Fabrication Of Cell-selective Surfaces And Their Influence On Cell Migration

Cell migration plays an essential role in many physiological and pathological processes,such as embryonic development,wound healing,vascular development,immune response and tumor metastasis.In vivo,cells can migrate directively into the desired position in response to biochemical and biophysical gradients.Hence,the gradient biomaterials have been developed extensively to realize the directive migration of cells in regenerative medicine and tissue engineering.However,undesired cell adhesion and migration can also cause improper regeneration of tissues or disease,which will reduce the final effect of these gradient biomaterials.Thus,there is an urgent and realistic need for the development of novel biomaterials that can realize the selective adhesion and directed cell migration simultaneously.Dynamic control of Bone mesenchymal stem cell(BMSC)behaviors on biomaterial surface is critically involved in regulating the cell fate and tissue regeneration.Herein,a stimuli-responsive surface based on host-guest interaction with cell selectivity was developed to regulate the migration of BMSCs in situ by dynamic manipulation of cell-specific peptides.Azobenzene-grafted BMSC-affinitive peptides(EPLQLKM,Azo-E7)were grafted to β-cyclodextran(β-CD)-modified poly(2-hydroxyethyl methacrylate)-b-poly(2-hydroxyethyl methacrylate-co-glycidyl methacrylate)(PHG)brushes,which were prepared by using surface-initiated atom transfer radical polymerization(SI-ATRP).Cell adhesion assay showed that the combination effect of resisting property of PHG and MSC-affinity of E7 could promote the selective adhesion of BMSCs over other types of cells such as RAW264.7 macrophages and NIH3T3 fibroblasts to some extent.UV-Vis spectroscopy proved that the competing guest molecules,amantadine hydrochloride(Ama),could release Azo-E7 peptides from the CD surface to different extents,and the effect was enhanced when UV irradiation was employed simultaneously.As a result,the decrease of cell adhesion density and migration rate could be achieved in situ.The cell density and migration rate could be reduced over 40% by adding 20μmol/L Ama,suggesting that this type of surface is a new platform for dynamic regulation of stem cell behaviors in situ.Selective adhesion and directional migration of endothelial cells(ECs)on biomaterials is critical to realize the rapid endothelialization.In this study,a Cys-Ala-Gly(CAG)peptide density gradient was generated on homogeneous cell-resisting poly(2-hydroxyethyl methacrylate-co-glycidyl methacrylate)brushes by immersing the brushes in a complementary gradient solution of CAG and competitive mercapto-terminated methoxyl poly(ethylene glycol).The adhesion and spreading of smooth muscle cells(SMCs)was impaired effectively on the gradient surface.About six folds of adherent ECs over SMCs were achieved at the position(10 mm)of highest CAG density on the gradient surface in a co-culture condition.Due to the gradient cues,ECs migrated fastest with the best directionality of 86.7% at the middle of the gradient,leading to the maximum net displacement as well.The biosurfaces in the first two chapters are based on the model materials such as glass,which cannot be used in vivo to verify their effect in real physiological environment.Although the endothelial cells on the CAG peptide gradient surface showed a trend of directive migration,the movement in the direction perpendicular to the gradient was still irregular,which limits the maximization of migration efficiency.Therefore,we prepared a micropatterned poly(D,L-lactide-co-caprolactone)(PLCL)film with stripes and transformed the CAG peptide modified P(HEMA-co-GMA)brushes onto it.The platelet adhesion and hemolysis test proved the good blood compatibility of this material.In vitro cell experiments showed that the surface had good endothelial cell selectivity.When the proportion of peptides in the reaction solution was large(90%),the density of endothelial cells could reach 3.6 folds than that of smooth muscle cells.Under the contact guidance effect of the stripe pattern,the cells showed highly oriented morphology in parallel to the stripe direction,which may enhance the directive cell migraiton,especially in the direction parallel to the stripes.In summary,selective cell adhesion and directive migration of target cells were achieved simultaneously by combining the antifouling polymer brushes and selective peptides.And the stripe micropatterns can enhance cell orientation,which is beneficial for directive migration.