Hyperplasia In Grafts Research Articles

Glutathione S-Transferase α4 Alleviates Hyperlipidemia-Induced Vascular Neointimal Hyperplasia in Arteriovenous Grafts via Inhibiting Endoplasmic Reticulum Stress.

Neointimal hyperplasia causes the failure of coronary artery bypass grafting. Our previous studies have found that endothelial dysfunction is 1 candidate for triggering neointimal hyperplasia, but which factors are involved in this process is unclear. Glutathione S-transferase α4 (GSTA4) plays an important role in metabolizing 4-hydroxynonenal (4-HNE), a highly reactive lipid peroxidation product, which causes endothelial dysfunction or death. Here, we investigated the role of GSTA4 in neointima formation after arteriovenous grafts (AVGs) with or without high-fat diet (HFD). Compared with normal diet, HFD caused endothelial dysfunction and increased neointima formation, concomitantly accompanied by downregulated expression of GSTA4 at the mRNA and protein levels. In vitro, overexpression of GSTA4 attenuated 4-HNE-induced endothelial dysfunction and knockdown of GSTA4 aggravated endothelial dysfunction. Furthermore, silencing GSTA4 expression facilitated the activation of 4-HNE-induced endoplasmic reticulum stress and inhibition of endoplasmic reticulum stress pathway alleviated 4-HNE-induced endothelial dysfunction. In addition, compared with wild-type mice, mice with knockout of endothelial-specific GSTA4 (GSTA4 endothelial cell KO) exhibited exacerbated vascular endothelial dysfunction and increased neointima formation caused by HFD. Together, these results demonstrate the critical role of GSTA4 in protecting the function of endothelial cells and in alleviating hyperlipidemia-induced vascular neointimal hyperplasia in arteriovenous grafts.

Neointimal dissection – a rare complication to endovascular treatment in grafts and stent grafts

BackgroundNeointima formation and hyperplasia in vascular grafts may lead to graft complications threatening the patency of the vascular reconstruction. A rare complication to endovascular treatment of grafts and stent grafts is dissection inside the graft.Case reportWe present here a case of a 69-year-old female with acute occlusion of the limb of an aorto-bifemoral graft for the third time, 16 years after the primary operation. As at the first two occasions, catheter-based intra-arterial thrombolysis was performed, but with residual stenosis inside the graft. During stent placement, dissection of the neointima or fibrin sheet occluded the inflow to the stent. The complication was resolved with placement of kissing stents.ConclusionsIt is important to recognize iatrogenic neointima dissection inside graft and stent grafts, as continued thrombolysis will not solve this, but increase the risk of hemorrhagic complications.

MFN2 Prevents Neointimal Hyperplasia in Vein Grafts via Destabilizing PFK1.

Mechanical forces play crucial roles in neointimal hyperplasia after vein grafting; yet, our understanding of their influences on vascular smooth muscle cell (VSMC) activation remains rudimentary. A cuff mouse model was used to study vein graft hyperplasia. Fifteen percent to 1 Hz uniaxial cyclic stretch (arterial strain), 5% to 1 Hz uniaxial cyclic stretch or a static condition (venous strain) were applied to the cultured VSMCs. Metabolomics analysis, cell proliferation and migration assays, immunoblotting, co-immunoprecipitation, mutagenesis, pull-down and surface plasmon resonance assays were employed to elucidate the potential molecular mechanisms. RNA-sequencing in vein grafts and the controls identified changes in metabolic pathways and downregulation of mitochondrial protein MFN2 (mitofusin 2) in the vein grafts. Exposure of VSMCs to 15% stretch resulted in MFN2 downregulation, mitochondrial fragmentation, metabolic shift from mitochondrial oxidative phosphorylation to glycolysis, and cell proliferation and migration, as compared with that to a static condition or 5% stretch. Metabolomics analysis indicated an increased generation of fructose 1,6-bisphosphate, an intermediate in the glycolytic pathway converted by PFK1 (phosphofructokinase 1) from fructose-6-phosphate, in cells exposed to 15% stretch. Mechanistic study revealed that MFN2 physically interacts through its C-terminus with PFK1. MFN2 knockdown or exposure of cells to 15% stretch promoted stabilization of PFK1, likely through interfering the association between PFK1 and the E3 ubiquitin ligase TRIM21 (E3 ubiquitin ligase tripartite motif [TRIM]-containing protein 21), thus, decreasing the ubiquitin-protease-dependent PFK1 degradation. In addition, study of mechanotransduction utilizing pharmaceutical inhibition indicated that the MFN2 downregulation by 15% stretch was dependent on inactivation of the SP1 (specificity protein 1) and activation of the JNK (c-Jun N-terminal kinase) and ROCK (Rho-associated protein kinase). Adenovirus-mediated MFN2 overexpression or pharmaceutical inhibition of PFK1 suppressed the 15% stretch-induced VSMC proliferation and migration and alleviated neointimal hyperplasia in vein grafts. MFN2 is a mechanoresponsive protein that interacts with PFK1 to mediate PFK1 degradation and therefore suppresses glycolysis in VSMCs.

