Comparison of synthetic and natural scaffolds for application in aortic valve tissue engineering

Aims: The aim of the study was to compare endothelialised synthetic and natural aortic valve scaffolds under dynamic conditions in a newly developed bioreactor.

Material and methods: Fibroblasts (FBs) and endothelial cells (ECs) were isolated from saphenous vein segments and expanded in culture. Polyurethane valve scaffolds (Group A, n=4) and cryopreserved/thawed aortic homograft valves (Group B, n=4) were primarily seeded with FBs, followed by a colonization with ECs using a special rotating seeding device. Each seeding procedure was followed by an exposure to low pulsatile flow (750–1100ml/min) in a novel self-made dynamic Bioreactor (EU-Patent pending) for 5 days. Samples were taken before and after perfusion and analysed by scanning electron microscopy (SEM) and immunohistochemical staining (IHC).

Results: SEM evaluation showed a confluent cell layer in both groups. IHC staining of both groups with CD31 (ECs-antibody) and TE-7 (FBs-antibody) revealed a positive reaction of both cell layers before and after low flow conditioning. Higher expression of extracellular matrix antibodies (collagen IV and ICAM) was observed on the inner surface of both groups after conditioning. However, the results of Group A had higher colonization efficiency than Group B.

Conclusion: New synthetic polyurethane scaffolds present better colonization results than natural scaffolds and may offer a new option for aortic valve replacement.