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Background Vascular remodeling is central to the development of transplant coronary artery vasculopathy (CAV). For remodeling to occur, a sustained blood and nutrient supply is essential. Here we report on the presence of angiogenesis within the neointima of coronary arteries from cardiac transplant recipients. Methods Coronary arteries from 57 cardiac transplant recipients with CAV were analyzed. Immunocytochemistry with antibodies raised against endothelial cells (CD31, CD34, and vWF), vascular smooth muscle cells (SmA), and activated endothelial cells (MHC 2, P-SEL, E-SEL, and VCAM-1) was performed. Results A total of 89% of patients had significant angiogenesis. These vessels appeared as endothelial lined channels and were present in a concentric circumferential pattern within the mid portion of the neointima. These new vessels were present at an interface between an area of intimal hyperplasia and below an area of fibrous regeneration. These 2 distinct zones were present in 64% of the cases, and were clearly demonstrated with an elastic van Gieson (EVG) stain and are distinctly different from that seen in native atherosclerosis. Endothelial activation markers were strongly expressed by the endothelial cells lining new vessels, suggesting that they are functional and may aid in the recruitment of inflammatory cells. Conclusions These data suggest that angiogenesis is present within the intima of CAV lesions and may contribute to the continued obliteration of the vessel lumen. The vessels appear to originate in the intima and may represent the location of the donor endothelium before transplantation. Inhibition of endothelial damage may provide therapeutic options to prevent the progression of CAV.

Diverse heterozygous mutations of bone morphogenetic receptor type II (BMPR-II) underlie the inherited form of the vascular disorder primary pulmonary hypertension (PPH). As yet, the molecular detail of how such defects contribute to the pathogenesis of PPH remains unclear. BMPR-II is a member of the transforming growth factor-beta cell signalling superfamily. Ligand binding induces cell surface receptor complex formation and activates a cascade of phosphorylation events of intracellular intermediaries termed Smads, which initiate transcriptional regulation. Some 30% of PPH-causing mutations localize to exon 12, which may be spliced out forming an isoform depleted of the unusually long BMPR-II cytoplasmic tail. To further elucidate the consequences of BMPR2 mutation, we sought to characterize aspects of the cytoplasmic domain function by seeking intracellular binding partners. We now report that Tctex-1, a light chain of the motor complex dynein, interacts with the cytoplasmic domain of BMPR-II and demonstrate that Tctex-1 is phosphorylated by BMPR-II, a function disrupted by PPH disease causing mutations within exon 12. Finally we show that BMPR-II and Tctex-1 co-localize to endothelium and smooth muscle within the media of pulmonary arterioles, key sites of vascular remodelling in PPH. Taken together, these data demonstrate a discrete function for the cytoplasmic domain of BMPR-II and justify further investigation of whether the interaction with and phosphorylation of Tctex-1 contributes to the pathogenesis of PPH.

Endothelial activation in the donor heart has been described variably after brain death and transplantation. We aimed to characterize the time course of endothelial activation in right ventricle (RV) and left ventricle (LV) during the acute phase of clinical transplantation.We studied biopsy specimens from the RVs and the LVs of 40 donor hearts: at initial assessment of the donor, at end-ischemia, and after 10 minutes of reperfusion. We also included follow-up RV biopsy specimens at 1 week, 1 month, and 3 months after surgery. Six of the patients had cystic fibrosis and were domino donors.P-selectin and vascular cell adhesion molecule 1 (VCAM-1), but not E-selectin were up-regulated in brain-dead and in domino donors vs controls. Unused donor hearts (n = 6) had significantly less up-regulation of P-selectin and of VCAM-1. We found no difference between the RV and the LV during surgery, but we did see important time-dependent variations. P-selectin was present in 85% of vessels throughout transplantation and decreased to approximately 60% after transplantation (p0.001). We initially detected VCAM-1 in 20% of vessels, which decreased to 5% during storage, then increased to 47% at reperfusion, and gradually decreased thereafter (p0.001). E-selectin expression increased progressively from 15% initially to 45% at reperfusion and then decreased after surgery (p = 0.001). Thrombomodulin expression was decreased at baseline, and the decrease was accentuated afterward (p = 0.02). Patients with donor organ failure did not have a specific pattern of endothelial activation.Cardiac transplantation is associated with marked endothelial activation, with no difference between the two ventricles. The changes persist in the post-operative period, even in the absence of acute rejection.