Arterial cyclic stretch regulates Lamtor1 and promotes neointimal hyperplasia via circSlc8a1/miR-20a-5p axis in vein grafts.

Rationale: Neointimal hyperplasia caused by dedifferentiation and proliferation of venous smooth muscle cells (SMCs) is the major challenge for restenosis after coronary artery bypass graft. Herein, we investigated the role of Lamtor1 in neointimal formation and the regulatory mechanism of non-coding RNA underlying this process.Methods: Using a “cuff” model, veins were grafted into arterial system and Lamtor1 expression which was correlated with the activation of mTORC1 signaling and dedifferentiation of SMCs, were measured by Western blot. Whole transcriptome deep sequencing (RNA-seq) of the grafted veins combined with bioinformatic analysis identified highly conserved circSlc8a1 and its interaction with miR-20a-5p, which may target Lamtor1. CircSlc8a1 was biochemically characterized by Sanger sequencing and resistant to RNase R digestion. The cytoplasmic location of circSlc8a1 was shown by fluorescence in situ hybridization (FISH). RNA pull-down, luciferase assays and RNA immunoprecipitation (RIP) with Ago2 assays were used to identify the interaction circSlc8a1 with miR-20a-5p. Furthermore, arterial mechanical stretch (10% elongation) was applied in vitro.Results: In vivo, Lamtor1 was significantly enhanced in grafted vein and activated mTORC1 signaling to promote dedifferentiation of SMCs. Arterial mechanical stretch (10% elongation) induced circSlc8a1 expression and positively regulated Lamtor1, activated mTORC1 and promoted SMC dedifferentiation and proliferation. Local injection of circSlc8a1 siRNA or SMC-specific Lamtor1 knockout mice prevented neointimal hyperplasia in vein grafts in vivo.Conclusions: Our study reveals a novel mechanobiological mechanism underlying the dedifferentiation and proliferation of venous SMCs in neointimal hyperplasia. CircSlc81/miR-20a-5p/Lamtor1 axis induced by arterial cyclic stretch may be a potential clinical target that attenuates neointimal hyperplasia in grafted vessels.

Hypoproliferative human neural progenitor cell xenografts survived extendedly in the brain of immunocompetent rats

BackgroundThere is a huge controversy about whether xenograft or allograft in the “immune-privileged” brain needs immunosuppression. In animal studies, the prevailing sophisticated use of immunosuppression or immunodeficient animal is detrimental for the recipients, which results in a short lifespan of animals, confounds functional behavioral readout of the graft benefits, and discourages long-term follow-up.MethodsNeuron-restricted neural progenitor cells (NPCs) were derived from human embryonic stem cells (ESCs, including H1, its gene-modified cell lines for better visualization, and HN4), propagated for different passages, and then transplanted into the brain of immunocompetent rats without immunosuppressants. The graft survivals, their cell fates, and HLA expression levels were examined over time (up to 4 months after transplantation). We compared the survival capability of NPCs from different passages and in different transplantation sites (intra-parenchyma vs. para- and intra-cerebroventricle). The host responses to the grafts were also investigated.ResultsOur results show that human ESC-derived neuron-restricted NPCs survive extendedly in adult rat brain parenchyma with no need of immunosuppression whereas a late-onset graft rejection seems inevitable. Both donor HLA antigens and host MHC-II expression level remain relatively low with little change over time and cannot predict the late-onset rejection. The intra-/para-cerebroventricular human grafts are more vulnerable to the immune attack than the intrastriatal counterparts. Prevention of graft hyperplasia by using hypoproliferative late passaged human NPCs further significantly extends the graft survival time. Our new data also shows that a subpopulation of host microglia upregulate MHC-II expression in response to the human graft, but fail to present the human antigen to the host immune system, suggestive of the immune-isolation role of the blood–brain barrier (BBB).ConclusionsThe present study confirms the “immune privilege” of the brain parenchyma and, more importantly, unveils that choosing hypoproliferative NPCs for transplantation can benefit graft outcome in terms of both lower tumor-genic risk and the prolonged survival time without immunosuppression.

