Heart allograft vascular disease: an obliterative vascular disease in transplanted hearts

Allograft coronary artery thrombosis: a case report of early cardiac allograft left ventricular myocardial infarction

Cardiac allograft dysfunction is a major cause of morbidity and mortality in the early post-transplantation period. This is a critical condition that requires prompt diagnosis and management. We present the case of a 57-year-old man with ischemic cardiomyopathy who underwent cardiac transplantation and developed a rare case of coronary artery thrombosis in the setting of heparin-induced thrombocytopenia and thrombosis syndrome (HITTS) within the first 2 postoperative weeks. Transmural myocardial infarction (MI) was initially noted on cardiac magnetic resonance (CMR) imaging as regional left ventricular wall motion abnormalities and transmural hyperenhancement after gadolinium administration, prompting further evaluation of the coronary circulation with angiography.

Y-box binding protein-1 implicated in translational control of fetal myocardial gene expression after cardiac transplant

Peri-transplant surgical trauma and ischemia/reperfusion injury in accepted murine heterotopic heart grafts has been associated with myofibroblast differentiation, cardiac fibrosis and biomechanical-stress activation of the fetal myocardial smooth muscle α-actin (SMαA) gene. The wound-healing agonists, transforming growth factor β1 and thrombin, are known to coordinate SMαA mRNA transcription and translation in activated myofibroblasts by altering the subcellular localization and mRNA-binding affinity of the Y-box binding protein-1 (YB-1) cold-shock domain (CSD) protein that governs a variety of cellular responses to metabolic stress. YB-1 accumulated in polyribosome-enriched regions of the sarcoplasm proximal to cardiac intercalated discs in accepted heart grafts. YB-1 binding to a purine-rich motif in exon 3 of SMαA mRNA that regulates translational efficiency increased substantially in perfusion-isolated, rod-shaped adult rat cardiomyocytes during phenotypic de-differentiation in the presence of serum-derived growth factors. Cardiomyocyte de-differentiation was accompanied by the loss of a 60 kDa YB-1 variant that was highly expressed in both adult myocardium and freshly isolated myocytes and replacement with the 50 kDa form of YB-1 (p50) typically expressed in myofibroblasts that demonstrated sequence-specific interaction with SMαA mRNA. Accumulation of p50 YB-1 in reprogrammed, de-differentiated myocytes was associated with a 10-fold increase in SMαA protein expression. Endomyocardial biopsies collected from patients up to 14 years after heart transplant showed variable yet coordinately elevated expression of SMαA and p50 YB-1 protein and demonstrable p50 YB-1:SMαA mRNA interaction. The p60 YB-1 variant in human heart graft samples, but neither mouse p60 nor mouse or human p50, reacted with an antibody specific for the phosphoserine 102 modification in the YB-1 CSD. Modulation of YB-1 subcellular compartmentalization and mRNA-binding activity may be linked with reprogramming of contractile protein gene expression in ventricular cardiomyocytes that could contribute to maladaptive remodeling in accepted, long-term heart grafts.

Intracellular MHC class II controls regulatory tolerance to allogeneic transplants

MHC class II (MHCII) genes have been implicated in the regulation of T lymphocyte responses. However, the mechanism of MHCII-driven regulation remains unknown. Matching for MHCII between donors and recipients of allografts favors regulatory T cell tolerance to transplants and provides a unique opportunity to study this regulation. In this study, we investigated MHCII regulation using transfer of donor MHCII genes in recipients of cardiac allografts. Transfer of MHCII IA(b) genes in the bone marrow of CBA mice (H-2(k)) prior to the grafting of IA(b+) fully allogeneic C57BL/6 (B6, H-2(b)) heart transplants resulted in donor-specific tolerance associated with long-term survival of B6, but not third-party, allografts without sustained immunosuppression. Strikingly, the majority of accepted heart transplants (>170 d) were devoid of allograft vasculopathy. Further studies indicated that intracellular IA(b) initiated the tolerogenic process, which was mediated by regulatory T cells (Tregs) that polarized antigraft responses to Th2 cytokine producers. This mechanism seems to be unique to MHCII genes, because previous MHC class I gene-based therapies failed to produce Tregs. These results demonstrate the key role of MHCII in the induction of Tregs. They also underscore a potential mechanism of specific inactivation of T cells in this model; when activated by IA(b+) grafts, IA(b)-specific Tregs repress the entire alloresponse to C57BL/6 transplants (including MHC I and minor Ags), thus mediating T cell tolerance.

