Performance and Morphology of Decellularized Pulmonary Valves Implanted in Juvenile Sheep
ABSTRACT Because of cryopreserved heart valve-mediated immune responses, decellularized allograft valves are an attractive option in children and young adults. The objective of this study was to investigate the performance and morphologic features of decellularized pulmonary valves implanted in the right ventricular outflow tract of juvenile sheep.
Right ventricular outflow tract reconstructions in juvenile sheep (160±9 days) using cryopreserved pulmonary allografts (n=6), porcine aortic root bioprostheses (n=4), or detergent/enzyme-decellularized pulmonary allografts (n=8) were performed. Valve performance (echocardiography) and morphologic features (gross, radiographic, and histologic examination) were evaluated 20 weeks after implantation.
Decellularization reduced DNA in valve cusps by 99.3%. Bioprosthetic valves had the largest peak and mean gradients versus decellularized valves (p=0.03; p<0.001) and cryopreserved valves (p=0.01; p=0.001), which were similar (p=0.45; p=0.40). Regurgitation was minimal and similar for all groups (p=0.16). No cusp calcification was observed in any valve type. Arterial wall calcification was present in cryopreserved and bioprosthetic grafts but not in decellularized valves. No autologous recellularization or inflammation occurred in bioprostheses, whereas cellularity progressively decreased in cryopreserved grafts. Autologous recellularization was present in decellularized arterial walls and variably extending into the cusps.
Cryopreserved and decellularized graft hemodynamic performance was comparable. Autologous recellularization of the decellularized pulmonary arterial wall was consistently observed, with variable cusp recellularization. As demonstrated in this study, decellularized allograft valves have the potential for autologous recellularization.
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ABSTRACT: Undesirable processes of inflammation, calcification, or immune-mediated reactions are limiting factors in long-term survival of heart valves in patients. In this study, we target the modulatory effects of ice-free cryopreservation (IFC) of xenogeneic heart valve leaflet matrices, without decellularization, on the adaptive human immune responses in vitro. We tested porcine leaflet matrices from fresh untreated, conventionally cryopreserved (CFC), and IFC pulmonary valves by culturing them with human blood mononuclear cells for 5 d in vitro. No other tissue treatment protocols to modify possible immune responses were used. Matrices alone or in addition with a low-dose second stimulus were analyzed for induction of proliferation and cytokine release by flow cytometry-based techniques. Evaluation of the α-Gal epitope expression was performed by immunohistochemistry with fluorochrome-labeled B4 isolectin. None of the tested leaflet treatment groups directly triggered the proliferation of immune cells. But when tested in combination with a second trigger by anti-CD3, IFC valves showed significantly reduced proliferation of T cells, especially effector memory T cells, in comparison with fresh or CFC tissue. Moreover, the cytokine levels for interferon-γ (IFNγ), tumor necrosis factor α, and interleukin-10 were reduced for the IFC-treated group being significantly different compared with the CFC group. However, no difference between treatment groups in the expression of the α-Gal antigen was observed. IFC of xenogeneic tissue might be an appropriate treatment method or processing step to prevent responses of the adaptive immune system. Copyright © 2014 Elsevier Inc. All rights reserved.Journal of Surgical Research 10/2014; 193(2). DOI:10.1016/j.jss.2014.10.016 · 2.12 Impact Factor
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ABSTRACT: Decellularized allogeneic nonvalved pulmonary artery patches for arterioplasty are a relatively new option compared with cryopreserved allogeneic, crosslinked xenogeneic bioprosthetic or synthetic materials. This study examines the midterm experience with a new decellularized allogeneic patch for congenital cardiac reconstructions. For this prospective postmarket approval, nonrandomized, inclusive observational study, we collected data on a consecutive cohort of 108 patients with cardiovascular reconstructions using 120 decellularized allogeneic pulmonary artery patches (MatrACELL; LifeNet Health, Inc, Virginia Beach, VA) between September 2009 and December 2012. One hundred of the patches were used for pulmonary arterioplasties. Two patients were lost early to follow-up and excluded from subsequent survival and durability analyses. Data included demographics, surgical outcomes, subsequent reoperations, and catheter reinterventions. These variables were also collected for an immediately preceding retrospective consecutive cohort of 100 patients with 101 pulmonary arterioplasty patches who received classical cryopreserved pulmonary artery allografts (n = 59 patches and patients) or synthetic materials (n = 41 patients with 42 patches) for pulmonary arterioplasties between 2006 and 2009. In 106 patients with 118 decellularized patches, there were no device-related serious adverse events, no device failures, and no evidence of calcifications on chest roentgenograms. In contrast, the prior comparative pulmonary arterioplasty cohort of 100 patients experienced an overall 14.0% patch failure rate requiring device-related reoperations (p < 0.0001) at mean duration of 194 ± 104 days (range, 25 to 477 days). The intermediate-term data obtained in this study suggest favorable performance by decellularized pulmonary artery patches, with no material failures or reoperations provoked by device failure.The Annals of thoracic surgery 02/2014; 97(4). DOI:10.1016/j.athoracsur.2013.12.005 · 3.65 Impact Factor
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ABSTRACT: Purpose To determine the best method for decellularisation of aortic valve conduits (AVCs) that efficiently removes the cells while preserving the extracellular matrix (ECM) by examining the valvular and conduit sections separately. Material/methods Sheep AVCs were decellularised by using three different protocols: detergent-based (1% SDS + 1% SDC), detergent and enzyme-based (Triton + EDTA + RNase and DNase), and enzyme-based (Trypsin + RNase and DNase) methods. The efficacy of the decellularisation methods to completely remove the cells while preserving the ECM was evaluated by histological evaluation, scanning electron microscopy (SEM), hydroxyproline analysis, tensile test, and DAPI staining. Results The detergent-based method completely removed the cells and left the ECM and collagen content in the valve and conduit sections relatively well preserved. The detergent and enzyme-based protocol did not completely remove the cells, but left the collagen content in both sections well preserved. ECM deterioration was observed in the aortic valves (AVs), but the ultrastructure of the conduits was well preserved, with no media distortion. The enzyme-based protocol removed the cells relatively well; however, mild structural distortion and poor collagen content was observed in the AVs. Incomplete cell removal (better than that observed with the detergent and enzyme-based protocol), poor collagen preservation, and mild structural distortion were observed in conduits treated with the enzyme-based method. Conclusions The results suggested that the detergent-based methods are the most effective protocols for cell removal and ECM preservation of AVCs. The AVCs treated with this detergent-based method may be excellent scaffolds for recellularisation.Advances in Medical Sciences 08/2014; DOI:10.1016/j.advms.2014.08.004 · 0.96 Impact Factor