years. It contains a heterogeneous population of cells, including macrophages,1,2 T cells,3 B cells,1,2 dendritic cells,1,2 progenitor cells,4,5 and fibroblasts that can differentiate into myofibroblasts.6 It also contains an adrenergic nervous system,7 a lymphatic network,8 and vasa vasorum, a specialized microvasculature that plays a major role in normal vessel wall biology and pathology that is the subject of the present review. Under physiological conditions, the adventitial vasa vasorum and lymphatic vessels take up molecules that are transmitted from the blood to the adventitia by mass transport through the arterial wall.9–11 Vascular injury at the luminal side of the vessel wall significantly impacts the adventitia by convection of soluble factors, microparticles and macroparticles, mediators such as products of oxidation, tissue cytolysis, and proteolysis from the intima to the adventitia by hydraulic conductance.12 As a result, the adventitia becomes the primary early site for the vessel wall response to arterial injury, which includes myofibroblast migration into the vessel wall,13,14 inflammatory cell accumulation, …

A112: Prevention of Late Stage Renal Failure in BXSB SLE Mouse Model with Human Bone Marrow Derived Mesenchymal Stem Cell Treatment

Background/Purpose:The purpose of the study is to adequately regenerate renal tissue to sustain dialysis free survival by human bone marrow derived mesenchymal stem cells (hMSC) infusion to the SLE mouse model (BXSB mice). We aimed to test whether injection of single cell suspension into aged male BXSB either via intracarotid artery or under the renal capsule would prevent late stage kidney failure.Methods:Mice, BXSB (n = 15) and C57Bl/6 (n = 3), were received from Jackson Laboratories, in January 2013. At 17 weeks of age we injected (n = 4) BXSB mice with 1,000,000 hMSCs via intracarotid artery. The procedure was repeated at 19 weeks of age for (n = 3) BXSB mice. At 20 weeks of age we injected (n = 2) BXSB mice and (n = 2) C57Bl/6 mice with 1,000,000 human bone marrow derived MSCs under the renal capsule of the left kidneys. Mice then were followed up for 6 or 9 weeks duration, depending on intrarenal or intracarotid, and then sacrificed. Post mortem renal pathology, and targeted gene expression in renal parenchyma for inflammation and fibrosis were determined.Results:H&amp;E stained sections of renal parenchyma of 26 week old BXSB (n = 4) showed moderate focal segmental and global glomerulosclerosis, tuft adhesions to the capsule, tubular dilatation and microcysts, protein casts, and matrix deposition. Glomerular sizes were enlarged. Age and sex matched littermate BXSB mouse 9 weeks after intracarotid hMSC injection showed only minor segmental sclerosis, mild glomerular enlargement with normal tubular structure. Glomerular sizes were still much enlarged. There was no glomerular sclerosis. The other two littermates that were injected with hMSCs intrarenaly (L) kidney showed even more significant improvement as compared to intracarotid hMSC injected BXSB mice. There was no glomerulosclerosis in either kidney. Left kidney that received the MSC injections showed normal tubular and vessel walls, and glomeruli except borderline cellular increase. R kidney showed mild segmental necrosis but normal tubular structure. In both L and R kidneys minimal regenerative changes in the tubules was also observed.RT‐PCR analysis of kidneys showed remarkable suppression of IL‐17, which correlates with nephritis activity in SLE models, and significant decrease in CTLA4 expression, a co‐stimulatory molecule that plays role in in B and T cell interaction, in kidneys injected with hMSCs. Similarly, there was significant decrease in the mRNA expression of IL‐17 and CTLA4 in the intracarotid injected BXSB mice as compared to uninjected BXSB controls.Conclusion:Treatment with single cell suspension of hMSCs in BXSB mice prevented/delayed renal failure both clinically and histopathologically. Pathways that are involved in Th17 activation and IL‐17 secretion which correlates with SLE nephritis activity were significantly suppressed after hMSC treatment in BXSB mice. In addition co‐stimulatory molecule activity CTLA4 that play roles in B cells activation of T cells was diminished after hMSC treatment.We suggest that MSCs are efficient treatments in delaying or preventing end stage kidney disease in BXSB animal model of SLE. In human MSCs might also be therapeutic in lupus end stage kidney disease.

