Mario Lescan

Platelets induce apoptosis via membrane-bound FasL

After tissue injury, both wound sealing and apoptosis contribute to restoration of tissue integrity and functionality. Although the role of platelets (PLTs) for wound closure and induction of regenerative processes is well established, the knowledge about their contribution to apoptosis is incomplete. Here, we show that PLTs present the death receptor Fas ligand (FasL) on their surface after activation. Activated PLTs as well as the isolated membrane fraction of activated PLTs but not of resting PLTs induced apoptosis in a dose-dependent manner in primary murine neuronal cells, human neuroblastoma cells, and mouse embryonic fibroblasts. Membrane protein from PLTs lacking membrane-bound FasL (FasL(△m/△m)) failed to induce apoptosis. Bax/Bak-mediated mitochondrial apoptosis signaling in target cells was not required for PLT-induced cell death, but increased the apoptotic response to PLT-induced Fas signaling. In vivo, PLT depletion significantly reduced apoptosis in a stroke model and an inflammation-independent model of N-methyl-d-aspartic acid-induced retinal apoptosis. Furthermore, experiments using PLT-specific PF4Cre(+) FasL(fl/fl) mice demonstrated a role of PLT-derived FasL for tissue apoptosis. Because apoptosis secondary to injury prevents inflammation, our findings describe a novel mechanism on how PLTs contribute to tissue homeostasis.

Application of a rotating bioreactor consisting of low-cost and ready-to-use medical disposables for in vitro evaluation of the endothelialization efficiency of small-caliber vascular prostheses.

The incomplete endothelialization of especially small-caliber vascular prostheses after implantation in patients is a major disadvantage in cardiovascular interventions. The lack of an endothelium leads to the occurrence of thrombosis at the luminal surface of artificial vascular prostheses. Thus, the development of new graft materials and coatings for induction of complete endothelialization on the implant surfaces is a promising approach to improve hemocompatibility and maintain long-term graft patency. In this study, we designed a rotation model to evaluate the early endothelial cell (EC) seeding efficiency of different small-caliber vascular devices, such as stents and vascular grafts. The suitability of the designed rotation model for endothelialization studies was investigated by seeding and cultivation of prostheses with ECs followed by scanning electron microscopy. Furthermore, the viability of attached ECs was determined by calcein acetoxymethyl ester (AM) staining. The rotation model consisting of low-cost medical disposables enabled sterile incubation and cultivation of ECs with vascular devices. Simultaneously, the rotation of the bioreactor ensured a uniform distribution and adhesion of cells to the devices. Calcein AM staining of adherent cells on prostheses revealed excellent cell viability. Moreover, using the designed rotation model, an influence of different coatings and materials on the adhesion and spreading of ECs was demonstrated. The rotating bioreactor described and used in this study not only saves time and money but is also eminently useful for the accelerated preclinical evaluation of the endothelialization efficiency of different materials and surface coatings of small-caliber vascular devices.

Aortic elongation and the risk for dissection: the Tübingen Aortic Pathoanatomy (TAIPAN) project†

OBJECTIVES We measured aortic dimensions, particularly length parameters, using 3D imaging with the aim of refining the risk-morphology for Stanford type A aortic dissection (TAD). METHODS Computer tomography angiography studies were analysed using the curved multiplanar reformats. At defined landmarks, the diameters and lengths of aortic segments were recorded. Three groups were compared retrospectively: patients actually suffering from a TAD (TAD-group; n  = 150), patients before suffering a TAD (preTAD-group n  = 15) and a healthy control group ( n  = 215). Receiver operating characteristic curves (ROCs) were analysed (control versus preTAD) to study the diagnostic value of the individual variables. RESULTS Median diameters of preTAD (43 mm) and TAD (50 mm) aortas were significantly ( P  < 0.001) larger than those of the control group (35 mm). Ninety-three percent of preTAD and 68% of TAD aortas were less than 55 mm in the mid-ascending aorta. The ascending aorta and the aortic arch were significantly longer in both preTAD and TAD aortas compared to control aortas ( P  < 0.001); in the control aortas the central line distance from the aortic valve to the brachiocephalic trunk was 93 mm. In preTAD aortas, it was 111 mm, and it was 117 mm in TAD aortas ( P  < 0.001). In ROC analysis, the area under the curve was 0.912 for the ascending diameter and 0.787 for the ascending and arch lengths. CONCLUSIONS TAD-prediction based on the aortic diameter is ineffective. Besides circumferential dilatation, ascending aorta elongation precedes TAD and appears to be a useful additional parameter for prognostication. We propose a diagnostic score involving ascending aorta diameter and length.