Computationally guided in-vitro vascular growth model reveals causal link between flow oscillations and disorganized neotissue

Disturbed shear stress is thought to be the driving factor of neointimal hyperplasia in blood vessels and grafts, for example in hemodialysis conduits. Despite the common occurrence of neointimal hyperplasia, however, the mechanistic role of shear stress is unclear. This is especially problematic in the context of in situ scaffold-guided vascular regeneration, a process strongly driven by the scaffold mechanical environment. To address this issue, we herein introduce an integrated numerical-experimental approach to reconstruct the graft–host response and interrogate the mechanoregulation in dialysis grafts. Starting from patient data, we numerically analyze the biomechanics at the vein–graft anastomosis of a hemodialysis conduit. Using this biomechanical data, we show in an in vitro vascular growth model that oscillatory shear stress, in the presence of cyclic strain, favors neotissue development by reducing the secretion of remodeling markers by vascular cells and promoting the formation of a dense and disorganized collagen network. These findings identify scaffold-based shielding of cells from oscillatory shear stress as a potential handle to inhibit neointimal hyperplasia in grafts.

MiRNA-200c-3p promotes endothelial to mesenchymal transition and neointimal hyperplasia in artery bypass grafts.

Increasing evidence has suggested a critical role for endothelial‐to‐mesenchymal transition (EndoMT) in a variety of pathological conditions. MicroRNA‐200c‐3p (miR‐200c‐3p) has been implicated in epithelial‐to‐mesenchymal transition. However, the functional role of miR‐200c‐3p in EndoMT and neointimal hyperplasia in artery bypass grafts remains largely unknown. Here we demonstrated a critical role for miR‐200c‐3p in EndoMT. Proteomics and luciferase activity assays revealed that fermitin family member 2 (FERM2) is the functional target of miR‐200c‐3p during EndoMT. FERMT2 gene inactivation recapitulates the effect of miR‐200c‐3p overexpression on EndoMT, and the inhibitory effect of miR‐200c‐3p inhibition on EndoMT was reversed by FERMT2 knockdown. Further mechanistic studies revealed that FERM2 suppresses smooth muscle gene expression by preventing serum response factor nuclear translocation and preventing endothelial mRNA decay by interacting with Y‐box binding protein 1. In a model of aortic grafting using endothelial lineage tracing, we observed that miR‐200c‐3p expression was dramatically up‐regulated, and that EndoMT contributed to neointimal hyperplasia in grafted arteries. MiR‐200c‐3p inhibition in grafted arteries significantly up‐regulated FERM2 gene expression, thereby preventing EndoMT and reducing neointimal formation. Importantly, we found a high level of EndoMT in human femoral arteries with atherosclerotic lesions, and that miR‐200c‐3p expression was significantly increased, while FERMT2 expression levels were dramatically decreased in diseased human arteries. Collectively, we have documented an unexpected role for miR‐200c‐3p in EndoMT and neointimal hyperplasia in grafted arteries. Our findings offer a novel therapeutic opportunity for treating vascular diseases by specifically targeting the miR‐200c‐3p/FERM2 regulatory axis. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Perivascular delivery of resolvin D1 inhibits neointimal hyperplasia in a rabbit vein graft model

