Crosslinked pullulan/cellulose acetate fibrous scaffolds for bone tissue engineering

Natural polymer based fibrous scaffolds have been explored for bone tissue engineering applications; however, their inadequate 3-dimensionality and poor mechanical properties are among the concerns for their use as bone substitutes. In this study, pullulan (P) and cellulose acetate (CA), two polysaccharides, were electrospun at various P/CA ratios (P-80/CA(20), P-50/CA(50), and F-20/CA(80)%) to develop 3D fibrous network. The scaffolds were then crosslinked with trisodium trimetaphosphate (STMP) to improve the mechanical properties and to delay fast weight loss. The lowest weight loss was observed for the groups that were crosslinked with P/STMP 2/1 for 10 min. Fiber morphologies of P-50/CA(50), were more uniform without phase separation and this group was crosslinked most efficiently among groups. It was found that mechanical properties of P-20/CA(80) and P-50/CA(50) were higher than that of P-80/CA(20). After crosslinking strain values of P-50/CA(50) scaffolds were improved and these scaffolds became more stable. Unlike P-80/CA(20), uncrosslinked P-50/CA(50) and P-20/CA(80) were not lost in PBS. Among all groups, crosslinked P-50/CA(50) scaffolds had more uniform pores; therefore this group was used for bioactivity and cell culture studies. Apatite-like structures were observed on fibers after SBF incubation. Human Osteogenic Sarcoma Cell Line (Saos-2) seeded onto crosslinked P-50/CA(50) scaffolds adhered and proliferated. The functionality of cells was tested by measuring ALP activity of the cells and the results indicated their osteoblastic differentiation. In vitro tests showed that scaffolds were cytocompatible. To sum up, crosslinked P-50/CA(50) scaffolds were proposed as candidate cell carriers for bone tissue engineering applications.