Orthotopic branched endovascular aortic arch repair in patients who cannot undergo classical surgery

OBJECTIVES Our goal was to assess the results after orthotopic branched endovascular aortic arch repair using a new double-branch endoprosthesis in patients with thoracic aortic disease affecting the aortic arch who cannot undergo classical surgery. METHODS Within a 4-year period, 15 patients with thoracic aortic disease affecting the aortic arch were treated with the Bolton Relay plus double-branch endoprosthesis (Bolton Medical, Sunrise, FL, USA). We assessed clinical outcome, occurrence of endoleaks and the need for secondary interventions. The median logistic EuroSCORE I level was 13.6 (4.2; 22.8). RESULTS The in-hospital mortality rate was 6.7%. A disabling stroke was observed in 1 (6.7%) patient, whereas non-disabling strokes occurred in 2 (13.3%) patients. Type I and III endoleaks occurred in 6.7%. The median follow-up period was 263 (1st quartile 84; 2nd quartile 564) days. Four patients died during the follow-up period. Aortic-related survival was 100%. CONCLUSIONS Orthotopic branched endovascular aortic arch repair using the Bolton Relay Plus double-branch endoprosthesis is a safe and feasible technique enriching the armamentarium to treat patients with thoracic aortic disease who cannot undergo classical surgery. Aortic-related survival is excellent, and the occurrence of disabling stroke and endoleaks warranting treatment is low. Further studies are needed to assess the long-term durability of this new method.

Beneficial Effects On Cardiac Performance and Cardioprotective Properties of Milrinone after Cold Ischemia

Background: Cold Ischemia-Reperfusion Injury (CIRI) is regarded as the major cause of early graft dysfunction after cardiac transplantations and is associated with rejection episodes. Consequently, it is one of the main therapeutic targets in order to improve survival after heart transplantation. The aim of this study was to evaluate hemodynamic effects of milrinone and its influence on the markers of myocardial damage when used in a piglet working heart model with a cold ischemia-reperfusion setting. Methods: Hearts of 18 piglets were examined in a homologous blood-perfused, working heart model to get baseline measurements. After hypothermic cardioplegic arrest and storage on ice for 60 minutes, the hearts received either milrinone or served as controls. All hearts were examined for 45 minutes in the working heart model. Hemodynamic parameter changes, h-FABP levels and myocardial oxygen consumption were assessed. Results: Significant difference between the groups was observed in cardiac output (MIL +14% vs. CON -33%; p<0.05), coronary sinus blood flow (MIL +84% vs. CON +17%; p<0.05) and relaxation (MIL +5% vs. CON -22%; p<0.01). In addition, significantly higher h-FABP (heart fatty acid binding proteine) levels after cold ischemia were measured in CON group (CON: 18.75 ng/ml; MIL 6.29 ng/ml; p<0.01). Conclusions: Milrinone has a positive effect on cardiac function after cardioplegic cardiac arrest with following cold-ischemia period in an isolated piglet heart model. Its use in a heart transplantation setting induces an improved hemodynamic performance and a better preservation from reperfusion injury.

Aortic elongation in aortic aneurysm and dissection: the Tübingen Aortic Pathoanatomy (TAIPAN) project

OBJECTIVES To study the lengths and diameters of aortic segments in healthy and diseased aortas and to assess the role of aortic elongation in Type A aortic dissection (TAD) prediction. METHODS Ectasia and aneurysm were defined by ascending aorta diameters of 45-54 mm and ≥55 mm, respectively. Computed tomography angiography studies of 256 healthy, 102 ectasia, 38 aneurysm, 17 pre-TAD and 166 TAD aortas were analysed using curved multiplanar reformats. RESULTS The study groups were structurally equal. The diameter of the ascending aorta was 35 mm in the control group and was larger (P < 0.001) in the pre-TAD (43 mm) and TAD (56 mm) groups. The length of the ascending aorta from the aortic annulus to the brachiocephalic trunk was 92 mm in the control group, 113 mm in the ectasia group, 120 mm in the aneurysm group and 111 mm and 118 mm in the pre-TAD and TAD groups (all P < 0.001 compared with the control group). An ascending aorta length of 120 mm was exceeded in 2% of the control group, 31% of the ectasia group, 50% of the aneurysm group, 24% of the pre-TAD group and 48% of the TAD group. The correlation between the diameter and the length of the ascending aorta was r = 0.752; therefore, both parameters must be examined separately. A score considering both parameters identified 23.5% of pre-TAD patients, significantly more than the diameter alone, and 31.4% of ectasia aortas were elongated. CONCLUSIONS Patients with ectatic (45-54 mm diameter) and elongated (≥120 mm) ascending aortas represent a high-risk subpopulation for TAD.

