Monomeric glutaraldehyde fixation and amino acid detoxification of decellularized bovine pericardium for production of biocompatible tissue with tissue-guided regenerative potential.

The effect of monomeric glutaraldehyde fixation and amino acid detoxification on biocompatibility and tissue-guided regenerative potential of decellularized bovine pericardium was evaluated. The degree of cross-linking, porosity, enzymatic degradation, alpha-galactosyl content, the efficacy of detoxification, and cytotoxicity towards human epithelial cells were assessed. Tissue was subcutaneously implanted for eight weeks in male juvenile Sprague-Dawley rats, and mechanical properties, host cell infiltration, and calcification were evaluated. Three groups were compared i) decellularized tissue, ii) decellularized, monomeric glutaraldehyde fixed and amino acid detoxified tissue, and iii) commercial glutaraldehyde fixed non-decellularized tissue (Glycar®) (n = 6 rats per group). The fixation process gave a high degree of cross-linking (>85%), and was resistant to enzymatic degradation, with no significant effect on porosity. The detoxification process was effective, and the tissue was not toxic to mammalian cells in vitro. Tissue from both decellularized groups had significantly higher (p < 0.05) porosity and host cell infiltration in vivo. The process mitigated calcification. A non-significant decrease in the alpha-galactosyl content was observed, which increased when including the alpha-galactosidase enzyme. Mechanical properties were maintained. The fixation and detoxification process adequately removes free aldehyde groups and reduces toxicity, preventing enzymatic degradation and allowing for host cell infiltration while mitigating calcification and retaining the mechanical properties of the tissue. This process can be considered for processing decellularized bovine pericardium with tissue-guided regeneration potential for use in cardiovascular bioprostheses; however, methods of further reducing antigenicity, such as the use of enzymes, should be investigated.

Comparison of the function and structural integrity of cryopreserved pulmonary homografts versus decellularized pulmonary homografts after 180 days implantation in the juvenile ovine model.

Homograft availability and durability remain big challenges. Increasing the post-mortem ischaemic harvesting time beyond 24 h increases the potential donor pool. Cryopreservation, routinely used to preserve homografts, damages the extracellular matrix (ECM), contributing to valve degeneration. Decellularization might preserve the ECM, promoting host-cell infiltration and contributing towards better clinical outcomes. This study compared the performance of cryopreserved versus decellularized pulmonary homografts in the right ventricle outflow tract (RVOT) of a juvenile ovine model. Homografts (n = 10) were harvested from juvenile sheep, subjected to 48 h post-mortem cold ischaemia, cryopreserved or decellularized and implanted in the RVOT of juvenile sheep for 180 days. Valve performance was monitored echocardiographically. Explanted leaflet and wall tissue evaluated histologically, on electron microscopical appearance, mechanical properties and calcium content. In both groups the annulus diameter increased. Cryopreserved homografts developed significant (¾) pulmonary regurgitation, with trivial regurgitation (») in the decellularized group. Macroscopically, explanted cryopreserved valve leaflets retracted and thickened while decellularized leaflets remained thin and pliable with good coaptation. Cryopreserved leaflets and walls demonstrated loss of interstitial cells with collapsed collagen, and decellularized scaffolds extensive, uniform ingrowth of host-cells with an intact collagen network. Calcific deposits were shown only in leaflets and walls of cryopreserved explants. Young fibroblasts, with vacuoles and rough endoplasmic reticulum in the cytoplasm, repopulated the leaflets and walls of decellularized scaffolds. Young's modulus of wall tissue in both groups increased significantly. Cryopreserved valves deteriorate over time due to loss of cellularity and calcification, while decellularized scaffolds demonstrated host-cell repopulation, structural maintenance, tissue remodelling and growth potential.

Use of Fondaparinux Off-Label or Approved Anticoagulants for Management of Heparin-Induced Thrombocytopenia.

