Alexander Jabs

Peripheral blood mononuclear cells acquire myofibroblast characteristics in granulation tissue.

Background: Bone marrow-derived cell populations possess progenitor cell capacities. Emerging evidence also suggests significant plasticity of differentiated mononuclear cell lineages. We therefore assessed the distribution of transplanted peripheral blood mononuclear cells (PBMCs) in granulation tissue formation, and evaluated their possible transdifferentiation into myofibroblasts. Methods: Silastic tubes were inserted into the peritoneal cavity of rats, followed by injection of PKH26-labelled PBMCs isolated from donor animals. At 3, 14 and 21 days, the distribution of PKH26+ cells as well as their colocalization with myofibroblast/smooth muscle cell [α-smooth muscle (α-SM) actin] or macrophage markers (ED1/ED2) were determined. Results: Round-shaped PKH26+ cells accumulated around the implants at 3 days, while myofibroblasts were rare. Later, peritoneal granulation tissue constituted an inner, multilayered capsule primarily comprising α-SM actin+ cells that was surrounded by more loosely organized inflammatory connective tissue. PKH26-labelled, spindle-shaped cells were abundantly found in tissue capsules. As a key finding, granulation tissue at 14 and 21 days contained cells with both PKH26 and α-SM actin labelling. Accordingly, a subpopulation of cells staining positive for macrophage markers showed a spindle-shaped morphology and α-SM actin expression. Conclusions: Transplanted PBMCs contribute to granulation tissue, and acquire myofibroblast characteristics during de novo tissue formation. Mononuclear cells may transdifferentiate into myofibroblast-like cells within an inflammatory environment.

Pathogen burden, inflammation, proliferation and apoptosis in human in-stent restenosis: Tissue characteristics compared to primary atherosclerosis

Pathogenic events leading to in-stent restenosis (ISR) are still incompletely understood. Among others, inflammation, immune reactions, deregulated cell death and growth have been suggested. Therefore, atherectomy probes from 21 patients with symptomatic ISR were analyzed by immunohistochemistry for pathogen burden and compared to primary target lesions from 20 stable angina patients. While cytomegalovirus, herpes simplex virus, Epstein-Barr virus and Helicobacter pylori were not found in ISR, acute and/or persistent chlamydial infection were present in 6/21 of these lesions (29%). Expression of human heat shock protein 60 was found in 8/21 of probes (38%). Indicated by distinct signals of CD68, CD40 and CRP, inflammation was present in 5/21 (24%), 3/21 (14%) and 2/21 (10%) of ISR cases. Cell density of ISR was significantly higher than that of primary lesions (977 ± 315 vs. 431 ± 148 cells/mm2; p < 0.001). There was no replicating cell as shown by Ki67 or PCNA. TUNEL+ cells indicating apoptosis were seen in 6/21 of ISR specimens (29%). Quantitative analysis revealed lower expression levels for each intimal determinant in ISR compared to primary atheroma (all p < 0.05). In summary, human ISR at the time of clinical presentation is characterized by low frequency of pathogen burden and inflammation, but pronounced hypercellularity, low apoptosis and absence of proliferation.

Neointimal Expression of Rapamycin Receptor FK506-Binding Protein FKBP12 : Postinjury Animal and Human In-Stent Restenosis Tissue Characteristics

Despite excellent clinical results for sirolimus (rapamycin)-eluting stents, the exact mechanisms of antirestenotic activity and affected cellular targets are incompletely understood. Therefore, we determined the presence and tem- porospatial expression pattern of FKBP12, the primary intracellular receptor of rapamycin, in rat carotid arteries after balloon injury, as well as in human in-stent restenosis and primary stable coronary atheroma. FKBP12 expression was assessed by immunohistochemistry. Rat carotid arteries revealed maximal expression in 57.7 ± 4.0% of neointimal cells at day 7. A large proportion of these FKBP12+ cells showed luminally confined co-expression with dendritic cell markers. Despite a considerably thicker neointima at day 28, presence of FKBP12 decreased (8.5 ± 1.9%, p = 0.02) with a scattered pattern in luminal and deep neointima. Likewise, human in-stent restenosis atherectomy specimens (time after stent implantation 2–12 months) revealed a comparable extent of cellular rapamycin receptor expression (9.3 ± 1.0%) that significantly differed from that found in primary stable atheroma (1.3 ± 0.4%, p < 0.001). In conclusion, the rapamycin receptor is predominantly present during early neointima formation, while mature neointimal atheromas show a relatively low expression without confinement to luminal areas. Co-expression of FKBP12 and dendritic cell markers suggests that dendritic cells may be another important target for early and long-term rapamycin effects.

