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Gustav Steinhoff

Publications and source records attributed to Gustav Steinhoff.

At least 19 recordsLinked to original sources
PubMed2006

Ischemic acidosis causes apoptosis in coronary endothelial cells through activation of caspase-12.

OBJECTIVE: Myocardial ischemia has been shown to induce apoptosis of endothelial cells (EC). However, the mechanism of this endothelial injury is still poorly understood. To analyse the signaling pathway of ischemia-induced EC apoptosis was the aim of the present study. METHODS: The primary culture of rat coronary EC was exposed to simulated ischemia (glucose-free anoxia at pH(o) 6.4). Apoptosis was defined by staining of nuclei with Hoechst-33342 and TUNEL. Cytosolic Ca2+ and pH were measured with Fura-2 and BCECF, respectively. RESULTS: Apoptosis (29.2+/-1.7% of cells) induced by exposure to simulated ischemia for 2 h was accompanied by cytosolic Ca2+ overload (1090+/-52 nmol/l) and acidosis (pHi = 6.52+/-0.13). Simulated ischemia had no significant effect on caspase-8 cleavage, but induced cleavage of caspase-3 and caspase-12 and led to a slight release of cytochrome C. Prevention of cytosolic acidosis (anoxia at pH(o) 7.4) had no effect on cytochrome C release, but significantly reduced apoptosis, attenuated cytosolic Ca2+ overload, and prevented cleavage of caspase-12. A similar effect was achieved by inhibition of Ca2+ release channels in the endoplasmic reticulum with ryanodine and xestospongin C. Knock-down of caspase-12 with small interfering RNA suppressed caspase-3 activation and reduced apoptotic cell number by about 70%. CONCLUSION: Acidosis, rather than anoxia, is an important trigger of apoptosis in EC under simulated ischemia. The main pathway of the simulated ischemia-induced apoptosis consists of the Ca2+ leak from the ER followed by activation of caspase-12 and caspase-3.

Acidosis↗
PubMed2006

Intramyocardial delivery of human CD133+ cells in a SCID mouse cryoinjury model: Bone marrow vs. cord blood-derived cells.

OBJECTIVE: The regenerative potential of endothelial and hematopoietic progenitor cells in the heart may vary according to their origin. This study was designed to compare the functional effects of CD133+ cells from human cord blood and bone marrow in a mouse model of myocardial injury. METHODS: 5 x 10(5) CD133+ cells from bone marrow (BM(CD133)) or cord blood (UCB(CD133)) were injected in the necrosis border zone of NOD/SCID (non-obese diabetic/severe combined immunodeficiency) mice with left ventricular cryoinjury (CI+). Transplanted cells were tracked by immunostaining for hNuclear antigen and by PCR for hDNA. Echocardiography was used to measure contractility. Scar size, capillary density, and cardiomyocyte apoptosis were evaluated by histology. In addition, the myogenic and endothelial differentiation capacity of BM(CD133) and UCB(CD133) was compared in vitro. RESULTS: DNA was detected 4 weeks after cell injection by PCR, but hNuc+ cells were found by immunostaining only after 48 h. Capillary density in both BM(CD133) and UCB(CD133) cell-treated CI+ mice was higher than in control CI+ mice, but not different between BM(CD133) and UCB(CD133) cell-treated hearts. There were no differences in scar size and myocardial mass among BM(CD133), UCB(CD133) and control CI+ mice, but cardiomyocyte apoptosis was reduced by both BM(CD133) and UCB(CD133) cells. The post-injury deterioration of shortening fraction (46.2+/-1% in sham-operated mice and 41.3+/-0.8% in control CI+ mice) was prevented by BM(CD133) cells (45.4+/-0.9%), but not by UCB(CD133) cells (40.8+/-0.7%). On the other hand, both BM(CD133) and UCB(CD133) cells abolished post-injury mortality. In vitro, neither cultivated BM(CD133) or UCB(CD133) cells developed into myocytes, but both readily differentiated towards an endothelial cell phenotype. CONCLUSIONS: While both cord blood and marrow CD133+ cells have some beneficial effects on post-injury angiogenesis and survival, only marrow cells appear to improve myocardial contractility.

