The importance of decellularized medical products has significantly increased during the last years. In this paper, we evaluated the effects of selected physical and procedural decellularization (DC) factors with the aim to systematically assess their influence on DC results. 72 porcine aortic walls (AW) were divided into three groups and exposed to a DC solution for 4 h and 8 h, either continuously or in repeated cycles. The AW were rocked (90bpm), whirled (10 l/min), sonicated (120W, 45 kHz) or exposed to a combination of these treatments, followed by 10 washing cycles. Defining successful DC as removal of nuclei while keeping an intact extracellular matrix (ECM), we equalized the efficiency to the penetration depth (PD), obtained by DAPI fluorescence and H&E staining. Additionally, we performed scanning electron microscopy (SEM), Pentachrome and Picrosirius-Red staining. Results showed that significantly higher DC depths are achieved on outer compared to inner surfaces (61 ± 7%; p < 0.001). Furthermore, the PD showed a high time dependency for all samples. Compared to continuous rocking, we achieved a significant increase in the DC efficiency through cyclic treatments ( ∼ 43%), whirling ( ∼ 19%) and sonication ( ∼ 49%). The combined treatment supported these results. In all procedures, a skeletonized but intact Collagen fibrous network was obtained as confirmed by SEM analysis. In conclusion, we systematically identified essential factors to significantly enhance DC procedures. We highly recommend considering these factors in future DC protocols. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 153-162, 2018.

OBJECTIVES We evaluated the outcome of patients in cardiogenic shock receiving a paracorporeal pulsatile biventricular assist device as a bridge to transplantation. METHODS We performed a retrospective single-centre analysis of all patients who received a Berlin Heart Excor® at our institution between 2004 and 2019. RESULTS A total of 97 patients (90 adults, 7 paediatric) were analysed. Eighty-four patients were in Interagency Registry for Mechanically Assisted Circulatory Support level 1 (80 adults, 4 paediatric). Diagnoses were dilated cardiomyopathy (n = 41), ischaemic cardiomyopathy (n = 17) or myocardial infarction (n = 4), myocarditis (n = 15), restrictive cardiomyopathy (n = 2), graft failure after heart transplant (n = 7), postcardiotomy heart failure (n = 5), postpartum cardiomyopathy (n = 3), congenital heart disease (n = 1), valvular cardiomyopathy (n = 1) and toxic cardiomyopathy (n = 1). All patients were in biventricular heart failure and had secondary organ dysfunction. The mean duration of support was 63 days (0–487 days). There was a significant decrease in creatinine values after assist device implantation (from 1.83 ± 0.79 to 1.12 ± 0.67 mg/dl, P = 0.001) as well as a decrease in bilirubin values (from 3.94 ± 4.58 to 2.65 ± 3.61 mg/dl, P = 0.084). Cerebral stroke occurred in 16 patients, bleeding in 15 and infection in 13 patients. Forty-eight patients died on support, while 49 patients could be successfully bridged to transplantation. Thirty-day survival and 1-year survival were 70.1% and 41.2%, respectively. CONCLUSIONS A pulsatile biventricular assist device is a reasonable therapeutic option in cardiogenic shock, when immediate high cardiac output is necessary to rescue the already impaired kidney and liver function of the patient.

