Outcomes of transcatheter mitral valve replacement for degenerated bioprostheses, failed annuloplasty rings, and mitral annular calcification.

Aims: We sought to evaluate the outcomes of transcatheter mitral valve replacement (TMVR) for patients with degenerated bioprostheses [valve-in-valve (ViV)], failed annuloplasty rings [valve-in-ring (ViR)], and severe mitral annular calcification [valve-in-mitral annular calcification (ViMAC)]. Methods and results: From the TMVR multicentre registry, procedural and clinical outcomes of ViV, ViR, and ViMAC were compared according to Mitral Valve Academic Research Consortium (MVARC) criteria. A total of 521 patients with mean Society of Thoracic Surgeons score of 9.0 ± 7.0% underwent TMVR (322 patients with ViV, 141 with ViR, and 58 with ViMAC). Trans-septal access and the Sapien valves were used in 39.5% and 90.0%, respectively. Overall technical success was excellent at 87.1%. However, left ventricular outflow tract obstruction occurred more frequently after ViMAC compared with ViR and ViV (39.7% vs. 5.0% vs. 2.2%; P < 0.001), whereas second valve implantation was more frequent in ViR compared with ViMAC and ViV (12.1% vs. 5.2% vs. 2.5%; P < 0.001). Accordingly, technical success rate was higher after ViV compared with ViR and ViMAC (94.4% vs. 80.9% vs. 62.1%; P < 0.001). Compared with ViMAC and ViV groups, ViR group had more frequent post-procedural mitral regurgitation ≥moderate (18.4% vs. 13.8% vs. 5.6%; P < 0.001) and subsequent paravalvular leak closure (7.8% vs. 0.0% vs. 2.2%; P = 0.006). All-cause mortality was higher after ViMAC compared with ViR and ViV at 30 days (34.5% vs. 9.9% vs. 6.2%; log-rank P < 0.001) and 1 year (62.8% vs. 30.6% vs. 14.0%; log-rank P < 0.001). On multivariable analysis, patients with failed annuloplasty rings and severe MAC were at increased risk of mortality after TMVR [ViR vs. ViV, hazard ratio (HR) 1.99, 95% confidence interval (CI) 1.27-3.12; P = 0.003; ViMAC vs. ViV, HR 5.29, 95% CI 3.29-8.51; P < 0.001]. Conclusion: The TMVR provided excellent outcomes for patients with degenerated bioprostheses despite high surgical risk. However, ViR and ViMAC were associated with higher rates of adverse events and mid-term mortality compared with ViV.

Valve-in-valve transcatheter aortic valve implantation with CoreValve/Evolut R© for degenerated small versus bigger bioprostheses.

OBJECTIVES: We present our single center experience with Medtronic CoreValve and Evolut R regarding procedural outcome and 3 years follow-up in patients with degenerated bioprostheses. METHODS: From 1645 patients who underwent transfemoral TAVI at our institution between February 2009 and December 2016, 37 patients with degenerated bioprosthesis were treated with Medtronic CoreValve/Evolut R. All data concerning baseline characteristic, procedural outcomes and follow-up were entered into a dedicated database. RESULTS: Mean age was 83.9 ± 4.4 years and patients showed an average logistic EuroSCORE of 33.2 ± 16.7%. Successful ViV deployment was achieved in all cases, a permanent pacemaker was implanted in 16.2%, no periinterventional stroke and no coronary obstruction occurred. Mortality at 30 days was 2.7%, at 1-year follow-up 5.7% and at three years 13.5%. Depending on bioprosthesis size <23 mm versus ≥23 mm echocardiographic mean gradients post implantation were significantly higher in the smaller bioprostheses, 22.8 mmHg ± 9.4 mmHg versus 15.1 ± 7.1, P = 0.013. CONCLUSION: ViV-TAVI with CoreValve/R is demonstrated to be safe and effective in terms of no coronary obstruction and very low mortality up to 3 years despite slightly higher mean transprosthetic gradients especially in very small bioprostheses.

