Enhanced Neovascular Formation in a Novel Hydrogel Matrix Consisting of Citric Acid and Collagen

Abstract

Three-dimensional regenerative tissue with large bulk generally requires blood perfusion through a vascular network to maintain its viability, and one promising approach is induction of neovascular growth from the recipient bed into the tissue. To induce ingrowth of a vascular network, it is necessary to furnish the regenerative tissue with a scaffold structure for neovasculature and a delivery system for an angiogenic growth factor. As such a scaffold structure, the present study created novel hydrogel materials by chemically cross-linking alkali-treated collagen (AlCol) with trisuccinimidyl citrate (TSC). Many prototypes, consisting of several concentrations of TSC and AlCol, were implanted into the subfascial space of the rat rectus muscle, and 7 days later, the implanted materials were excised for histological analysis. Cross-sections were stained and neovascular development in the materials was evaluated by measuring vessel density, length and number of joints and branches. Significant ingrowth of vascularized granulation was observed in some materials, which surpassed the angiogenic ability of Matrigel(TM). Further, combination with basic fibroblast growth factor (bFGF) significantly increased the vascular formation in these gels. The TSC-AlCol gel functioned as a favorable scaffold for neovascular formation and also as a reservoir for controlled delivery of bFGF.