Preparation And Properties Of A Novel Tissue Engineering Tracheal Scaffold With A Gelatin-chondroitin Sulfate-hyaluronan Material And Orientated Structure

In this study,porous scaffold of gelatin-chondroitin sulfate-hyaluronan-polyvinyl alcohol(GCH-PVA)with orientated microtubule structure was fabricated using unidirectional freeze-drying method to mimic the composition and structure of tracheal cartilage extracellular matrix.The orientated porous composite scaffold with good structure and properties was fabricated by optimizing fabrication technical parameters,including mould material,concentration,temperature gradient,composite ratio and evaluating its physicochemical properties and biological performance.The experiments' results of varying fabrication technical parameters and characterizing pore structure and hydrophilicity of PVA scaffold indicates that the best fabrication technical parameters were the Teflon mould,concentration of 7%(w/v),and temperature gradient of 60 oC.Then the GCH-PVA composite scaffolds of different mass ratios were prepared and their properties were studied,including physicochemical properties,mechanical properties and biocompatibility.Physicochemical properties indicated that scaffolds with different mass ratios have no obvious difference in pore morphology and pore size.The porosity and hydrophilicity of composite scaffolds tended to increase with the increasing of PVA content.The scaffold mechanical properties were systematically studied with compression test,stress relaxation test,cyclic compressive test and multiple frequency compressive test.The compression test showed that compressive strength and compressive elastic modulus decreased gradually with the increasing content of PVA.The stress relaxation test results showed that the composite scaffolds can perform stable mechanical reaction to stress and the incorporation of small amount of PVA in GCH scaffold was beneficial to provide high and stable support force when stressed.The cyclic compressive test results indicated that all composite scaffolds showed obvious viscoelasticity and can recover from large strains without permanent damage.And their relative energy dissipation lay in the range of 30%-50% which are close to that of cartilage tissue(50%-80%).But composite scaffolds with PVA showed higher relative energy dissipation,which are more close to natural tissue and have better ability to keep shape integrity during cyclic compression.Multiple frequency compressive test results showed that the loss tangent of composite scaffolds lays in the range of 0.08-0.16 close to the cartilage tissue(0.25),which indicated that the composite scaffolds have similar viscoelasticity to cartilage tissue.To mimic the tracheal ring shape,scaffolds with ring shape were fabricated,and the mechanical test showed that the ring shape scaffolds have lower stress strength,but the energy dissipations and loss tangent are more close to the native cartilage tissue,being 50%-80% and 0.1-0.19,respectively.The in vitro biocompatibility test showed that all scaffolds are good for cell proliferation and adhesion and the PVA incorporation improved cell proliferation and adhesion ability.