Cardiac allograft vasculopathy: real or a normal morphologic variant?

BACKGROUND

Naive coronary vessels may appear to have intimal thickening histologically characteristic of cardiac allograft vasculopathy (CAV). This study appraises the experimental and clinical impact of this observation.

METHODS

Tissue sections from 12 naive hearts of miniature swine, 13 native porcine hearts of recipients of heterotopic cardiac allografts, 3 native human hearts and 3 human hearts with CAV were compared with light microscopy and morphometric analysis. Results were also compared with morphometric data previously gathered from 3 grafts in a standard experimental model of CAV (rejectors) and 3 grafts harvested from swine rendered tolerant to their donor hearts (chimeras).

RESULTS

In the naive and native porcine hearts, the prevalence of CAV "mimics" was 0% to 6.94% (mean +/- SD: 1.99 +/- 1.97%) and 0% to 7.57% (2.97 +/- 2.20%), respectively (p = 0.12). The prevalence of CAV in the grafts of porcine rejectors and chimeras was 9.9% to 14.8% (12.4 +/- 2.5%) and 0.6% to 4.5% (2.6 +/- 2.0%), respectively (p < 0.05). CAV in the chimeras was similar in prevalence to that of the naive and native hearts. In native human hearts and human grafts, the prevalence was 1.86% to 2.00% (1.95 +/- 0.08%) and 9.09% to 17.50% (12.80 +/- 4.29%), respectively (p = 0.01).

CONCLUSIONS

Smooth muscle bundles inside the internal elastic laminae are similarly prevalent in human and porcine coronary vasculature. Their histologic similarity to intimal thickening of CAV could lead to an inaccurate distinction between graft tolerance and CAV in both clinical and experimental studies of heart transplantation.

Case report of a Quilty lesion within a coronary artery

The Quilty lesion is the moniker of a lymphoid proliferation that resides predominantly in the endocardium and underlying myocardium within transplanted hearts. It has been described in the endocardium, myocardium, and epicardium. Although its pathogenesis is not understood, it is generally considered that the Quilty lesion is not a manifestation of acute rejection. However, its clinical significance and relation to acute rejection, such as its pathogenesis, are still not completely understood. Immunohistochemical studies distinguish between the cellular infiltrates of Quilty lesions and those associated with acute rejection. We describe, what we believe to be, the first case of a Quilty lesion in an epicardial coronary artery from an 8-year-old girl with congenital heart disease who required retransplantation 25 months after her cardiac transplantation for severe graft coronary artery disease. The lesion consisted of an intramural nodular aggregate of numerous T and B lymphocytes, with fewer macrophages, characteristic of a Quilty lesion.

T Cell Costimulation in the Development of Cardiac Allograft Vasculopathy

Cardiac allograft vasculopathy (CAV) is a form of coronary arterial stenosis and a leading cause of death in patients who survive beyond the first year after heart transplantation. Histopathologically, this lesion is concentric diffuse intimal hyperplasia of the arterial wall that is accompanied by extensive infiltration of inflammatory cells, including T cells. Many studies have explored the potential risk factors related to this arterial lesion and its pathogenesis. Continuous minor endothelial cell damage evokes inflammatory processes including T cell activation. Costimulatory molecules play crucial roles in this T cell activation. Many costimulatory pathways have been described, and some are involved in the pathogenesis of CAV, atherogenesis, and subsequent plaque formation. In this review, we summarize the present knowledge of the role of these pathways in CAV development and the possibility of manipulating these pathways as a means to treat heart allograft vascular disease and atherosclerosis.