AC133 Antigen↗
PubMed2006

Importance of endothelial nitric oxide synthase for the hypothermic protection of lungs against ischemia-reperfusion injury.

OBJECTIVES: The hypothesis that the protective effects of mild hypothermia against the pulmonary ischemia-reperfusion injury are mediated by endothelial nitric oxide synthase was tested. METHODS: Endothelial nitric oxide synthase knock-out and wild-type mice were sham operated or underwent a 1-hour occlusion of the left pulmonary hilum, followed by 5 hours of reperfusion. Temperature in the left pleural cavity during ischemia was maintained at either 36 degrees C (normothermia) or 32 degrees C (hypothermia). Inflammatory response (myeloperoxidase activity), endothelial barrier function (extravasation of Evans blue-labeled albumin), and endothelial nitric oxide synthase expression and phosphorylation were determined at the end of reperfusion. RESULTS: After normothermic ischemia both strains had a similar mortality (wild-type, 22.9%; knock-out, 15.4%), which was completely abolished by hypothermia. Endothelial barrier function was disturbed after normothermic ischemia in both wild-type and knock-out mice. Mild hypothermia significantly reduced pulmonary Evans blue extravasation in wild-type mice, but not in knock-out mice. Myeloperoxidase activity increased after normothermic ischemia to the same degree in both strains. This response was significantly attenuated by hypothermia in wild-type mice, but not in knock-out mice. In wild-type mice, endothelial nitric oxide synthase expression and phosphorylation were higher after hypothermic ischemia than after normothermic ischemia. No effect of ischemia on expression of inducible nitric oxide synthase was found in wild-type or knock-out mice. CONCLUSION: Hypothermic protection against pulmonary ischemia-reperfusion injury is dependent on endothelial nitric oxide synthase and is associated with increased expression and phosphorylation of endothelial nitric oxide synthase.

Animals↗
PubMed2006

Circulating endothelial cells demonstrate an attenuation of endothelial damage by minimizing the extracorporeal circulation.

OBJECTIVE: Detachment of endothelial cells may represent serious injury of the endothelium after cardiopulmonary bypass. We investigated whether the extent of endothelial injury is related to the type of cardiopulmonary bypass system used (conventional or minimized) and determined circulating endothelial cells as well as von Willebrand factor and soluble thrombomodulin. METHODS: Twenty patients scheduled for elective coronary bypass grafting were randomly assigned to either the minimal extracorporeal circulation system or the standard cardiopulmonary bypass. Ten healthy volunteers served as controls. Circulating endothelial cells per milliliter of full blood were perioperatively determined by immunomagnetic cell separation technique. Endothelial plasma markers were measured by enzyme-linked immunosorbent assay. RESULTS: Preoperative circulating endothelial cell numbers did not differ between the experimental groups, but were significantly higher than in the healthy controls (18.6 +/- 5.6 vs 7.2 +/- 3.8, P < .001). At 6 hours, circulating endothelial cell numbers increased significantly compared with baseline in both experimental groups and peaked at 12 hours after cardiopulmonary bypass initiation, each time with significantly lower values in the minimal extracorporeal circulation group (6 hours: 44.0 +/- 9.9 vs 29.6 +/- 9.8, P = .007; 12 hours: 48.1 +/- 6.8 vs 31.8 +/- 7.1, P < .001). Likewise, von Willebrand factor and soluble thrombomodulin postoperatively increased in both groups with a tendency toward lower levels in the minimal extracorporeal circulation group. Although circulating endothelial cells gradually declined, continually with lower numbers in the minimal extracorporeal circulation group, the endothelial plasma markers remained elevated during observation time. CONCLUSIONS: Circulating endothelial cells represent a novel marker of the intrinsic endothelial damage caused by cardiopulmonary bypass. Its analysis facilitates the evaluation of cardiopulmonary bypass modifications as the minimal extracorporeal circulation system could be proven to be less injurious to endothelium and myocardium.

Aged↗
PubMed2006

Pericardial suction blood separation attenuates inflammatory response and hemolysis after cardiopulmonary bypass.