Transcatheter Aortic Valve Implantation in Nonagenarians: Procedural Outcome and Mid-Term Results.

BACKGROUND: For nonagenarians with symptomatic severe aortic stenosis transcatheter aortic valve implantation (TAVI) has become a feasible therapeutic option. Therefore, the aim of this study was to evaluate the procedural outcomes and mid-term follow-up in this patient group and compare this to octogenarians. METHODS: From 1359 patients who underwent TAVI at our institution between March 2009 and February 2016, 82 patients were nonagenarians and 912 were octogenarians. In nonagenarians, mean age was 91.9±1.4years and compared to octogenarians showed a significantly higher logistic EuroScore (27.7±14.8% vs. 23.1±14.4, p=0.005) and STS Score (8.5±4.8% vs. 6.3±6.7, p=0.001). RESULTS: There were no significant differences with regard to stroke rate, pacemaker implantation rate and major vascular complications between the two groups. Thirty-day mortality was 9.8% in nonagenarians and 4.1% in octogenarians (p=0.04). At 1 year, all-cause mortality increased to 30.9% vs. 18.6% (n.s.). CONCLUSION: Nonagenarians showed an increased periprocedural mortality during TAVI and higher mortality in follow-up compared to octogenarians. Age alone is not a predictive factor but indication for treatment should be carefully evaluated by the heart team on an individual basis.

Clopidogrel significantly lowers the development of atherosclerosis in ApoE-deficient mice in vivo.

The anti-platelet drug clopidogrel has been shown to modulate adhesion molecule and cytokine expression, both playing an important role in the pathogenesis of atherosclerosis. The aim of this study was to investigate the impact of clopidogrel on the development and progression of atherosclerosis. ApoE(-/-) mice fed an atherogenic diet (cholesterol: 1 %) for 6 months received a daily dose of clopidogrel (1 mg/kg) by i.p. injection. Anti-platelet treatment was started immediately in one experimental group, and in another group clopidogrel was started 2 month after beginning of the atherogenic diet. Blood was analysed at days 30, 60 and 120 to monitor the lipid profile. After 6 months the aortic arch and brachiocephalic artery were analysed by Sudan IV staining for plaque size and by morphometry for luminal occlusion. Serum levels of various adhesion molecules were investigated by ELISA and the cellular infiltrate was analysed by immunofluorescence. After daily treatment with 1 mg/kg clopidogrel mice showed a significant reduction of atherosclerotic lesions in the thoracic aorta and within cross sections of the aortic arch [plaque formation 55.2 % (clopidogrel/start) vs. 76.5 % (untreated control) n = 8, P < 0.05]. After treatment with clopidogrel P-/E-selectin levels and cytokine levels of MCP-1 and PDGFß were significantly reduced as compared to controls. The cellular infiltrate showed significantly reduced macrophage and T-cell infiltration in clopidogrel-treated animals. These results show that clopidogrel can effectively delay the development and progression of 'de-novo' atherosclerosis. However, once atherosclerotic lesions were already present, anti-platelet treatment alone did not result in reverse remodelling of these lesions.

Clopidogrel reduces post-transplant obliterative bronchiolitis.

