Development of microcarrier systems for bone tissue engineering

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2015
Aydoğdu, Hazal
Current strategies in bone tissue engineering have largely focused on development of carrier systems for repair and regeneration of bone tissue defects. The microcarrier systems offer an efficient method of delivery of cells with non-invasive injectable system. In this study, three-dimensional hydrogel microspheres were developed via water-in-oil emulsion method. In the first part of the thesis, porous pullulan (PULL) microspheres, with average size of 153±46 µm, were prepared and the surface of the microspheres were modified with (a) silk fibroin (SF) by reductive amination via surface oxidation of PULL microspheres, and (b) biomimetic mineralization by incubating the PULL microspheres in order to enhance the cell attachment and proliferation. The degradation analyses revealed that PULL microspheres had a slow degradation rate with 8% degradation in a two weeks’ period, which would support new bone tissue formation. Furthermore, the mechanical analysis showed that the microspheres had good mechanical properties that were enhanced significantly with the biomimetic mineralization with SBF incubation. Cell culture studies were conducted with SaOs-2 cell line and revealed that the SF coating and mineralization on the surface of PULL microspheres significantly increased the initial cell attachment and proliferation. In the second part of the thesis, urine derived mesenchymal stem cells were encapsulated in microspheres composed of oxidized PULL (oxPULL), alginate (ALG) and gelatin (GEL). The oxPULL with a degree of oxidation of 68±4%, and gelatin were crosslinked via borax catalyzed crosslinking while alginate was crosslinked with calcium and the average size for microspheres was found to be 530±32 µm. The cell culture studies indicated that the cells were successfully encapsulated, retained their viability and proliferated. According to these results, it can be suggested that the PULL microcarriers are suitable for use as injectable systems and have potential in bone tissue engineering applications.

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Citation Formats
H. Aydoğdu, “Development of microcarrier systems for bone tissue engineering,” M.S. - Master of Science, Middle East Technical University, 2015.