Objective: Brain death appears to predominantly affect the right ventricle (RV) and right ventricular failure is a common complication of clinical cardiac transplantation. It is not clear to what extent myocardial energy stores are affected in the operative sequence. We aimed to describe the time-dependent variation in high energy phosphate (HEP) metabolism of the two ventricles, and the relationship with endothelial activation and postoperative functional recovery. Methods: Fifty-two human donors had serial biopsies from the RV and the left ventricle (LV) at (1 initial evaluation, (2) after haemodynamic optimisation, (3) end of cold ischaemia, (4) end of warm ischaemia, (5) reperfusion, and (6) at 1 week postoperatively. HEP was measured by chemiluminescence in biopsies 1-5 and adhesion molecules (P-selectin, E-selectin, VCAM-I) and thrombomodulin were analysed by immunohistochemistry in biopsies 5-6. Seventeen donors and five recipients had RV intraoperative pressure-volume recordings by a conductance catheter. Six patients served as live controls. Results: Brain death did not affect HEP metabolism quantitatively. There was no difference between the RV and LV at any time point, but significant time-dependent changes were observed. The RV was prone to HEP depletion at retrieval, with ATP/ADP falling from 3.89 to 3.13, but recovered during cold ischaemia. During warm ischaemia the ATP/ADP ratio fell by approximately 50%. from 5.48 for the RV and 4.26 for the LV, with partial recovery at reperfusion (P< 0.005). Hearts with impaired function in the recipient showed marked variations in HEP levels at reperfusion, and those organs with RV dysfunction failed to replenish their energy stores However, these organs were not different from normally functioning allografts in terms of endothelial activation and clinical risk factors. There was poor correlation between pressure-volume and HEP data in either donor or recipient studies. Hearts followed-up with HEP and pressure-volume studies showed improvement in the recipient, despite functioning against a higher pulmonary vascular resistance. Conclusions: HEP are preserved over a wide range of contractile performance in the donor heart, with no metabolic difference between the two ventricles. No correlation with endothelial activation was seen either. Preservation efforts should be directed to the vulnerable periods of implantation and reperfusion.

There is strong evidence that obliterative bronchiolitis (OB) in lung transplant recipients is related to acute rejection as graded by parenchymal perivascular infiltrates. OB (chronic rejection) is a small airways, rather than a parenchymal, scarring process. Moreover, there has been no study of the microcirculation in the small airways in lung transplantation. This study assesses the microvasculature around small airways (SA) in post-mortem lung allograft specimens.The microvasculature of SA (n = 19) from 5 patients who died within 24 hours of lung transplantation (Group A) and SA in OB lungs (11 patients, median post-transplant survival 1,371 days) was assessed by the use of monoclonal antibodies to the vascular endothelium, namely von Willebrand factor (vWF) and CD31. The second group was further sub-divided into Group B (airways not obliterated, n = 18), Group C (sub-total airways obliteration, n = 21) and Group D (airways with total luminal obstruction, n = 14).The measured median circumference of the SA in the 4 groups was 2.1, 2.1, 2.5 and 2.3 mm, respectively (p = 0.66). Using CD31 as the endothelial marker, the median number of blood vessels per unit length of airway circumference (BVPL) was 3.5 vessels/mm for Group A, 0.8 for Group B, 1.3 for Group C and 2.8 for Group D, (p0.001). Large blood vessels (circumference0.20 mm) were present in 95%, 11%, 14% and 21% of each group, respectively (p0.001). Similar trends were confirmed with the vWF endothelial antibodies.OB after lung transplantation is associated with a decrease in microvascular supply to the small airway. This ischemic event may lead to airway damage or increase the tendency to repair by scarring. The small airways then appear to respond to this insult by angiogenesis, which may either occur too late to prevent permanent airway damage or be inadequate in restoring adequate blood supply to the airway.

BACKGROUND: Transplant coronary artery vasculopathy (CAV) is a fibro-proliferative process that leads to lumen occlusion and cardiac failure. Current theories suggest that the process evolves over time in response to inflammation and proliferation of donor derived medial smooth muscle cells (SMC). Animal models of cardiac transplantation have suggested that the neointima is formed by recipient derived circulating progenitor cells. The aim of this investigation is to determine the origin of the neointimal SMC within epicardial coronary arteries from human cardiac allografts by using sex mis-matched recipients and donors, and a Y specific chromosome probe. METHODS: Coronary arteries from 14 patients previously assessed histologically to have CAV were analyzed-eight male recipients of female donor organs, 2 female-to-female, and 4 male-to-male transplants. A double immunocytochemistry and in-situ hybridization technique using a Y chromosome DNA probe and either antibodies to smooth muscle actin or Ham-56 a macrophage marker were employed. RESULTS: No Y chromosome bodies could be identified in the female-to-female allografts. In the 4 male donor and male recipient cases, cells positive for the Y chromosome probe were identified. In sex mis-matched transplants, female to male, inflammatory cells marked with Ham-56 were also positive for Y chromosome probe. Flattened cells positive for Y chromosome were observed just beneath the endothelial surface. When double stained, these were identified as infiltrating macrophages. No double staining smooth muscle cells and Y chromosome positive cells could be identified within the neointima. CONCLUSIONS: This study confirms the source of SMC of the neointima of CAV lesions from epicardial coronary arteries to be of donor origin. In contrast to animal models, circulating progenitor cells do not appear to play a role within the neointima of human transplant CAV.