Survival after lung transplantation is mainly limited by the development of chronic lung allograft dysfunction (CLAD). The aim of this study was to investigate if platelet inhibition by clopidogrel has an influence on the formation of obliterative bronchiolitis, the histopathological correlate to bronchiolitis obliterans syndrome, present in the majority of patients suffering from CLAD. C57Bl/6(H2(b) ) donor tracheas were orthotopically transplanted into CBA.J(H2(k) ). Mice received different doses of clopidogrel alone or in combination with tacrolimus or everolimus. Grafts were analyzed by histology and immunofluorescence method on postoperative days 15, 30 or 60. Cytokines were analyzed by real-time polymerase chain reaction on postoperative day 21 and alloantibodies by FACS. Mice treated with 20 mg/kg/day clopidogrel for 30 days showed reduced obliteration [34.40 ± 3.76% (20 mg/kg/day clopidogrel) vs. 49.92 ± 2.11% (control), n = 5, P < 0.05]. Platelet inhibition resulted in significant lower infiltration of T cells and macrophages, and we also found significantly lower expression of IL-12, IL-4, IL-6, TNF-α, TGF-ß, PDGFß, MCP1, P-/E-selectin, ICAM1 and CD40L after treatment with clopidogrel. Combination of 1 mg/kg/day clopidogrel and 0.05 mg/kg/day everolimus or 12 mg/kg/day tacrolimus revealed a synergistic effect. Humoral immunity as manifested by donor-specific alloantibody secretion was also impaired after treatment with clopidogrel. Here, we can show that platelet inhibition by clopidogrel as a single treatment and in combination with tacrolimus or everolimus reduced the development of fibrosis and obliteration in tracheal allografts.

Cytomegalovirus Donor Seropositivity Negatively Affects Survival After Heart Transplantation.

BACKGROUND: Prior studies have shown that cytomegalovirus (CMV) infection is a risk factor for the development of cardiac allograft vasculopathy (CAV) and is associated with reduced long-term survival after heart transplantation (HTx). The aim of this International Society for Heart and Lung Transplantation Transplant Registry study was to compare posttransplant survival in different CMV donor:recipient serologic combinations. METHODS: We performed a retrospective cohort study, using the International Society for Heart and Lung Transplantation Thoracic Transplant Registry, on 15 885 adult primary heart transplant recipients with known CMV serologic status between July 2004 and June 2014. Posttransplant survival and risk of developing CAV were compared across 4 groups: CMV-seronegative recipients (R-) receiving CMV-positive grafts (D+), intermediate-risk patients (D+R+ and D-R+), and low-risk patients (D-R-). RESULTS: Baseline characteristics (donor/recipient age, body mass index, recipient serum creatinine, blood group, donor cause of death, recipient diagnosis, and ischemic time) were mostly balanced between the groups. Kaplan-Meier survival analyses over a follow-up of 10 y revealed significantly worse survival for both D+ groups as compared to the CMV low-risk group (D+R+: 56.61% [95% confidence interval, 53.94-59.41] versus D-R-: 63.09% [59.74-66.64] P < 0.01 and D+R-: 57.69% [56.03-59.39] versus D-R-; P < 0.001), whereas recipient seropositivity alone was not associated with reduced survival (D-R+ versus D-R-P = 0.178). The risk of developing CAV after HTx was not significantly increased in D+ as compared to D- groups. CONCLUSIONS: In a large contemporary cohort, CMV status at the time of HTx was not associated with CAV development. However, there was a significant association between donor CMV seropositivity and reduced short- and long-term survival after HTx. Approaches to mitigate the impact of CMV on posttransplant survival are needed.

Nintedanib reduces alloimmune-induced chronic airway changes in murine tracheal allografts.

BACKGROUND: The major obstacle for long-term survival after successful lung transplantation is the development of bronchiolitis obliterans (BO) which is one phenotype of chronic lung allograft dysfunction (CLAD). Nintedanib has beneficial effects treating neoplastic diseases and idiopathic pulmonary fibrosis by blocking tyrosine kinase receptors. These receptors play an important role in alloimmune-mediated proliferative diseases. The aim of this study was to determine the effect of nintedanib on proliferative airway changes after orthotopic trachea transplantation in mice. METHODS: C57BL/6 mice (H-2b) donor tracheas were orthotopically transplanted into CBA/J mice (H-2k). After transplantation, recipients were daily treated with nintedanib (60 mg/kg; p.o.). Histological and immunofluorescence analysis were performed after 30 days and intragraft gene expression measurements after 14 days of treatment, respectively. RESULTS: Tracheal allografts from mice treated with nintedanib showed significantly less features of chronic rejection than untreated allografts reflected in a higher epithelium/lamina propria ratio (ELR) [ELR: 0.65 ± 0.13 nintedanib vs. 0.50 ± 0.07 untreated controls; p < 0.05] and a reduced submucosal smooth muscle actin (SMA) content [SMA: 1.26% ± 0.78% nintedanib vs. 2.18% ± 1.01% untreated controls; p < 0.01]. Furthermore, lower T cell, macrophage and dendritic cell infiltration was detected in the nintedanib treated grafts. The protein and intragraft mRNA expression of receptor subtypes was considerably decreased in grafts of nintedanib treated mice. The mRNA expression of relevant immune mediators was affected by nintedanib treatment. CONCLUSION: Receptor blocking by nintedanib reduced alloimmune-induced inflammation and chronic airway changes in mouse trachea allografts and might be a promising approach to diminish the development of BO in lung transplants.