Feasibility and safety of left ventricular endomyocardial biopsy via transradial access: Technique and initial experience

Endomyocardial biopsy constitutes an essential part of the diagnostic algorithm in patients with heart failure of unknown origin, but usually requires transfemoral access.

Insights into vascular pathology after intracoronary brachytherapy

Die Restenose nach Angioplastie stellt weiterhin eine erstrangige Limitierung interventioneller Therapieverfahren dar. Verschiedene Evidenzen zeigen, dass die Expression von Promotoren myofibroblastoider Aktivität von der Neoadventitia zur Neointima wandert. Brachytherapie vermag die Aktivität (Proliferation, Migration) vaskulärer Zellen zu inhibieren, die intimale Rekrutierung dieser Zellen zu vermindern, und beeinflusst das vaskuläre Remodeling positiv, indem die adventitiale Konstriktion im Bereich der Gefäßverletzung verhindert wird. Diese Brachytherapie-Effekte sind dosisabhängig. Klinische und experimentelle Daten demonstrieren, dass die Restenose durch die Balance von arteriellem Remodeling und intimaler Hyperplasie determiniert wird. Offenbar spielt brachytherapieinduziertes positives Remodeling die entscheidende Rolle bei der Vergrößerung des luminalen Durchmessers nach PTCA und, im Falle von Unterdosierung bzw. Dosisabfall, als Ursache negativer Edge-Effekte. Für den klinischen Verlauf wahrscheinlich bedeutungsvoll und bisher eher unterschätzt sind Heilungs-Defekte, endotheliale Dysfunktion und Stent-Gefäßwand-Fehllage, die beitragen könnten zu später Thrombose und verzögerter intimaler Hyperplasie im Langzeitverlauf nach intrakoronarer Brachytherapie. Post-angioplasty restenosis is a major limitation of interventional cardiology. A large body of evidence reveals that expression of myofibroblast activity promoters moves progressively from the neoadventitia to the neointima. Brachytherapy inhibits vascular cell activity (proliferation, migration), mitigates recruitment of intimal cells, and shows a favorable prophylactic effect on late vascular remodeling by preventing adventitial constriction at the injured site. These effects of brachytherapy are dose related. Clinical and experimental data demonstrate that restenosis is determined by the balance between arterial remodeling and intimal hyperplasia. Apparently, brachytherapy-induced positive remodeling plays the principal role in increasing the luminal diameter after PTCA and, in case of a lower dose or dose fall-off, to cause detrimental edge effects. With regard to clinical course, healing defects, endothelial dysfunction and stent-vessel wall malapposition are apparently important and possibly underestimated features of vascular pathology, since they may contribute to late thrombosis and delayed intimal hyperplasia in long-term course after intracoronary brachytherapy.

Transcatheter aortic valve implantation with the new-generation Evolut R™

Background The Medtronic Evolut R (EVR) is a novel transcatheter heart valve designed to allow precise implantation at the intended position and to minimize prosthesis dysfunction as well as procedural complications. Our aim was to compare short-term functional and clinical outcomes of the new EVR with the established Medtronic CoreValve (CV) system. Methods and results Of 151 patients undergoing transfemoral transcatheter aortic valve implantation with a self-expanding valve at our institution between January 2013 and January 2016, 86 were treated with EVR and 65 with CV. Patients treated with EVR had a significantly lower rate of more-than-mild aortic regurgitation and a higher rate of device success. Recapture maneuvers to optimize valve deployment were performed in 22.1% of the EVR procedures. Transvalvular post-procedural gradients were slightly higher in the EVR group, while no differences were observed in the incidence of safety endpoints at 30 days, vascular complications, or need for permanent pacemaker implantation following asystole or complete atrioventricular block. Conclusions These initial single-center experience data on the short-term outcomes after EVR valve implantation show a substantially reduced rate of more-than-mild paravalvular regurgitation and higher device success, while 30-day safety outcomes were similar to the CV system. Clinical outcome data from long-term follow-up and larger scale multicenter experience are now necessary.

