Search

Blood-contacting medical devices of different biomaterials are often used to treat various cardiovascular diseases. Thrombus formation is a common cause of failure of cardiovascular devices. Currently, there are no clinically available biomaterials that can totally inhibit thrombosis under the more challenging environments (e.g., low flow in the venous system). Although some biomaterials reduce protein adsorption or cell adhesion, the issue of biomaterial associated with thrombosis and inflammation still exists. To better understand how to develop more thrombosis-resistant medical devices, it is essential to understand the biology and mechano-transduction of thrombus nucleation and progression. In this review, we will compare the mechanisms of thrombus development and progression in the arterial and venous systems. We will address various aspects of thrombosis, starting with biology of thrombosis, mathematical modeling to integrate the mechanism of thrombosis, and thrombus formation on medical devices. Prevention of these problems requires a multifaceted approach that involves more effective and safer thrombolytic agents but more importantly the development of novel thrombosis-resistant biomaterials mimicking the biological characteristics of the endothelium and extracellular matrix tissues that also ameliorate the development and the progression of chronic inflammation as part of the processes associated with the detrimental generation of late thrombosis and neo-atherosclerosis. Until such developments occur, engineers and clinicians must work together to develop devices that require minimal anticoagulants and thrombolytics to mitigate thrombosis and inflammation without causing serious bleeding side effects.

Cardiac allograft vasculopathy (CAV) is a serious complication of heart transplantation in adults and children. Risk factors include human leukocyte antigen mismatches, number and duration of rejection episodes, type of immunosuppression, antibody-mediated rejection, hypertension, hyperlipidemia, obesity, smoking, diabetes, cytomegalovirus infection, mode of donor brain death, donor age and ischemia/reperfusion injury. Endothelial injury and dysfunction in CAV are characterized by changes in adhesion molecules and up-regulation of major histocompatibility class II antigens followed by endothelial activation of complement C4d. Subsequently, activation of the coagulation cascade leads to deposition of fibrin on endothelium followed by proliferation and migration of vascular smooth muscle cells. The development of a special type of microvessels with phenotypic characteristics of arterial capillaries ("capioles") seems to provide a survival advantage for patients with CAV. Novel therapies of CAV include statins, and heparin-induced extracorporeal low-density lipoprotein apheresis. B beta15-42 which is a fibrin peptide has been shown to improve the graft microvasculature and to reduce ischemia/reperfusion-induced damage. Despite these advances, there is a need to identify and stratify individual CAV risk factors, to develop early biomarkers of CAV, and to better decipher the events that lead to antibody-mediated rejection.

Chronic villitis of unknown etiology (CVUE) and massive chronic intervillositis (MCI) are placental lesions associated with infiltration of mononuclear cells in the chorionic villi and the intervillous spaces, respectively. It is not well known whether immune cells in CVUE and MCI have similar phenotypic characteristics.A cross-sectional study of third trimester placentas was conducted to identify immune cell subpopulations in CVUE and MCI (n = 17/group). CVUE was diagnosed with HE staining and antibody to CD3 in serial sections; and MCI, by the presence of massive infiltration of mononuclear cells in the intervillous spaces. Immune cells, ICAM-1 expression and nuclear factor κB (NF-κB) activation were determined immunohistochemically.CVUE and MCI showed similar infiltrates, mainly CD68+ and CD3+ cells. Most cells (80%) were CD45RB+, and one third were CD45RO+ in both lesions. There were slightly more CD8+ than CD4+ cells in both CVUE and MCI. More than 90% of cells in CVUE and MCI were ICAM-1+ with NFκB nuclear localization. Syncytiotrophoblast ICAM-1 expression was significantly (p0.001) higher in MCI (mean of 81.0; range of 71.6-86.0) than in CVUE (52.4; 36.4-59.4) or normal placentas (0.2; 0.0-0.6). Both, failure of physiologic transformation of spiral arteries and placental atherosclerosis-like lesions of atherosis were significantly more frequent in MCI than in CVUE or normal placentas (p = 0.044 and p = 0.007, respectively).These finding suggest that MCI and CVUE have very similar infiltration of immune cells although MCI has more severe placental lesions.

Introduction Massive chronic intervillositis (MCI), also known as chronic intervillositis of unknown etiology, is a placental lesion associated with massive infiltration of mononuclear cells in the intervillous space, poor perinatal outcome, and high rate of recurrence. Our previous demonstration of increased syncytiotrophoblast (st) intercellular adhesion molecule-1 (ICAM-1) expression in villitis lesions and the finding of extensive monocyte/macrophagic cells in the maternal intervillous space in MCI, led us to further investigate stICAM-1 in MCI. Materials and methods A cross-sectional study of placentas from the third trimester of pregnancy (34–41 weeks gestation) was conducted to determine stICAM-1 in MCI ( n = 7). MCI stICAM-1 expression was compared to stICAM-1 in villitis ( n = 7) and in normal villi from placentas with ( n = 7) and without ( n = 7) villitis. Maternal cells within villi in MCI were identified in placentas mismatched for maternal/fetal human leukocyte antigen (HLA)-DRw52. Villitis was diagnosed with hematoxylin and eosin staining and antibody to CD3 in serial sections, and ICAM-1 in syncytiotrophoblasts was confirmed with antibodies to ICAM-1 and cytokeratin. Results Placentas with MCI had higher stICAM-1 (79.8%) than placentas with villitis (27.1%), normal villi from placentas with villitis (11.5%), and normal villi from placentas without villitis (0.3%). Maternal cells were identified within villi of placentas ( n = 5) mismatched (mothers positive, fetuses negative) for HLA-DRw52. Conclusions Placentas with MCI have more stICAM-1 than placentas with or without villitis lacking MCI. The finding that MCI and villitis have prominent stICAM-1 and maternal cells in the villi suggests that MCI and villitis could have a similar pathophysiologic mechanism.