Direct Impact of Human Platelets on the Development of Transplant Arteriosclerosis.

BACKGROUND: Platelets play an important role in the pathogenesis of inflammatory and proliferative vascular changes. The aim of this study was to investigate whether human platelets are able to induce transplant arteriosclerosis in a humanized C57/Bl6-Rag2-/-γc-/- mouse xenograft model. METHODS: Nonactivated and in vitro-activated human platelets were analyzed and phenotyped for surface markers by flow cytometry. Side branches of human mammary arteries were implanted into the infrarenal aorta of recipients, followed by daily application of human platelets and histological analyzed on day 30 after transplantation. RESULTS: Human platelets collected by apheresis had low levels of platelet activation markers. However, after in vitro activation, expression was markedly increased. Sixty minutes after injection in recipient mice, nonactivated human platelets become significantly activated. Increased adhesion of platelets to the vascular endothelium was detected by in vivo fluorescence microscopy. After intravenous injection of nonactivated or activated platelets, human xenografts showed pronounced intimal proliferation. Immunohistological analysis showed that the group treated with activated human platelets exhibited significantly increased intragraft protein expression of intracellular adhesion molecule-1 and platelet-derived growth factor receptor beta and smooth muscle cell migration into the neointima. CONCLUSIONS: These data demonstrate that an isolated daily application of both in vivo- and in vitro-activated human platelets results in the development of transplant arteriosclerosis in a humanized mouse transplantation model.

Microvasculature in murine tracheal allografts after combined therapy with clopidogrel and everolimus.

OBJECTIVES: Survival after lung transplantation is mainly limited by the development of chronic lung allograft dysfunction. Previous studies have suggested T-cell mediated proliferation and microvascular changes in experimental small airways models as potential therapeutic targets. The aim of this study was to assess microvascular changes in murine orthotopic tracheal allografts after treatment with everolimus alone or in combination with clopidogrel. METHODS: C57Bl/6 (H-2b) donor tracheas were orthotopically transplanted into CBA (H-2k) recipients. Mice received daily injections of everolimus (0.05 mg/kg) alone or combined with clopidogrel (1 mg/kg). Twenty-eight days after transplantation, ratio of the thickness of tracheal epithelium and lamina propria was measured as an indicator for chronic rejection. Additionally, graft oxygenation and graft perfusion were detected on postoperative days 4, 10 and 28. Quantitative reverse transcription polymerase chain reaction analysis was used for gene expression analysis. RESULTS: While syngeneic grafts showed a stable tissue pO2 and undisturbed microvascular perfusion, rejecting allografts had a drastic decline in both parameters as well as a flattened epithelium and an increased thickness of the lamina propria. Treatment with everolimus reduced allogeneic fibroproliferation, but had no protective effects on the microvasculature; polymerase chain reaction analysis indicated hypoxic stress and inflammation. Combining everolimus with clopidogrel improved microvascular integrity in the tracheal grafts, but had no synergistic effect in preventing obliterative bronchiolitis development. CONCLUSIONS: These data demonstrate that the ability of everolimus to reduce the development of post-transplant obliterative bronchiolitis is not caused by microvascular protection and has no synergistic effects with clopidogrel in acute airway rejection.