The replacement of graft endothelium by recipient-type cells conditions allograft rejection mediated by indirect pathway CD4(+) T cells

BACKGROUND

Whereas the participation of alloreactive T cells sensitized by indirect allorecognition in graft rejection is well documented, the nature of recipient antigen presenting cells recognized by indirect pathway CD4(+) T cells within the graft has yet to be identified. The purpose of this study was to determine the role played by graft endothelium replacement in the immune recognition of cardiac allografts rejected by indirect pathway CD4(+) T cells.

METHODS

Transgenic RAG2(-/-) mice expressing I-A(b)-restricted male antigen H-Y-specific TcR were studied for their capacity to reject H-2(k) male cardiac allografts. Chronic vascular rejection in this model was due to the indirect recognition of H-Y antigen shed from H-2(k) male allograft and presented by the recipient's own I-A(b) APC to transgenic T cells.

RESULTS

Immunohistochemical analysis of rejected grafts revealed the presence of numerous microvascular endothelial cells (EC) that expressed recipient's I-A MHC class II molecules. This observation suggested that graft endothelium replacement by I-A(b)-positive cells of recipient origin could stimulate the rejection of male H-2(k) graft by I-A(b)--restricted H-Y--specific T cells. To investigate further this possibility, hearts from H-2(b)--into--H-2(k) irradiation bone marrow (BM) chimera were transplanted in transgenic recipients. A direct correlation was observed between the presence of I-A(b)-positive EC within myocardial microvessels and the induction of acute rejection of chimeric H-2(k) male cardiac allografts transplanted in transgenic recipients.

CONCLUSIONS

We conclude that graft endothelium replacement by recipient-type cells is required for the rejection of cardiac allograft mediated by indirect pathway alloreactive CD4(+) T cells.

Differential effects of rapamycin, cyclosporine A, and FK506 on human coronary artery smooth muscle cell proliferation and signalling

BACKGROUND

Immunosuppressive agents are at the forefront of preventing organ rejection after transplantation. However, their effects on vascular smooth muscle cell-mediated intimal hyperplasia that occurs in post-transplant coronary artery disease are less well known.

METHODS AND RESULTS

We investigated the in vitro effects of three immunosuppressive agents cyclosporine A (CsA), FK506 (tacrolimus), and rapamycin (sirolimus, Rapa) on cultured human coronary artery smooth muscle cells (cSMC). CsA inhibited both platelet-derived growth factor (PDGF)-stimulated DNA synthesis and serum-induced proliferation at high concentrations (> or =1000 ng/ml). The growth-inhibitory effect of CsA was not altered by anti-TGF-beta neutralising antibodies nor was autocrine TGF-beta release detected in CsA-treated culture medium. At inhibitory doses, CsA inhibited ERK kinase activation by PDGF, although cytotoxicity was also apparent. Most notably, CsA visibly prevented PDGF-induced altered cell morphology. Rapa was a highly potent and effective inhibitor of cSMC proliferation (reduction in DNA synthesis by >50% from 0.01 ng/ml), acting through inhibition of 70-kDa S6 kinase (p70S6k). FK506 (1-1000 ng/ml) did not affect cSMC proliferation alone, although a > or =250-fold excess of FK506 over Rapa completely reversed the inhibitory effect of Rapa, confirming that these two agents share a common intracellular receptor, the FK506-binding protein (FKBP).

CONCLUSION

Rapa is a powerful inhibitor of cSMC proliferation, while CsA slighly inhibits cSMC proliferation, although only at higher concentrations that may be toxic. These results indicate that therapeutic immunosuppression with Rapa may be additionally useful in prevention or delay of posttransplant coronary artery disease.

Histomorphometric comparison of cardiac allograft vasculopathy in miniature swine

BACKGROUND

Whether the pathologic characteristics of vascular lesions manifested in recipients with cardiac allograft vasculopathy (CAV) differ with the severity of the histocompatibility barrier crossed at transplantation or with the type or amount of immunosuppression used to prolong graft survival is unclear. We used miniature swine to determine whether a wide variance in heart transplantation protocols, both in histoincompatibility and immunosuppression, affects the histomorphometry of CAV.