ObjectiveInflammation is a key driver of excessive neointimal hyperplasia within vein grafts. Recent work demonstrates that specialized proresolving lipid mediators biosynthesized from omega-3 polyunsaturated fatty acids, such as resolvin D1 (RvD1), actively orchestrate the process of inflammation resolution. We investigated the effects of local perivascular delivery of RvD1 in a rabbit vein graft model. MethodsIpsilateral jugular veins were implanted as carotid interposition grafts through an anastomotic cuff technique in New Zealand white rabbits (3-4 kg; N = 80). RvD1 (1 μg) was delivered to the vein bypass grafts in a perivascular fashion, using either 25% Pluronic F127 gel (Sigma-Aldrich, St. Louis, Mo) or a thin bilayered poly(lactic-co-glycolic acid) (PLGA) film. No treatment (bypass only) and vehicle-loaded Pluronic gels or PLGA films served as controls. Delivery of RvD1 to venous tissue was evaluated 3 days later by liquid chromatography-tandem mass spectrometry. Total leukocyte infiltration, macrophage infiltration, and cell proliferation were evaluated by immunohistochemistry. Elastin and trichrome staining was performed on grafts harvested at 28 days after bypass to evaluate neointimal hyperplasia and vein graft remodeling. ResultsPerivascular treatments did not influence rates of graft thrombosis (23%), major wound complications (4%), or death (3%). Leukocyte (CD45) and macrophage (RAM11) infiltration was significantly reduced in the RvD1 treatment groups vs controls at 3 days (60%-72% reduction; P < .01). Cellular proliferation (Ki67 index) was also significantly lower in RvD1-treated vs control grafts at 3 days (40%-50% reduction; P < .01). Treatment of vein grafts with RvD1-loaded gels reduced neointimal thickness at 28 days by 61% vs bypass only (P < .001) and by 63% vs vehicle gel (P < .001). RvD1-loaded PLGA films reduced neointimal formation at 28 days by 50% vs bypass only (P < .001). RvD1 treatment was also associated with reduced collagen deposition in vein grafts at 28 days. ConclusionsLocal perivascular delivery of RvD1 attenuates vein graft hyperplasia without associated toxicity in a rabbit carotid bypass model. This effect appears to be mediated by both reduced leukocyte recruitment and decreased cell proliferation within the graft. Perivascular PLGA films may also impart protection through biomechanical scaffolding in this venous arterialization model. Our studies provide further support for the potential therapeutic role of specialized proresolving lipid mediators such as D-series resolvins in modulating vascular injury and repair.

Enhancement of Nitric Oxide Production Is Responsible for Minimal Intimal Hyperplasia of Autogenous Rabbit Arterial Grafts.

Vascular endothelium induces smooth muscle cell (SMC) relaxation mainly mediated by endothelium-derived nitric oxide (EDNO) and endothelium-derived hyperpolarizing factor (EDHF). It has previously been reported that functions of these endothelium factors have been greatly impaired in vein grafts. The present study was undertaken to determine whether the functions of EDNO and EDHF might be altered in artery graft.Methods and Results:In rabbits, the right carotid artery was excised and implanted in its original position as an autogenous graft ("artery graft") and the non-operated left carotid artery served as the "control artery". Histochemical changes, acetylcholine (ACh)-induced effects on the intracellular concentration of Ca2+([Ca2+]i) in endothelial cells, endothelium-dependent SMC hyperpolarization and relaxation, and tissue cGMP content were examined on post-operative day 28. "Artery graft" displayed a minimal amount of intimal hyperplasia. When compared with the "control artery", it exhibited greater ACh-induced, endothelium-dependent relaxation, but the reverse was true when EDNO production was blocked. In the "artery graft" (vs. the "control artery"), basal cGMP content was greater, whereas the [Ca2+]iincrease in endothelial cells and the endothelium-dependent SMC-hyperpolarization induced by ACh were less. It is suggested that the [Ca2+]i-independent EDNO production covers the loss of function of endothelium-dependent SMC hyperpolarization and minimizes intimal hyperplasia caused by surgical operation in autogenous carotid artery graft.

Tropoelastin inhibits intimal hyperplasia of mouse bioresorbable arterial vascular grafts.

Small resorbable vascular grafts can block due to the over-proliferation of smooth muscle cells in neointimal hyperplasia. We show here that the proliferation of these cells is restricted in this type of graft. This is achieved with a simple dip, non-covalent coating of tropoelastin. It is in principle amendable to other grafts and is therefore an attractive process. This study is particularly significant because: (1) it shows that smooth muscle cell proliferation can be reduced while still accommodating the growth of endothelial cells, (2) small vascular grafts with an internal diameter of less than 1mm are amenable to this process, and (3) this process works for resorbable grafts.

Nanoparticle-mediated arresten gene inhibits neointimal formation of vein grafts: an experimental research.