BACKGROUND: Life-threatening heparin-induced thrombocytopenia (HIT) is treated with the alternative nonheparin anticoagulants argatroban, lepirudin, or danaparoid. Frequently, the pentasaccharide fondaparinux is used off-label. OBJECTIVES: The authors sought to investigate the safety and efficacy of the different anticoagulants for treating HIT. METHODS: In a national, multicenter registry study, hospitalized patients who were diagnosed with HIT, an at least intermediate clinical HIT-risk (4Ts score ≥4 points), and received treatment with ≥1 dose of the aforementioned anticoagulants were included. Main outcome measures were the incidences of HIT-specific complications (thromboembolic venous/arterial events, amputations, recurrent/persistent thrombocytopenia, skin lesions) and bleedings. RESULTS: Of 195 patients, 46 (23.6%), 4 (2.1%), 61 (31.3%), and 84 (43.1%) had been treated first-line with argatroban, lepirudin, danaparoid, and fondaparinux, respectively. The composite endpoint of HIT-specific complications (thromboembolic events, amputation, skin necrosis) occurred in 11.7% of patients treated with approved alternative anticoagulation and in 0.0% of fondaparinux-treated patients. The all-cause in-hospital mortality rates were 14.4% during approved alternative anticoagulation and 0.0% during fondaparinux treatment. Bleeding complications occurred in alternatively anticoagulated patients and in fondaparinux-treated patients in 6.3% and 4.8%, respectively. Post hoc analysis of clinical and laboratory features confirmed "true" HIT in at least 74 of 195 (38.0%) patients; 35 of 74 (47.3%) were treated with fondaparinux. CONCLUSIONS: Fondaparinux is effective and safe in suspected acute HIT; no HIT-specific complications occurred in the fondaparinux-treated patients, even among those with a high clinical HIT probability. Further data from randomized controlled trials are urgently needed because lepirudin was recalled from the market; danaparoid access has been limited and is not approved in the United States; and argatroban is contraindicated in patients with impaired liver function, and activated partial thromboplastin time confounding may interfere with monitoring. (Retrospective Registry of Patients With Acute Heparin-induced Thrombocytopenia Type II; NCT01304238).

Reprogramming Bone Marrow Stem Cells to Functional Endothelial Cells in a Mini Pig Animal Model.

BACKGROUND The aims of this study were to compare the morphological, biochemical, and functional properties of reprogrammed bone marrow stem cell (BMSC)-derived arterial endothelial cells (AECs) and venous endothelial cells (VECs), following adenosine triphosphate (ATP)-stimulation in a mini pig animal model. MATERIAL AND METHODS Bone marrow aspiration was performed in six adult mini pigs. Harvested mononuclear cells were isolated, cultured, and treated with vascular endothelial growth factor (VEGF) (16 µg/ml). Transformed cells were characterized using immunofluorescence staining for CD31 and von Willebrandt factor (vWF) and expression of endothelial nitric oxide synthase (eNOS). Cell release of nitric oxide (cNO) was measured using spectrophotometry. Matrigel assays were used to investigate angiogenesis in transformed BMSCs. RESULTS Reprogrammed BMSCs in culture showed a typical cobblestone-like pattern of growth. Immunofluorescence staining was positive for CD31 and vWF expression. Expression of eNOS, using immunofluorescence staining and Western blot, showed no difference between the reprogrammed BMSCs and VECs. Spectrophotometric examination following stimulation with 10mmol/l ATP, showed comparable cNO release for reprogrammed BMSCs (10.87±1.76 pmol/106 cells/min) and VECs (13.23±2.16 pmol/10^6 cells/min), but reduced cNO release for AECS (3.44±0.75 pmol/10^6 cells/min). Matrigel assay for angiogenesis showed vascular tube formation of differentiated BMSC endothelial cells (grade 3.25). BMSCs cultured without VEGF did not demonstrate vascular tube formation. CONCLUSIONS The findings of this study showed that eNOS expression and release of NO could be used to show that BMSCs can be reprogrammed to functional VECs and AECs.

Does prolonged post-mortem cold ischemic harvesting time influence cryopreserved pulmonary homograft tissue integrity?

