Preparation And Characterization Of Microspheres Containing Granulocyte-macrophage Colony Stimulating Factor For Sustained Release

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a cytokine which exhibits activity in the hematopoietic and immune systems. GM-CSF was originally cloned based on its ability to stimulate the proliferation and differentiation of hematopoetic precursors of the granulocyte monocyte lineage. The serum elimination half-life of human GM-CSF in humans is approximately one hour, and therefore daily injections are required to achieve therapeutic effects, To induce the frequency of GM-CSF administration and improve the therapeutic efficency, the sustained-release microsphere containing GM-CSF was prepared using biodegradable polymer as carrier and evaluated in vitro.The microsphere was prepared by double-emulsion solvent evaporation technique. To investigate the best conditions and material to encapsulate GM-CSF, BSA was chosen as a model drug. Microspheres were prepared using four different materials of Poly(D,L-lactic acid)(PLA) and D,L-lactide/glycollide copolymer(PLGA) as carriers. Single factor design and orthogonal design are used to optimize the conditions for the process. The protein loading and encapsulation rate were detected by ultraviolet spectrometry method. The particle size distribution and appearance were evaluated with scanning electronic microscope,Furthermore, drug release behavior in vitro from different types of microspheres was studied under the simulated physiology circumstance. Finally, the optimal formulation and the best material were chosen for GM-CSF. Then we analyzed the concentration of GM-CSF microsphere with fluorometric spectrometry method.The result shows that all of four materials of PLGA and PLA microspheres have complete smooth and round shape, no significant difference in particle size distribution, the microspheres'average size is 35.16μm, the protein loading and encapsulation rate are (2.30±0.163)% and (42.09±1.81)% respectively. The protein release in vitro shows that there is initial burst release phenomenon. Subsequently the releasing of drug goes into stability and sustains releasing for 10 days, the microspheres release morphology after degradation was evaluated with scanning electronic microscope, which shows that the release speed of drug is different, the...