BackgroundTissue engineering represents a promising new method for treating heart valve diseases. The aim of this study was evaluate the importance of conditioning procedures of tissue engineered polyurethane heart valve prostheses by the comparison of static and dynamic cultivation methods.MethodsHuman vascular endothelial cells (ECs) and fibroblasts (FBs) were obtained from saphenous vein segments. Polyurethane scaffolds (n = 10) were primarily seeded with FBs and subsequently with ECs, followed by different cultivation methods of cell layers (A: static, B: dynamic). Group A was statically cultivated for 6 days. Group B was exposed to low flow conditions (t1= 3 days at 750 ml/min, t2= 2 days at 1100 ml/min) in a newly developed conditioning bioreactor. Samples were taken after static and dynamic cultivation and were analyzed by scanning electron microscopy (SEM), immunohistochemistry (IHC), and real time polymerase chain reaction (RT-PCR).ResultsSEM results showed a high density of adherent cells on the surface valves from both groups. However, better cell distribution and cell behavior was detected in Group B. IHC staining against CD31 and TE-7 revealed a positive reaction in both groups. Higher expression of extracellular matrix (ICAM, Collagen IV) was observed in Group B. RT- PCR demonstrated a higher expression of inflammatory Cytokines in Group B.ConclusionWhile conventional cultivation method can be used for the development of tissue engineered heart valves. Better results can be obtained by performing a conditioning step that may improve the tolerance of cells to shear stress. The novel pulsatile bioreactor offers an adequate tool for in vitro improvement of mechanical properties of tissue engineered cardiovascular prostheses.

The aim of the study was to compare the behavior of seeded cells on synthetic and natural aortic valve scaffolds during a low-flow conditioning period. Polyurethane (group A) and aortic homograft valves (group B) were consecutively seeded with human fibroblasts (FB), and endothelial cells (EC) using a rotating seeding device. Each seeding procedure was followed by an exposure to low pulsatile flow in a dynamic bioreactor for 5 days. For further analysis, samples were taken before and after conditioning. Scanning electron microscopy showed confluent cell layers in both groups. Immunohistochemical analysis showed the presence of EC and FB before and after conditioning as well as the establishment of an extracellular matrix (ECM) during conditioning. A higher expression of ECM was observed on the scaffolds' inner surface. Realtime polymerase chain reaction showed higher inflammatory response during the conditioning of homografts. Endothelialization caused a decrease in inflammatory gene expression. The efficient colonization, the establishment of an ECM, and the comparable inflammatory cell reaction to the scaffolds in both groups proved the biocompatibility of the synthetic scaffold. The newly developed bioreactor permits conditioning and cell adaption to shear stress. Therefore, polyurethane valve scaffolds may offer a new option for aortic valve replacement. ASAIO Journal 2013;59:309-316.

Transcatheter aortic valve implantation (TAVI) is a fast-growing, exciting field of invasive therapy. During the last years many innovations significantly improved this technique. However, the prostheses are still associated with drawbacks. The aim of this study was to create cell-seeded biohybrid aortic valves (BAVs) as an ideal implant by combination of assets of biological and artificial materials. Furthermore, the influence of TAVI procedure on tissue-engineered BAV was investigated. BAV (n=6) were designed with decellularized homograft cusps and polyurethane walls. They were seeded with fibroblasts and endothelial cells isolated from saphenous veins. Consecutively, BAV were conditioned under low pulsatile flow (500 mL/min) for 5 days in a specialized bioreactor. After conditioning, TAVI-simulation was performed. The procedure was concluded with re-perfusion of the BAV for 2 days at an increased pulsatile flow (1100 mL/min). Functionality was assessed by video-documentation. Samples were taken after each processing step and evaluated by scanning electron microscopy (SEM), immunohistochemical staining (IHC), and Live/Dead-assays. The designed BAV were fully functioning and displayed physiologic behavior. After cell seeding, static cultivation and first conditioning, confluent cell layers were observed in SEM. Additionally, IHC indicated the presence of endothelial cells and fibroblasts. A significant construction of extracellular matrix was detected after the conditioning phase. However, a large number of lethal cells were observed after crimping by Live/Dead staining. Analysis revealed that the cells while still being present directly after crimping were removed in subsequent perfusion. Extensive regions of damaged cell-layers were detected by SEM-analysis substantiating these findings. Furthermore, increased ICAM expression was detected after re-perfusion as manifestation of inflammatory reaction. The approach to generate biohybrid valves is promising. However, damages inflicted during the crimping process seem not to be immediately detectable. Due to severe impacts on seeded cells, the strategy of living TE valves for TAVI should be reconsidered.