Combination of clopidogrel and everolimus dramatically reduced the development of transplant arteriosclerosis in murine aortic allografts.

Our group has shown that platelet inhibition with clopidogrel, an antagonist of the P2Y12 adenosine diphosphate receptor on platelets, reduced the formation of transplant arteriosclerosis. The aim of this study was to investigate whether a combination of cyclosporin or everolimus with clopidogrel has a beneficial effect on the development of transplant arteriosclerosis. Fully MHC mismatched C57Bl/6 (H2(b)) donor aortas were transplanted into CBA.J (H2(k)) recipients and mice received either clopidogrel alone (1 mg/kg/day) or in combination with cyclosporin (2 mg/kg/day) or everolimus (0.05 mg/kg/day). Grafts were analysed by histology and morphometry on day 30 after transplantation. In mice treated with clopidogrel alone, transplant arteriosclerosis was significantly reduced [intima proliferation 56 +/- 11% vs. 81 +/- 7% (control)/n = 7]. Daily application of everolimus reduced the development of transplant arteriosclerosis compared with untreated controls [intima proliferation of 29 +/- 9% vs. 81 +/- 7% (control)/n = 7]. Strikingly, combination of clopidogrel and everolimus almost abolished the formation of transplant arteriosclerosis [intima proliferation: 11 +/- 8% vs. 81 +/- 7% (control)/n = 7]. By contrast, combination of cyclosporin and clopidogrel compared with clopidogrel alone showed no additive effect. These results demonstrate that combination of platelet- and mammalian target of Rapamycin-inhibition can dramatically reduce the development of transplant arteriosclerosis.

Angiographic assessment of cardiac allograft vasculopathy: results of a Consensus Conference of the Task Force for Thoracic Organ Transplantation of the German Cardiac Society.

Angiograms of cardiac transplant (HTx) recipients were to be evaluated in a ring experiment and a joint consensus on criteria of angiographic evaluation of coronary arteries of HTx patients was to be reached. Twenty-four coronary angiograms from 11 hospitals were circulated. One hundred eighty-eight blinded evaluations were returned. A joint evaluation by six experienced cardiologists was used as reference standard and a consensus evaluation form was developed. Significant lesions (stenosis 75%, 50% in the left main coronary artery) were diagnosed in 10/23 abnormal coronary angiograms (41.7%). Interventional revascularization was recommended in 8/10 (80%). In 21 coronary angiograms distal pruning was found and in 11/21 (52.4%) cases with distal pruning occlusion of at least one peripheral vessel was detected. The best kappa value (0.7) was found for the presence of at least one clinically significant stenosis. Agreement on the site and grade of local stenosis was much less. Some agreement on remodeling was found in assessing diffuse narrowing in the LCA (kappa=0.371, P<0.001). The kappa value for peripheral obliteration was 0.331 (P=0.001). Angiographic evaluation of cardiac allograft vasculopathy, particularly of diffuse and peripheral disease and remodeling, needs standardization. This should be performed in a downward compatible improvement process.

Unaltered levels of transplant arteriosclerosis in the absence of the B cell homing chemokine receptor CXCR5.

Chemokine receptors and their ligands are crucial for lymphocyte trafficking under both homeostatic and inflammatory conditions. The chemokine receptor CXCR5 controls B cell migration and the organization of B cell follicles. The aim of this study was to investigate the impact of CXCR5 on the development of transplant arteriosclerosis. Fully MHC mismatched BALB/c (H2(d)) donor aortas were transplanted into C57BL/6-CXCR5(-/-) (H2(b)), C57BL/6-CXCR5(+/-) (H2(b)) or C57BL/6-CXCR5(+/+) (H2(b)) recipients. Grafts were analysed by morphometry and immunofluorescence and intra-graft cytokine mRNA production was analysed by RT-PCR. Transplant arteriosclerosis was evident in CXCR5+/+ and CXCR5+/- mice and only mildly reduced in CXCR5-/- recipients indicating that absence of CXCR5 had no substantial effect on the development of transplant arteriosclerosis. Analysis of the cellular infiltrate of aortic grafts implanted in CXCR5-/- recipients revealed no differences in the number of T-cells, macrophages and B cells as compared to controls. Intra-graft cytokine production showed no significant changes in Th1 (IL-12) and Th2 (IL-4) cytokines as well as in TGF-beta and iNOS production. These data suggest that lack of CXCR5 expression by recipient T- and B-cells has little effect on the development of transplant arteriosclerosis.