OBJECTIVES: Retransfusion of pericardial suction blood (PSB) is critically considered under the aspect of the biocompatibility of the cardiopulmonary bypass (CPB). We investigated various indicators of inflammation and blood cell activation associated with CPB and re-transfusion of PSB during cardiac surgery. DESIGN: Thirty-five patients undergoing elective coronary artery bypass grafting were prospectively randomized into two groups. In group A (n = 15, retransfusion group) the pericardial suction blood was continuously retransfused during CPB, in group B (n = 20, no-retransfusion group) the suction blood was separated. Parameters indicating the status of the inflammation and blood cell activation were analyzed before and at the end of CPB, latest after 90 minutes on CPB. RESULTS: Patients' perioperative data did not differ between groups. The inflammatory markers C-reactive protein, PMN-Elastase and Interleukin-6 increased in both groups after CPB (p < 0.04) with significantly lower values in the no-retransfusion group (p < 0.02). Leukocytes and platelet activation markers beta-Thromboglobulin and soluble P-Selectin also experienced a significant elevation during observation time (p < 0.02) without any difference between the groups. Free hemoglobin and LDH tremendously increased during CPB with lower values in the no-retransfusion group. CONCLUSIONS: Cardiotomy suction is a major cause of hemolysis and contributes significantly to the systemic inflammatory response.

Biomarkers↗
PubMed2006

Effects of poly-2-methoxyethylacrylate (PMEA)-coating on CPB circuits.

OBJECTIVES: In this study, the immuno- and neuroprotective effect of a novel cardiopulmonary bypass coating was investigated. DESIGN: Thirty nine patients scheduled for elective coronary artery bypass grafting were randomly assigned to either PMEA-coated (n = 19) or non-coated CPB circuits (n = 20). Pericardial suction blood was separated and retransfused only if needed at the end of operation. Neurocognitive functions were examined preoperatively and 7-10 days postoperatively using a standard neuropsychological test battery. Assuming an inflammatory etiology, the most cogent inflammatory markers were perioperatively analyzed. RESULTS: Postoperatively, patients of the PMEA-coated group performed better in Go/NoGo and Mini-Mental-test than patients of the non-coated group (p < 0.04). Other neurocognitive testing did not reveal significant differences between the groups. Although most inflammatory parameters showed a significant intraindividual increase during or shortly after CPB, there was no difference in inflammatory alteration between the groups. CONCLUSIONS: PMEA-coating of cardiopulmonary bypass surfaces revealed some minor benefits in preservation of neurocognitive functions after surgery. The immediate inflammatory response remained mostly unaffected. Suction blood separation may additionally contribute to proper postoperative outcome.

Acrylates↗
PubMed2006

Stem cell therapy for ischemic heart disease: beginning or end of the road?

Despite improvements in emergency treatment, myocardial infarction is often the beginning of a downward spiral leading to congestive heart failure. Other than heart transplantation, current therapeutic means aim at enabling the organism to survive with a heart that is working at a fraction of its original capacity. It is therefore no surprise that cardiac stem cell therapy has raised many hopes. However, neither the ideal source and type of stem cell nor the critical cell number and mode of application have been defined so far. Early reports on myocardial repair by adult bone marrow stem cells from rodent models promoted an unparalleled boost of clinical and experimental cell therapy studies. The phenomenon of stem/progenitor cell-induced angiogenesis in ischemic myocardium has ever since been reproduced by numerous groups in a variety of small and large animal models. Myogenesis, however, is an altogether different matter. Many of the initial clinical studies were fueled by the suggestion that early hematopoietic stem cells have a plasticity high enough to enable cross-lineage differentiation into cells of cardiomyocyte phenotype, but the initial enthusiasm has largely faded. The myogenic potential of stroma cell-derived mesenchymal stem cells is much better documented in animal models, but transfer to the clinical setting faces a variety of obstacles. In clinical pilot trials, we and others have demonstrated the feasibility and safety of administering progenitor cells derived from autologous bone marrow to the myocardium of patients with ischemic heart disease. Clinical efficacy data are still rare, but the few controlled trials that have been completed uniformly show a tendency towards better heart function in cell-treated patients. This review is an attempt to describe the scientific basis for cardiac cell therapy from the point of view of the clinician, focusing on problems that arise with beginning translation into the clinical setting.

