ABSTRACT
Objective To prepare controlled release microspheres of vascular endothelial growth factor(VEGF)& calcium alginate and observe their effect on proliferation of human umbilical vein endo- thelial cells(HUVEC)in order to provide theoretical basis for controlled release of VEGF facilitating an- giogenesis of tissue engineering bone.Methods VEGF-calcium alginate microspheres were prepared by using the needle extrusion/external gelation method to investigate physicochemical character and in vitro release of VEGF.According to the different ingredients added into the culture medium,the seconda- ry cultured HUVEC were divided into four groups,ie,control group,microsphere group,VEGF group and VEGF-calcium alginate microsphere group,in which the proliferation of the cultured HUVEC was ob- served with cell counting method,MTT method and flow cytometry.Results The calcium alginate mi- crospheres were revealed as spherical shape and evenly distributed,with mean grain diameter of(560?50)?m,carrying capacity of 0.72 ng/mg and the encapsulation efficiency of 54%.Smooth controlled re- lease in VEGF-alginate microspheres lasted for more than 10 days.Proliferation of the cultured HUVEC was accelerated the most in VEGF group at the beginning but in EGF-calcium alginate microsphere group at midanaphase compared with other groups,with statistical difference(P＜0.05).There was no statis- tical difference upon cell counting,cell activity and time point of cell cycle between control group and mi- crosphere group.Conclusion VEGF-sodium alginate microapheres can continue activity of VEGF,re- lease VEGF for over 10 days and promote proliferation cultured HUVEC for a long time.
ABSTRACT
Protozoans,the natural host of the facultative intracellular pathogen Legionella species,play an important role in survival,proliferation,virulence and stress resistance of Legionella species. By repeating transformation and selection,a spontaneous mutant of plasmid over expressing green fluorescent protein was obtained. This mutant replicates and is maintained stably in Legionella cells. The colonies of L. pneumophila harbouring the mutated plasmid were intense green in colour even under the daylight. After feeding BF1 strain of Tetrahymena thermophila with transformed L. pneumophila,the intracellular dynamic of changing of bacterial shape,bacterial proliferation and lysis of the host cell due to the bacterial proliferation were observed clearly under fluorescent microscopy. Thus,the present paper provides a simple and intuitionistic strategy for investigating the ecological and cellular relationship between L. pneumophila and its host.