Recently, we established a new rat model of venous arterialization by grafting the jugular vein into carotid arteries. In many respects, the morphological features of this murine vascular graft model resemble those of human venous bypass graft diseases. Using this model, we studied nanoparticles that mediated the arresten gene to inhibit the neointimal formation of vein grafts. Thirty healthy Wistar female rats were randomly divided into three groups. Rat models of grafting the jugular vein into carotid arteries were established. Before and after surgery, all rats were subjected to anticoagulant drugs; and these were subcutaneously injected through different reagents after surgery. Group A: subcutaneous injection of nanoparticles to mediate the arresten gene (0.2 mL); group B: subcutaneous injection of blank nanoparticles (0.2 mL); group C: subcutaneous injection of saline (0.2 mL). At two weeks after the operation, veins of the objective blood vessel were obtained. Pathological changes of local vascular tissues and the new intima hyperplasia of experimental vascular segments were observed. Immunohistochemistry was used to observe the expression of MMPs. (I) After two weeks, pathological intimal hyperplasia reactions were more obvious in groups B and C than in group A (P<0.05). The difference between groups B and C was not statistically significant (P>0.05); (II) the expression of MMP-2 could be observed in different degrees among the three groups. The expression of MMP-2 markedly increased in groups B and C compared to group A (P<0.05), but the difference between these two groups was not statistically significant (P>0.05). (I) Nanoparticle-mediated arresten genes can reduce intimal hyperplasia in grafts; (II) we have recently shown that this gene reduced intimal hyperplasia, and this reduction is related to the reduced expression of MMP-2. This shows that the arresten gene can inhibit the degradation of the extracellular matrix (ECM).

Abstract 184: Polo Like Kinase 1 Regulates Smooth Muscle Cell Proliferation in the G2-M Phase in Human Coronary Artery Bypass Conduits

Proliferation of smooth muscle cells (SMCs) and the resultant intimal hyperplasia cause coronary artery bypass graft (CABG) failure. Internal mammary artery (IMA) graft is immune to intimal hyperplasia (IH), but a saphenous vein graft is prone to develop neointima. The fate of SMCs is determined by the balance between the mitogenic and anti-mitogenic signals. Mitosis of SMCs through the cell cycle involves crossing the two restriction (R)-points in G1 and G2 phase, respectively. Upon loss of proper G1/S control, cells will progress into the G2-phase where G2 R-point can prevent cell proliferation. In this study, we examined the effect of mitogenic PDGF-BB stimulation on the G2 R-point and its relationship with the phosphorylation of PLK1, Cdc2 and Histone H3 in isolated SMCs of human bypass graft conduits. We observed increased expression and phosphorylation of PLK1 in PDGF-stimulated SV-SMCs compared to control SMCs without the treatment. Furthermore, PLK1 was phosphorylated and activated for a longer period of time in PDGF-stimulated SV- than IMA-SMCs. PLK1 m-RNA level was higher in PDGF-stimulated SV-SMCs than IMA. An ATP-competitive inhibitor of PLK1 attenuated PDGF-BB-induced proliferation in IMA and SV-SMCs. Cell proliferation was measured using cell count and immunoblotting against phospho-Histone H3 (pHistone) at Ser-10. Treatment with PLK1 inhibitor reduced PDGF-induced Cdc2 activation. Silencing the PLK1 gene by siRNA transfection of SV- and IMA-SMCs significantly reduced the expression of pHistone. These data demonstrate differential activity of PDGF-BB-induced PLK1, which was quantitatively and temporally greater in SV-SMCs than in the IMA. PLK1 inhibitor completely blocked the phosphorylation of PLK1 and attenuated proliferation in SV-SMCs. This in part, could suggest that PLK1 plays a critical role in the development of neointimal hyperplasia in SV grafts following CABG. Thus, inhibition of PLK1 activity could be a target in developing better therapeutic approach to prevent vein-graft disease.

