Abstract 2193: Towards Optimal Therapeutic Angiogenesis for Critical Limb Ischemia-Determining Ideal Release Period of Basic Fibroblast Growth Factor -
Introduction: Sustained-release system of basic Fibroblast growth factor (bFGF) is essential to achieve effective neovascularization in vivo because of short half-life of bFGF; however, optimal release period has been unclear. We have developed a sustained-release system of bFGF utilizing gelatin hydrogel (GH) that can vary the release period by changing the water content (WC) of GH. The purpose of this study was to evaluate the optimal release period of bFGF in nondiabetic (NDM) and diabetic (DM) ischemic limb.
Methods: NDM C57BL/6 mice with unilateral hindlimb ischemia were randomly divided into following groups (n=8 to 10 each): no treatment (Group Non-Tx), intramuscular injection of bFGF (10μg) incorporated with 98% of WC of GH that released bFGF about 1 week (Group 1W), bFGF with 95% WC of GH (release period of 2 weeks, Group 2W), and bFGF with 85% WC of GH (release period of 4 weeks, Group 4W). We applied the same group profiles except for dose of bFGF (40μg) to streptozotocin-induced DM mice. Hindlimb blood flow was evaluated with the laser Doppler perfusion image index (LDPII: ratio of ischemic to nonischemic limb blood flow) 4 weeks after the treatment. Vascular density and maturity were evaluated by von-Willebrand staining and α-smooth muscle actin staining, respectively.
Results: (Table⇓) The LDPII, vascular density, and vascular maturity in the 1W and 2W were higher than the 4W, and the data were not different between the 1W and 2W. In the DM mice, however, vascular maturity was highest in the 2W among the groups. Release period of 4 weeks did not enhance neovascularization in NDM and DM mice.
Conclusions: In NDM ischemic limb, release period of 1 week achieved sufficient neovascularization. Longer release period was necessary in DM ischemic limb; which indicates that impairment of collateral development in DM mice might require longer stimulation by bFGF. However, prolonged release period was unnecessary for therapeutic angiogenesis both in NDM and DM mice.