Comparison of transcatheter aortic valve implantation with the newest-generation Sapien 3 vs. Direct Flow Medical valve in a single center cohort

BACKGROUND The latest generation transcatheter heart valves including Edwards Sapien 3 (ES3) and Direct Flow Medical (DFM) were designed to allow precise implantation at the intended position and to minimize prosthesis dysfunction as well as procedural complications. Our aim was to compare short-term functional and clinical outcomes of these 2 transcatheter aortic valve systems. METHODS Of 174 patients undergoing transfemoral transcatheter aortic valve implantation (TAVI) at our institution between August 2013 and June 2015, 113 were treated with ES3 and 61 with DFM. Device success, residual aortic regurgitation and early safety endpoints were defined according to the updated VARC-2 criteria and prespecified as primary endpoints. RESULTS Patients treated with ES3 had a significantly higher rate of procedural success (ES3 94% vs. DFM 79%, p=0.005), mainly driven by lower postprocedural gradients (ES3 8.6±0.5mmHg vs. DFM 14.6±1.4mmHg by invasive recordings; p=0.00012) and no incidence of more than mild aortic regurgitation. The occurrence of safety endpoints at 30days was low and comparable in the DFM vs. ES3 group (ES3 88% vs. DFM 95% of patients without endpoints, p=0.26). No significant differences were observed in 30day mortality, stroke or the incidence of new permanent pacemaker implantation. CONCLUSIONS These single-center experience data show a higher rate of device success for ES3 treated patients, while 30day safety outcome was similar in both groups. Long-term follow-up and larger scale multicenter experience will have to assess possible effects of these observations on long-term clinical outcomes.

Parameters of blood viscosity do not correlate with the extent of coronary and carotid atherosclerosis and with endothelial function in patients undergoing coronary angiography

While the role of physical forces on the control of atherogenesis and the modulation of endothelial function is well known, studies investigating the impact of shear stress on the extent of central atherosclerosis and flow-mediated dilation in humans produced controversial results. We investigated the relationship between viscosity, coronary atherosclerosis, carotid intima-media thickness and flow-mediated dilation in patients undergoing coronary angiography. 451 patients (306 males, mean age 66 ± 10) were enrolled. Viscosity, which was calculated using a validated formula, showed a positive association with platelet activation (P = 0.01), leukocyte counts (P = 0.006) and C-reactive protein (P = 0.03), a marker of inflammation; surprisingly, visocsity showed a negative association with FMD (FMD decreased 0.14 ± 0.05% per each cPoise increase in viscosity) but only in patients without coronary artery disease. Viscosity showed no association with the extent of coronary or carotid artery disease. We provide cross-sectional data on the relationship between whole blood viscosity and parameters of vascular structure and function. While viscosity correlated with parameters of vascular inflammation, it showed no relationship with the presence and severity of central atherosclerosis.

Neointimale Hyperplasie durch luminale Zellrekrutierung und nicht durch transmurale Migration