Experimental evaluation of the JenaClip transcatheter aortic valve.

OBJECTIVE: Transcatheter techniques of aortic valve replacement are a treatment option for valvular heart disease in high-risk surgical candidates. We evaluated a self-expanding valve system with a novel mechanism of fixation in an experimental setting in an acute animal model and ex vivo in aortic root specimens. METHOD: A self-expanding nitinol stent containing a pericardial tissue valve was implanted in a transapical approach in 15 sheeps. The valve was introduced under fluoroscopic guidance through a 22F sheath by means of a specially designed delivery catheter. Deployment was performed on the beating heart without cardiopulmonary bypass or rapid ventricular pacing and facilitated by positioning feelers anchoring the device to the native aortic cusps. To investigate release and anchoring of the device during retrograde implantation, the stent was also implanted in aortic root specimens obtained from an autopsy series. RESULTS: In animal experiments, stent deployment was primarily successful in 12 (80%) animals. Positioning feelers facilitated implantation by confirming the correct implantation plane of the stent and anchoring to the native aortic cusps. If primary location was not satisfactory the stent was retracted into the catheter and repositioned. After successful implantation no significant changes of hemodynamics were observed. Two animals (13%) developed ventricular fibrillation early in this experimental series due to displacement of one positioning element into a coronary ostium, major regurgitation was observed in two animals. Ex vivo evaluation of the device in aortic root specimens proved feasibility of stent release and leaflet fixation; ex vivo implantation was successful in all cases. CONCLUSION: In this study, we demonstrate feasibility of a leaflet-fixation device in nondiseased aortic valves. The JenaClip provides an effective concept of fixation with positioning feelers that allows exact positioning without outflow obstruction and anchoring the valve to the native leaflets. Further studies are necessary to investigate this concept in diseased aortic valves.

Platelets and Immune Responses During Thromboinflammation.

Besides mediating hemostatic functions, platelets are increasingly recognized as important players of inflammation. Data from experiments in mice and men revealed various intersection points between thrombosis, hemostasis, and inflammation, which are addressed and discussed in this review in detail. One such example is the intrinsic coagulation cascade that is initiated after platelet activation thereby further propagating and re-enforcing wound healing or thrombus formation but also contributing to the pathophysiology of severe diseases. FXII of the intrinsic pathway connects platelet activation with the coagulation cascade during immune reactions. It can activate the contact system thereby either creating an inflammatory state or accelerating inflammation. Recent insights into platelet biology could show that platelets are equipped with complement receptors. Platelets are important for tissue remodeling after injury has been inflicted to the endothelial barrier and to the subendothelial tissue. Thus, platelets are increasingly recognized as more than just cells relevant for bleeding arrest. Future insights into platelet biology are to be expected. This research will potentially offer novel opportunities for therapeutic intervention in diseases featuring platelet abundance.

Preservation of Microvascular Integrity in Murine Orthotopic Tracheal Allografts by Clopidogrel.