Background: The use of pig organs transgenic for human decay accelerating factor (hDAF) has largely overcome the problems of hyperacute rejection. With improved immunosuppressive protocols, life supporting grafts are showing greater survival times bringing the possibility of clinical xenotransplantation closer. Examination of the histopathology of the rejection process provides insight into the underlying mechanism and may suggest ways in which new immunosuppressive strategies should be directed. Methods: 44 baboons (Papio anubis) underwent heart transplants of which 39 were from transgenic donors. The transplanted organs were examined histologically and stained for evidence of immunoglobulin and complement deposition as well as cellular infiltrates. Results: In the transgenic animals survival times were 2 to 99 days (mean 23.5) and the heterotopic group and 1 to 39 days (mean 11.7) in the orthotopic group. There were 3 cases of hyperacute rejection between the 2 groups. Rejected organs showed areas of old and recent myocardial infarction associated with vascular thrombosis. There was widespread deposition within vessels of immunoglobulins IgM and IgG together with complement fractions C3 and C5b to 9 in those organs that were rejected. The amount of complement positive in the longer surviving organs was less than those rejecting early. Cellular infiltate was predominantly macrophage with some later appearing T or natural killer cells. Conclusions: The histopathological changes support the importance of immunoglobulin and complement in delayed xenograft or acute vascular rejection. With time there is an increase in cellular infiltrate predominantly macrophages and these findings suggest an increasingly important role for the cells and the rejection process. The presence of areas of infarction and underlying vascular thrombosis is in keeping with endothelial activation and the establishment of procoagulant phenotype which may be due to immunoglobulin, complement, secreted cytokines and direct cellular effects.

BACKGROUND A series of immunosuppressed cynomolgus monkeys were used in porcine-to-primate and primate-to-primate renal transplantation. In a number of animals nodal and extranodal lymphomas as well as areas of lymphoid hyperplasia in multiple organs (posttransplant lymphoproliferative disorder, PTLD) were recorded. METHODS PTLD was characterized with respect to manifestation sites, histopathology, immunophenotype, and association with primate Epstein Barr-like Virus by in situ hybridization and quantitative polymerase chain reaction. RESULTS PTLD was observed in 10 of 245 xenotransplanted and 9 of 231 allotransplanted monkeys; its detection in xenotransplanted animals was significantly earlier after transplantation than that in allo-transplanted animals (median, 40 and 104 days, respectively; P

The mechanisms that contribute to inflammatory damage following ischemic stroke are poorly characterized, but studies indicate a role for both complement and P-selectin. In this study, we show that compared with wild-type mice, C3-deficient mice showed significant improvement in survival, neurological deficit, and infarct size at 24 h after middle cerebral artery occlusion and reperfusion. Furthermore, P-selectin protein expression was undetectable in the cerebral microvasculature of C3-deficient mice following reperfusion, and there was reduced neutrophil influx, reduced microthrombus formation, and increased blood flow postreperfusion in C3-deficient mice. We further investigated the use of a novel complement inhibitory protein in a therapeutic paradigm. Complement receptor 2 (CR2)-Crry inhibits complement activation at the C3 stage and targets to sites of complement activation. Treatment of normal mice with CR2-Crry at 30 min postreperfusion resulted in a similar level of protection to that seen in C3-deficient mice in all of the above-measured parameters. The data demonstrate an important role for complement in cerebrovascular thrombosis, inflammation, and injury following ischemic stroke. P-selectin expression in the cerebrovasculature, which is also implicated in cerebral ischemia and reperfusion injury, was shown to be distal to and dependent on complement activation. Data also show that a CR2-targeted approach of complement inhibition provides appropriate bioavailability in cerebral injury to enable complement inhibition at a dose that does not significantly affect systemic levels of serum complement activity, a potential benefit for stroke patients where immunosuppression would be undesirable due to significantly increased susceptibility to lung infection.

left ventricular (LV) function. Median NA use was higher in the control group at 6 h (0.6 vs 0 g/kg/min; p 0.01). NA was weaned off by 6 h in 5/7 HR pigs compared with 0/7 controls (p 0.03). These 5 pigs were also weaned off vasopressin. MAP was higher in HR pigs at 6 h (75 vs 51 mmHg; p 0.05) and at fixed NA (71 vs 36; p 0.005). PRSW analysis found a greater increase in LV contractility in the HR group at 6 h compared with 0 h (p 0.014), equating to an increase in SWI of 85% vs 43%. LV contractility was increased in the HR group at fixed NA compared with 0 h (p 0.001), equating to a SWI increase of 85% vs 3%. HR in this model reduces noradrenaline requirements and improves circulatory haemodynamics and LV contractility. These results support the use of HR in the management of the brain dead organ donor.