Deferoxamine-fibrin accelerates angiogenesis in a rabbit model of peripheral ischemia.

The intramuscular (i.m.) injection of a modified fibrin meshwork plus deferoxamine was tested in a rabbit model of acute hind-limb ischemia. After excision of the left external iliac and femoral arteries, 12 rabbits at the Milwaukee Heart Institute were divided into two groups: control and fibrin meshwork plus deferoxamine (FDEF) i.m. The rabbits underwent angiography before surgery, immediately after, and 1 month postoperatively. These data were compiled through counting by means of a grid overlay. Another 12 rabbits at the Vakhidov Center of Surgery, which did not undergo angiography, underwent lower limb-calf blood pressure (L-CBP) measurements made immediately after surgery and at postoperative days 10, 20 and 30. Biopsies from thigh skeletal muscles of rabbits that had L-CBP measurements underwent alkaline phosphatase staining on day 30 to determine the percentage of biopsied area that was occupied by capillaries. The number of arteries and arterioles crossing 71 grid intersections immediately post-surgery decreased from 30.2 +/- 2.3 to 18.0 +/- 2.0 (p < 0.05). One month postsurgery this number increased to 29.2 +/- 2.4 in controls (p < 0.05 vs immediately post-surgery) and to 59.6 +/- 3.2 in the FDEF group (p < 0.001 vs immediately post-surgery). By day 30 the L-CBP ratio improved in the FDEF group (0.8 +/- 0.02) vs controls (0.3 +/- 0.04). By day 30 the capillary density increased from that of normal muscle tissue (198.6 +/- 12.9/mm2) to 292 +/- 12.4/mm2 in the FDEF group (p < 0.05), but decreased in the control group to 98.7 +/- 7.7/mm2. I.m. injection of FDEF considerably accelerated angiogenesis in severely ischemic hind-limb tissue in this model, making it a viable treatment method for clinical use in patients who have critical limb ischemia.

Direct fibrin injection to promote new collateral growth in hind limb ischemia in a rabbit model.

UNLABELLED: Local stimulation of angiogenesis is a new approach for the treatment of critical limb ischemia. Our investigation tested intramuscular (i.m.) injection of a modified fibrin meshwork in a rabbit model. METHODS: The left external iliac and femoral arteries were excised in 24 rabbits that were divided into four groups: control; i.m. saline injection; fibrin meshwork plus low dose (2.5 mg) fibrinogen i.m.; fibrin meshwork plus high-dose (5.0 mg) fibrinogen i.m. Angiography was performed before surgery, immediately after surgery, and one month postoperatively. Lower limb-calf blood pressure was measured immediately after surgery and at postoperative days 10, 20, and 30. On day 30, conventional indirect immunostaining was performed to determine the percentage of the area occupied by capillaries. RESULTS: Immediately after surgery, in all four groups, the number of contract-opacified arteries (COA) crossing a specific segment of a grid decreased from 5.3 +/- 1.3 to 3.2 +/- 1.0 (p < 0.05); the number of grid intersections decreased from 30.2 +/- 6.5 to 19.3 +/- 4.8 (p < 0.05); and the total number of grids with COA decreased from 18.3 +/- 3.8 to 12.2 +/- 2.5 (p < 0.05). One month after surgery, in the control group, these parameters were 6.2 +/- 1.1, 33.2 +/- 5.7 and 20.3 +/- 1.5, respectively; in the saline-treated group, these parameters were 6.1 +/- 0.8, 28.3 +/- 6.9 and 19.8 +/- 1.1, respectively (p > 0.05 versus control and versus baseline data). When fibrin containing 5.0 mg fibrinogen was used, these parameters increased to 8.5 +/- 0.9, 48.3 +/- 5.1, and 27.1 +/- 0.9, respectively (p < 0.001 versus immediately after surgery and p < 0.05 versus control). In all four series, no Doppler flow signal was detected from the posterior tibial artery by day 10. By day 30, the lower limb-calf blood pressure ratio had improved in all four series, but was significantly improved in only the two groups treated with fibrin sealant (0.3 +/- 0.05 control; 0.3 +/- 0.08 saline; 0.6 +/- 0.06 fibrinogen 2.5; 0.7 +/- 0.05 fibrinogen 5.0). CONCLUSION: Intramuscular injection of a fibrin meshwork considerably increased angiogenesis in the severely ischemic hind limb and may be strongly recommended for clinical use in patients with limb-threatening ischemia.