BACKGROUND: Survival after lung transplantation is mainly limited by the development of chronic lung allograft dysfunction (CLAD). The aim of this study was to investigate if platelet inhibition by clopidogrel has a functionally relevant influence on the microvascular integrity of orthotopic tracheal allografts as an anatomic basis for the development of CLAD. METHODS: We orthotopically transplanted C57Bl/6 (H-2) tracheas into CBA.J (H-2) recipients who afterwards received clopidogrel (1 mg/kg). Morphometric analysis was performed by measuring epithelial height in proportion to thickness of the lamina propria (epithelium-lamina propria ratio). Tissue oxygenation was determined using a fluorescence quenching technique, and graft perfusion monitoring was performed by laser Doppler flowmetry and lectin-binding assay. Immunohistochemistry was used for detection of CD31 and inducible nitric oxide synthase while iron deposition was shown with Prussian blue reaction. Quantitative reverse transcription polymerase chain reaction analysis was used for gene expression analysis. RESULTS: Isografts maintained good oxygenation and perfusion throughout the experiment, while both were drastically reduced in allografts. Treatment with clopidogrel attenuated graft hypoxia and reduced loss of perfusion. Additionally, clopidogrel led to increased epithelium-lamina propria ratio while iron deposition was impaired. Gene expression analysis revealed elevated levels of angiogenic vascular endothelial growth factor in the clopidogrel group. Improved endothelial function was shown by immunohistochemistry (CD31, inducible nitric oxide synthase). CONCLUSIONS: Continuous administration of clopidogrel significantly improved tissue oxygenation, limited microvascular leakiness, and prevented airway ischemia. These data demonstrate that clopidogrel ameliorates microvascular injury during acute airway rejection, which is a known predisposing factor for the development of CLAD.

Effect of donor cell type on complement-dependent cytotoxicity crossmatch outcome for patients immunized against HLA class-II antigens.

OBJECTIVES: In the Eurotransplant zone, the crossmatch serum exchange program was established to reduce unnecessary organ shipment, using the complement-dependent cytotoxicity crossmatch as the reference to make the decision. Crossmatching at the donor center dictates whether the transplant should be shipped to the recipient center where a decisive crossmatch would then be done. However, in recent years, the target cell used for the crossmatching has changed from spleen cells to peripheral blood lymphocytes. In this study, we assess the impact of this change on the outcome of complement-dependent cytotoxicity crossmatches for patients immunized against HLA-class II. MATERIALS AND METHODS: The influence of the donor cell type was analyzed by crossmatching unseparated peripheral blood lymphocytes, separated T and B lymphocytes, as well as spleen cells from 12 organ donors with sera from 40 immunized kidney retransplant candidates. Negative sera and sera harboring only anti-HLA class-II antibodies were used as additional controls. We did more than 1200 complement-dependent cytotoxicity crossmatches. RESULTS: Crossmatches with sera containing anti-HLA class-I plus class-II alloantibodies (n=113 per cell type) were positive in 42% of peripheral blood lymphocytes, 72% of spleen cells, and 81% of B cells. Crossmatches with sera containing exclusively anti- HLA class-II antibodies (n=89 per cell type) were positive in 1% of peripheral blood lymphocytes, 30% of spleen cells, and in 31% of B cells. Overall, spleen or separated B cells identified approximately 30% more positive donor-recipient pairs. CONCLUSIONS: The data show that the change from spleen cells to peripheral blood lymphocytes as donor target cells for complement-dependent cytotoxicity crossmatching increased risk of false negative results for patients harboring anti-HLA class-II antibodies.

Small Molecule Tyrosine Kinase Inhibitor Nintedanib Reduces Development of Cardiac Allograft Vasculopathy in Murine Aortic Allografts.