The preoperative management of a patient with a large aneurysm of the sinus of valsalva and takotsubo cardiomyopathy

We report a case of a 43-year-old woman, who presented with thoracic interscapular pain at a peripheral hospital. In addition, the patient reported retrosternal pain, which had occurred only hours before–after an upsetting telephone call. The CT imaging ruled out an aortic dissection but revealed a huge sinus valsalva aneurysm (SVA) while the laboratory parameters showed slightly elevated troponin T value. Echocardiography showed an akinesia of the midventricular and apical left ventricular wall, accompanied by normal basal contractility. Stenotic coronary disease and endomyocarditis could be excluded as the origin of the contractility disorders. The synopsis of the findings and patient’s medical history led to the assumption of the takotsubo cardiomyopathy triggered by stress due to the worrying telephone call and the pain originating from the symptomatic SVA. We decided to perform an elective operation of the symptomatic aneurysm after restitution of the ejection fraction—as expected in takotsubo cardiomyopathy—instead of an emergency operation.

Custom-made Stent Grafts for the Treatment of Pseudoaneurysms after Childhood Coarctation Surgery

Background Post‐coarctation of the aorta (CoA) pseudoaneurysms is a complication of open repair. Thoracic endovascular repair (TEVAR) is feasible but complicated by proximity to the supra‐aortic trunks and severe arch angulation. Methods We describe three cases of post‐CoA pseudoaneurysms treated with custom‐made Relay stent grafts (Vascutek, Scotland). Results Technical and clinical success was achieved in all three cases with no mortality, morbidity, endoleaks, or complications. In all three, pseudoaneurysm sac shrinkage was observed at the follow‐ups; in one case, there was complete resolution. Conclusion Redo open surgery is challenging because of adhesions of the thoracic cavity and associated morbidity and mortality. TEVAR is less invasive and offers fewer complications. Custom‐made modifications overcome difficult anatomies including short landing zones and diameter variability.

Hybrid Off-pump Second-Stage Aortic Arch Repair after Type A Dissection.

BACKGROUND  Ascending aorta or hemi-arch repair are common in the acute phase of type A dissection. Postdissection aneurysms can develop with antegrade perfusion of the false lumen in the dissected aortic arch and require reoperation. METHODS  From 2012 to 2018, we reoperated nine patients with postdissection aneurysms using a hybrid technique without cardiopulmonary bypass. The patients had a EuroSCORE II of 13% and a logistic EuroSCORE I of 45% and were not candidates for frozen elephant trunk surgery. The median interval since the acute ascending repair was 184 (92; 528) days. All patients were treated by median resternotomy, ascending to carotid bypass on a partially clamped ascending graft, and transfemoral endovascular repair with a Relay NBS (nonbare stent) or conformable Gore C-TAG stent graft. RESULTS  Technical success was achieved in all cases. Mean follow-up was 405 (220; 672) days. There was no disabling stroke, endoleak, paraplegia, in-hospital, or late mortality. In all patients, the false lumen was completely thrombosed at the aortic arch level with a median aneurysm shrinkage of 13 mm in the distal arch. There was no bird beak or stent graft migration. Distal stent-induced new entry was observed in one case. Reinterventions were not necessary due to diameter stability. CONCLUSION  Complete debranching with transfemoral thoracic endovascular aneurysm repair showed encouraging results in patients with relevant comorbidities. The used stent grafts performed well in the mid-term follow-up period with no endoleaks or migration.

De Novo Synthesis of Elastin by Exogenous Delivery of Synthetic Modified mRNA into Skin and Elastin-Deficient Cells

Elastin is one of the most important and abundant extracellular matrix (ECM) proteins that provide elasticity and resilience to tissues and organs, including vascular walls, ligaments, skin, and lung. Besides hereditary diseases, such as Williams-Beuren syndrome (WBS), which results in reduced elastin synthesis, injuries, aging, or acquired diseases can lead to the degradation of existing elastin fibers. Thus, the de novo synthesis of elastin is required in several medical conditions to restore the elasticity of affected tissues. Here, we applied synthetic modified mRNA encoding tropoelastin (TE) for the de novo synthesis of elastin and determined the mRNA-mediated elastin synthesis in cells, as well as ex vivo in porcine skin. EA.hy926 cells, human fibroblasts, and mesenchymal stem cells (MSCs) isolated from a patient with WBS were transfected with 2.5 μg TE mRNA. After 24 hr, the production of elastin was analyzed by Fastin assay and dot blot analyses. Compared with untreated cells, significantly enhanced elastin amounts were detected in TE mRNA transfected cells. The delivered synthetic TE mRNA was even able to significantly increase the elastin production in elastin-deficient MSCs. In porcine skin, approximately 20% higher elastin amount was detected after the intradermal delivery of synthetic mRNA by microinjection. In this study, we demonstrated the successful applicability of synthetic TE encoding mRNA to produce elastin in elastin-deficient cells as well as in skin. Thus, this auspicious mRNA-based integration-free method has a huge potential in the field of regenerative medicine to induce de novo elastin synthesis, e.g., in skin, blood vessels, or alveoli.