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Background— Degeneration of xenografts or homografts is a major cause for reoperation in young patients after pulmonary valve replacement. We present the early results of fresh decellularized pulmonary homografts (DPH) implantation compared with glutaraldehyde-fixed bovine jugular vein (BJV) and cryopreserved homografts (CH). Methods and Results— Thirty-eight patients with DPH in pulmonary position were consecutively evaluated during the follow-up (up to 5 years) including medical examination, echocardiography, and MRI. These patients were matched according to age and pathology and compared with BJV (n=38) and CH (n=38) recipients. In contrast to BJV and CH groups, echocardiography revealed no increase of transvalvular gradient, cusp thickening, or aneurysmatic dilatation in DPH patients. Over time, DPH valve annulus diameters converge toward normal z -values. Five-year freedom from explantation was 100% for DPH and 86±8% and 88±7% for BJV and CH conduits, respectively. Additionally, MRI investigations in 17 DPH patients with follow-up time >2 years were compared with MRI data of 20 BJV recipients. Both patient groups (DPH and BJV) were at comparable ages (mean, 12.7±6.1 versus 13.0±3.0 years) and have comparable follow-up time (3.7±1.0 versus 2.7±0.9 years). In DPH patients, the mean transvalvular gradient was significantly ( P =0.001) lower (11 mm Hg) compared with the BJV group (23.2 mm Hg). Regurgitation fraction was 14±3% and 4±5% in DPH and BJV groups, respectively. In 3 DPH recipients, moderate regurgitation was documented after surgery and remained unchanged in follow-up. Conclusions— In contrast to conventional homografts and xenografts, decellularized fresh allograft valves showed improved freedom from explantation, provided low gradients in follow-up, and exhibited adaptive growth.

A 55-year-old, previously healthy man was admitted to another hospital with deep-venous thrombosis in both legs and massive pulmonary embolism verified by chest computed tomography (CT). He presented with severe dyspnea and hypotension refractory to inotropes. Fibrinolytic therapy with recombinant tissue plasminogen activator was initiated, but the patient further deteriorated and required cardiopulmonary resuscitation for a period of 30 minutes. After return of spontaneous circulation, he remained in cardiogenic shock despite the use of inotropes and vasopressors, which is why our hospital was contacted. Our mobile extracorporeal membrane oxygenation (ECMO) team was dispatched and the patient received veno-arterial ECMO support with a 24 French venous cannula inserted via the right femoral vein and advanced into the right atrium and a 17 French arterial cannula inserted into the right femoral artery and advanced into the right iliacal artery. With an ECMO blood flow of 4.5 L/min, hemodynamics stabilized and the patient was transported to Hannover Medical School. Here, the patient was mechanically ventilated with an inspiratory oxygen fraction of 1.0 …

Immunogenicity of human allografts leads to gradual valve degeneration. Pulmonal cell-free valvular scaffolds obtained by methods of tissue engineering have proved to induce in-vivo guided tissue regeneration and represent a promising valve substitute especially for children. Here we describe the successful orthotopic implantation of decellularized aortic valves in the systemic circulation in sheep. Allogenic detergent decellularized (0.5% sodium deoxycholate/0.5% SDS) aortic valve (AV) conduits (n = 12) were implanted orthotopically as root replacement in lambs (35–45 kg). Fresh native AV conduits served as controls (n = 6). After three and nine months follow-up the valves were investigated for functionality by echocardiography, for morphology and histological appearance. Decellularization resulted in complete loss of cells in AV wall, cusp and myocardial cuff, no influence on scaffold microarchitecture was observed. During 9 months follow-up no signs of conduit dilatation, aortic stenosis (transvalvular gradient max. 6.1 ± 5.1mmHg) or reduction of cusp mobility were observed in the decellularized group. Regurgitation in these valves was trivial in all cases. The grafts showed no histological signs of rejection and partial repopulation of the valvular scaffolds with autologous cells. In contrast, control animals developed mild to severe AV insufficiency. Histological investigation revealed significant calcific degeneration and massive rejection of these valves. Decellularized AV conduits may represent a durable AV substitute resistant to high systemic pressure. Furthermore, cell-removal prevents the allograft valve from immunologic deterioration and early graft degeneration.

Background— The in vivo regeneration capacity of decellularized heart valve grafts is still controversial. The aim of this study was to evaluate function, morphological changes, and cellular composition of decellularized versus re-endothelialized ovine pulmonary valves (PV) after implantation into lambs for 1 or 3 months. Methods and Results— PV (n=21) were decellularized using detergents. Twelve PV were repopulated with autologous jugular veins endothelial cells (ECs) in a dynamic pulsatile bioreactor under simulated physiological conditions. Morphological evaluation before implantation included histological stainings (H&E, Movat-pentachrome, von-Kossa, DAPI), immunostainings (anti-perlecan, anti-eNOS, anti-procollagen-I, anti-SM-α-actin), electron microscopy (EM), and DNA extraction. Decellularization led to cell-free scaffolds with preserved extracellular matrix (ECM) including basement membrane. Reseeded PV (n=5) were completely covered with ECs expressing endothelial nitric oxide synthase (eNOS) and von Willebrand factor (vWF). The function of orthotopically implanted decellularized and re-endothelialized PV (n=7, each) was analyzed after 1 and 3 months by echocardiography and revealed no differences in competence between both groups. A confluent EC monolayer expressing eNOS/vWF was only found in re-endothelialized PV but not in decellularized PV, whereas the valve matrices were comparable repopulated with interstitial cells expressing SM-α-actin and procollagen-I. More thrombotic and neointima formations were observed in decellularized PV. No signs of calcification were detected in both PV types. Conclusion— In vitro re-endothelialization of detergent-decellularized valves with autologous ECs under simulated physiological conditions significantly improves total EC valve coverage 3 months after implantation, whereas the valve repopulation with interstitial cells in vivo occurs most likely by cell migration inside the scaffold.

Background— Tissue engineering (TE) of heart valves reseeded with autologous cells has been successfully performed in vitro. Here, we report our first clinical implantation of pulmonary heart valves (PV) engineered with autologous endothelial progenitor cells (EPCs) and the results of 3.5 years of follow-up. Methods and Results— Human PV allografts were decellularized (Trypsin/EDTA) and resulting scaffolds reseeded with peripheral mononuclear cells isolated from human blood. Positive stain for von Willebrand factor, CD31, and Flk-1 was observed in monolayers of cells cultivated and differentiated on the luminal surface of the scaffolds in a dynamic bioreactor system for up to 21 days, indicating endothelial nature. PV reseeded with autologous cells were implanted into 2 pediatric patients (age 13 and 11) with congenital PV failure. Postoperatively, a mild pulmonary regurgitation was documented in both children. Based on regular echocardiographic investigations, hemodynamic parameters and cardiac morphology changed in 3.5 years as follows: increase of the PV annulus diameter (18 to 22.5 mm and 22 to 26 mm, respectively), decrease of valve regurgitation (trivial/mild and trivial, respectively), decrease (16 to 9 mm Hg) or a increase (8 to 9.5 mm Hg) of mean transvalvular gradient, remained 26 mm or decreased (32 to 28 mm) right-ventricular end-diastolic diameter. The body surface area increased (1.07 to 1.42 m 2 and 1.07 to 1.46 m 2 , respectively). No signs of valve degeneration were observed in both patients. Conclusions— TE of human heart valves using autologous EPC is a feasible and safe method for pulmonary valve replacement. TE valves have the potential to remodel and grow accordingly to the somatic growth of the child.