This study investigated cryopreserved pulmonary homograft (CPA) structural integrity after prolonged cold ischemic harvesting times in a juvenile sheep model. Three groups with different post-mortem cold ischemic harvesting times were studied, i.e. Group 1 (24 h, n = 10); group 2 (48 h, n = 10); group 3 (72 h, n = 10). In each group, 5 CPAs were studied in vitro after cryopreservation and thawing. The other 5 CPAs were implanted in juvenile sheep for a minimum of 180 days. Serology samples were obtained and echocardiography was performed before euthanasia. Hematoxylin and eosin (H&E), scanning electron microscopy (SEM), von Kossa, Picrosirius red, α-actin, immunohistochemistry [von Willebrand factor (vWF), CD4, CD31 and CD34] and calcium content analyses were performed on explanted CPAs. The in vitro and in vivo studies failed to demonstrate any change in tensile strength, Young's Modulus and thermal denaturation (Td) results between the groups. SEM demonstrated a reduction in endothelial cells (50 % at 24 h, 60.9 % at 48 h and 40.9 % at 72 h), but H&E could not demonstrate autolysis in any CPA in vitro. All cultures were negative. In the explanted groups, IgE, IgM and IgG results were inconclusive. Echocardiography demonstrated normal valve function in all groups. H&E and Picrosirius red staining confirmed tissue integrity. vWF, CD31 and CD34 staining confirmed a monolayer of endothelial cells in all explanted valves. Calcium content of explanted CPA leaflets was similar. This experimental study supports the concept of prolonging the cold ischemic harvesting time of cryopreserved homografts to reduce homograft shortage.

Autocrine control of angiogenesis by endogenous acetylcholine in an in vitro model using human endothelial cells: evidence for an autocrine cholinergic system in endothelial cells.

We wanted to elucidate whether acetylcholine as the endogenous ligand at cholinoceptors (ChRs) may have effects on angiogenesis and whether they are transduced through muscarinic or nicotinic ChRs. Human umbilical vein endothelial cells were cultured until confluence and thereafter seeded in Matrigel in vitro angiogenesis assays for 18 hours. During the entire cell culture and angiogenesis period, cells were treated with vehicle, eserine (1 µM), in the absence or presence of additional atropine (1 µM) or mecamylamine (1 µM). Finally, the resulting angiogenetic network was investigated histologically. Eserine significantly enhanced acetylcholine formation. When acetylcholine acted through muscarinic ChRs (eserine + mecamylamine), we observed enhanced complexity of the angiogenic network pattern with increased tube length and cell number. In contrast, when acting through nicotinic ChRs (eserine + atropine), we found reduced complexity of pattern with less branches, shorter tubes, and reduced cell number. If acting on both types of ChRs (eserine alone), there were only very small effects. Using α-bungarotoxin, lobeline, and dihydro-ß-erythroidine, we also could show that these effects to various degrees involve α7, α3/ß2, and α4/ß2 n-ChRs. In conclusion, our results support the hypothesis that human umbilical vein endothelial cells possess an autocrine nonneuronal cholinergic system regulating angiogenesic branch formation through the partially opposing effects of n-ChRs and m-ChRs.

Arrhythmogenic effects by local left ventricular stretch: effects of flecainide and streptomycin.