Cell Survival↗
PubMed2005

Human cord blood cells induce angiogenesis following myocardial infarction in NOD/scid-mice.

OBJECTIVE: We tested the hypothesis that intravenously administered human umbilical cord blood (hUCB) cells contribute to repair processes following myocardial infarction. METHODS: hUCB mononuclear cells containing 0.11% to 1.1% CD34(+) cells were injected in the tail vein of NOD/scid mice that had (MI+) or had not (MI-) previously undergone ligation of the left anterior coronary artery (LAD). Homing to bone marrow and solid organs was determined by polymerase chain reaction (PCR) for human DNA (hDNA) using human-specific primers of Locus D7Z1. Immunostaining was used for phenotypic analysis, and capillary density as well as myocardial scar formation was assessed. Moreover, expression of stromal cell-derived factor-1 (SDF-1) was studied in infarcted and in normal hearts. RESULTS: hDNA was detected in marrow, spleen, and liver of both MI+ and MI- mice 24 h, 1 week, and 3 weeks after cell injection. In the heart, however, hDNA was detected in 10 of 19 MI+ mice but in none of the MI- mice (p=0.002). Infarct size was smaller in cell-treated MI+ mice than in untreated MI+ hearts (38.7 versus 47.8%, P<0.05), and there was also less collagen deposition. In cell-treated MI+ mice, capillary density in the infarct border zone was approximately 20% higher (p=0.03), and clusters of hUCB-derived cells were detected in the perivascular interstitium. Occasionally, chimeric capillaries composed of human and mouse endothelial cells were found, but the vast majority of neo-vessels appeared to consist of mouse cells only. Up to 70% of the cord blood-derived cells in the heart were CD45(+). There was no evidence of cardiomyocyte differentiation as determined by co-localization of HNA or HLA-I with GATA-4 or Connexin 43. In infarcted myocardium, expression of SDF-1 mRNA was approximately 7-fold higher than in normal hearts. CONCLUSIONS: hUCB cells migrate to infarcted, not to normal myocardium, where they engraft, participate in neoangiogenesis, and beneficially influence remodelling processes. Cord blood cells may hence be useful for cell therapy of ischemic heart disease.

Animals↗
PubMed2005

Rat cytomegalovirus and Listeria monocytogenes infection enhance chronic rejection after allogenic rat lung transplantation.

The role of infection in the pathomechanism of obliterative bronchiolitis (OB) after human lung transplantation is controversial. In a rat lung transplantation model, we analyzed the effect of viral [rat cytomegalovirus (RCMV)] and bacterial infection [Listeria monocytogenes (LM)] on the development of chronic allograft rejection. Fisher rats underwent single left lung transplantation with allografts from Lewis rats. Postoperatively, animals were infected with either RCMV or LM, or served as noninfected controls. Animals were killed on day 120 and both lungs were evaluated histopathologically for chronic airway and chronic vascular rejection. Infection with RCMV produced a significant increase in the incidence of chronic airway rejection (66.7% vs. 20%), compared with noninfected long-term surviving animals. In rats with bacterial infection (LM) a similar increase of chronic airway changes as in viral infection (50% vs. 20%) was observed. Chronic rejection of allografts infected with either RCMV or LM was associated with significantly enhanced expression of intercellular adhesion molecule-1 (ICAM-1) on the endothelium. More infiltrating leukocytes (CD18, CD11a, CD44) and ED1-positive macrophages were found in allografts of infected animals. In this experimental model of chronic airway rejection in long-term surviving rats, not only viral but also bacterial infection resulted in enhanced development of chronic airway and vascular rejection. These results support our hypothesis that infectious complications have a substantial influence on the development of OB in human lung allografts.

Animals↗
PubMed2005

Evaluation of coated oxygenators in cardiopulmonary-bypass systems and their impact on neurocognitive function.