Restenosis post angioplasty remains the major limitation of several therapeutic interventions including stent implantation. This explains the ongoing interest in its basic pathogenic mechanisms and factors. The aim of the present study was to assess the localization and maximal expression of Bcl-2, a central anti-apoptotic protooncogene, and of heat shock protein 47 (HSP47), a marker of early collagen synthesis, in the context with hyperplastic neointima formation as well as concomitant transmural remodeling processes following angioplasty. 0, 4, 24 and 48 hours, 4, 7 and 14 days post balloon traumatization by use of a rat carotid artery model, specific vascular wall compartments were evaluated concerning area, cell density as well as Bcl-2 and HSP47 expression by immunohistochemistry and morphometry, supplemented by electron microscopy (TEM). Neointimal cell accumulation was detected 4 days post angioplasty, characterized by luminal cells adherent to the internal elastic lamina, associated with maximal Bcl-2 and HSP47 expression amounting to 49% and 41%, respectively. With ongoing neointimal formation, a luminal prevalence of both key determinants and a decreasing expression in basal neointimal areas were found. In the media, a temporally reduced cell density was observed significant at 48 hours post trauma. Constitutive HSP47 expression of the media was constant during the entire observation period, whereas sparse Bcl-2 signalling was induced post angioplasty maximal on day 2 with 3% and on day 14 with 5%. The adventitia demonstrated a transient structural separation between day 4 and 7, exhibiting an inner layer with sparse cellularity and an outer layer with extremely high cell density as well as pronounced neovascularization. In this outer adventitia layer, a high frequency of signals for both Bcl-2 and HSP47 were observed amounting to 29% and 57%, respectively. Complementary TEM analysis gave no evidence of transmural migratory events propagated by adventitial cells and thereby supports early neointimal formation by luminal cell recruitment and marked co-expression of anti-apoptotic Bcl-2 and matrix-generating HSP47 as important survival factors. Clinical implications of these findings may be seen in the integration of proapoptotic substances with temporal efficacy in order to prevent restenosis, e.g., by use of coated stents. Die Restenose bleibt die wesentliche Limitierung verschiedener interventioneller Therapiemassnahmen, auch der Stentimplantation. Dies erklärt das unverändert große Interesse an ihren zugrundeliegenden Pathogenesemechanismen und -faktoren. Ziel der vorliegenden Arbeit war es, Lokalisation und Expressionsmaxima von Bcl-2, einem zentralen anti-apoptotischen Protoonkogen, und von Hitzeschockprotein 47 (HSP47), einem Marker früher Kollagensynthese, im Kontext mit der Formierung hyperplastischer Neointima und parallelen transmuralen Umbauprozessen nach Angioplastie zu untersuchen. 0, 4, 24 und 48 Stunden, 4, 7 und 14 Tage nach Ballontrauma wurden am Modell der A. carotis der Ratte einzelne Gefässwandkompartimente hinsichtlich Fläche, Zelldichte sowie Bcl-2- bzw. HSP47-Expression (immun-)histochemisch und morphometrisch evaluiert, ergänzt durch Elektronenmikroskopie (TEM). Neointimale Zellakkumulation war bereits 4 Tage nach Angioplastie nachweisbar, ausgewiesen durch Adhäsion luminaler Zellen an die Lamina elastica interna, assoziiert mit maximaler Bcl-2- sowie HSP47-Expression von 49% bzw. 41% aller gezählten Zellen. Mit zunehmender Neointima demarkierte sich eine lumennahe Prävalenz beider Zieldeterminanten mit abnehmender Expression zu basalen Arealen. In der Media fand sich eine temporäre, lediglich 48 Stunden nach Trauma signifikant verminderte Zelldichte. Die konstitutive HSP47-Expression der Media war im gesamten Beobachtungszeitraum konstant, während für Bcl-2 nach Angioplastie wenige Signale nachweisbar waren mit Maximalwerten von 3% am Tag 2 und 5% am Tag 14. Die Adventitia wies eine transiente strukturelle Zweiteilung zwischen Tag 4 und 7 auf mit einer inneren, extrem zellarmen Schicht und einer äußeren Schicht bei sehr hoher Zelldichte sowie ausgeprägter Neovaskularisation. In dieser äußeren Adventitia waren hohe Signaldichten von Bcl-2 und HSP47 bis zu 29% bzw. 57% nachweisbar. Komplementäre TEM-Untersuchungen ergaben keine Hinweise auf die transmurale Migration adventitialer Zellen und stützen somit eine frühe Neointimaformierung durch luminale Zellrekrutierung bei hoher Co-Expression des anti-apoptotischen Bcl-2 und des Matrix-generierenden HSP47 als wichtige Überlebensfaktoren. Klinische Implikationen dieser Befunde könnten in der Integration befristet pro-apoptotischer Substanzen zur Restenoseprävention, z.B. in beschichteten Stents, liegen.

Drug-Eluting Stent-Induced Vascular Dysfunction: Common and Missing Links

We read with great interest the study by Shiroto et al. ([1][1]), who identify the Rho-kinase (ROCK) pathway to play a role in the pathogenesis of drug-eluting stent (DES)-induced coronary hyperconstrictive responses. Specifically, they observed paclitaxel-induced up-regulation of ROCK in cultured