Mechanical stretch has been shown to provoke arrhythmia. We wanted to analyze ventricular arrhythmia induced by local left ventricular stretch in order to find out, where arrhythmias originate and whether they can be prevented pharmacologically. Isolated rabbit hearts (Langendorff technique) were submitted to increased left ventricular stretch at the left wall by insertion of an additional intraventricular balloon and adjusting the end-diastolic pressure (EDP) to 25 mmHg for 10 min followed by 20 min recovery at normal EDP of 5-8 mmHg. Activation and repolarization processes were investigated by ventricular 256 electrode epicardial mapping. The hearts were treated during the whole procedure either with vehicle, 0.5 µM flecainide (sodium channel blocker) or 100 µM streptomycin (here used as stretch-activated ion-channel blocker). In addition, we performed a series of experiments, in which we enhanced EDP to 30 mmHg (global stretch instead of local stretch) by inflating the left ventricular pressure balloon (strain, 0.148 ± 0.034). Each series was performed with n = 6. Stretch resulted in local strain of 25% at the left wall together with a local slowing of the activation process at the left wall, in a change in the activation pattern, and in ventricular arrhythmia. Coronary flow was not affected. Ventricular arrhythmias originated from the border between the stretched area and the non-stretched region. Flecainide and streptomycin reduced the prolongation of the activation process at the stretched left wall and mitigated the difference in total activation time between left and front wall but only partially prevented arrhythmia. In the additional global stretch experiments relative coronary flow and the other parameters remained unchanged, in particular TAT. Thus, in contrast to the local stretch series, there was no difference in the change in TAT between left and front wall. Only rare single ventricular extrasystoles (<1/min; originating from LV (front and left wall) i.e. from within the stretched region) were seen during stretch (but not at the beginning) and during recovery. Local left ventricular stretch can elicit ventricular arrhythmias. Local slowing of electrical activation seems involved so that the difference in total activation time of the stretched free left wall and the non-stretched increased.

Frequent off-label use of fondaparinux in patients with suspected acute heparin-induced thrombocytopenia (HIT)--findings from the GerHIT multi-centre registry study.

INTRODUCTION: In life-threatening immune heparin-induced thrombocytopenia (HIT), treatment with an approved non-heparin anticoagulant is essential. However, off-label use with fondaparinux has been reported in the literature. The study aim was to collect data on "real-life" management of patients with suspected acute HIT regarding diagnostic and therapeutic strategies. PATIENTS AND METHODS: In a national multi-centre registry study, patients with a 4T's HIT-probability score of ≥ 4 points and treatment with at least one dose of (A)rgatroban, (L)epirudin, (D)anaparoid, or (F)ondaparinux were retrospectively evaluated. RESULTS: Of 195 patients, the 4T's scores were 4/5/6/7/8 points in 46 (23.6%)/50 (25.6%)/74 (38.0%)/13 (6.7%)/7 (3.6%) patients, respectively. During heparin therapy, 47 (24.1%) thromboembolic events, 5 (2.6%) skin lesions, 1 (0.5%) amputation, 24 (12.3%) Hb-relevant bleedings, and 2 (1.0%) fatalities occurred. A functional heparin-induced platelet activation assay was performed in 96.9%, a platelet factor 4/heparin-dependent enzyme immunoassay in 89.2%, a particle gel immunoassay in 12.3%, and a serotonin-release assay in none of the patients. Argatroban was used in 16.4%, lepirudin in 2.1%, danaparoid in 23.6%, fondaparinux in 40.0% of the patients; the sequential therapy strata were: AF (5.6%), DA (5.6%), DF (2.6%), DL (2.1%), ADF (1.5%), and DFL (0.5%). CONCLUSIONS: The current diagnostic laboratory strategy for suspected HIT is mostly (>96%) based on the recommended 2-step strategy (immunoassay plus functional assay). However, there is a wide fondaparinux off-label use (up to 50.3%) for suspected HIT, even in those patients with a high clinical pretest probability. Efficacy and safety of fondaparinux for HIT-treatment require further evaluation.

Body mass index affects connexin43 remodeling in patients with atrial fibrillation.