Tissue Factor Activity in Dialysis Access Grafts

Intimal hyperplasia at the venous anastomosis of dialysis grafts causes early failure. We developed a sheep model of arteriovenous prosthetic grafts that fail rapidly due to intimal hyperplasia with histologic features nearly identical to human access grafts. A prominent feature of lesion development in this model is formation of luminal thrombus that becomes organized into stenosing lesions by macrophage and myofibroblast infiltration. To better understand this process, we examined the presence and activity of tissue factor (TF) in this system. This protein is the physiological initiator of coagulation invivo and is known to contribute to development of intimal hyperplasia after vascular injury. Expanded polytetrafluorethylene (ePTFE) grafts were placed between the carotid artery and external jugular vein in sheep. Grafts were examined for luminal TF activity using a novel exvivo assay. In a separate series of grafts, immunohistochemistry was used to localize smooth muscle cells, monocytes, and TF protein. At 2 days, luminal TF activity already was higher in the venous and arterial end of the graft than in the adventitia. This high level of activity persisted at 8weeks. TF activity was higher in the venous end of the grafts than in the arterial end at 2 and 8weeks (40% and 47% increase, n=5, n=3, respectively, P<0.05). Immunohistochemistry revealed TF protein localized in regions with or adjacent to fibrin accumulation and often in regions close to the lumen. This study further examines the development of intimal hyperplasia in ePTFE dialysis access grafts. In this model, TF levels on the luminal surface were increased throughout the arteriovenous grafts and the adjacent vessels as early as 2days after engraftment and for as long as 8weeks thereafter. The highest levels of activity were found in the venous end of the graft, where hyperplasia is most robust. Increased activity of TF is associated with luminal thrombus, which provides a scaffolding for development of intimal hyperplasia. These findings present an opportunity to develop strategies to limit TF activity within the graft. Further studies using agents delivered locally or incorporated into the graft matrix to block the luminal activity of TF are warranted.

Nano keeps MK2 inhibitor intact and on target

Encapsulating a kinase inhibitor in a pH-sensitive nanoparticle may be a strategy to prevent intimal hyperplasia in vascular grafts.

English

&nbsp; High-volume intra- and extra cranial artery bypass surgery has been widely used, but it remains a difficult technique for most of surgeons. The objective of this study is to explore a training mode and platform. Six healthy dogs were divided into three groups at random. Twelve high-volume common carotid-external carotid bypasses were operated on both sides of six dogs (n=12). Digital subtraction angiography (DSA) and color Doppler sonography were taken to measure the hemodynamic parameters of grafts one week (n=4), four weeks (n=4) and 24 weeks (n=4) after the operations. The grafts were taken out for histopathological examination 24 weeks after the operations. The high-volume common carotid-external carotid bypass model (n=12) was successfully established in six dogs under microscope. Post-operative DSA in Week 1 (n=4), Week 4 (n=4) and Week 24 (n=4) showed bilateral external carotid blood flow was supplied by contralateral common carotid grafts. Both ends and the whole grafts were patent. Color Doppler sonography showed clearly that the blood flow volume of grafts was higher than 90 ml/min. Histopathological examination taken 24 weeks after the operations showed intimal hyperplasia of grafts. Dog model of high-volume common carotid-external carotid bypass has the advantages of similar material, high volume, similar blood pressure, feasible operation and high patent rate compared to the traditional microsurgery model, making it a better simulation training platform which is closer to the real surgical procedure for surgeons willing to master the technique of high-volume bypass operation. &nbsp; Key words: Dog, animal model, bypass, high-volume, vascular anastomosis.

Abstract 153: IL-10 Accelerates Re-Endothelialization and Inhibits Post-injury Intimal Hyperplasia following Carotid Artery Denudation by Attenuating TNF-alpha-induced Endothelial Cell Dysfunction

The association of inflammation with atherosclerosis and restenosis is now fairly well established. Restenosis, a persistent complication of percutaneous vascular interventions, is thought to be a complex response to injury, which includes early thrombus formation, neointimal growth and acute inflammation. Mononuclear phagocytes are likely participants in the host response to vascular injury, via the secretion of cytokines and chemokines, including TNF-alpha (TNF). Others and we have previously shown that IL-10 inhibits TNF and other inflammatory mediators produced in response to cardiovascular injuries. The specific effect of IL-10 on endothelial cell (EC) biology is not well elucidated. Here we report that in a mouse model of carotid denudation, IL-10 knock-out mice (IL10KO) displayed significantly delayed ReEndothelialization and enhanced neointimal growth compared to their WT counterparts. Exogenous treatment of recombinant IL-10 dramatically blunted the inflammatory cell infiltration and neointimal thickening while significantly accelerating the recovery of the injured endothelium both WT and IL10KO mice. In vitro, IL10 co-treatment reversed TNF-mediated growth arrest, EC cell cycle inhibition, EC-monocyte adhesion and EC apoptosis. At signaling level, IL-10 reduced TNF-induced activation of JNK MAP kinase while simultaneously activating PI3K/Akt pathway. Because IL-10 function and signaling are important components for control of inflammatory responses, these results may provide insights necessary to develop strategies for modulating vascular repair and other accelerated arteriopathies, including transplant vasculopathy and vein graft hyperplasia.

