Alfred Kocher

NEOVASCULARIZATION OF ISCHEMIC MYOCARDIUM BY HUMAN BONE MARROW-DERIVED ANGIOBLASTS PREVENTS CARDIOMYOCYTE APOPTOSIS, REDUCES REMODELING AND IMPROVES CARDIAC FUNCTION

Left ventricular remodeling is a major cause of progressive heart failure and death after myocardial infarction. Although neoangiogenesis within the infarcted tissue is an integral component of the remodeling process, the capillary network is unable to support the greater demands of the hypertrophied myocardium, resulting in progressive loss of viable tissue, infarct extension and fibrous replacement. Here we show that bone marrow from adult humans contains endothelial precursors with phenotypic and functional characteristics of embryonic hemangioblasts, and that these can be used to directly induce new blood vessel formation in the infarct-bed (vasculogenesis) and proliferation of preexisting vasculature (angiogenesis) after experimental myocardial infarction. The neoangiogenesis resulted in decreased apoptosis of hypertrophied myocytes in the peri-infarct region, long-term salvage and survival of viable myocardium, reduction in collagen deposition and sustained improvement in cardiac function. The use of cytokine-mobilized autologous human bone-marrow–derived angioblasts for revascularization of infarcted myocardium (alone or in conjunction with currently used therapies) has the potential to significantly reduce morbidity and mortality associated with left ventricular remodeling.

Effectiveness of haemodialysis access with an autologous tissue-engineered vascular graft: a multicentre cohort study

BACKGROUND Application of a tissue-engineered vascular graft for small-diameter vascular reconstruction has been a long awaited and much anticipated advance for vascular surgery. We report results after a minimum of 6 months of follow-up for the first ten patients implanted with a completely biological and autologous tissue-engineered vascular graft. METHODS Ten patients with end-stage renal disease who had been receiving haemodialysis through an access graft that had a high probability of failure, and had had at least one previous access failure, were enrolled from centres in Argentina and Poland between September, 2004, and April, 2007. Completely autologous tissue-engineered vascular grafts were grown in culture supplemented with bovine serum, implanted as arteriovenous shunts, and assessed for both mechanical stability during the safety phase (0-3 months) and effectiveness after haemodialysis was started. FINDINGS Three grafts failed within the safety phase, which is consistent with failure rates expected for this high-risk patient population. One patient was withdrawn from the study because of severe gastrointestinal bleeding shortly before implantation, and another died of unrelated causes during the safety period with a patent graft. The remaining five patients had grafts functioning for haemodialysis 6-20 months after implantation, and a total of 68 patient-months of patency. In these five patients, only one intervention (surgical correction) was needed to maintain secondary patency. Overall, primary patency was maintained in seven (78%) of the remaining nine patients 1 month after implantation and five (60%) of the remaining eight patients 6 months after implantation. INTERPRETATION Our proportion of primary patency in this high-risk cohort approaches Dialysis Outcomes Quality Initiative objectives (76% of patients 3 months after implantation) for arteriovenous fistulas, averaged across all patient populations.

Selective downregulation of VEGF-A(165), VEGF-R(1), and decreased capillary density in patients with dilative but not ischemic cardiomyopathy.

Cardiomyopathy (CM) comprises a heterogeneous group of diseases, including ischemic (ICM) and dilative (DCM) forms. The pathogenesis of primary DCM is not clearly understood. Recent studies in mice show that vascular endothelial growth factor (VEGF) is involved in ICM. Whether VEGF plays a role in human CM is unknown. We examined the mRNA and protein expression of VEGF and its receptors in hearts of patients with end-stage DCM and ICM and in healthy individuals using real-time polymerase chain reaction and Western blotting. Number of capillaries, area of myocytes, and collagen were calculated in cardiac biopsies using transmission electron microscopy. In DCM, except for VEGF-C, mRNA transcript levels of VEGF-A165, VEGF-A189, and VEGF-B and the protein level of VEGF-A and VEGF-R1 were downregulated compared with controls (P <0.05). However, in ICM, mRNA transcript levels of VEGF isoforms and protein levels of VEGF-C were upregulated. The vascular density was decreased in DCM but increased in ICM compared with controls (P <0.05). Muscular hypertrophy was not different for ICM and DCM, although DCM had more collagen (P <0.05). Blunted VEGF-A and VEGF-R1 protein expression and downregulated mRNA of the predominant isoform of VEGF-A, VEGF-A165, to our knowledge shown here for the first time, provide evidence that the VEGF-A defect in DCM is located upstream. Whether downregulation of certain VEGF isoforms in DCM is a cause or consequence of this disorder remains unclear, although upregulated VEGF levels in ICM are most likely the result of ischemia.

