3D Cell Migration Into The Biomaterials Mediated By Immuno-response

As one of the fundamental functions,cell migration plays a crucial role in a variety of physiological and pathological processes.Especially,the 3D migration can better mimic the cell behaviors during the process of tissue regeneration in vivo,which is more important and difficult in the field of tissue engineering.In this study,the Transwell molds were combined with traditional scaffolds and stimuli-responsive intelligent biomaterials to mimic the induced cell migration based on the immune-response.Firstly,endothelial cells cultured atop the scaffolds were promoted to migrate into the collagen-chitosan scaffolds by chemoattractants such as vascular endothelial growth factor(VEGF)and tumor necrosis factor-alpha(TNF-?)secreted by the pro-inflammatory macrophages.The phenotype of macrophages was mediated by 50 ng/mL interferon-gamma(IFN-?)and different concentrations of lipopolysaccharide(LPS,150-300 ng/mL).The cell migration depth which monitored by confocal laser scanning microscopy had a positive correlation with LPS concentration,and thereby the TNF-a concentration.The endothelial cells(ECs)migrated easier to a deeper zone of the scaffolds prepared at-10 ?(186.7±15.0?m in pore diameter)than that at-20?(108.1 ± 13.0?m in pore diameter)as well,proving that the pore microstructures of biomaterials affect the 3D cell migration.In order to investigate the influence of stimuli-responsive biomaterials on cell migration,a dual-network hydrogel crossl inked with carbon-carbon double bond and Schiff base was prepared,and further incubated in mediums of different pH values(pH 7.4 and pH 5)to adjust its crosslinking degree.The pH 5 treatment enabled the hydrogel with increased mesh size and larger swelling ratio compared with that treated at pH 7.4.However,the mechanical property obviously decreased.In vitro tests proved that the endothelial cells(ECs)migrated easier to a deeper zone of the hydrogel treated at pH 5 than that at pH 7.4,while the bone mesenchymal stem cells(BMSCs)migrated deeper into the hydrogel treated at pH 7.4.As another kind of intelligent biomaterials,the photo-responsive hydrogels have a wide range of applications in biomedical field.A dual-network hydrogel crosslinked with carbon-carbon double bond and coumarin group was thus fabricated,whose crosslinking density was adjusted by photo-irradiation at X=254 nm.The photo-irradiation increased the swelling ratio and pore diameters significantly,while the mechanical property obviously decreased.In vitro tests proved that the endothelial cells migrated easier to a deeper zone of the photo-responsive hydrogel being irradiated at ?=254 nm than the orginal control,proving that the endothelial cells(ECs)migrated more distances into the softer biomaterials.This work provides a useful strategy to study the factors affecting the 3D cell migration process,such as pore microstructure and modulus of materials,and the biochemical signals,which is helpful to reveal wound healing and tissue regeneration process in the long run.