Cell migration plays a crucial role in a variety of physiological and pathological processes ranging from wound healing,revascularization,immune response,tumor metastasis,embryonic development and so on[1].When a signal gradient exists,the imbalanced force exerted on the cells leads to cell membrane and cytoskeletal polarization.At that time,the cell ends are rendered differently,so as to guide the directional movement of cells.Cell migration consists of two-dimensional and three-dimensional migration.Most of the experiments have been based on planar migration [2].However,compared with two-dimensional cell migration,the three-dimensional migration can better simulate morphology of cells in vivo and provide the theoretical knowledge about the repair of blood vessels.In this study,a kind of initial model based on Transwell was proposed.Phenotypes of macrophages were polarized by 50 ng/ml interferon-gamma and different contents of lipopolysaccharide(150-300ng/mL)to produce vascular endothelial growth factor as the chemo-attractant for endothelial cells.Using Transwell model,cell invasion through the collagen-chitosan scaffolds was observed to mimic the cell migration during blood vessel repair in vivo.The results show that as the concentration of lipopolysaccharide increased,cells could migrate obvious deeper into the scaffolds compared with inactivated macrophages measured by the confocal laser scanning microscopy.More importantly,the endothelial cells could migrate deeper into the scaffolds with large pores than that with small pores fabricated by freeze-drying under different temperatures.This research proposes a useful strategy to promote the invasion and proliferation of endothelial cells into a scaffold combined with the macrophage induction,which may be further applied to the cardiovascular therapeutics.