title: The effect of the controlled release of basic fibroblast growth factor from ionic gelatin-based hydrogels on angiogenesis in a murine critical limb ischemic model.
abstract: The localized delivery of exogenous, angiogenic growth factors has become a promising alternative treatment of peripheral artery disease (PAD) and critical limb ischemia. In the present study, we describe the development of a novel controlled release vehicle to promote angiogenesis in a murine critical limb ischemic model. Ionic, gelatin-based hydrogels were prepared by the carbodiimide-mediated amidation reaction between the carboxyl groups of gelatin or poly-L-glutamic acid molecules and the amine groups of poly-L-lysine or gelatin molecules, respectively. The degree of swelling of the synthesized hydrogels was assessed as a function of EDC/NHS ratios and the pH of the equilibrating medium, while the release kinetic profile of basic fibroblast growth factor (FGF-2) was evaluated in human fibroblast cultures. The degree of swelling (DS) decreased from 26.5+/-1.7 to 18.5+/-2.4 as the EDC concentration varied from 0.75 to 2.5 mg/ml. Eighty percent of the FGF-2 was released at controlled rates from gelatin-polylysine (gelatin-PLL) and gelatin-polyglutamic acid (gelatin-PLG) hydrogel scaffolds over a period of 28 days. Cell adhesion studies revealed that the negatively charged surface of the gelatin-PLG hydrogels exhibited superior adhesion capabilities in comparison to gelatin-PLL and control gelatin surfaces. Laser Doppler perfusion imaging as well as CD31(+) capillary immunostaining demonstrated that the controlled release of FGF-2 from ionic gelatin-based hydrogels is superior in promoting angiogenesis in comparison to the bolus administration of the growth factor. Over 4 weeks, FGF-2 releasing gelatin-PLG hydrogels exhibited marked reperfusion with a Doppler ratio of 0.889 (+/-0.04) which was 69.3% higher than in the control groups.
authors.affiliation: Department of Biomedical Engineering, MCA 219 McArthur Engineering Building, University of Miami, Coral Gables, FL 33124, USA.
authors.forename: Hans
authors.initials: H
authors.lastname: Layman
authors.forename: Maria-Grazia
authors.initials: MG
authors.lastname: Spiga
authors.forename: Toby
authors.initials: T
authors.lastname: Brooks
authors.forename: Si
authors.initials: S
authors.lastname: Pham
authors.forename: Keith A
authors.initials: KA
authors.lastname: Webster
authors.forename: Fotios M
authors.initials: FM
authors.lastname: Andreopoulos
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry / Q000378:metabolism; D002448:Cell Adhesion / Q000502:physiology; D002478:Cells, Cultured; D003692:Delayed-Action Preparations; D004337:Drug Carriers / Q000737:chemistry / Q000378:metabolism; D005121:Extremities / Q000098:blood supply / Q000473:pathology; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism*; D005780:Gelatin / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D020100:Hydrogels / Q000737:chemistry*; D007511:Ischemia / Q000188:drug therapy; D017078:Laser-Doppler Flowmetry; D051379:Mice; D008807:Mice, Inbred BALB C; D015394:Molecular Structure; D018919:Neovascularization, Physiologic
chemical_list: D001672:Biocompatible Materials; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D020100:Hydrogels; D016222:Fibroblast Growth Factor 2; D005780:Gelatin