INTRODUCTION: Coronary artery bypass graft surgery (CABG) using cardiopulmonary bypass (CPB) is assumed to be associated with a decline of neurocognitive functions. This study was designed to analyse the neurocognitive function of patients with coronary heart disease before and after CABG and to determine possible protective effects of oxygenator surface coating on neurological outcome. METHODS: Forty patients scheduled for selective CABG were prospectively randomized into two groups of 20 patients each according to the type of hollow-fibre membrane oxygenator used. Non-coated oxygenators (Group A) were compared to phosphorylcholine (PC)coated oxygenators (Group B). A battery of six neurological tests was administered preoperatively, 7-10 days and 4-6 months after surgery. RESULTS: One patient of Group A suffered from a perioperative stroke and died on postoperative day 3, presumably because of sudden heart failure. Two patients of Group A (10%) developed a symptomatic transitory delirious psychotic syndrome (STPT) on postoperative days 3 and 5. None of the patients of Group B had perioperative complications. The test analysis revealed a trend of declined neurocognitive function early after CABG, but did not show any difference in neurocognitive outcome between the two groups. DISCUSSION: PC coating of the oxygenators did not show any significant benefit on neurocognitive function after CABG using CPB.

Aged↗
PubMed2004

Biomatrix/polymer composite material for heart valve tissue engineering.

BACKGROUND: Decellularized extracellular matrix has been suggested as a scaffold for heart valve tissue engineering or direct implantation. However, cell removal impairs the physical properties of the valve structure and exposes bare collagen fibers that are highly thrombogenic. Matrix/polymer hybrid valves with improved biological and mechanical characteristics may be advantageous. METHODS: Porcine aortic valves were decellularized enzymatically and impregnated with biodegradable poly(hydroxybutyrate) by a stepwise solvent exchange process. Biocompatibility was tested in vitro using cell proliferation and coagulation assays. Proinflammatory activity was assessed in vivo by implantation of matrix/polymer patches in the rabbit aorta. Biomechanic valve properties and fluid dynamics were tested in a pressure/flow-controlled pulse duplicating system. Matrix/polymer hybrid valves were implanted in pulmonary and aortic position in sheep. RESULTS: Biocompatibility assays indicated that human blood vessel cells survive and proliferate on matrix/polymer hybrid tissue. In vitro activation of cellular and plasmatic coagulation cascades was lower than with uncoated control tissue. After implantation in the rabbit aorta, matrix/polymer hybrid patches healed well, with complete endothelialization, mild leukocyte infiltration, and less calcification than control tissue. Matrix/polymer hybrid tissue had superior tensile strength and suture retention strength, and hybrid valves showed good fluid dynamic performance. The two valves in aortic position performed well, with complete endothelialization and limited inflammatory cell invasion after 12 weeks. Of the two valves in pulmonary position, one failed. CONCLUSIONS: Matrix/polymer hybrid tissue valves have good biological and biomechanic characteristics and may provide superior replacement valves.

Absorbable Implants↗
PubMed2004

Up-regulation of endothelial nitric oxide synthase inhibits pulmonary leukocyte migration following lung ischemia-reperfusion in mice.

Endogenous nitric oxide (NO) is known to modulate post-ischemic inflammatory response in various organs. However, the role of nitric oxide synthase isoforms (NOS) in mediating pulmonary post-ischemic inflammatory response is poorly understood. We therefore studied post-ischemic endothelial adhesion molecule expression and leukocyte migration in endothelial NOS knockout (eNOS-KO) mice subjected to pulmonary ischemia and reperfusion in vivo. Under anesthesia and mechanical ventilation, the left pulmonary hilum in wild-type (WT) and eNOS-KO mice was clamped for 1 hour, followed by reperfusion for up to 24 hours. In WT mice, we observed a selective up-regulation of both eNOS mRNA and protein in lung tissue, while inducible NOS (iNOS) and neuronal NOS (nNOS) remained unchanged. Survival in eNOS-KO mice was reduced due to severe pulmonary edema, underlining an increased susceptibility to ischemia-reperfusion (I/R) injury. Interstitial tissue infiltration by CD18- and CD11a-positive white blood cells as well as lung tissue water content peaked at 5 hours of reperfusion and were found significantly higher than in WT mice. Enhanced leukocyte-endothelial interaction was associated with pronounced up-regulation of vascular cell adhesion molecule (VCAM) in eNOS-KO mice during post-ischemic reperfusion. We conclude that eNOS attenuates post-ischemic inflammatory injury to the lung most probably via inhibition of endothelial adhesion molecule expression.