Background Failure of physiologic transformation of spiral arteries has been reported in preeclampsia, fetal growth restriction, fetal death, and spontaneous preterm labor with intact or ruptured membranes. Spiral arteries with failure of physiologic transformation are prone to develop atherosclerotic-like lesions of atherosis. There are striking parallels between preeclampsia and atherosclerotic disease, and between lesions of atherosis and atherosclerosis. Endothelial activation, identified by intercellular adhesion molecule-1 expression, is present in atherosclerotic-like lesions of heart transplantation, and is considered a manifestation of rejection. Similarly, endothelial activation/dysfunction has been implicated in the pathophysiology of atherosclerosis and preeclampsia. Intercellular adhesion molecule-1-overexpressing-activated endothelial cells are more resistant to trophoblast displacement than nonactivated endothelium, and may contribute to shallow spiral artery trophoblastic invasion in obstetrical syndromes having failure of physiologic transformation. Objective We sought to determine whether failure of spiral artery physiologic transformation was associated with activation of interstitial extravillous trophoblasts and/or spiral artery endothelium and presence of acute atherosis in the placental basal plate. Study Design A cross-sectional study of 123 placentas (19-42 weeks' gestation) obtained from normal pregnancies (n = 22), preterm prelabor rupture of membranes (n = 26), preterm labor (n = 23), preeclampsia (n = 27), intrauterine fetal death (n = 15), and small for gestational age (n = 10) was performed. Failure of spiral artery physiologic transformation and presence of cell activation was determined using immunohistochemistry of placental basal plates containing a median of 4 (minimum: 1; maximum: 9) vessels per placenta. Endothelial/trophoblast cell activation was defined by the expression of intercellular adhesion molecule-1. Investigators examining microscopic sections were blinded to clinical diagnosis. Pairwise comparisons among placenta groups were performed with Fisher exact test and Wilcoxon rank sum test using a Bonferroni-adjusted level of significance (.025). Results We found that 87% (94/108) of placentas having spiral arteries with failure of physiologic transformation (actin-positive and cytokeratin-negative) in the basal plate, and 0% (0/15) of placentas having only spiral arteries with complete physiologic transformation (cytokeratin-positive and actin-negative), had arterial endothelial and/or interstitial extravillous trophoblasts reactive with the intercellular adhesion molecule-1 activation marker ( P R 2 = 0.84) was found between expression of spiral artery endothelial and interstitial extravillous trophoblast intercellular adhesion molecule-1 ( P P = .001). All placentas (30/30, 100%) with atherosis were identified in placentas having concomitant spiral artery endothelial and interstitial extravillous trophoblast activation. Conclusion Failure of spiral artery physiologic transformation in the placental basal plate is associated with interstitial extravillous trophoblast and arterial endothelial activation along with increased frequency of spiral artery atherosis. These findings may be used to improve the characterization of different disorders of the placental bed such as in refining the existing tools for the early prediction of risk for preterm, preeclamptic, and other abnormal pregnancies.

Cardiac allograft vasculopathy (CAV) is a serious complication of heart transplantation in adults and children. Risk factors include human leukocyte antigen mismatches, number and duration of rejection episodes, type of immunosuppression, antibody-mediated rejection, hypertension, hyperlipidemia, obesity, smoking, diabetes, cytomegalovirus infection, mode of donor brain death, donor age and ischemia/reperfusion injury. Endothelial injury and dysfunction in CAV are characterized by changes in adhesion molecules and up-regulation of major histocompatibility class II antigens followed by endothelial activation of complement C4d. Subsequently, activation of the coagulation cascade leads to deposition of fibrin on endothelium followed by proliferation and migration of vascular smooth muscle cells. The development of a special type of microvessels with phenotypic characteristics of arterial capillaries ("capioles") seems to provide a survival advantage for patients with CAV. Novel therapies of CAV include statins, and heparin-induced extracorporeal low-density lipoprotein apheresis. B beta15-42 which is a fibrin peptide has been shown to improve the graft microvasculature and to reduce ischemia/reperfusion-induced damage. Despite these advances, there is a need to identify and stratify individual CAV risk factors, to develop early biomarkers of CAV, and to better decipher the events that lead to antibody-mediated rejection.

Cardiac allograft vasculopathy (CAV) is one of the most common long-term complications in patients following heart transplantation. Because of its irreversible nature, early detection is essential to impact progression. Thus, imaging techniques play a crucial role in the diagnosis and subsequent treatment. Major advancements in imaging and analysis are required to overcome the limitations of current techniques. Coronary angiography which is the standard method, presents low sensitivity in detection, especially at an early stage. Intravascular ultrasonography is a more reliable alternative but is limited to the epicardial vessels. Novel non-invasive techniques, such as stress echocardiography and nuclear imaging, have been introduced but not without limitations. Here, we review various imaging methods and associated analyses to improve diagnostic predictions. We discuss recent advances in the diagnosis of coronary artery disease and their potential translation in the diagnosis of CAV. Additionally, we present potential biomarkers that have been identified for CAV. Finally, we provide a discussion on microvessels with novel anticoagulant properties that are mostly identified in patients with severe CAV.