Varying levels of 6-keto-prostaglandin F1α and thromboxane B2 in serum and endothelialization and hyperplasia in small-diameter grafts seeded with CD34+ bone marrow cells in canines.

The aim of the present study was to investigate the serum levels of 6-keto-prostaglandin (PG)F1α and thromboxane (TX)B2, as well as the endothelialization and hyperplasia of polytetrafluoroethylene (PTFE) and Dacron prostheses seeded with CD34+ cells in medium-term observation. A total of 24 crossbred dogs were randomly distributed into PTFE or Dacron groups. CD34+ cells were isolated from bone marrow aspirate and collected using an immunomagnetic bead-based system. The PTFE or Dacron prostheses were implanted into the abdominal aortic artery and inferior vena cava of the dogs. In each group, 8 dogs were implanted with prostheses that had been seeded with CD34+ cells, while 4 dogs were implanted with prostheses that had been seeded with autogenous blood as a control. Serum concentrations of 6-keto-PGF1α and TXB2 were determined at days 0, 10, 30 and 60 following surgery. The grafts were removed and examined at days 10, 30, 60 and 100 following surgery. Finally, CD34 factor staining was used to identify endothelial cells, while light and electron microscopy were applied to examine endothelialization and patency. The results revealed that confluent endothelial cells appeared on the neointima of prostheses seeded with CD34+ cells at day 30 following surgery. In the control groups compared with the experimental groups, there were fewer endothelial cells and the neointima was significantly thicker in the arterial (PTFE, 174±1.41 vs. 117±2.83 μm, respectively; P=0.001; Dacron, 187.5±3.5 vs. 100±1.41 μm, respectively; P<0.001) and venous (PTFE, 230.5±6.36 vs. 135±5.66 μm, respectively; P=0.001; Dacron, 249±2.83 vs. 121.5±3.54 μm, respectively; P<0.001) prostheses. In the experimental groups, intimal hyperplasia in the venous prostheses (PTFE, 135±5.66 μm; Dacron, 121.5±3.54 μm) was more severe compared with that in the arterial prostheses (PTFE, 117±2.83 μm; Dacron, 100±1.41 μm) at day 60. Compared with the 6-keto-PGF1α concentrations in the experimental groups, those in the control groups were significantly lower on day 10 (PTFE, 135±6.01 vs. 80.5±4.35 pg/l, respectively; P=0.001; Dacron, 145±6.54 vs. 81.2±5.10 pg/l, respectively; P<0.001) and were then maintained at a lower level. By contrast, the TXB2 concentration, following marked increases on day 10 in the experimental and control groups (PTFE, 635±32.8 vs. 1,256±63.5 pg/l, respectively; P<0.001; Dacron, 652±30.9 vs. 1,136±53.2 pg/l, respectively; P=0.001), remained at a high level in the control groups. Therefore, the results of the present study indicate that it is possible to achieve rapid endothelialization in PTFE or Dacron prostheses by implanting CD34+ cells. Endothelialization inhibited the reduction in the concentration of 6-keto-PGF1α and the increase in the concentration of TXB2. In addition, endothelialization inhibited excessive intimal hyperplasia and thrombosis. Thus, CD34+ cell seeding provides a theoretical basis for the clinical application of artificial vessel endothelialization.