Animals↗
PubMed2004

Mechanical and structural properties of a novel hybrid heart valve scaffold for tissue engineering.

Hybrid heart valve scaffolds were fabricated from decellularized porcine aortic heart valve matrices and enhanced with bioresorbable polymers using different protocols: (i) dip coating of lyophilized decellularized matrices, and (ii) impregnation of wet decellularized matrices. The following polymers were evaluated: poly(4-hydroxybutyrate) and poly(3-hydroxybutyrate-co4-hydroxybutyrate). Tensile tests were conducted to assess the biomechanical behavior of valve leaflet strips. Suture retention strength was evaluated for the adjacent conduit. A pulse duplicator system was used for functional testing of the valves under physiological systemic load conditions. The properties of the hybrid structures were compared with native, decellularized, and glutaraldehyde-fixed specimens. Mechanisms of the polymer impregnation process were studied with IR spectroscopy, fluorescent microscopic imaging, and SEM. Altogether this study demonstrates the feasibility and improved biomechanical function of a novel hybrid heart valve scaffold for an application in tissue engineering.

Animals↗
PubMed2003

Autologous bone-marrow stem-cell transplantation for myocardial regeneration.

Implantation of bone-marrow stem cells in the heart might be a new method to restore tissue viability after myocardial infarction. We injected up to 1.5x10(6) autologous AC133+ bone-marrow cells into the infarct border zone in six patients who had had a myocardial infarction and undergone coronary artery bypass grafting. 3-9 months after surgery, all patients were alive and well, global left-ventricular function was enhanced in four patients, and infarct tissue perfusion had improved strikingly in five patients. We believe that implantation of AC133+ stem cells to the heart is safe and might induce angiogenesis, thus improving perfusion of the infarcted myocardium. See Commentary page 11

Aged↗
PubMed2002

Absence of PERV specific humoral immune response in baboons after transplantation of porcine cells or organs.

Xenotransplantation of pig organs seems a promising way of overcoming the prevailing limitation on allotransplantation due to donor numbers. However, as porcine endogenous retroviruses (PERVs) can infect human cells in vitro, there is substantial concern regarding the risk of a PERV infection in xenogeneic transplant recipients. Cultured porcine endothelial cells, stimulated peripheral blood mononuclear cells, and pancreatic islet cells can release PERV infectious for human cells in vitro, but it is currently unknown whether PERV is released in vivo, whether these viral particles can infect the transplant recipient, and whether they are pathogenic. In a retrospective study 15 immunosuppressed baboons were tested for a specific immune response against PERV after transplantation of porcine endothelial cells, mononuclear blood cells, and lungs. Anti-PERV antibody expression was analyzed with peptide-based, enzyme-linked immunosorbent assays and highly sensitive Western Blot assays. This xenotransplantation study using nonhuman primates found no evidence of PERV specific humoral immune response. Our data suggest that no productive PERV infection and no continuous PERV release takes place in the nonhuman primates analyzed in this study.

Animals↗
PubMed2002

[Cardiac tissue engineering].

BACKGROUND: Cardiac tissue engineering is a relatively new interdisciplinary approach to replace diseased cardiovascular tissues with vital structures based on autologous cells. VARIOUS FORMS: This includes the re-seeding of decellularized allogenic or xenogenic scaffolds with autologous cells, the fabrication of organoids based on artificial, biodegradable polymers, and cell transplantation in solid organs. FUTURE CLINICAL APPLICATION: Tissue engineering heart valves, vascular grafts, as well as transplantation of contractile cells or stem cells for myocardial regeneration are not far from their first clinical application. Even though the development of an entirely tissue engineered replacement heart is not yet conceivable, tissue engineering strategies will most likely lead to a significant improvement in the treatment of both acquired and congenital heart disease.

Cell Transplantation↗