Acute cellular rejection (ACR), antibody-mediated rejection (AMR), and cardiac allograft vasculopathy (CAV) are important limitations for the long-term survival of heart transplant recipients. Although much progress has been made in reducing ACR with modern immunosuppressive treatments and continuous biopsy surveillance, there is still a long way to go to better understand and treat AMR, to enable early detection of patients at risk of CAV, and to reduce the development and sustained progression of this irreversible disease that permanently compromises graft function. This review considers the advances made in ACR detection and treatment allowing a more prolonged survival and the risk factors leading to endothelial injury, dysfunction, inflammation, and subsequent CAV, as well as new treatment modalities for CAV. The review also evaluates the controversies around the definition, pathogenesis, and treatment of AMR. To date, much progress is still needed to significantly reduce post-transplant complications and increase graft and patient survival.

Early risk-prediction is essential to prevent cardiac allograft vasculopathy (CAV) and graft failure in heart transplant patients. We developed multivariate models to identify patients likely to experience CAV, severe CAV, and failure due to CAV, at 1, 5 and 10 years. A cohort of 172 patients was followed prospectively for 6.7 ± 3.9 years. Logistic regression models were developed and cross-validated using bootstrap resampling. Predictive markers of atherothrombosis (myocardial fibrin deposition, and loss of vascular antithrombin and tissue plasminogen activator) and arterial endothelial activation (intercellular adhesion molecule-1 expression) were measured in serial biopsies obtained within 3 months posttransplant. Most markers were univariately associated with outcome. Multivariate models showed that loss of tissue plasminogen activator was the dominant and, in most cases, only predictor of long-term CAV (p < 0.001), severe CAV (p < 0.001), and graft failure due to CAV (p < 0.001). The models discriminated patients having adverse outcomes, had particularly high negative predictive values (graft failure due to CAV: 99%, 99% and 95% at 1, 5 and 10 years) and predicted event incidence and time to event. Early absence of atherothrombotic risk identifies a patient subgroup that rarely develops CAV or graft failure, implying that this low-risk subgroup could possibly be followed with fewer invasive procedures.

While tissue perfusion and angiogenesis subsequent to acute femoral artery occlusion are suppressed in NADPH oxidase 2 ( Nox2)-null ( Nox2−/−) mice, studies have not established the role of Nox2 in collateral artery enlargement. Rac2 is a small GTPase that binds Nox2 and activates Nox2-based NAD(P)H oxidase but, unlike Nox2, is primarily restricted to bone marrow-derived cells. In this study, we used Rac2-null ( Rac2−/−) and Nox2−/− mice with a novel method of identifying primary hindlimb collaterals to investigate the hypothesis that collateral growth requires these molecules. When initial experiments performed with femoral ligation demonstrated similar perfusion and collateral growth in Rac2−/− and wild-type C57BL/6J (BL6) mice, subsequent experiments were performed with a more severe ischemia model, femoral artery excision. After femoral excision, tissue perfusion was suppressed in Rac2−/− mice relative to BL6 mice. Histological assessment of ischemic injury including necrotic and regenerated muscle fibers and lipid and collagen deposition demonstrated greater injury in Rac2−/− mice. The diameters of primary collaterals identified during Microfil injection with intravital microscopy were enlarged to a similar extent in BL6 and Rac2−/− mice. Intimal cells in collateral cross sections were increased in number in both strains and were CD31 positive and CD45 negative. Circulating leukocytes and CD11b+ cells were increased more in Rac2−/− than BL6 animals. Experiments performed in Nox2−/− mice to verify that the unexpected results related to collateral growth were not unique to Rac2−/− mice gave equivalent results. The data demonstrate that, subsequent to acute femoral artery excision, perfusion recovery is impaired in Rac2−/− and Nox2−/− mice but that collateral luminal expansion and intimal cell recruitment/proliferation are normal. These novel results indicate that collateral luminal expansion and intimal cell recruitment/proliferation are not mediated by Rac2 and Nox2.

We investigated in a longitudinal, multicenter, cohort study whether combined lipid apheresis and lipid-lowering medication can reduce extremely high levels of lipoprotein(a) (Lp[a]) and thus prevent major adverse coronary events (MACE) more efficaciously than lipid-lowering medication alone.Eligible patients had coronary artery disease and Lp(a) levelsor =2.14 micromol/l (95th percentile). All patients received lipid-lowering medications alone until maximally tolerated doses were no longer effective, followed by combined lipid apheresis and lipid-lowering medication. The rates of the primary outcome, MACE, were recorded for both periods.A total of 120 patients were included. The mean duration of lipid-lowering therapy alone was 5.6+/-5.8 years, and that of apheresis was 5.0+/-3.6 years. Median Lp(a) concentration was reduced from 4.00 micromol/l to 1.07 micromol/l with apheresis treatment (P0.0001); the corresponding mean annual MACE rate per patient was 1.056 versus 0.144 (P0.0001).Lowering of Lp(a) levels by apheresis was efficacious and safe, and we recommend this therapy for patients in whom maximally tolerated doses of medication alone have failed to control coronary artery disease-associated events.

Recent studies have established that age is the major risk factor for vascular disease. Numerous aberrant changes occur in vascular structure and function during aging, and animal models are the primary means to determine the underlying mechanisms of age-mediated vascular pathology. The Fischer 344/Brown Norway F1 hybrid (F344xBN) rat thoracic aorta has been shown to display age-related pathology similar to what occurs in humans. This study utilized the F344xBN rat aorta and both morphometric and global gene expression analyses to identify appropriate time points to study vascular aging and to identify molecules associated with the development and progression of vascular pathology. In contrast to some previous studies that indicated age-related abrupt changes, a progressive increase in intimal and medial thickness, as well as smooth muscle cell-containing intimal protrusions, was observed in thoracic aorta. This structural vascular pathology was associated with a progressive, but nonlinear, increase in global differential gene expression. Gene products with altered mRNA and protein expression included inflammation-related molecules: specifically, the adhesion molecules ICAM-1 and VCAM-1 and the bone morphogenic proteins osteopontin and bone sialoprotein-1. Intimal-associated macrophages were found to increase significantly in number with age. Both systemic and tissue markers of oxidant stress, serum 8-isoprostane and 3-nitrotyrosine, respectively, were also found to increase during aging. The results demonstrate that major structural abnormalities and altered gene expression develop after 6 mo and that the progressive pathological development is associated with increased inflammation and oxidant stress.

