Roles of genipin crosslinking and biomolecule conditioning in collagen-based biopolymer: Potential for vascular media regeneration.

The vascular media, a layer of the blood vessel wall containing smooth muscle cells (SMCs), are often the target functional tissue in the construction of artificial vessel. It contributes to mechanical properties and biological functions of vessels. The present study aimed to study effects of crosslinking and biomolecule conditions in the development of mechanically strong and stable, biologically functional constructs with potential for vascular media regeneration. Genipin was used to crosslink collagen-chitosan-elastin (CCE) constructs. Results revealed that mechanical strength, stiffness, and stability of CCE constructs significantly increased with genipin concentration, but crosslinking significantly inhibited SMC contraction of and invasion in gel constructs. No contraction or invasion was observed in those crosslinked with genipin at 5 mM or above. attenuated total reflectance Fourier transform infrared results showed crosslinking changed functional groups on CCE depending on genipin concentration. To enhance biological activities on crosslinked constructs, soluble molecule factors were incorporated, and their effects on SMC activities were evaluated. These conditions include heparin, platelet-derived transforming growth factor (PDGF), high-concentrated fetal bovine serum (h-FBS), a mixture of heparin and PDGF, and a mixture of h-FBS and PDGF. The h-FBS and PDGF mixture was found to stimulate a 3.2-fold increase in SMC contraction of the crosslinked gels. It was also found that PDGF and h-FBS, separately and in combination, induced SMC invasion in the crosslinked gels, while heparin attenuated PDGF-induced SMC invasion. Our study suggests that designing high-performance acellular constructs to encourage tissue regeneration should use a combination of crosslinking condition and biomolecule factor, striking a balance between mechanical properties and biological functions.