OBJECTIVETo improve the biological properties of decellularized aortic valves by polyethylene glycol (PEG)-mediated covalent incorporation of vascular endothelial growth factor (VEGF).

METHODSPEG crosslinking of decellularized aortic valves were completed via a Michael-type addition reaction, followed by covalent incorporation of VEGF through another Michael-type addition reaction between the unsaturated propylene acyl of PEG and the thiol groups on cysteine residues of VEGF. The effect of VEGF incorporation was evaluated by enzyme-linked immunosorbent assay (ELISA) and immune fluorescence assay. The endothelial progenitor cells (EPCs) were seeded on decellularized aortic valves with or without these modifications, and after 10 days of culture, the valves were examined for DNA content and by hematoxylin-eosin staining and scanning electron microscopy.

RESULTSImmune fluorescence and ELISA showed that the maximal VEGF incorporation on the decellularized aortic valve reached 908.94∓0.27 pg. Compared with the unmodified valves and the valves with PEG crosslinking, decellularized aortic valves with covalent incorporation of VEGF significantly promoted the adhesion and proliferation of EPCs, which formed a confluent cell monolayer on the valve surface.

CONCLUSIONSPEG-mediated covalent incorporation of VEGF in the decellularized aortic valves improves the adhesion and proliferation of the seeded EPCs to facilitate the construction of tissue-engineered heart valves.