The role of a hypercoagulable microvasculature in the development of cardiac allograft vasculopathy (CAV) after heart transplantation in humans is not well understood. The aim of this study was to identify an animal model by which to further evaluate the role of coagulation in the pathogenesis of CAV.Adult male PVG (RT-1(c)) rats were transplanted into ACI (RT-1(av1)) recipients (n = 29). ACI donors into ACI recipients (n = 31) and rats with a sham operation (n = 33) served as controls. All rats received cyclosporine (10 mg/kg/day) on Days 0 to 9 after surgery. Grafts and native hearts were harvested at 10 days to 3 months after surgery. Hearts were processed for immunohistochemistry and light microscopy. A hypercoagulable microvasculature was defined as presence of microvascular fibrin and capillary antithrombin. CAV was defined as the presence of concentric intimal proliferation and chronic inflammatory infiltrate in the arterial intima, and assessed by computer-assisted image analysis.Donor and recipient hearts from PVG-ACI rats showed high levels of fibrin (donors 7.5% to 21.9%, recipients 5.1% to 20.2%) and antithrombin (donors 5.2% to 27.9%, recipients 3.3% to 20.8%) at 10 days to 3 months post-transplant. ACI-ACI donor and recipient hearts had lower deposition of fibrin (donors 0.9% to 9.9%, recipients 0% to 4.0%) and antithrombin (donors 1.4% to 15.2%, recipients 0.8% to 4.5%). Hearts from sham-operated rats had negligible amounts of fibrin (0% to 1.5%) and antithrombin (0% to 2.8%). There was a strong association (p0.001) between presence of fibrin and capillary antithrombin and development of CAV.A hypercoagulable microvasculature in a rat model of heart transplantation was associated with development of CAV, as found in humans.

Given the central importance of the microvasculature in heart transplant recipients, we investigated the possibility of increasing cardiac perfusion after reduction of low-density lipoprotein (LDL)-cholesterol, lipoprotein (a), C-reactive protein (CRP) and fibrinogen plasma levels after apheresis treatment in transplanted patients.Ten long-term heart transplant recipients were examined with positron emission tomography (PET) to measure myocardial perfusion before and after a single heparin-mediated extracorporeal LDL/fibrinogen precipitation (HELP)-apheresis treatment. PET studies were performed the mornings before and after the apheresis treatment. Myocardial blood flow at rest and during adenosine-induced hyperemia was measured using (13)N-ammonia.HELP-apheresis reduced the plasma levels of LDL-cholesterol, lipoprotein (a) and C-reactive protein by 48% (p0.001), fibrinogen by 42% (p = 0.02), plasma viscosity by 14% (p = 0.004) and erythrocyte aggregation by 28% (p0.02). Osmolality (1%) and hematocrit (2%) remained stable. A single apheresis treatment increased median corrected rest flow by 17.5% (p = 0.007) and median hyperemic flow by 27% (p = 0.02). Median coronary flow reserve increased by 8.1% (p = 0.09). Hyperemic flow after adenosine infusion increased plasma vascular endothelial growth factor levels only before HELP-apheresis (+60%), indicating better ischemic tolerance after apheresis (p = 0.01).Myocardial perfusion in transplanted hearts increases significantly after single HELP-apheresis treatment. The present study is only a proof of concept, providing complementary evidence to clinical long-term studies showing that cholesterol reduction either with statins and/or apheresis improves heart transplant outcome.

Objective Leukocyte infiltration into the intestinal wall is central to the pathogenesis of tissue injury that occurs in patients with a variety of inflammatory bowel diseases. Migration of leukocytes from the intestinal circulation into bowel tissues is mediated by chemotactic substances and adhesion molecules (i.e., intercellular adhesion molecule-1 [ICAM-1] and E-selectin) on the surface of endothelial cells lining blood vessels. Short-chain fatty acids (SCFAs) derived from dietary fiber decrease inflammatory responses in colon cells. However, the effect of SCFAs on vascular adhesion molecules is unknown. We investigated the effects of SCFAs on vascular endothelial cell adhesion molecule expression. Methods We assessed the effect of physiologically relevant concentrations of butyrate on expression of ICAM-1 protein and mRNA in cultures of human umbilical vein endothelial cells. We also assessed the effect of butyrate on levels of HLA-DR, E-selectin, vascular cell adhesion molecule-1, and endoglin. In additional experiments, we evaluated the effect of butyrate on ICAM-1 mRNA stability and the effect of valerate, isobutyrate, and propionate on ICAM-1 expression. The effect of butyrate on ICAM-1 expression was compared with that of trichostatin A, a specific inhibitor of histone deacetylase. Data were evaluated with Student’s t tests or Tukey’s multiple comparison tests, with P < 0.05 considered statistically significant. Results Butyrate concentrations of 2.5 to 5 mM significantly increased endothelial expressions of ICAM-1 protein and mRNA. The effect of butyrate (5 mM) on ICAM-1 expression was time dependent, with significant increases in levels occurring after 16 h of incubation. Butyrate (5 mM) also increased expression of E-selectin but not of HLA-DR, vascular cell adhesion molecule-1, or endoglin. Isobutyrate had little effect on ICAM-1 expression, whereas valerate and propionate significantly increased expression of ICAM-1 but were weaker stimulants compared with butyrate. Butyrate (5 mM) did not alter stability of ICAM-1 mRNA. The effect of butyrate (5 mM) was comparable to that of trichostatin A. The stimulatory effect of butyrate on ICAM-1 expression was reversed after 48 h of butyrate withdrawal. Conclusions Butyrate increases vascular endothelial expressions of ICAM-1 and E-selectin. We speculate that butyrate-induced effects on vascular adhesion molecules modulate gut inflammation. The role of SCFAs and fiber in the pathogenesis and modulation of gut inflammation in vivo requires further study.

