title: Enhancement of osteoblastic differentiation in alginate gel beads with bioactive octacalcium phosphate particles.
abstract: The present study investigated whether alginate (Alg) hydrogel microbeads have a role in maintaining mouse bone marrow stromal ST-2 cells and release the cells after being stimulated by synthetic octacalcium phosphate (OCP), which is a mineral crystal capable of stimulating osteoblastic differentiation during a conversion process to hydroxyapatite (HA). The ST-2 cell suspension in the alginate solution, which contained various concentrations of OCP granules with diameters less than 53 μm, was extruded drop-wise into a stirred gelation solution containing BaCl2 using an encapsulator with nitrogen gas stream. The Alg-microbeads (Alg/OCP · ST-2 microbeads) that were generated, which had a diameter of approximately 400 μm, were incubated for up to 14 d and then assessed for osteoblastic differentiation. Alg-microbeads with cells were also incubated to identify the possible conversion from OCP to HA. Osteoblast differentiation markers in ST-2 cells, alkaline phosphatase (ALP) and collagen type I, were up-regulated in the presence of higher amounts of OCP. X-ray diffraction analysis and Fourier transform infrared spectroscopy confirmed that the OCP tended to convert to HA over time, suggesting that the OCP in Alg-microbeads interacts three-dimensionally with ST-2 cells and stimulates its osteoblastic differentiation. The release of ST-2 cells from the microbeads was also estimated. ST-2 cells were identified outside of the microbeads, although the cell number tended to decrease with increasing OCP. These results suggest that Alg/OCP microbeads could be used as a vehicle to activate osteoblastic cells and deliver them to sites where bone regeneration is needed.
authors.affiliation: Division of Craniofacial Function Engineering, Tohoku University Graduate School of Dentistry, Sendai 980-8575, Japan. Division of Advanced Prosthetic Dentistry, Tohoku University Graduate School of Dentistry 980-8575, Sendai, Japan.
authors.forename: Kosei
authors.initials: K
authors.lastname: Endo
authors.forename: Takahisa
authors.initials: T
authors.lastname: Anada
authors.forename: Masumi
authors.initials: M
authors.lastname: Yamada
authors.forename: Minoru
authors.initials: M
authors.lastname: Seki
authors.forename: Keiichi
authors.initials: K
authors.lastname: Sasaki
authors.forename: Osamu
authors.initials: O
authors.lastname: Suzuki
mesh_terms: D000464:Alginates / Q000737:chemistry*; D000818:Animals; D018786:Bone Substitutes / Q000138:chemical synthesis; D002130:Calcium Phosphates / Q000737:chemistry*; D002454:Cell Differentiation / Q000502:physiology; D002460:Cell Line; D005782:Gels / Q000737:chemistry; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000502:physiology*; D051379:Mice; D008863:Microspheres; D010006:Osteoblasts / Q000166:cytology* / Q000502:physiology*; D010012:Osteogenesis / Q000502:physiology; D054457:Tissue Scaffolds
chemical_list: D000464:Alginates; D018786:Bone Substitutes; D002130:Calcium Phosphates; D005782:Gels; D006603:Hexuronic Acids; C022045:octacalcium phosphate; D020723:Glucuronic Acid