Tissue engineering of heart valves: PEGylation of decellularized porcine aortic valve as a scaffold for in vitro recellularization

BACKGROUND: Poly (ethylene glycol) (PEG) has attracted broad interest for tissue engineering applications. The aim of this study was to synthesize 4-arm -PEG-20kDa with the terminal group of diacrylate (4-arm-PEG-DA) and evaluate its dual functionality for decellularized porcine aortic valve (DAV) based on its mechanical and biological properties. METHODS: 4-arm-PEG-DA was synthesized by graft copolymerization of linear PEG 20,000 monomers, and characterized by IR(1)H NMR and (13)C NMR; PEGylation of DAV was achieved by the Michael addition reaction between propylene acyl and thiol, its effect was tested by uniaxial planar tensile testing, hematoxylin and eosin (HE) and scanning electron microscopy (SEM). Gly-Arg-Gly-Asp-Ser-Pro-Cys (GRGDSPC) peptides and vascular endothelial growth factor-165 (VEGF(165)) were conjugated onto DAV by branched PEG-DA (GRGDSPC-PEG-DAV-PEG-VEGF(165)). RESULTS: Mechanical testing confirmed that PEG-cross-linking significantly enhanced the tensile strength of DAV. Immunofluoresce confirmed the GRGDSPC peptides and VEGF(165) were conjugated effectively onto DAV; the quantification of conjunction was completed roughly using spectrophotometry and ELISA. The human umbilical vein endothelial cells (HUVECs) grew and spread well on the GRGDSPC-PEG-DAV-PEG-VEGF(165). CONCLUSIONS: Therefore, PEGylation of DAV not only can improve the tensile strength of DAV, and can also mediate the conjugation of bioactive molecule (VEGF(165) and GRGDSPC peptides) on DAV, which might be suitable for further development of tissue engineered heart valve.