Fibrinogen is far more important as a risk factor for acute cardiovascular syndromes than generally recognized. Evidence from a recent metaanalysis (including 22 studies of 63,736 subjects and 5,717 events [1] suggests that the risk for myocardial infarction and stroke almost doubles if the fibrinogen level exceeds 3.03 g/l (measured according to Clauss) with an odds ratio of 1.99 and a 95% confidence interval of 1.85-2.13. The predictive value of fibrinogen levels equally applies to men and women, young and old, primary and secondary prevention. Repeated fibrinogen measurements are particularly helpful with emphasis on high risk patients: concentrations of the upper tertile indicate a 92% higher risk of impending acute cardiovascular syndromes, as evidenced by a metaanalysis evaluating five prospective studies with 9,639 participants and 671 events [1]. Together with other risk factors such as hypertension, hypercholesterolemia, or diabetes, the risk of fatal and nonfatal acute cardiovascular syndromes may further increase by 6-12- fold, while fibrinogen remains an independent risk factor for both cardiac and extracardiac atherothrombotic complications, as well as for iatrogenic complications like restenosis following PTCA or stenting. Fibrin(ogen) and his effector thrombin substantially determine the extent and outcome of atherothrombotic complications, because they are the molecules linking the mutually dependent events of atherogenesis, coagulation/fibrinolysis, rheology/vasotonus, and inflammation. Interventional studies on fibrinolytic and defibrinating substances, as well as GpIIb/IIIa-inhibitors for treatment of acute cardiovascular syndromes have confirmed the benefit of fibrinogen reduction and extended the experimental evidence for the relevance of fibrin(ogen) in the pathogenesis of these syndromes. Accordingly, the preventive use of fibrates leading to moderate reductions in plasma cholesterol and fibrinogen diminished significantly the rate of reinfarction. The emerging possibilities from a more than 50% fibrinogen reduction (by studies using H.E.L.P. apheresis) strengthened the therapeutic concept to free the blood from all risk factors-as effective as it can be-in order to achieve an optimal plaque regression, since changes in the blood composition strongly affect the fragility and stability of the atherosclerotic plaques.

Use of cryopreserved small-diameter elastic arterial allografts for an arterial bypass procedure has been suggested. But, the long-term patency of the cryopreserved arteries in vivo has not been 10...

A major impediment for the long-term success of heart transplantation is the development of transplant coronary artery disease (CAD). Several risk factors for the development of transplant CAD are associated with the transformation of a normal thromboresistant microvasculature into a prothrombogenic microvasculature. Prothrombogenicity is characterized by loss of anticoagulation (i.e. loss of antithrombin), loss of fibrinolytic activity (i.e., loss of tissue plasminogen activator) and presence of endothelial activation (i.e. upregulation of endothelial intercellular adhesion molecule-1 and major histocompatibility class II antigen human leukocyte antigen-DR) in the arterial allograft microvasculature. Microvascular prothrombogenicity during the first trimester after transplantation is directly associated with subsequent development of transplant CAD. Although the mechanisms responsible for the loss of thromboresistant endothelium are unclear, the fact that changes in the anticoagulant, fibrinolytic, and activational status of endothelial cells may occur early after transplantation suggests a peritransplant phenomenon as an initiating event. Reducing prothrombogenicity of the cardiac microvasculature early after transplantation could slow the development of transplant CAD and significantly improve allograft survival.

A procoagulant microvasculature is associated with accelerated development of coronary artery disease (CAD) and failure in heart transplant patients. This study was performed to evaluate how changes in natural anticoagulation within cardiac allografts affect outcome. We prospectively studied 141 consecutive cardiac allograft recipients who underwent transplantation between 1988 and 1997. Serial endomyocardial biopsy specimens (6.5 ± 0.1 biopsy specimens/patient) obtained during the first 3 months after transplantation were studied immunohistochemically to evaluate vascular antithrombin, and annual coronary angiograms (3.8 ± 0.2 angiograms/patient) were studied to evaluate CAD. Antithrombin was present in arteries and veins, but not in capillaries, of all donor heart biopsy samples. Allografts that maintained vascular antithrombin had the best prognosis. Allografts with early and persistent loss of vascular antithrombin (n = 21) developed CAD earlier (p

Background —Adhesion molecules on arterial endothelium have been implicated in spontaneous atherosclerosis and transplant coronary artery disease (CAD). We studied whether elevated serum-soluble intercellular adhesion molecule-1 (sICAM-1) during the immediate posttransplant period was a risk factor for CAD, posttransplant ischemic events, or cardiac graft failure. Methods and Results —We initially studied serum sICAM-1 in a subset of 16 cardiac allograft recipients (5.5±0.7 samples per patient) to determine a cutoff point that best correlated with presence of arterial and arteriolar endothelial ICAM-1 in matching endomyocardial biopsies. The cutoff value was 308 ng/mL. Subsequently, we prospectively evaluated serum sICAM-1 in serial samples (5.3±0.1 per patient) obtained during the first 3 months after transplantation in a validation subset of 130 recipients and correlated early sICAM-1 levels with long-term outcome. Serum sICAM-1 >308 ng/mL correlated significantly with ICAM-1 on arterial and arteriolar endothelium ( P =0.02). Cardiac allograft recipients with serum sICAM-1 >308 ng/mL had 2.67 (95% CI, 1.28 to 5.59, P =0.009) times greater risk of CAD and 3.63 (95% CI, 1.05 to 12.5, P =0.04) times greater risk of graft failure. Recipients with sICAM-1 >308 ng/mL also developed more severe CAD ( P =0.009) and more ischemic events ( P =0.03) after transplantation. Conclusions —Serum sICAM-1 levels can be used to noninvasively assess risk of transplant CAD, posttransplant ischemic events, and cardiac graft failure.