METHODS

We compared explanted hearts from major histocompatibility complex Class I-disparate recipients who were treated for 12 days with cyclosporine (Group 1) with minor-antigen-disparate hearts transplanted into mixed chimeric recipients previously engrafted with donor hematopoietic progenitor cells (Group 2). We analyzed coronary intimal lesions using computerized morphometry, immunohistochemistry, and TUNEL assay. Myocardial cytokine-gene expression was determined using RNAse protection assays and reverse-transcriptase polymerase chain reaction.

RESULTS

The prevalence of CAV in Group 2 was significantly less than that observed in Group 1, but the severity of the lesions in both groups was similar. The vascular lesions that developed in both groups demonstrated the presence of alpha-smooth-muscle-actin-positive spindle cells expanding the intima, with few inflammatory cells. We noted an absence of proliferating cell nuclear antigen activity and TUNEL-positive cells in both groups. We observed prominent myocardial interferon-gamma gene expression only in Group 1.

CONCLUSION

Despite differences in myocardial interferon-gamma gene expression, the histology and severity of the vascular lesions in CAV did not vary significantly with different histoincompatibilities or treatment protocols. These results suggest that the origin of CAV cannot be determined by histology alone.

Cardiopulmonary transplantation: experience of a lung transplant group

Cardiopulmonary transplantation (CPT) is indicated for patients eligible for heart transplantation (HT) or lung transplantation (LT) who have severe concomitant lung or heart disease. Only 2 groups perform CPT in Spain. We report our experience with 18 CPTs representing 8.2% and 5% compared with LT (220) and HT (362), respectively, from February 13, 1990 to October 15, 2002. The mean time on a waiting list was 138 days. The current number of surviving patients is 7 (39%), with a mean follow-up of 602 days (range, 3 to 4627 days). They all remain asymptomatic with normal respiratory function in 4 patients. No cardiac graft rejection has been detected. Two patients experienced sustained gastroparesis during the first year with spontaneous resolution. Death occurred within the first 3 months in 9 patients. These outcomes contrast with the early mortality associated with LT and HT in our series, namely 10.6% and 11%, respectively. The different causes of death were as follows: sepsis and multiorgan failure in 5 patients, hemorrhagic shock in 3 patients, and suture dehiscence and fungal aortic perforation in 1 patient. Late mortalities were recorded in 2 cases. Overall patient survival in our series is lower than that reported by the International Registry (IR), with an early mortality rate of 50% (30% IR). Nevertheless, our survival rate at 10 years after transplantation is 30% (26% IR). We conclude that CPT should be considered despite the greater early morbidity and mortality.

Treatment by mycophenolate mofetil of advanced graft vascular disease in non-human primate recipients of orthotopic aortic allografts

Failure to control chronic graft dysfunction [e.g. graft vascular disease (GVD)] is the primary cause of immunologic graft failure. This is the first study of mycophenolate mofetil (MMF) for the treatment of GVD in non-human primate recipients of aortic allografts. Abdominal aortic allografts were exchanged between mixed leukocyte reaction (MLR) -mismatched, blood-group-compatible cynomolgus monkeys. Six control recipients were untreated. Individualized treatment with frequent dose adjustments of MMF insured that treatment was close to the maximum tolerated dose (mean 99.2 mg/kg/day). Immune-mediated injury proceeded unhindered until day 45, after which MMF treatment began. Changes in intimal volume (IV) were quantified by intravascular ultrasound (IVUS) and compared to histology on day 105. Serial IVUS measurements of IV (mm(3)) in controls showed progressive GVD. In four out of six animals, MMF was well tolerated, thus enabling optimum treatment; in all these animals, IV was significantly less than in the control animals (p = 0.02). In the two remaining animals, high doses were not tolerated; at day 105, there was no significant difference in IV between them and the controls. We found a significant correlation between the mean MMF tolerated dose and the inhibition of progression of IV (r = -0.88, p = 0.015). When high MMF doses were tolerated, MMF slowed progression of GVD.

