BFGF-PLGA Microspheres Promote The Survival Of Venous Flaps In Rabbits Experimental Study

Objective To prepare the basic fibroblast growth factor (bFGF)-Polylactic-co- glycolic acid(PLGA)sustained release microspheres (MS) by W/O/W multiple emulsion evaporation method, and investigate their effects on the survival of venous flaps.Methods In this study, BCA and ELISA were established in the determination of sustained-release microspheres content of bovine serum albumin BSA and bFGF-PLGA microspheres slow-release of bFGF in vitro release of simulated.BSA were used as a model protein drug and fabricated protein loaded PLGA microspheres were prepared for injectable cell delivery used as microspheres.The formulation of bFGF-PLGA [poly( lactic-co- glycolic -acid)]-MS was optimized by orthogonal design. The morphology,size distribution, drug loading volume encapsulation efficiency and in vitro drug release behavior of bFGF-PLGA-MS being measured. In 24 New Zealand white rabbits , lateral abdominal wall skin flap supplied by the epigastric vein was created, and five days before operation, respectively, intradermal injection of bFGF-PLGA microspheres (Ⅰgroup) , bFGF solution or bFGF- impregnated PLGA (Ⅱgroup) and normal saline (Ⅲgroup). After seven days,①calculation of the survival area of skin;②Rabbit skin samples from CD34+ immunohistochemical staining to detect the expression of CD34+ blood vessels, and the average number of vascular.Results The bFGF MS prepared based on optimized formulation exhibited well-defind properties,with the even and uniform sphere in appearance, regular particles without adhesion, about 98% of particles with a size distribution between 12.50 to 43.49μm,with a mean particle size of 26.93μm and size span of 0.611±6.60. The drug loading volume and encap sulation efficiency of bFGF MS reached [(23.11±0.44 )×10^-3]% and (86.51±0.83) % , respectively. In the burst release phase, the rate of in vitro drug release amounted to 27.78% , but rose to 81.56% accumulatively 30 days later.The in vitro drug release of bFGF MS corresponded with Higuichi equation ( r =0.997). after 7 days, The sustained-release microspheres, blank microspheres and normal saline group, the average survival of the flap were 72.03±1.81,51.03±1.77,50.49±2.36% (P <0.05), the average number of blood vessels were 34.01±2.30,23.81±3.03,22.56±2.26 /cm2 (P <0.05).Conclusion1.bFGF MS with good morphology, high drug loading volume and encapsulation efficiency can be obtained using optimized formulation.2. 5 preoperative days,local subcutaneous injection of the bFGF MS can promote the survival of venous flaps through a long period due to sustained release of bFGF.