BACKGROUND: Nintedanib is a small molecule tyrosine kinase inhibitor that blocks the action of the platelet-derived growth factor receptor (PDGFR), the vascular endothelial growth factor receptor (VEGFR) and the fibroblast growth factor receptor. All of these receptors have been shown to be involved in the development of cardiac allograft vasculopathy (CAV) after heart transplantation. We therefore hypothesized that blocking these tyrosine kinase receptors with nintedanib could prevent CAV. METHODS: CBA/JRj (H2k) mice underwent an abdominal aortic transplantation with a graft derived from fully allogeneic C57BL/6JRj (H2b) mice. Nintedanib was given daily from the first day after transplantation until harvest on day 14 for polymerase chain reaction analysis of intragraft cytokine expression or harvest on day 30 for histological analysis of the graft. RESULTS: Nintedanib treatment resulted in significantly reduced neointima formation in the aortic graft compared with untreated control allografts. Interestingly, the immigration of smooth muscle cells into the neointima was markedly reduced while graft infiltrating macrophages and T cells were not altered in nintedanib-treated animals. The expression of the growth factor PDGF was significantly reduced in the nintedanib group going along with a distinctly reduced expression of the corresponding receptors PDGFR α and -ß. CONCLUSIONS: Treatment with nintedanib caused a significant reduction of CAV development after aortic transplantation in mice. We hypothesize the attenuated neointima formation in nintedanib-treated animals to be mediated by a direct inhibition of intimal smooth muscle cell proliferation via reduced expression of PDGF and the appropriate receptors PDGFR α + ß.

Effects of different serotonin receptor subtype antagonists on the development of cardiac allograft vasculopathy in murine aortic allografts.

BACKGROUND: Cardiac allograft vasculopathy (CAV) is the main obstacle for long-term survival after heart transplantation. Alloimmune mediated chronic vascular rejection results in several mechanisms like platelet activation, immigration of inflammatory cells through the endothelial layer and proliferation and migration of smooth muscle cells (SMCs). Serotonin (5-HT) promotes these processes via activation of 5-HT2 receptors. We hypothesized that inhibiting 5-HT2 receptors ameliorates the development of CAV. METHODS: CBA/JRj mice recieved aortic grafts from C57BL/6 mice. After transplantation until recovery of organs, recipients were treated with serotonin receptor antagonists: sarpogrelate (5-HT2A), SB 204741 (5-HT2B) or terguride (5-HT2A+B). Mice were sacrificed after 14 days for qRT-PCR analysis or after 30 days for histological evaluation. Serum serotonin ELISA was done at both time points. RESULTS: Elevated serum serotonin levels were significantly reduced after 5-HT2A antagonist treatment as was 5-HT2A receptor expression. This went along with reduced inflammation characterized by significantly fewer infiltrating macrophages and pro-inflammatory intragraft cytokines and with reduced tissue remodeling evident as significantly less neointima formation. CONCLUSION: Inhibition of the 5HT/5-HT2A receptor axis leads to significantly reduced neointima proliferation after aortic transplantation associated with reduced transendothelial migration of macrophages and decreased expression of inflammatory cytokines. These findings have translational implications as inhibitors of 5HT2A like sarpogrelate are already approved for clinical use.

Impact of sheath diameter of different sheath types on vascular complications and mortality in transfemoral TAVI approaches using the Proglide closure device.

OBJECTIVE: Evaluation of the impact of the sheath diameter on vascular complications and mortality in transfemoral aortic valve implantation. METHOD: Between 2012 and 2014, 183 patients underwent the procedure using a sheath diameter of 18-24 F. This collective was divided into two groups: group 1, with a sheath diameter of 18F (G1, n = 94), consisted of patients with 18F Medtronic Sentrant and 18 F Direct Flow sheaths, and group 2 with a sheath diameter of 19-24 F (G2, n = 89) consisted of patients with Edwards expandable e-sheath and Solopath sheaths. Perclose-Proglide® was used as a closure device in all patients. RESULTS: G1 had significantly more female patients (64.9% vs. 46.1% in G2, p = 0.01) and the average BMI was lower (26 ± 4.5% vs. 27.4 ± 4.7%, p = 0.03). There was no significant difference in the incidence of major and minor vascular complications (G1: 12.8% vs. G2: 12.4%, p = 0.9). 30-day mortality was similar in both groups (G1: 6.4 ± 2.5% [95% CI: 0.88-0.98], G2: 3.7 ± 1.9% [95% CI: 0.92-0.99]. The Kaplan Meier analysis of survival revealed no significant differences either. CONCLUSION: The difference in sheath diameter had no effect on either incidence or severity of vascular complications. There was no impact on mortality either.