Current methods of platelet storage are unsatisfactory because of the short shelf life of platelets and the rapid loss of platelet viability. We have developed a cryopreservation method that results in less damage from freezing and higher recovered function of platelets. Platelets were cryopreserved using a combination of epinephrine (EPN) and dimethyl sulfoxide (Me 2 SO) as cryoprotectants. The response of platelets to agonists was studied by flow cytometry and aggregation tests. Cryopreserving platelets with Me 2 SO decreased platelet annexin V binding due to freezing. The combination of EPN with Me 2 SO enhanced Me 2 SO cryoprotection and decreased platelet microparticle generation, suggesting that cryopreserving platelets using this combination is associated with increased platelet integrity. Platelet cryopreservation with an Me 2 SO/EPN combination also increased platelet aggregability, which was demonstrated by decreasing the lag phase and increasing the aggregation density to 66.39% ± 6.6 that of fresh platelet-rich plasmas. We conclude that adding EPN as a combined cryoprotectant improves the quality of Me 2 SO-frozen platelets. As a method of aggregation of cryopreserved platelets, this method is comparable to that of normal fresh platelets and may improve the conditions for platelet transfusion.

Background. Transplant-induced coronary artery disease is a leading cause of graft failure in cardiac allograft recipients after the first year of transplantation, but there presently is no test to identify patients at high risk for developing the disease. Our research is focused on development of a predictive test to identify patients at high risk of developing the disease. Methods. Sixty-eight cardiac allograft recipients transplanted and followed at Methodist Hospital between 1982 and 1996 were studied. Serial annual angiograms were used to diagnose coronary artery disease, and serial endomyocardial biopsies were used to detect cellular infiltrates and microvascular disease. Biopsy-matched serum samples were used for cardiac troponin-T determinations as measures of myocardial damage, and serum antibodies to endothelial cells were determined by using flow cytometry, enzyme-linked immunosorbent assay and immunoblotting techniques. The endothelial antibody data were evaluated statistically for associations with angiographic changes, biopsy findings and biochemical evidence of myocardial damage. Findings. Antibodies to endothelial cells were identified by all three techniques, and significant associations were found for the amount of antibody identified by Western immunoblotting with histological rejection grades in biopsies, which were confirmed immunocytochemically as macrophages ( p p = 0.03). These antibodies also associated significantly with vascular antithrombin depletion ( p = 0.02), biochemical evidence of myocardial damage ( p = 0.005) and subsequent development of coronary artery disease ( p = 0.03). Interpretation. The significant association of anti-endothelial antibodies with cellular infiltrates, depletion of vascular antithrombin and myocardial damage suggests a role for antibody in the development of transplant-induced arteriopathy. The significant association of anti-endothelial antibodies with the future development of coronary artery disease further suggests that assessment of these antibodies may provide a non-invasive test to predict the development of transplant-induced coronary artery disease.

Objective: Lactoferrin is an iron-binding protein that has been implicated in protection against infections and allogeneic recognition reactions and in the control of cell growth. We studied the biochemical characteristics and expression of the unique lactoferrin epitopes (LF 1 ) in human placentas. Study Design: Immunohistologic studies of normal human term placentas were done by using monoclonal antibodies to LF 1 . Double-antibody experiments were done by using monoclonal antibodies to markers of inflammation (macrophages, human leukocyte antigen [HLA-DR]). LF 1 was studied immunochemically by using lactoferrin fragments produced by the reaction of lactoferrin with trypsin or N -glycanase. Results: Anti-LF 1 monoclonal antibodies reacted with most interstitial cytotrophoblasts in the basal plate and with villous cytotrophoblasts of some but not all chorionic villi. Cytotrophoblasts expressing LF 1 were associated with large numbers of HLA-DR–reactive macrophages. Anti-LF 1 monoclonal antibodies reacted with 2 distinct tryptic fragments of lactoferrin, and these reactivities were not affected by treatment with N -glycanase. Conclusion: Placental cytotrophoblasts express unique epitopes of lactoferrin (LF 1 ). Such expression is increased in the presence of activated macrophages. This expression could be an extraembryonic response to inflammation and maternal allogeneic recognition as an effort to protect trophoblastic cells. The LF 1 epitopes might represent conserved polypeptide epitopes on 2 homologous lobes of lactoferrin. (Am J Obstet Gynecol 1999;181:460-7.)

