Vascularization in vivo caused by the controlled release of fibroblast growth factor-2 from an injectable chitosan/non-anticoagulant heparin hydrogel.

Addition of various heparinoids to the lactose-introduced, water-soluble chitosan (CH-LA) aqueous solution produces an injectable chitosan/heparinoid hydrogel. In the present work, we examined the capability of the chitosan/non-anticoagulant heparin (periodate-oxidized (IO(4)-) heparin) hydrogel to immobilize fibroblast growth factor (FGF)-2, as well as the controlled release of FGF-2 molecules from the hydrogel in vitro and in vivo. The hydrogel was biodegraded in about 20 days after subcutaneous injection into the back of a mouse. When the FGF-2-incorporated hydrogel was subcutaneously injected into the back of both mice and rats, a significant neovascularization and fibrous tissue formation were induced near the injected site. These results indicate that the controlled release of biologically active FGF-2 molecules is caused by biodegradation of the hydrogel, and that subsequent induction of the vascularization occurs.

Inhibition of vascular prosthetic graft infection using a photocrosslinkable chitosan hydrogel.

BACKGROUND: Despite improvements in surgical techniques and antimicrobial therapies, prosthetic aortic graft infections remain a clinical problem. It is well known that chitosan has strong antibacterial activities to a wide variety of bacteria including Staphylococcus aureus, epidermidis and Escherichia coli (E. coli). The antibacterial activity by adhering a photocrosslinkable chitosan hydrogel to Dacron grafts was investigated in vitro and in vivo using a rabbit model. MATERIALS AND METHODS: The photocrosslinkable chitosan hydrogel (50microl) coated grafts (3 x 2mm fragments) were evaluated on a resistance against E. coliin vitro. The graft infections in vivo were also initiated through implantation of a Dacron graft fragment into the infrarenal aorta of a rabbit, followed by a topical inoculation with 10(6) colony-forming units of E. coli. The graft infection was allowed to develop over the following 1 week. RESULTS: The photocrosslinkable chitosan hydrogel-coated grafts exhibited a resistance against E. coliin vitro. Furthermore, application of 0.1ml photocrosslinkable chitosan hydrogel on the Dacron implant in vivo substantially inhibited graft infection with E. coli. CONCLUSIONS: These preliminary results suggested the potential use of a photocrosslinkable chitosan hydrogel in directing graft infection prophylaxis.