Cardiac allograft vasculopathy and dysregulation of the NO synthase pathway

Cardiac allograft vasculopathy is the most aggressive form of atherosclerosis in humans and is the leading cause of death after the first year of heart transplantation. Endothelial dysfunction is a major contributing factor to the acceleration of coronary vascular disease in these individuals. A reflection of this endothelial dysfunction is the severe impairment in endothelium-dependent vasodilation that occurs early after transplantation. The etiology of this allograft endothelial alteration is multifactorial and may include preexisting atherosclerosis of the graft vessels, reperfusion injury during transplantation, denervation, disruption of the lymphatic system, and acute and chronic immune injury, as well as traditional risk factors for coronary artery disease (hyperlipidemia, diabetes, hypertension, or hyperhomocysteinemia) and pathogens, such as cytomegalovirus. The alteration in endothelial function affects vasomotor tone of the coronary arteries. Evidence indicates that there may be an impairment of endothelial production and/or activity of NO. Because NO is a potent vasodilator, its deficiency would explain the abnormal vasomotor tone in these individuals. In addition, because NO inhibits key processes in vascular inflammation and atherosclerosis, its absence may contribute to the acceleration of transplant vascular disease. Recent studies from our group and others have shed light on the mechanisms of endothelial dysfunction and its importance in cardiac allograft vasculopathy. In addition, the alteration in endothelial function contributes to vascular inflammation and progression of the disease.

Short-term angiopeptin therapy and the incidence of graft vessel disease after heart transplantation

BACKGROUND

Graft vessel disease, the major limitation for long-term success after heart transplantation, is triggered by injury to the graft vessel endothelium, resulting in the expression of adhesion molecules, the migration of leukocytes into the graft, and the release of growth factors. Angiopeptin, a stable analog of somatostatin, is a growth-hormone inhibitor with additional anti-proliferative effects. We evaluated angiopeptin for prevention of graft vasculopathy after cardiac transplantation in the first prospective, randomized, double-blind, clinical trial.

METHODS

Thirty-one patients received treatment with either angiopeptin (n = 13) or placebo (n = 18). Patients were randomized according to the presence of hypercholesterolemia, recipient cytomegalovirus-antibody status, and donor age. All patients received standard triple-drug immunosuppression. Angiopeptin 1.5 mg or placebo was given subcutaneously immediately before surgery and twice a day after transplantation from Day 1 to Day 14. Furthermore, 1.5 mg was added to each liter of cardioplegic solution, 1.5 mg was given intravenously during surgery, and another 3 mg was given during the first 6 post-operative hours. During the first post-operative year, angiopeptin 1.5 mg or placebo was added to each treatment for acute rejection (twice a day subcutaneously). Baseline angiography was performed within the first 4 post-operative weeks and annually thereafter. Twenty-three patients each underwent an additional intracoronary ultrasound.

RESULTS

One- and 4-year survival rates were comparable: 85% and 85% for the group receiving angiopeptin, and 89% and 78% for the placebo group, respectively. One patient in the control group died of myocardial infarction caused by graft vessel disease. Although the mean number of rejection and infection episodes was similar, the overall incidence of newly occurring graft vessel disease after 2 and 4 years was greater in the control cohort: 9% vs 38% after 2 years and 27% vs 44% after 4 years (p = 0.183, 0.448). Comparison of the results of intracoronary ultrasound performed in a sub-group of patients confirmed that trend: the modified Stanford score, the mean intimal thickness, and the mean intimal index were lower in the angiopeptin group. Again, because of the relatively small number of patients available for evaluation, the difference did not reach statistical significance.

CONCLUSIONS

Short-term peri-operative angiopeptin treatment along with additional injections during rejection episodes within the first year resulted in a marked decrease in graft vessel disease 2 and 4 years after heart transplantation. Based on our results, continuous, long-term application of slow-release angiopeptin could significantly decrease or even prevent graft vessel disease.

