Biodegradable gelatin hydrogel potentiates the angiogenic effect of fibroblast growth factor 4 plasmid in rabbit hindlimb ischemia.

OBJECTIVES We investigated the potentiation of gene therapy using fibroblast growth factor 4 (FGF4)-gene by combining plasmid deoxyribonucleic acid (DNA) with biodegradable gelatin hydrogel (GHG). BACKGROUND Virus vectors transfer genes efficiently but are biohazardous, whereas naked DNA is safer but less efficient. Deoxyribonucleic acid charges negatively; GHG has a positively charged structure and is biodegradable and implantable; FGF4 has an angiogenic ability. METHODS The GHG-DNA complex was injected into the hindlimb muscle (63 mice and 55 rabbits). Gene degradation was evaluated by using (125)I-labeled GHG-DNA complex in mice. Transfection efficiency was evaluated with reverse-transcription nested polymerase chain reaction and X-Gal histostaining. The therapeutic effects of GHG-FGF4-gene complex (GHG-FGF4) were evaluated in rabbits with hindlimb ischemia. RESULTS Gelatin hydrogel maintained plasmid in its structure, extending gene degradation temporally until 28 days after intramuscular delivery, and improving transfection efficiency. Four weeks after gene transfer, hindlimb muscle necrosis was ameliorated more markedly in the GHG-FGF4 group than in the naked FGF4-gene and GHG-beta-galactosidase (control) groups (p < 0.05, Kruskal-Wallis test). Synchrotron radiation microangiography (spatial resolution, 20 microm) and flow determination with microspheres confirmed significant vascular responsiveness to adenosine administration in the GHG-FGF4 group, but not in the naked FGF4-gene and the control. CONCLUSIONS The GHG-FGF4 complex promoted angiogenesis and blood flow regulation of the newly developed vessels possibly by extending gene degradation and improving transfection efficiency without the biohazard associated with viral vectors.