title: Pullulan microcarriers for bone tissue regeneration.
abstract: Microcarrier systems offer a convenient way to repair bone defects as injectable cell carriers that can be applied with small incisions owing to their small size and spherical shape. In this study, pullulan (PULL) microspheres were fabricated and characterized as cell carriers for bone tissue engineering applications. PULL was cross-linked by trisodium trimetaphosphate (STMP) to enhance the stability of the microspheres. Improved cytocompatibility was achieved by silk fibroin (SF) coating and biomimetic mineralization on the surface by incubating in simulated body fluid (SBF). X-ray diffraction (XRD), scanning electron microscopy (SEM) and fluorescent microscopy analysis confirmed biomimetic mineralization and SF coating on microspheres. The degradation analysis revealed that PULL microspheres had a slow degradation rate with 8% degradation in two weeks period indicating that the microspheres would support the formation of new bone tissue. Furthermore, the mechanical tests showed that the microspheres had a high mechanical stability that was significantly enhanced with the biomimetic mineralization. In vitro cell culture studies with SaOs-2 cells showed that cell viability was higher on SF and SBF coated microspheres on 7th day compared to PULL ones under dynamic conditions. Alkaline phosphatase activity was higher for SF coated microspheres in comparison to uncoated microspheres when dynamic culture condition was applied. The results suggest that both organic and inorganic surface modifications can be applied on PULL microspheres to prepare a biocompatible microcarrier system with suitable properties for bone tissue engineering.
authors.affiliation: Middle East Technical University, Department of Biomedical Engineering, Ankara 06800, Turkey.
authors.forename: Hazal
authors.initials: H
authors.lastname: Aydogdu
authors.affiliation: Middle East Technical University, Department of Biomedical Engineering, Ankara 06800, Turkey; Middle East Technical University, Department of Engineering Sciences, Ankara 06800, Turkey; METU BIOMATEN Center of Excellence in Biomaterials and Tissue Engineering, Ankara 06800, Turkey.
authors.forename: Dilek
authors.initials: D
authors.lastname: Keskin
authors.affiliation: METU BIOMATEN Center of Excellence in Biomaterials and Tissue Engineering, Ankara 06800, Turkey. Electronic address: erkanturkerbaran@gmail.com.
authors.forename: Erkan Turker
authors.initials: ET
authors.lastname: Baran
authors.affiliation: Middle East Technical University, Department of Biomedical Engineering, Ankara 06800, Turkey; Middle East Technical University, Department of Engineering Sciences, Ankara 06800, Turkey; METU BIOMATEN Center of Excellence in Biomaterials and Tissue Engineering, Ankara 06800, Turkey. Electronic address: tezcaner@metu.edu.tr.
authors.forename: Aysen
authors.initials: A
authors.lastname: Tezcaner
mesh_terms: D001861:Bone Regeneration / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D020099:Coated Materials, Biocompatible / Q000737:chemistry* / Q000494:pharmacology; D005349:Fibroins / Q000737:chemistry; D005936:Glucans / Q000737:chemistry* / Q000494:pharmacology; D006801:Humans; D008855:Microscopy, Electron, Scanning; D008856:Microscopy, Fluorescence; D008863:Microspheres; D011122:Polyphosphates / Q000737:chemistry; D013499:Surface Properties; D014961:X-Ray Diffraction
chemical_list: D020099:Coated Materials, Biocompatible; D005936:Glucans; D011122:Polyphosphates; C009109:pullulan; D005349:Fibroins; C009293:trimetaphosphoric acid
keywords: Biomimetic mineralization; Bone tissue engineering; Microspheres; Pullulan; SF coating