Fabrication Of Biomimetic Vessels Based On Patterned Tubular Scaffolds

Due to the wide ranges of applications in the treatment of cardiovascular diseases and the construction of vascularized tissue models,tissue engineered blood vessels have drawn wide attention.So far,a variety of methods have been developed to construct tissueengineered blood vessels.Such vascular structures generally include typical endothelial cell(EC)hollow tubular structures that are coated with circumferentially oriented smooth muscle cells.Tissue engineered blood vessels can be constructed by 3D printing,cell sheet rolling and the like.In this thesis,we used capillaries as the templates to fabricate tubular scaffolds with micro and nano structure by controlling the self-assembly of colloidal particles and polymer casting.The specific research contents are as follows:(1)A patterned tissue-engineered biomimetic vascular scaffold with circumferentially stretched inverse opal pores was designed and fabricated.High-quality hollow tubular colloidal crystals were obtained by controlling the self-assembly of colloidal nanoparticles in glass capillaries.Based on the polymer molding technique,inverse opal polymer tubular scaffolds with ordered porous structures on the outer surface were obtained.Finally,the scaffolds were expanded,so that the circular pores on the surface were stretched into elliptical,of which the long axis parallel to the circumferential direction and the aspect ratio could be regulated by the expansion factor.(2)A study was conducted on the construction of biomimetic blood vessels based on circumferentially oriented inverse opal patterned tubular scaffolds.The effects of plasma treatment on the microstructure,hydrophilicity and cell adhesion properties of the surfaces were investigated.We researched the adhesion and growth of two vascular related cells on the scaffolds and found the larger expansion ratio had more significant induced effect on the circumferential growth of cells.At the same time,based on the patterned tubular scaffolds,we could achieve the circumferentially ordered growth of smooth muscle cells on the outer wall and the complete confluent monolayer growth of endothelial cells on the inner wall.(3)We employed biodegradable polylactic acid-glycolic acid copolymer(PLGA)and polylactic acid(PLA)for the preparation of the patterned inverse opal tubular scaffolds.The properties of tensile strength and thermal stability of the inverse opal films prepared by these two materials were investigated.The ordered porous structure tubular stent with stable structure at physiological temperature was obtained through the optimization of conditions.Cell experiments found that SMC cells could adhered to the biodegradable scaffold and orientedly grow and degradation characteristics of the material are related to the expansion factor.(4)A tissue-engineered biomimetic vascular scaffold with heterogeneous striped inverse opal was designed and fabricated.By synergistically adjusting colloidal particles self-assembly process in capillary,the heterogeneous striped hollow colloidal crystals were obtained.The width and spacing of stripe patterns can be regulated by changing the capillary diameter and colloidal particle concentration.Simultaneous replication of heterogeneous stripes and ordered nanostructures was achieved by polymer solution casting.Cell experiments found that this micro and nano composite patterned scaffolds has a certain ability to induce cells orientation.