New directions in strategies using cell therapy for heart disease.

Congestive heart failure remains a major public health problem and is frequently the end result of cardiomyocyte apoptosis and fibrous replacement after myocardial infarction, a process referred to as left ventricular remodeling. Cardiomyocytes undergo terminal differentiation soon after birth and are generally considered to irreversibly withdraw from the cell cycle. In response to ischemic insult adult cardiomyocytes undergo cellular hypertrophy, nuclear ploidy, and a high degree of apoptosis. A small number of human cardiomyocytes retain the capacity to proliferate and regenerate in response to ischemic injury. However, whether these cells are derived from a resident pool of cardiomyocyte stem cells or from a renewable source of circulating bone marrow-derived stem cells that home to the damaged myocardium is at present not known. Replacement and regeneration of functional cardiac muscle after an ischemic insult to the heart could be achieved by either stimulating proliferation of endogenous mature cardiomyocytes or resident cardiac stem cells or by implanting exogenous donor-derived or allogeneic cells such as fetal or embryonic cardiomyocyte precursors, bone marrow derived mesenchymal stem cells, or skeletal myoblasts. The newly formed cardiomyocytes must integrate precisely into the existing myocardial wall in order to augment synchronized contractility and avoid potentially life-threatening alterations in the electrical conduction of the heart. A major impediment to survival of the implanted cells is altered immunogenicity by prolonged ex vivo culture conditions. In addition, concurrent myocardial revascularization is required to ensure viability of the repaired region and prevent further scar tissue formation. Human adult bone marrow contains endothelial precursors which resemble embryonic angioblasts and can be used to induce infarct bed neovascularization after experimental myocardial infarction. This results in protection of cardiomyocytes against apoptosis, induction of cardiomyocyte proliferation and regeneration, long-term salvage and survival of viable myocardium, prevention of left ventricular remodeling, and sustained improvement in cardiac function. It is reasonable to anticipate that cell therapy strategies for ischemic heart disease will need to incorporate (a) a renewable source of proliferating, functional cardiomyocytes, and (b) angioblasts to generate a network of capillaries and larger size blood vessels for supply of oxygen and nutrients to both the chronically ischemic endogenous myocardium and to the newly implanted cardiomyocytes

Bilateral lung transplantation with intra- and postoperatively prolonged ECMO support in patients with pulmonary hypertension

OBJECTIVE Lung transplantation for pulmonary hypertension (PH) is usually performed on cardiopulmonary bypass, with the disadvantage of full systemic anticoagulation, uncontrolled allograft reperfusion and aggressive ventilation. These factors can be avoided with intra- and postoperatively prolonged extracorporeal membrane oxygenator (ECMO) support. PATIENTS AND METHODS Between February 1999 and March 2001, 17 consecutive patients with PH (systolic pulmonary artery pressure >70 mmHg) of different etiologies underwent bilateral lung transplantation (BLTX). There were 11 females and six males in the age range from 7 to 50 years (mean age, 28.4+/-12.9 years). Six patients were preoperatively hospitalized, four in the intensive care unit (ICU), one was on ECMO for 3 weeks pretransplantation, and one was resuscitated and bridged with ECMO for 1 week until transplantation. Femoral venoarterial ECMO support with heparin-coated circuits was set up after induction of anesthesia and discontinued at the end of surgery (n=3) or extended for 12 h median into the postoperative period (n=14). Postoperative ventilation pressure was kept below 25 mmHg. Allograft function at 2 h after discontinuation of ECMO, outcome and adverse events were monitored in all patients. Mean follow up time was 18+/-11.4 months. RESULTS The perioperative mortality was 5.9% (n=1). Arterial oxygen pressure measured 2 h after weaning from ECMO, and under standard mechanical ventilation with a peak pressure of 25 mmHg and inspired oxygen fraction of 0.4, was 157+/-28 mmHg. The mean pulmonary artery pressures were reduced to 29+/-3,4 from 66+/-15 mmHg before transplantation. Postoperative complications included rethoracotomy due to bleeding (n=4) and temporary left ventricular failure (n=4). Median ICU stay was 12 days. Incidence of rejection within the first 100 days was 0.4 per patient. CONCLUSION BLTX with intraoperative and postoperatively prolonged ECMO support provides excellent initial organ function due to optimal controlled reperfusion and non-aggressive ventilation. This results in improved outcome even in advanced forms of PH.