[Utility of pravastin in cardiac transplant dyslipidemia]

Patients undergoing cardiac transplantation are at increased risk of dyslipidemia (60% to 80%). Lipid-lowering treatment in these patients should be aggressive given the known role of dyslipidemia in chronic transplant rejection. The objective of this study was to evaluate the efficacy and safety of pravastatina therapy and its effect upon cyclosporine levels in a population of dyslipidemic cardiac transplant patients.A total of 20 cardiac transplant patients were enrolled in this 39-week length prospective observational study. Patients had serum cholesterol levels exceeding 200 mg/dl, and received pravastatin therapy at the adequate dose to obtain an optimal lipid profile without significant adverse effects. Pravastatin, at a mean dose of 50 18 mg/day, produced a significant reduction in total cholesterol levels (from 291 32 to 203 25 mg/dl, p < 0.05), LDL cholesterol (from 187 34 to 102 15 mg/dl, p < 0.05) and an increase in HDL-cholesterol levels (from 48 16 to 55 14, p < 0.05). A slight asymptomatic increase in CPK levels was observed but no differences in cyclosporine levels. Pravastatin has shown to be an effective and safe therapy in dyslipidemic cardiac transplant patients.

Depletion of recipient CD4+ but not CD8+ T lymphocytes prevents the development of cardiac allograft vasculopathy

BACKGROUND

We have described that chimeric rat hearts bearing recipient-type antigen-presenting cells (APCs) do not reject acutely, but develop cardiac allograft vasculopathy (CAV) in untreated recipients. This suggests that CAV is triggered either by CD8+ direct allorecognition or by CD4+ indirect allorecognition. To determine the allorecognition pathway responsible for CAV in this model, recipients of chimeric hearts underwent either CD8+ or CD4+ T cell depletion.

METHODS

Chimeric hearts were created via bone marrow transplantation in two fully major histocompatibility-mismatched rat strain combinations. DA recipients were thymectomized and treated with Ox8 and Ox38 murine monoclonal antibodies, which deplete CD8+ and CD4+ T cells, respectively. Chimeric PVG hearts bearing DA APCs, abbreviated PVG(DA), were heterotopically transplanted into recipients undergoing thymectomy alone or recipients undergoing thymectomy plus either CD4+ or CD8+ T cell depletion.

RESULTS

PVG(DA) allografts survived 100 days, but developed CAV in thymectomized recipients and in those permanently depleted of CD8+ T cells. In contrast, chimeric hearts transplanted into permanently CD4+ T cell-depleted recipients survived 100 days and demonstrated no evidence of CAV.

CONCLUSIONS

In this specific strain combination, recipient CD8+ T cells are neither necessary nor sufficient for the development of CAV, whereas recipient CD4+ T cells are required for the development of CAV. These findings suggest that CAV is dependent on CD4+ indirect allorecognition and that CD8+ direct allorecognition stimulated by nonprofessional APCs plays a minor role.

Late cardiac reoperation after cardiac transplantation

BACKGROUND

The intermediate and long-term results of cardiac transplantation continue to improve. Subsequent cardiac procedures may be required to extend patient survival and protect graft function.

METHODS

The medical records of all adult and pediatric cardiac transplant recipients who underwent a subsequent cardiac procedure at our institution were reviewed.

RESULTS

Three hundred sixty patients have undergone primary orthotopic transplantation in our institution. Seventeen patients (12 adults, 5 children) underwent a subsequent procedure requiring cardiopulmonary bypass including cardiac retransplantation (10), coronary artery bypass grafting (3), ascending aortic replacement (2), tricuspid valve repair (1), and myotomy and myomectomy (1 patient). Mean interval from time of transplantation to second procedure was 8.3 years. There was one perioperative death. Two patients, both retransplants, died late postoperatively at 22 and 84 months, respectively. Overall mean follow-up in the late survivors is 26.6 months. All survivors are currently asymptomatic and doing well.

CONCLUSIONS

A variety of subsequent cardiac procedures, in addition to retransplantation, can be performed safely in carefully selected cardiac transplant recipients. The intermediate term results are gratifying in terms of survival and freedom from symptoms.

