Use of a special bioreactor for the cultivation of a new flexible polyurethane scaffold for aortic valve tissue engineering

Abstract

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.

Developing a Clinically Relevant Tissue Engineered Heart Valve—A Review of Current Approaches

“…After one week of implantation in utero, scaffolds demonstrated cellular integration characterized by increased cellularity and glycosaminoglycan (GAG) content . Furthermore, human fibroblasts and endothelial cells isolated from saphenous vein were used to seed a polyurethane nanofibrous scaffold . The fibroblasts were able to spread on the fibrous scaffold, while the endothelial cells formed a monolayer over the fibroblasts.…”

“…The fibroblasts were able to spread on the fibrous scaffold, while the endothelial cells formed a monolayer over the fibroblasts. The cells responded better to a dynamic culture setting, showing more proliferation and ECM production . Although these studies are promising, the direct application of primary cells for TEHVs may not be suitable for clinical translation, as allogenic cells can induce an immune response in the recipient of the TEHV .…”

Cells for tissue engineering of cardiac valves

“…This tissue construct could be a tissue model for valve regeneration. Instead of PGA, polyurethane fibrous scaffolds were used to generate a similar tissue construct that contained both fibroblasts and ECs (Aleksieva et al, 2012). Furthermore, instead of applying a static culture, as was done previously, this experiment implemented both dynamic and static conditioning.…”

A Novel Seeding and Conditioning Bioreactor for Vascular Tissue Engineering

“…FBs and ECs were phenotypically characterized by morphological observation and immunocytochemical staining (ICC) in eight-well-chamber slides (BD Bioscience, Franklin Lakes, NJ, USA) using specific antibodies as previously described [49]. Briefly, vascular cells were stained against EC-specific CD31 (10.25 μg/mL; Dako Deutschland GmbH, Hamburg, Germany) and FB-specific TE-7 (2 μg/mL, Millipore Corporation BioScience Division, Temecula, CA, USA), respectively, according to manufacturer's protocol using EnVision ™ + Dual Link System-HRP (Dako Deutschland GmbH, Hamburg, Germany).…”