BACKGROUND: Increased body mass index (BMI) is often found to be a risk factor for cardiac disease. However, it is unclear whether BMI also affects the gap junction remodeling process in atrial fibrillation (AF). The aim of the study was to see if BMI can influence the connexin43 (Cx43) distribution in patients with sinus rhythm (SR) and AF. METHODS: We investigated a total of 51 white Caucasian patients of both gender (mean age: 69 years, 30% diabetes mellitus, ejection fraction [EF] > 50%) with SR or AF, with either BMI < 27 or ≥ 27 undergoing cardiac surgery for mitral valve repair, aortic valve repair, or coronary heart disease. We obtained human right atrial tissue for immunohistochemistry and investigated the CX43-positive polar and lateral membrane length in the different BMI (BMI < 27, BMI ≥ 27) and rhythm groups (SR or AF). RESULTS: In lean SR patients, Cx43 (BMI < 27) was found mainly at the cell poles while only 2% of the lateral membrane stained positive for Cx43. In obese SR patients (BMI > 27), 6.7 ± 0.7% of the lateral membrane was positive (p < 0.05). In AF generally, there was significantly more lateral Cx43 staining, which was significantly enhanced in obese AF patients. In lean AF patients, lateral Cx43 positivity increased to 14 ± 1% (p < 0.05), while in BMI > 27 AF patients, this was significantly enhanced to 22 ± 2% (p < 0.05). The BMI effect was independent from left atrial diameter, EF, and comorbidity. CONCLUSIONS: Enhanced BMI is associated with increased remodeling effects of AF on irregular Cx43 distribution.

Successful implantation of a decellularized equine pericardial patch into the systemic circulation.

BACKGROUND: In the past, successful use of decellularized xenogenic tissue was shown in the pulmonary circulation. This study, however, evaluates a newly developed decellularized equine pericardial patch under high pressure circumstances. MATERIAL AND METHODS: Seven decellularized equine pericardial scaffolds were implanted into the descending aorta of the juvenile sheep. The implanted patches were oversized to evaluate the durability of the decellularized tissue under high surface tension (Law of Laplace). After 4 months of implantation, all decellularized patches were inspected by gross examination, light microscopy (H&E, Serius red, Gomori, Weigert, and von Kossa straining), and immunohistochemical staining. RESULTS: The juvenile sheep showed fast recovery after surgery. There was no mortality during follow-up. At explantation, only limited adhesion was seen at the surgical site. Gross examination showed a smooth and pliable surface without degeneration, as well as absence of aneurysmatic dilatation. Light microscopy showed a well preserved extracellular scaffold with a monolayer of endothelial cells covering the luminal side of the patch. On the outside part of the patch, a well developed neo-vascularization was seen. Host fibroblasts were seen in all layers of the scaffolds. There was no evidence for structural deterioration or calcification of the decellularized equine pericardial scaffolds. CONCLUSIONS: In the juvenile sheep, decellularized equine tissue showed no structural deterioration, but regeneration and remodeling processes at systemic circulation.

Cerebroprotective effect of piracetam in patients undergoing open heart surgery.

OBJECTIVES: Reduction of cognitive function is a possible side effect after the use of cardiopulmonary bypass (CPB) during cardiac surgery. Since it has been proven that piracetam is cerebroprotective in patients undergoing coronary bypass surgery, we investigated the effects of piracetam on the cognitive performance of patients undergoing open heart surgery. METHODS: Patients scheduled for elective open heart surgery were randomized to the piracetam or placebo group in a double-blind study. Patients received 12 g of piracetam or placebo at the beginning of the operation. Six neuropsychological subtests from the Syndrom Kurz Test and the Alzheimer's Disease Assessment Scale were performed preoperatively and on day 3, postoperatively. To assess the overall cognitive function and the degree of cognitive decline across all tests after the surgery, we combined the six test-scores by principal component analysis. RESULTS: A total of 88 patients with a mean age of 67 years were enrolled into the study. The mean duration of CPB was 110 minutes. Preoperative clinical parameters and overall cognitive functions were not significantly different between the groups. The postoperative combined score of the neuropsychological tests showed deterioration of cognitive function in both groups (piracetam: preoperative 0.19 ± 0.97 vs. postoperative -0.97 ± 1.38, p <0.0005 and placebo: preoperative -0.14 ± 0.98 vs. postoperative -1.35 ± 1.23, p <0.0005). Patients taking piracetam did not perform better than those taking placebo, and both groups had the same decline of overall cognitive function (p = 0.955). CONCLUSION: Piracetam had no cerebroprotective effect in patients undergoing open heart surgery. Unlike the patients who underwent coronary surgery, piracetam did not reduce the early postoperative decline of neuropsychological abilities in heart valve patients.

Recellularization of aortic valves in pigs.