Mycophenolate mofetil: a pharmacoeconomic review of its use in solid organ transplantation

Most pharmacoeconomic studies of mycophenolate mofetil have focused on its use as part of maintenance immunosuppression for renal transplantation, involving short-term (3 to 12 months) time frames. In general, mycophenolate mofetil reduced the treatment costs for rejection episodes and graft failure which offset its higher drug acquisition cost compared with azathioprine. Several cost analyses have been modelled on the large multicentre trials of adult renal transplant recipients. The use of mycophenolate mofetil was associated with either cost savings or no additional costs after 6 or 12 months in French, US and Canadian analyses of triple or quadruple immunosuppressant therapy. A further cost analysis utilising a registry database of renal transplant recipients in the US found mycophenolate mofetil to be cost saving compared with azathioprine after 6.4 years when evaluating costs due to graft loss only. Of the limited cost-effectiveness analyses with the drug, one US study modelled the 1- and 10-year cost effectiveness of mycophenolate mofetil and various other immunosuppressants used in combined regimens. Long-term use of mycophenolate mofetil was less cost effective than other regimens, but the use of long-term mycophenolate mofetil in high-risk patients was shown to be a relatively cost-effective strategy. In another US analysis comparing mycophenolate mofetil with azathioprine as part of quadruple therapy, mycophenolate mofetil was associated with slightly lower costs during the first year after renal transplantation as well as improved clinical outcomes.

CONCLUSION

Pharmacoeconomic studies support the use of mycophenolate mofetil as part of immunosuppressant therapy in renal transplantation, at least in the short term. Although the cost effectiveness of mycophenolate mofetil in the long term is less clear, limited pharmacoeconomic data available appear promising. Among issues to be examined in future economic analyses in renal transplantation are the calcineurin-sparing potential of mycophenolate mofetil and the feasibility of using more efficient mycophenolate mofetil dosage regimens when using the drug on a long-term basis. Additional pharmacoeconomic analyses of mycophenolate mofetil are also needed in other types of solid organ transplantation.

Role of statins in the management of dyslipidemia after cardiac transplant: randomized controlled trial comparing the efficacy and the safety of atorvastatin with pravastatin

BACKGROUND

Cardiac transplant patients are at increased risk of dyslipidemia, a known pathogenetic factor in chronic rejection. The aim of this study was to compare the efficacy and the safety of treatment with atorvastatin (AT) and treatment with pravastatin (PV) in a population of dyslipidemic transplant patients.

METHODS

Thirty-nine transplant patients were randomized to receive a 4-month cycle of therapy with AT or PV, in a cross-over sequence. We analyzed the effects on their lipid profiles using Student t-test for paired data.

RESULTS AND CONCLUSION

Atorvastatin was significantly more effective than PV in reducing total cholesterol (33% vs 21%, p < 0.001), LDL cholesterol (45% vs 30%, p = 0.001), and triglycerides (24% vs 7.7%, p < 0.001), at lower doses and with comparable tolerability and safety.

Mouse model of transplant arteriosclerosis: role of intercellular adhesion molecule-1

Transplant-accelerated arteriosclerosis in coronary arteries is the major limitation to long-term survival of patients with heart transplantation. The pathogenesis of this disease is not fully understood. Herein, we describe a simplified model of artery allografts in the mouse that allows us to take advantage of transgenic, knockout, or mutant animals. Common carotid arteries or aortic vessels were end-to-end allografted into carotid arteries between C57BL/6J and BALB/c mice. Neointimal lesions were observed as early as 2 weeks after surgery and had progressed at 4 and 6 weeks postoperatively. The lumen of grafted arteries was significantly narrowed due to neointima hyperplasia 4 weeks after transplantation. Using this model, we studied the role of intercellular adhesion molecule-1 (ICAM-1) in the development of transplant arteriosclerosis in ICAM-1-deficient mice. Neointimal lesions of artery grafts from ICAM-1 -/- C57BL/6J to BALB/c mice were reduced up to 60% compared with wild-type controls. MAC-1 (CD11b/18)-positive cells adhering to the surface of ICAM-1 -/- artery grafts were significantly less as identified by en face immunofluorescence, and these positive cells were more abundant in intimal lesions of artery grafts in wild-type mice. Furthermore, the major cell component of neointimal lesions 4 weeks after surgery was found to be alpha-actin-positive smooth muscle cells, which were significantly reduced in lesions of ICAM-1 -/- artery grafts. Thus, this model has been proven to be useful for understanding the mechanism of transplant arteriosclerosis. Our findings demonstrate that ICAM-1 is critical in the development of allograft arteriosclerosis via mediation of leukocyte adhesion to, and infiltration into, the vessel wall.