Studies On Heparinized PLGA Ultrafine Fibrous Membranes And Vascular Tissue Engineering Scaffolds

Ultrafine polymer fibers can be conveniently produced via electrospinning technology, with diameter in the range of several-ten nanometers to several microns. This material composed with electrospun fibers has extremely large surface area and porous structure and very potential tissue engineering scaffold.In this experiment, poly(lactic acid-co-glycolic acid) (PLGA) ultrafine fibers are produced by electrospinning. And two heparinization methods, namely, physical blend and covalent coupling, were used to improve the anticoagulant properties of PLGA. Scanning electron microscopy (SEM) was used to analyze the effect of heparinization on the morphology of ultrafine fibers. Fourier transform infrared spectroscopy and X-ray Photoelectron Spectroscopy were used to illustrate the composition changes of PLGA. The biocompatibility and heamocompatibility were studied by vascular smooth muscle cells adhesion and proliferation assay, platelet adhesion, dynamic blood clotting tests, blood clot time assay. The results showed that PLGA ultrafine fibers, with average diameter 262±62 nm could be produced at 20 kV voltage, 1.0 ml/h flow rate and 20 cm distance. After physical blending of heparin, electrospun PLGA fibers showed smaller diameters. Both heparinization methods could improve the anticoagulant properties of electrospun PLGA membranes. Furthermore, physically blend samples exhibited better anticoagulant effect, comparing to the covalent coupled samples. Moreover, the more heparin content, the better anticoagulant effect, but the dissociated heparin will inhibit cells'adhesion on the material and the later proliferation.A specially designed collector device was employed to prepare small diameter PLGA electrospun vascular tissue engineering scaffolds and heparinized electrospun vascular tissue eingeering scaffolds. SEM was used to observe the scaffold's morphology. Tensile test at axial direction and cell culture experiments were carried out. The PLGA electrospun tubes of 1-4 mm had porous structrue and proper mechanical properties. When the tubes were immersed into a fluid, the flexibility could be improved. After 7-days cell culture, vascular smooth muscle cells could well attach on the surface of tubular scaffold and formed a lumen.