OBJECTIVES: Decellularized porcine heart valves treated with deoxycholic acid (DOA) have demonstrated complete recellularization and absence of calcification when implanted into the pulmonary position in sheep. We studied recellularization and calcification in stented DOA-treated heart valves compared with conventional stented glutaraldehyde-treated valves in the aortic position in juvenile pigs 6 months after implantation. METHODS: DOA heart valves (n=12) and glutaraldehyde-treated valves (Carpentier-Edwards) (n=15) were implanted into the aortic position in 8-month old 90 kg female pigs. Six months postoperatively, the valves were explanted and subjected to gross pathology examination, high-resolution (HR) X-ray imaging, and histological evaluation. RESULTS: Five DOA valves and five glutaraldehyde-treated valves were explanted after 6 months. Fourteen animals died before follow-up because of non-valve related causes and three because of infective endocarditis. Gross pathologic examination showed all DOA valves to be well functioning with only minor thrombotic depositions located mostly in the commissural area. Three glutaraldehyde valves had limited thrombosis and two had severe thrombosis. HR X-ray imaging demonstrated almost complete absence of cusp calcification in the DOA valves, but severe calcification in all glutaraldehyde valves. Overgrowth of endothelial cells and ingrowth of fibroblasts in the stent-adjacent area and basal part of the cusps were seen in all DOA valves, but not in glutaraldehyde valves. Immunohistochemistry revealed larger amounts of inflammatory cells in all glutaraldehyde valves compared with DOA valves. CONCLUSIONS: DOA-treated heart valves demonstrated greater recellularization and less calcification compared with standard glutaraldehyde-treated valves 6 months after implantation in the aortic position in pigs. DOA-treated heart valves demonstrated less calcification compared with standard glutaraldehyde-treated valves by qualitative analysis. Endothelial and fibroblast recellularization of the cusps was only observed in DOA-treated valves.

Surgical management of multiple coronary artery aneurysms, including the giant form.

Coronary artery aneurysms are clinically relevant, because thromboembolism, rupture, and hemodynamic problems related to compression may occur. Surgical management is not standardized, and an individual approach toward each aneurysm is prudent. Giant coronary artery aneurysms (larger than 20 mm in diameter) originate in different ways and are extremely rare, and their surgical treatment is also not well defined.Herein, we report the case of a 63-year-old man who had 2 aneurysms of the circumflex coronary artery and a 65-mm aneurysm of the right coronary artery. The diagnosis was established by use of transesophageal echocardiography, magnetic resonance imaging, and coronary angiography. An intraoperatively discovered smaller aneurysm of the right coronary artery was ligated. The giant thrombus-filled aneurysm of the right coronary artery was partially resected, because it compressed the right atrium and ventricle. A graft of the greater saphenous vein was constructed to the distal right coronary artery. The smaller, noncompressing aneurysms in the circumflex coronary artery were excluded by means of proximal and distal suture ligation, and bypass grafting was performed with use of skeletonized left internal mammary artery. The procedures were successful. We discuss the reasons behind our individual approach toward our patient's aneurysms.

Cerebroprotective effect of piracetam in patients undergoing coronary bypass burgery.

BACKGROUND: Reduction of cognitive function is a possible side effect after cardiac surgery using cardiopulmonary bypass. We investigated the cerebroprotective effect of piracetam on cognitive performance in patients undergoing coronary artery bypass surgery under cardiopulmonary bypass. MATERIAL/METHODS: Patients scheduled for elective, primary and isolated coronary bypass surgery were randomised either to piracetam or placebo group. The study was performed in a double blind fashion. Patients received either 12 g piracetam or placebo at the beginning of the operation. Six neuropsychological subtests from the Syndrom Kurz Test and the Alzheimer's Disease Assessment Scale were performed preoperatively and on the third postoperative day. To assess the overall cognitive function and the degree of cognitive decline across all tests after surgery we combined the six test-scores by principal component analysis. RESULTS: A total number of 120 patients were enrolled into the study. Preoperative overall cognitive function were not significantly different between the groups. The postoperative combined score of the neuropsychological tests showed a deterioration of cognitive function in both groups (placebo-pre: -0.06+/-0.99 vs placebo-post: -1.38+/-1.11; p<0.0005 and piracetam-pre: 0.06+/-1.02 vs piracetam-post: -0.65+/-0.93; p<0.0005). However, the piracetam patients performed significantly better compared to the placebo patients after the operation and had a less decline of overall cognitive function (p<0.0005). CONCLUSIONS: Piracetam has a cerebroprotective effect in patients undergoing coronary artery bypass surgery with the use of cardiopulmonary bypass. It reduces an early postoperative substantial decline of neuropsychological abilities.