BACKGROUND Development of coronary artery disease in cardiac allograft recipients is the major cause of graft failure after the first year of transplantation. Unfortunately, there is no noninvasive method of identifying patients at greatest risk of developing this disease. We have asked whether serum concentrations of cardiac troponin-T predict development of coronary artery disease. METHODS Annual coronary angiograms, serial endomyocardial biopsies, and serum cardiac troponin-T concentrations were obtained from 68 cardiac transplant patients who were followed for 68.8+/-11.9 months after surgery. Troponin-T concentrations were measured by using an enzyme-linked immunosorbent assay, and biopsies were assessed histologically for rejection grades and immunohistochemically for cellular infiltrates, arteriolar endothelial activation, fibrin deposits, and vascular fibrinolytic and anticoagulant components. RESULTS Troponin-T values did not associate with demographic, clinical, or laboratory findings, but they significantly associated with arteriolar endothelial activation (P

Analysis of global gene expression in mesenteric control and collateral arteries was used to investigate potential molecules, pathways, and mechanisms responsible for impaired collateral growth in the Spontaneously Hypertensive Rat (SHR). A fundamental difference was observed in overall gene expression pattern in SHR versus Wistar Kyoto (WKY) collaterals; only 6% of genes altered in collaterals were similar between rat strains. IngenuityPathway Analysis (IPA) identified major differences between WKY and SHR in net- works and biological functions related to cell growth and proliferation and gene expression. In SHR control arteries, several mechano-sensitive and redox-dependent transcription regulators were downregulated including JUN (5.29, P = 0.02), EGR1 (4.19, P = 0.01), and NFKB1 (1.959, P = 0.04). Predicted binding sites for NFKB and AP-1 were present in genes altered in WKY but not SHR collaterals. Immunostaining showed increased NFKB nuclear translocation in collateral arteries of WKY and apocynin-treated SHR, but not in untreated SHR. siRNA for the p65 subunit suppressed collateral growth in WKY, confirming a functional role of NFkB. Canonical pathways identified by IPA in WKY but not SHR included nitric oxide and renin- angiotensin system signaling. The angiotensin type 1 receptor (AGTR1) exhibited upregulation in WKY collaterals, but downregulation in SHR; phar- macological blockade of AGTR1 with losartan prevented collateral luminal expansion in WKY. Together, these results suggest that collateral growth impairment results from an abnormality in a fundamental regulatory mecha- nism that occurs at a level between signal transduction and gene transcription and implicate redox-dependent modulation of mechano-sensitive transcription factors such as NFKB as a potential mechanism.

Vascular endothelial growth factor (VEGF) is an endothelial cell-specific mitogen thought to play an important role in coronary collateral vessel formation. We used immunocytochemistry to determine VEGF expression in biopsies (n=283) of transplanted human hearts (n=109) with and without microvascular fibrin. Measures of vascular fibrin, alpha 2 plasmin-inhibitor (a 2 Pl), macrophages, neutrophils, and serum cardiac troponin T titers were used to evaluate myocardial damage. Antibody to T lymphocytes was used to evaluate cellular rejection, and HLA-DR, ICAM-1, and PAL-E antibodies were used to assess endothelial cell activation and phenotypic changes in the microcirculation. No VEGF immunoreactivity was detected in control donor hearts without fibrin, but the proportion of biopsies demonstrating VEGF immunoreactivity increased significantly in allografts with increasing fibrin and a 2 PI reactivity (P=0.0001). VEGF immunoreactivity was confined to areas of fibrin deposition and was associated with infiltrates of macrophages and neutrophils (P

An aggressive and potentially fatal form of coronary artery disease may develop after cardiac transplantation. We studied the role of vascular tissue plasminogen activator (t-PA), the primary mediator of fibrinolysis, in the development of this problem.We studied 78 consecutive recipients of cardiac allografts over a five-year period, and we collected follow-up data over a mean (+/- SE) of 32.5 +/- 2.0 months. The patients were studied with ventricular function tests, serial endomyocardial biopsies (16.6 +/- 0.5 per patient), and annual coronary angiography. Measurements of t-PA and its inhibitor were performed immunocytochemically on unfixed cryostat sections of endomyocardial-biopsy specimens with the use of monoclonal antibodies to t-PA and its inhibitor.In biopsy specimens obtained during the first three months of follow-up, 38 allografts had a normal distribution of t-PA in arteriolar smooth-muscle cells, whereas in 40 allografts there was depletion of t-PA that persisted in subsequent follow-up. Coronary artery disease developed during follow-up in 31 of 40 allografts (78 percent) with depletion of t-PA, but the disease developed in only 9 of the 38 allografts (24 percent) with normal t-PA levels (P0.001). Allografts with depletion of t-PA also had the t-PA inhibitor and were at greater risk for earlier and more severe disease than were allografts with normal arteriolar t-PA levels. Twelve patients whose allografts were depleted of t-PA either received a second transplant or died, whereas only one of the patients whose allografts had persistently normal t-PA levels died (P0.001).These findings reveal an association between the depletion of t-PA from arteriolar smooth-muscle cells and the subsequent development of coronary artery disease and decreased graft survival. Although we cannot be certain about a cause-and-effect relation, our data suggest a possible role for deficient fibrinolysis in the development of coronary artery disease in transplanted human hearts.

Vascular compensation to arterial occlusion is compromised by cardiovascular risk factors including obesity and hyperglycemia. The specific mechanisms mediating this impairment remain unclear. We have previously observed hindlimb collateral growth (CG), the primary compensation to peripheral artery occlusion, to be profoundly suppressed in diet-induced obese (DIO) relative to lean mice (130 vs. 10% diameter enlargement) while anti-oxidant therapy (apocynin, Apo) restored CG capacity in DIO but suppressed it in lean mice. In this study we utilize lean and DIO mice, with and without Apo treatment to assess the hypothesis that CG is impaired in obesity via redox-dependent inhibition of endothelial cell activation and reduced mobilization and/or recruitment of requisite macrophages. The right femoral artery was ligated distally to induce the gracilis artery to function as the primary collateral. The gracilis muscles of the right (exptl) and left (control) limbs were harvested 3 days post-ligation and immunostaining was performed to evaluate endothelial cell activation (# of ICAM-1 positive microvessels/mm 2 ) and macrophage recruitment (# of F4/80 positive cells/mm 2 ). ICAM-1 immunoreactivity was increased in all experimental limbs but was significant only within the DIO and Lean+Apo groups which are characterized by suppressed CG. The number of F4/80 positive cells was increased in the gracilis muscle of the experimental limb of all groups with a greater increase in the DIO than in Lean and DIO+Apo. FACS analysis of circulating monocytes demonstrated an increase at 1-day post-ligation followed by a decrease at day 3, with a greater percent decrease occurring in the DIO compared to Lean. The data suggest that mechanisms unrelated to deficits in mobilization, activation or recruitment mediate CG impairment in DIO.

