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.

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 (nϭ38) and CH (nϭ38) 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 86Ϯ8% and 88Ϯ7% for BJV and CH conduits, respectively. Additionally, MRI investigations in 17 DPH patients with follow-up time Ͼ2 years were compared with MRI data of 20 BJV recipients. Both patient groups (DPH and BJV) were at comparable ages (mean, 12.7Ϯ6.1 versus 13.0Ϯ3.0 years) and have comparable follow-up time (3.7Ϯ1.0 versus 2.7Ϯ0.9 years). In DPH patients, the mean transvalvular gradient was significantly (Pϭ0.001) lower (11 mm Hg) compared with the BJV group (23.2 mm Hg). Regurgitation fraction was 14Ϯ3% and 4Ϯ5% 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. (Circulation. 2011; 124[suppl 1]:S115-S123.)

OBJECTIVESDecellularized homografts have shown auspicious early results when used for pulmonary valve replacement (PVR) in congenital heart disease. The first clinical application in children was performed in 2002, initially using pre-seeding with endogenous progenitor cells. Since 2005, only non-seeded, fresh decellularized allografts have been implanted after spontaneous recellularization was observed by several groups.METHODSA matched comparison of decellularized fresh pulmonary homografts (DPHs) implanted for PVR with cryopreserved pulmonary homografts (CHs) and bovine jugular vein conduits (BJVs) was conducted. Patients’ age at implantation, the type of congenital malformation, number of previous cardiac operations and number of previous PVRs were considered for matching purposes, using an updated contemporary registry of right ventricular outflow tract conduits (2300 included conduits, >12 000 patient-years).RESULTSA total of 131 DPHs were implanted for PVR in the period from January 2005 to September 2015. Of the 131, 38 were implanted within prospective trials on DPH from October 2014 onwards and were therefore not analysed within this study. A total of 93 DPH patients (58 males, 35 females) formed the study cohort and were matched to 93 CH and 93 BJV patients. The mean age at DPH implantation was 15.8 ± 10.21 years (CH 15.9 ± 10.4, BJV 15.6 ± 9.9) and the mean DPH diameter was 23.9 mm (CH 23.3 ± 3.6, BJV 19.9 ± 2.9). There was 100% follow-up for DPH, including 905 examinations with a mean follow-up of 4.59 ± 2.76 years (CH 7.4 ± 5.8, BJV 6.4 ± 3.8), amounting to 427.27 patient-years in total (CH 678.3, BJV 553.0). Tetralogy-of-Fallot was the most frequent malformation (DPH 50.5%, CH 54.8%, BJV 68.8%). At 10 years, the rate of freedom of explantation was 100% for DPH, 84.2% for CH (P = 0.01) and 84.3% for BJV (P= 0.01); the rate of freedom from explantation and peak trans-conduit gradient ≥50 mmHg was 86% for DPH, 64% for CH (n.s.) and 49% for BJV (P < 0.001); the rate of freedom from infective endocarditis (IE) was 100% for DPH, 97.3 ± 1.9% within the matched CH patients (P = 0.2) and 94.3 ± 2.8% for BJV patients (P = 0.06). DPH valve annulus diameters converged towards normal Z-values throughout the observation period, in contrast to other valve prostheses (BJV).CONCLUSIONSMid-term results of DPH for PVR confirm earlier results of reduced re-operation rates compared with CH and BJV.

Background Limited availability of decellularized allogeneic heart valve substitutes restricts the clinical application thereof. Decellularized xenogeneic valves might constitute an attractive alternative; however, increased immunological hurdles have to be overcome. This study aims for the in vivo effect in sheep of decellularized porcine pulmonary heart valves (dpPHV) enzymatically treated for N‐glycan and DNA removal. Methods dpPHV generated by nine different decelluarization methods were characterized in respect of DNA, hydroxyproline, GAGs, and SDS content. Orthotopic implantation in sheep for six months of five groups of dpPHV (n = 3 each; 3 different decellularization protocols w/o PNGase F and DNase I treatment) allowed the analysis of function and immunological reaction in the ovine host. Allogenic doPHV implantations (n = 3) from a previous study served as control. Results Among the decellularization procedures, Triton X‐100 & SDS as well as trypsin & Triton X‐100 resulted in highly efficient removal of cellular components, while the extracellular matrix remained intact. In vivo, the functional performance of dpPHV was comparable to that of allogeneic controls. Removal of N‐linked glycans and DNA by enzymatic PNGase F and DNase I treatment had positive effects on the clinical performance of Triton X‐100 & SDS dpPHV, whereas this treatment of trypsin & Triton X‐100 dpPHV induced the lowest degree of inflammation of all tested xenogeneic implants. Conclusion Functional xenogeneic heart valve substitutes with a low immunologic load can be produced by decellularization combined with enzymatic removal of DNA and partial deglycosylation of dpPHV.

OBJECTIVES Decellularized pulmonary homografts (DPH) have shown excellent results for pulmonary valve replacement. However, controlled multicentre studies are lacking to date. METHODS Prospective European multicentre trial evaluating DPH for pulmonary valve replacement. Matched comparison of DPH to bovine jugular vein (BJV) conduits and cryopreserved homografts (CH) considering patient age, type of heart defect and previous procedures. RESULTS In total, 121 patients (59 female) were prospectively enrolled (August 2014–December 2016), age 21.3 ± 14.4 years, DPH diameter 24.4 ± 2.8 mm. No adverse events occurred with respect to surgical handling; there were 2 early deaths (30 + 59 years) due to myocardial failure after multi-valve procedures and no late mortality (1.7% mortality). After a mean follow-up of 2.2 ± 0.6 years, the primary efficacy end points mean peak gradient (16.1 ± 12.1 mmHg) and regurgitation (mean 0.25 ± 0.48, grade 0–3) were excellent. One reoperation was required for recurrent subvalvular stenosis caused by a pericardial patch and 1 balloon dilatation was performed on a previously stented LPA. 100% follow-up for DPH patients operated before or outside the trial (n = 114) included in the ESPOIR Registry, age 16.6 ± 10.4 years, diameter 24.1 ± 4.2 mm, follow-up 5.1 ± 3.0 years. The combined DPH cohort, n = 235, comprising both Trial and Registry data showed significantly better freedom from explantation (DPH 96.7 ± 2.1%, CH 84.4 ± 3.2%, P = 0.029 and BJV 82.7 ± 3.2%, P = 0.012) and less structural valve degeneration at 10 years when matched to CH, n = 235 and BJV, n = 235 (DPH 61.4 ± 6.6%, CH 39.9 ± 4.4%, n.s., BJV 47.5 ± 4.5%, P = 0.029). CONCLUSIONS: Initial results of the prospective multicentre ESPOIR Trial showed DPH to be safe and efficient. Current DPH results including Registry data were superior to BJV and CH. Trial registration clinicaltrials.gov identifier: NCT 02035540.