Can autologous vascular endothelial cell seeding increase the patency rate of small-diameter No-React-treated bovine internal mammary arteries? An in vivo study in juvenile sheep.

BACKGROUND: This study was performed to evaluate the possibility of seeding No-React-treated bovine small-diameter internal mammary arteries (SIMAs) and to record any improvement in patency rate. MATERIAL/METHODS: During the in vitro study, 12 seeded SIMAs were divided into two groups; group I (n=6) was endothelial cell (EC) seeded and group II (n=6) EC seeded after pre-coating with fibrin glue to evaluate the binding capacity. During the in vivo part of the study, eight juvenile sheep received either a seeded or a non-seeded SIMA. In the seeded group (n=3), a piece of jugular vein was harvested to culture autologous ECs. SIMA grafts were coated and seeded in a special bioreactor. In the control group (n=5), non-seeded SIMA grafts were implanted. No anti-coagulation was administered. Explantation was performed at three and six months post-implantation. Grafts were evaluated by gross examination, histology, and immunohistochemistry. RESULTS: By inserting two million ECs in the in vitro study, the seeding density in group I was 1.29+/-0.09 x 10(5) cells/cm(2) and 2.27+/-0.17 x 10(5) cells/cm(2) in group II (p<0.003). In the in vivo study the mean EC density of the implanted seeded grafts was 2.35+/-0.04 x 10(5) cells/cm(2). At explantation, the seeded grafts showed less inflammatory reaction and a higher patency rate compared with the non-seeded grafts. Histology showed a monolayer of ECs on the inner surface of seeded SIMAs at follow-up. CONCLUSIONS: Seeding of No-React-treated SIMA arterial grafts with autologous ECs increases the patency rate.

The effect of surface roughness on activation of the coagulation system and platelet adhesion in rotary blood pumps.

The surface roughness of left ventricular assist devices (LVADs) is important for the biocompatibility of blood pumps. However, little is known about the effect of surface roughness on the antithrombogenicity of the device. The present study investigated the effect of surface roughness on the activation of the coagulation system and platelet adhesion in an impeller-type blood pump. Three identical Baylor Gyro 710 centrifugal blood pumps (Baylor College of Medicine, Houston, TX, USA) were manufactured with impeller surface roughness of 0.05, 0.2, and 0.4 microm, respectively, as determined by a stylus profilometer and by scanning electron microscopy. Whole blood was anticoagulated (1-IU heparin/mL, ACT 250 s) and circulated for 60 min in an artificial circulatory system, simulating LVAD perfusion (5-L/min flow against 100 mm Hg). Enzyme-linked immunosorbent assays were developed to quantify fibrinogen- and von Willebrand factor (vWf) adsorption as well as platelet adhesion directly on the impellers of the pumps. Levels of prothrombin fragment F1.2 and thrombin-antithrombin (TAT) complex were measured in order to quantify activation of coagulation. Compared with the 0.05-microm surface, platelet adhesion was 40 and 76% higher on the 0.2- and 0.4-microm surface, respectively (P < 0.01). The evaluation of adsorbed fibrinogen and vWf showed significant higher protein antigen levels on the rougher surfaces (P < 0.01). Furthermore, nonpulsatile perfusion activated the coagulation system. By contrast, the surface roughness had no significant influence on plasma prothrombin F1.2 fragment- and TAT concentrations. Antithrombogenicity was significantly reduced in pumps with inferior metal-finishing quality.