title: Therapeutic site selection is important for the successful development of collateral vessels.
abstract: BACKGROUND
  Induction of collateral development to improve tissue perfusion is a promising approach for the treatment of arterial occlusive diseases. Several growth factors and cells have been reported to increase collateral circulation; however, the appropriate site for the delivery of these factors and cells is unclear. In this study, we identified the delivery site for growth factor in a rabbit model of limb ischemia and evaluated whether specific delivery of basic fibroblast growth factor (bFGF) to this site enhanced collateral augmentation.
  
  
  METHODS
  The left femoral artery of Japanese white rabbits was excised to induce limb ischemia. Twenty-eight days thereafter, angiograms were obtained to identify the typical pattern of collateral development in this model. Subsequently, bFGF (100 μg) was selectively injected into the left coccygeofemoral muscle (coccygeo group) or adductor muscle (adductor group), major thigh muscles in proximity. Collateral development was evaluated at 28 days after injection, and its mechanism was assessed by immunologic and morphometric analyses of muscle samples.
  
  
  RESULTS
  Angiographic evaluation of this model revealed that after femoral artery excision, collateral vessels generally developed in the left coccygeofemoral muscle, whereas few collateral vessels were detected in the left adductor muscle. At 28 days after injection, calf blood pressure ratio, defined as left pressure to right pressure, was significantly higher in the coccygeo group than in the adductor group (0.85 ± 0.05 vs 0.69 ± 0.05, respectively; P < .01). Similar results were observed in blood flow through the internal iliac artery (resting: 24.6 ± 6.1 vs 17.4 ± 8.0 mL/min, P < .01; maximum: 47.4 ± 12.3 vs 33.2 ± 10.7 mL/min, P < .01) and in the angiographic score (0.67 ± 0.13 vs 0.39 ± 0.11; P < .01). Immunologic analyses of the coccygeofemoral muscle at day 3 showed marked expressions of Ki-67, monocyte chemotactic protein 1, and FGF receptor 1 in the coccygeo group compared with the adductor group. Morphometric analyses of the same muscle at day 14 also revealed that collateral vessel density and wall thickness were significantly increased in the coccygeal group compared with the adductor group.
  
  
  CONCLUSIONS
  These findings demonstrated that selective bFGF delivery to the coccygeofemoral muscle markedly improved collateral development and limb perfusion compared with delivery to the adductor muscle, suggesting that site selection is important in increasing therapeutic efficacy.
authors.affiliation: Division of Vascular Surgery, Department of Surgery, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Nishiyama
authors.affiliation: Division of Vascular Surgery, Department of Surgery, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan; Division of Translational Research Center, The University of Tokyo Hospital, Tokyo, Japan. Electronic address: hkoyama-tky@umin.ac.jp.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Koyama
authors.affiliation: Division of Vascular Surgery, Department of Surgery, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Miyata
authors.affiliation: Department of Surgery, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Watanabe
mesh_terms: D043925:Angiogenesis Inducing Agents / Q000008:administration & dosage*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D018932:Chemokine CCL2 / Q000378:metabolism; D003097:Collateral Circulation / Q000187:drug effects*; D004195:Disease Models, Animal; D005263:Femoral Artery / Q000601:surgery; D016222:Fibroblast Growth Factor 2 / Q000008:administration & dosage*; D006614:Hindlimb; D007273:Injections, Intramuscular; D007511:Ischemia / Q000188:drug therapy* / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology; D019394:Ki-67 Antigen / Q000378:metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D011817:Rabbits; D051496:Receptor, Fibroblast Growth Factor, Type 1 / Q000378:metabolism; D020127:Recovery of Function; D012039:Regional Blood Flow; D013997:Time Factors
chemical_list: D043925:Angiogenesis Inducing Agents; D018932:Chemokine CCL2; D019394:Ki-67 Antigen; D016222:Fibroblast Growth Factor 2; D051496:Receptor, Fibroblast Growth Factor, Type 1