Biodegradable gelatin hydrogel enhances angiogenesis and its flow regulation induced by gene therapy
Research field:Cardiovascular physiology
Authors:Mori H, Kasahara H, Tanaka E, Ikeya E, Yamamoto Y, Ando K, Yoshida Y, Sakamoto H, Tabata Y, Shinozaki Y, Koide S, Nakazawa H
Address of presenting
author:		Hidezo Mori, MD
Tokai University School of Medicine, Dept. of Physiology, Boseidai Isehara, 259-1193, Japan
E-mail:coronary@keyaki.cc.u-tokai.ac.jp
Phone:+81-463-93-1121
Fax:+81-463-93-6684
Text of abstract Introduction
Concerning two major categories of gene transfer, viral vectors are efficient for gene transfer but biohazardous, in contrast, naked DNA is safer but less efficient. Gelatin hydrogel (GHG) is biodegradable, keeps negatively charged plasmid in its positively charged lattice structure, and extends the lacZ expression spatially and temporally (Kasahara et al (2000)).

Methods
We examined the promotive effects of GHG on angiogenesis induced by gene therapy in hindlimb ischemia in 17 rabbits. At 10 days after femoral arterial removal either of 3 gene therapies was performed; GHG-angiogenic growth factor (fibroblast growth factor-4 or vascular endothelial growth factor, AGF, n=6), naked AGF (n=6), and GHG-lacZ (Control, n=5).

Results
Four weeks after the gene transfer, macroscopic findings such as limb necrosis and muscle atrophy were ameliorated in two AGF-treated groups than in the control group (P < 0.05 Kruskal-Wallis test). Furthermore, GHG treatment attenuated ischemic tissue changes compared with naked AGF group. In naked AGF group, regional blood flow in the ischemic limb decreased to 58 +/-16% of the normal limb (flow ratio) at baseline and negligible increase during adenosine administration (68 +/- 19%). In GHG-AGF group, in contrast, the baseline flow (79 +/- 16%) was significantly higher (P < 0.05, ANOVA) than the control group (46 +/- 13%) and the flow ratio during adenosine administration (105 +/- 13%, P < 0.05) than the both naked AGF (68 +/- 19%) and control groups (49 +/- 13%). The vascular density ratio (adenosine / baseline) evaluated by synchrotron radiation microangiography (spatial resolution of 25 micrometer, Takeshita et al (1998)) was the highest for GHG-AGF group (133 +/- 11%) and decreased to 106 +/- 15% and to 86 +/- 10% in naked AGF and control groups (P < 0.05, ANOVA). Conventional angiography (resolution of 200 micrometer) could detect the difference between AGF treatment and control groups, but not the difference between naked AGF and GHG-AGF groups.

Conclusions
Thus, GHG promoted angiogenesis and its flow regulation induced by AGF gene therapy.

References
1. Takeshita S., Isshiki T., Ochiai M., Eto-K; Mori H., Tanaka E., Umetani K., Sato T. 1998. Circulation 98, 1261-3
2. Kasahara H., Tanaka E., Sato E., Ando K., Yoshida T., Sakamoto H., Y Tabata, S Koide, H Mori. 2000. FASEB J. 14, A144

Keywords:angiogenesis, gene therapy, microangiography, flow regulation, fibroblast growth factor-4

Created 2000-05-01