MRI of the carotid artery at 7 Tesla: Quantitative comparison with 3 Tesla

To evaluate the 7 Tesla (T) MRI of the carotid arteries, as quantitatively compared with 3T. The 7T MRI of the carotid arteries was performed in six healthy subjects and in two patients with carotid stenosis. The healthy group was scanned at 3T and at 7T, using current coil setups at both field strengths. T1 and T2 values of the normal carotid vessel wall were assessed at both field strengths. B1 (+) maps and signal to noise ratio (SNR) maps were obtained, as well as T1 weighted images with a resolution as high as 0.4 × 0.4 × 1.5 mm(3) . The T1 of the normal carotid vessel wall was found to be 1227 ± 47 ms at 3T and 1628 ± 130 ms at 7T, while a T2 of 55 ± 11 ms at 3T and 46 ± 4 ms at 7T was found. A twofold average gain in SNR at the carotid arteries was found with 7T. T1 weighted images showed an increased SNR at 7T for all subjects. Evaluation between 3T and 7T carotid MRI with optimized setups at both field strengths showed improved SNR at 7T, an increase in vessel wall T1 and a decrease in vessel wall T2.

Decorin and biglycan retain LDL in disease-prone valvular and aortic subendothelial intimal matrix

ObjectiveSubendothelial LDL retention by intimal matrix proteoglycans is an initial step in atherosclerosis and calcific aortic valve disease. Herein, we identify decorin and biglycan as the proteoglycans that preferentially retain LDL in intimal matrix at disease-prone sites in normal valve and vessel wall. MethodsThe porcine aortic valve and renal artery ostial diverter, initiation sites of calcific valve disease and renal atherosclerosis, respectively, from normal non-diseased animals were used as models in these studies. ResultsFluorescent human LDL was selectively retained on the lesion-prone collagen/proteoglycan-enriched aortic surface of the valve, where the elastic lamina is depleted, as previously observed in lesion-prone sites in the renal ostium. iTRAQ mass spectrometry of valve and diverter protein extracts identified decorin and biglycan as the major subendothelial intimal matrix proteoglycans electrostatically retained on human LDL affinity columns. Decorin levels correlated with LDL binding in lesion-prone sites in both tissues. Collagen binding to LDL was shown to be proteoglycan-mediated. All known basement membrane proteoglycans bound LDL suggesting they may modulate LDL uptake into the subendothelial matrix. The association of purified decorin with human LDL in an in vitro microassay was blocked by serum albumin and heparin suggesting anti-atherogenic roles for these proteins in vivo. ConclusionsLDL electrostatic interactions with decorin and biglycan in the valve leaflets and vascular wall is a major source of LDL retention. The complementary electrostatic sites on LDL or these proteoglycans may provide a novel therapeutic target for preventing one of the earliest events in these cardiovascular diseases.

Multimodality PET/MRI agents targeted to activated macrophages

The recent emergence of multimodality imaging, particularly the combination of PET and MRI, has led to excitement over the prospect of improving detection of disease. Iron oxide nanoparticles have become a popular platform for the fabrication of PET/MRI probes owing to their advantages of high MRI detection sensitivity, biocompatibility, and biodegradability. In this article, we report the synthesis of dextran-coated iron oxide nanoparticles (DIO) labeled with the positron emitter (64)Cu to generate a PET/MRI probe, and modified with maleic anhydride to increase the negative surface charge. The modified nanoparticulate PET/MRI probe (MDIO-(64)Cu-DOTA) bears repetitive anionic charges on the surface that facilitate recognition by scavenger receptor type A (SR-A), a ligand receptor found on activated macrophages but not on normal vessel walls. MDIO-(64)Cu-DOTA has an average iron oxide core size of 7-8 nm, an average hydrodynamic diameter of 62.7 nm, an r1 relaxivity of 16.8 mM(-1) s(-1), and an r 2 relaxivity of 83.9 mM(-1) s(-1) (37 °C, 1.4 T). Cell studies confirmed that the probe was nontoxic and was specifically taken up by macrophages via SR-A. In comparison with the nonmodified analog, the accumulation of MDIO in macrophages was substantially improved. These characteristics demonstrate the promise of MDIO-(64)Cu-DOTA for identification of vulnerable atherosclerotic plaques via the targeting of macrophages.