CMV-hyperimmune globulin for preventing cytomegalovirus infection and disease in solid organ transplant recipients: a meta-analysis

Abstract.  Objective:  The goal of this meta‐analysis was to investigate the impact of cytomegalovirus hyperimmune globulin (CMVIG) on cytomegalovirus (CMV) infection, CMV disease, and mid‐term survival in solid organ transplant recipients.

Catalytic Degradation of Vitamin D Up-regulated Protein 1 mRNA Enhances Cardiomyocyte Survival and Prevents Left Ventricular Remodeling after Myocardial Ischemia *

Vitamin D3 up-regulated protein 1 (VDUP1) is a key mediator of oxidative stress on various cellular processes via downstream effects on apoptosis signaling kinase 1 (ASK1) and p38 mitogen-activated protein kinase (MAPK). Here, we report that VDUP1 expression is significantly increased in rat hearts following acute myocardial ischemia, suggesting it may have important regulatory effects on cardiac physiological processes during periods of oxidative stress. Transfection of H9C2 cardiomyoblasts with a sequence-specific VDUP1 DNA enzyme to down-regulate VDUP1 mRNA expression significantly reduced apoptosis and enhanced cell survival under conditions of H2O2 stress, and these effects involved inhibition of ASK1 activity. Direct intracardiac injection of the DNA enzyme at the time of acute myocardial infarction reduced myocardial VDUP1 mRNA expression and resulted in prolonged reduction in cardiomyocyte apoptosis and ASK1 activity. Moreover, down-regulation of VDUP1 was accompanied by significant reduction in cardiac expression of pro-collagen type I α2 mRNA level, as well as marked reduction in myocardial scar formation. These features were accompanied by significant improvement in cardiac function. Together, these results suggest a direct role for VDUP1 in the adverse effects of ischemia and oxidative stress on cardiomyocyte survival, left ventricular collagen deposition, and cardiac function. Strategies to inhibit VDUP1 expression and/or function during acute ischemic events may be beneficial to cardiac functional recovery and prevention of left ventricular remodeling.

B-Cell activation and allosensitization after left ventricular assist device implantation is due to T-Cell activation and CD40 ligand expression

Left ventricular assist device (LVAD) implantation is frequently complicated by B-cell activation and allosensitization, posing a significant risk to successful transplant outcome. This study investigated whether B-cell hyperreactivity and alloantibody production in LVAD recipients involves T-cell dependent pathways. T-cell calcium flux and nuclear translocation of NFATc were used to determine states of T-cell activation. Flow cytometry was used to assess human T- and B-cell activation after culture with LVAD-derived biomaterial particles. Sera from LVAD recipients and controls were tested for the presence of anti-HLA antibodies, and for soluble CD40 ligand. LVAD-derived biomaterial induced rapid and sustained calcium flux into normal T cells, resulting in calcineurin-dependent nuclear translocation of NFATc. This resulted in increased T-cell expression of CD40 ligand and subsequent B-cell activation, which was reduced by inhibitors of T-cell activation (CsA or anti-CD25 mAb) or by anti-CD40 ligand mAb. LVAD recipients demonstrated higher frequencies of anti-HLA antibodies and serum levels of soluble CD40 ligand compared with heart failure controls. The results indicate that exposure of human mononuclear cells to LVAD-derived biomaterial leads to T-cell dependent B-cell activation via CD40--CD40 ligand interaction, and suggest that treatment with calcineurin inhibitors or monoclonal antibodies against either CD25 or CD40 ligand could be effective at preventing B-cell hyperreactivity and allosensitization after LVAD implantation.

