There-dimensional Pattern And Cell Response Of Porous Polylactide/Natural Polysaccharide Composite Scaffolds

Natural polysaccharides such as sodium alginate and chitosan have been "hot" candidates for scaffolds materials research due to their good biodegradability and biocompatibility. However the weak mechanical property is the main limitation for the further application. In this paper, polylactic acide (PLLA) was introduced to prepare composites to strengthen the mechanical properties. The compositing method, topological structure, surface morphology and culturing enviroument were systematically studied to obtain the composite scaffolds with good biocompatibility and mechanical properties, which will be used to replace and repair the bone or cartilage defect tissues.Calcium alginate hydrogel is widely used as the tissue engineering scaffold due to its good biocompability. In this paper, sodium alginate (SA), calcium carbonate and Glucono-Delta-Lactone (GDL) were selected as the materials to prepare the injectable calcium alginate hydrogel using in-situ transformation method. The influences of different concentrations of SA, f value (f=Ca2+/COO-), n value (n =Ca2+/GDL) on the hrdrogel mechanical strength, swelling ratio and pH value of the leaching liquor were investigated and the optium gelation condition was finally determined. Besides, the behaviours of the choncytes seeded in the gel by in-situ cell culture were studied as well.The mechanical property of the calcium alginate hydrogel was not suitable for the requirement of the tissue engineering scaffold, so the lysozyme-chitosan microspheres were introduced into the hydrogel to improve the mechanical strength. However, the results did not show obviously high strength as expected. Therefore, PLLA network was constructed to further strengthen the calcium alginate hydrogel and the mechanical property was dramatically improved. The biocompatibility of such composite scaffold was evaluated by in vitro cell culture and animal experiment. Results showed such composite scaffolds not only remedied the poor mechanical propertity of calcium alginate hydrogel but also improved the biocompability of the PLLA scaffolds.Chitosan scaffolds obtained by conventional freeze-drying method are always with sheet pore structures which inhibit the adherence and migration of seed cells.A novel hierarchically porous chitosan (HPCS) scaffold with large open pores and interconnected small pores on the surface was fabricated with ice particles as poroen. PLLA was introduced to strengthen the chitosan scaffold and a three-dimensional honeycomb patterned porous composite scaffolds with excellent mechanical property were obtained. A comparison of the morphology, mechanical properties and cell compatibility with the three different scaffolds were made. Results showed that honeycomb patterned porous structure was visible in the CS/PLLA composite scaffolds, wherein interconnected micro-pores embedded in larger open pores and formed uniform network. Hierarchically porous structure was visible in the HPCS scaffolds. The compressive strength of the CS/PLLA composite scaffolds was dramatically increased and the cells were grown better in the CS/PLLA composite scaffolds. So the topographical design of chitosan scaffolds remedied the traditional freeze-drying technique, improved cell biocompatibility and elongated the design of topological structure into the three dimension area, which provided a new breakthrough to the tissue engineering scaffold area.In this paper, PLLA with excellent mechanical propertity was introduced to composite with the natural polysaccharide and the composite scaffolds with both of good biocompatibility and mechanical strength were obtained. Besides, Honeycomb patterned porous composite scaffolds elongated the design of topological structure from two dimension to the three dimension area, which provided a new breakthrough to the tissue engineering scaffold area. At the same time, the biodynamic test instrument reactor was adopted to simulate the physiological environment. The morphology, secretion of the ECM and basic fibroblast growth factor (bFGF) of the seeded fibroblasts under different culture conditions were studied as well.