Radio-guided parathyroidectomy for recurrent renal hyperparathyroidism caused by graft hyperplasia

Radio-guided surgery offers several advantages in treatment of primary hyperparathyroidism. It is considered less helpful in renal hyperparathyroidism, but it could be of great advantage in the treatment of persistent or recurrent secondary hyperparathyroidism. One of the surgical options for symptomatic renal hyperparathyroidism is total parathyroidectomy with autotransplantation of hyperplastic parathyroid tissue in forearm muscles or sternocleidomastoid muscle. Recurrence can occur and is most likely caused by graft hyperplasia. In this report we present the case of 54-year-old woman with recurrent renal hyperparathyroidism caused by hyperplasia of the graft in sternocleidomastoid muscle. Unfortunately no sutures or clips were placed at initial surgery to identify the location of the parathyroid tissue. The preoperative assessment consisting of 99mTc-sestamibi scintigraphy identified a parathyroid tissue in the in the middle third of sternocleidomastoid muscle. The patient underwent a radio-guided neck re-exploration that allowed a rapid localization and excision of the hyperplastic graft.

Correlates of Saphenous Vein Graft Hyperplasia and Occlusion 1 Year After Coronary Artery Bypass Grafting

Intimal hyperplasia of saphenous vein grafts (SVGs) can lead to subsequent graft atherosclerosis and occlusion after coronary artery bypass grafting (CABG). This study examined whether patient characteristics, anatomic factors, and medications are associated with SVG intimal hyperplasia and occlusion after CABG. We performed a post hoc analysis of the Clopidogrel After Surgery for Coronary Artery Disease (CASCADE) trial, where 322 grafts were assessed by angiography and 90 grafts were examined by intravascular ultrasound at 1 year after CABG. We assessed the following correlates for intimal hyperplasia and occlusion: patient characteristics, discharge medications, target vessel characteristics, and SVG diameter. At 1 year, the SVG mean intimal area was 4.3 ± 2.1 mm(2), and the occlusion rate was 6.2% (13/209). Independent correlates of hyperplasia were larger SVG diameter (1.9 ± 0.2 mm(2)/mm; P<0.001), hypertension (0.7 ± 0.3 mm(2); P=0.03), and grafting to the right coronary territory (0.6 ± 0.3 mm(2); P=0.03), whereas statin (-0.8 ± 0.3 mm(2); P=0.01) and β-blocker use (-1.0 ± 0.4 mm(2); P=0.03) were associated with less hyperplasia. Low target vessel quality was an independent correlate of SVG occlusion (odds ratio, 5.2 ± 3.1; P<0.01). Hypertension, SVG diameter, grafting to the right coronary artery, and low quality of the target vessel correlate with the development of SVG hyperplasia or occlusion by 1 year after CABG, whereas β-blockers and statins are associated with less SVG disease. These new findings further our understanding of SVG remodeling after bypass surgery and may guide future research to help prevent post-CABG SVG disease. http://www.clinicaltrials.gov. Unique identifier: NCT00228423.

Abstract 175: Efficacy of Biomimetic Peptide-Fluorosurfactant Polymer Coated Expanded Poly(tetrafluoroethylene) Vascular Grafts in a Porcine Carotid Artery Interposition Model

Objectives Vascular grafts currently see limited use in small diameter applications due to the prevalence of thrombosis. Patency of ePTFE grafts could be improved by reducing thrombosis via an endothelial cell specific peptide fluorosurfactant polymer (FSP) coating. Methods In this study, ePTFE grafts were coated with cRRE-FSP, RGD-FSP, or Maltose-7 (M7)-FSP, sodded with porcine pulmonary artery endothelial cells (PPAECs), and evaluated in vivo in a porcine carotid artery interposition model. Grafts were excised after one month and evaluated by quantifying thrombosis and intimal hyperplasia and by qualitatively examining inflammation, smooth muscle cell infiltration, and endothelialization. Results Angiography of the grafts after one month showed at least partial patency in all grafts with the exception of one RGD-coated and one uncoated graft. Immunofluorescent staining of cell-sodded grafts showed a complete endothelial layer of adherent and spread PPAECs. Thrombus formation was present in two uncoated grafts and one RGD-coated graft. Intimal hyperplasia comprised mostly of smooth muscle cells was present in all grafts, but developed to the highest extent in RGD-coated grafts. Mean graft occlusion in M7 (24.7%) and cRRE-coated grafts (25.1%) was reduced by half compared to uncoated (58.5%) and RGD-coated grafts (53.9%). Conclusions Increased intimal hyperplasia in RGD grafts suggests that RGD, a prominent cell adhesion peptide, may facilitate ingrowth of more smooth muscle cells compared to the other grafts. These results show that cRRE-FSP coating of ePTFE grafts may reduce thrombosis, making it a promising candidate for improving graft patency.