Memantine for prevention of spinal cord injury in a rabbit model

BACKGROUND This study was conducted to investigate the effect of memantine, a noncompetitive N-methyl-d-aspartate receptor antagonist, on the neurologic outcome of spinal cord ischemia after aortic occlusion. MATERIALS AND METHODS New Zealand White rabbits were anesthetized and spinal cord ischemia was induced for 40 minutes by infrarenal aortic occlusion. Animals were randomly allocated to 3 groups. Group 1 (n = 8, control) received no pharmacologic intervention, group 2 (n = 8) received intra-aortic memantine infusion (20 mg/kg) after aortic crossclamping, and group 3 (n = 8) was treated with systemic memantine infusion (20 mg/kg) 45 minutes before aortic occlusion. Neurologic status was scored by the Tarlov system (in which 4 is normal and 0 is paraplegia) at 12, 24, 36, and 48 hours after the operation. Lumbar spinal root stimulation potentials and motor evoked potentials from lower limb muscles were monitored before, during, and after the operation. After the animals were killed, the spinal cords were studied histopathologically. RESULTS All potentials disappeared shortly after aortic crossclamping. They returned earlier in both memantine-treated groups than in the placebo group. Histologic examination of spinal cords revealed a few abnormal motor neurons in memantine-treated rabbits but found extensive injury in the control group. At 12 hours the median Tarlov scores were 0 in the control group (group 1), 2 in the intra-aortic memantine group (group 2, P =.001 versus control), and 3 in the systemic group (group 3, P =.0002 versus control). At 24 hours median Tarlov scores were 0, 2.5 (P =.0002), and 4 (P =. 0002), respectively. Finally, at both 36 and 48 hours median Tarlov scores were 0, 3 (P =.0006), and 4 (P =.0002), respectively. CONCLUSION Memantine significantly reduced neurologic injury related to spinal cord ischemia and reperfusion after aortic occlusion.

VEGF-A and -C but not -B mediate increased vascular permeability in preserved lung grafts

Background. Vascular endothelial growth factor (VEGF) is a potent endothelial cell growth and permeability factor, expressed in the lung. Overexpression of VEGF is associated with increased vascular permeability in the early stage of acute lung injury in mice. The role of various forms of VEGF in transplantation-induced lung injury is not well understood. Methods. VEGF mRNA and protein expression was measured in biopsies of preserved donor lung grafts as well as in control lung biopsies, using real-time reverse transcriptase–polymerase chain reaction and Western blot analysis. VEGF tissue expression was also evaluated by immunocytochemistry. Serum VEGF was measured in recipients after transplantation and in controls using ELISA. Results. Although VEGF-A and VEGF-C protein expression was up-regulated, their mRNA levels were decreased in donor versus control lung biopsies (P <0.05). VEGF-B mRNA was decreased, but its protein level was unchanged in donors. Flt-1 was unchanged, KDR gene expression was down-regulated in donors (P <0.05), and both receptors’ protein expression was under the detection level in donor and control lungs. VEGF-A was detected in pulmonary vessels and bronchi, whereas VEGF-C was only detectable in vessels of both donor and control lungs. After transplantation, serum VEGF increased (P <0.05) and returned to control baseline levels 12 weeks after surgery. Wet-to-dry lung weight was increased in donor versus control lungs. Conclusions. These results indicate that unventilated hypoxia increases vascular permeability in lung grafts and that this process is mainly regulated at VEGF-A and VEGF-C translational but not transcriptional level. Selective VEGF antagonism during graft preservation might be of benefit to counteract edema formation.