Vascular risk factors characterized by oxidative stress are correlated with impaired collateral growth through mechanisms largely unknown. Spontaneously hypertensive rats (SHR) with increased oxidative stress were used to investigate potential mechanisms mediating impaired collateral compensation. Microarray analysis of global gene expression was performed with control and collateral mesenteric artery samples (n=4) from SHR and their normotensive controls (WKY) 24 hours after model creation. In SHR control arteries, several mechano-sensitive and redox-dependent transcription regulators were down-regulated including Jun (-5.2X, P=0.02), Egr-1 (-4.1X, P=0.01), and NFkB1 (-1.95X, P=0.04). Collateral arteries of WKY and SHR exhibited a fundamentally different gene expression pattern (

BACKGROUND: Cardiac allograft vasculopathy (CAV) is the principal cause of long-term graft failure following heart transplantation. Early identification of patients at risk of CAV is essential to target invasive follow-up procedures more effectively and to establish appropriate therapies. We evaluated the prognostic value of the first heart biopsy (median: 9 days post-transplant) versus all biopsies obtained within the first three months for the prediction of CAV and graft failure due to CAV. METHODS AND FINDINGS: In a prospective cohort study, we developed multivariate regression models evaluating markers of atherothrombosis (fibrin, antithrombin and tissue plasminogen activator [tPA]) and endothelial activation (intercellular adhesion molecule-1) in serial biopsies obtained during the first three months post-transplantation from 172 patients (median follow-up = 6.3 years; min = 0.37 years, max = 16.3 years). Presence of fibrin was the dominant predictor in first-biopsy models (Odds Ratio [OR] for one- and 10-year graft failure due to CAV = 38.70, p = 0.002, 95% CI = 4.00-374.77; and 3.99, p = 0.005, 95% CI = 1.53-10.40) and loss of tPA was predominant in three-month models (OR for one- and 10-year graft failure due to CAV = 1.81, p = 0.025, 95% CI = 1.08-3.03; and 1.31, p = 0.001, 95% CI = 1.12-1.55). First-biopsy and three-month models had similar predictive and discriminative accuracy and were comparable in their capacities to correctly classify patient outcomes, with the exception of 10-year graft failure due to CAV in which the three-month model was more predictive. Both models had particularly high negative predictive values (e.g., First-biopsy vs. three-month models: 99% vs. 100% at 1-year and 96% vs. 95% at 10-years). CONCLUSIONS: Patients with absence of fibrin in the first biopsy and persistence of normal tPA in subsequent biopsies rarely develop CAV or graft failure during the next 10 years and potentially could be monitored less invasively. Presence of early risk markers in the transplanted heart may be secondary to ischemia/reperfusion injury, a potentially modifiable factor.

Prolyl 4-hydroxylase is a heterodimeric enzyme that is crucial in the biosynthesis of collagen. The beta subunit of this enzyme is a multifunctional protein which is also known as protein-disulfide isomerase. Immunofluorescence and monoclonal antibody (Mab) 5B5 were used to localize the beta subunit in human extraembryonic tissues. The strongest sites of 5B5 reactivity were extravillous cytotrophoblasts in the basal plate, uteroplacental arteries and amniochorion, syncytiotrophoblast displayed variable weaker reactivity. Only a small fraction of placental 5B5 antigen was detected as a component of prolyl-4-hydroxylase by affinity chromatography on immobilized polyproline. The results indicate a difference in the expression of an endoplasmic reticulum marker between villous and extravillous trophoblast. The predominance of 5B5 antigen in extravillous trophoblast could be associated with an increased ability to synthesize collagen or other enzymatic reactions associated with prolyl 4-hydroxylase beta subunit.

Lactoferrin (LF) and transferrin (Trf) are glycoproteins with strong affinities for ferric ions. Human syncytiotrophoblastic membranes analyzed by enzyme linked immunosorbent assay (ELISA) and immunoblotting were negative with monoclonal and polyclonal antibodies to LF. Immunohistological studies of 35 normal placentae showed that LF was absent from the trophoblast basement membranes, stroma and fetal stem vessel endothelium, but positive cells were occasionally noted in intervillous spaces and fetal stem vessels. In contrast, many LF-positive cells were identified within areas of immunopathology identified by the presence of T cells, HLA-DR-positive macrophages and platelets. Double-antibody experiments showed that the LF-positive cells in these areas reacted with CD15 and CD16 monoclonal antibodies (mAbs), indicating that the cells were polymorphonuclear neutrophils (PMN). PMN from peripheral blood analyzed by flow cytometry and immunocytology also showed reactivities with anti-LF, CD15 and CD16 and we consistently found that circulating PMN reacted better than placental PMN with antibodies to MHC class I antigens and gp 100, (CD67), which is a neutrophil activation marker. PMN adherent within placentae had no detectable MHC class I or CD67 antigens. These findings suggest PMN adherent to placental tissues down-regulate or alter plasma membrane markers. LF appears to play a role in placental inflammation, for LF-positive cells were significantly enriched in areas of immunopathology.