Thepreparation Of VEGF/bFGF-impregnated Microsphere And Its Effect On The Survival Of Ischemic Dorsal Random Skin Flap In A Rat Mode

Objective To prepare VEGF/bFGF-impregnated microsphere, and to evaluate its preservation of bioactivity and its effect on the endothelial cell ( EC ). When used in the ischemic dorsal random skin flap in a rat model, the retarder and different proportion of growth factors to the survival of flap was investigated..Methods The VEGF/bFGF-impregnated microsphere was prepared by the method of emulsified cold-condensation, and was observed under the microscope. Encapsulation rate, drug content and the drug release were tested, after cultured in the medium RPMI1640, the proliferation and viability of cultured EC were measured by method of cell counting and MTT. Then injected locally in the ischemic dorsal random skin flap in a SD rat, and the survival rates, capillary density, and perfusion of the flap were measured..Results The average diameter of impregnated microsphere was 11. 32±3. 64μm, the average rate of encapsulation rate and drug content for bFGF was 0.26%and 90.6% respectively,and that forVEGFwas 0.22%and 88.4% respectively. The total release rate was 93% and 90% .on the 7th day. When applied in the cultured EC, the cell number and cell viability in the bFGF-impregnated microsphere group were 24.0±2.16,and 0.756±0.042 respectively, and that for VEGF was 29.16±3.65 and 1.023±0.106 respectively, these data has a significant difference compared to the control group(P<0.05). The cell number and cell viability in the VEGF/bFGF-impregnated microsphere group were 34.51±4.79and1.328±0.098 respectively, which was much higher then the group above and the control(P<0.05). 7 days after injecting locally in the ischemic dorsal random skin flap in a SD rat, the survival rate of the flap was45.43±2.71%;58.45±2.70%;68.54±2.79%;54.38±4.52%;65.42±2.19%;63.75±2.24%;78.33±3.23%, respectively; the capillary density was18.68±5.44;25.41±4.06;31.16±4.38;21.28±3.82;28.75±2.36;32.74±4.67;39.32±3.73, respectively. These data in VEGF/bFGF-impregnated microsphere group was higher then other groups including the control(P<0.05). With different ratio in the VEGF and bFGF, the survival rate and capillary density were 63.75±2.24%and32.74±4.67respectively(VEGF/bFGF=1:1);65.79±3.48%and35.67±3.25respectively(VEGF/bFGF=1:2);77.5±3.95%and40.38±4.19respectively (VEGF/bFGF =1:3).Conclusion1.The modifiedmethod for preparing VEGF/bFGF-impregnated microsphere was a simple, effective and accurate. It can promote the releasion for a long period and the gelatin has no toxicity. 2.The impregnated microsphere can dramatically prolong the half-life of growth factors, and can promote the proliferation of EC and angiogenesis of the random skin flap, so the survival rate was elevated. It result in a prolonged drug action, and the dosage of which is accordingly reduced. 3.There is a synergistic effect of bFGF and VEGF, when applied together, it can reduce the dosage and has a more potent effect on the survival of ischemic random skin flap, especially on the ratio of 3:1.