title: Nano-fibrous scaffolding promotes osteoblast differentiation and biomineralization.
abstract: Nano-fibrous poly(L-lactic acid) (PLLA) scaffolds with interconnected pores were developed under the hypothesis that nano-fibrous scaffolding would mimic a morphological function of collagen fibrils to create a more favorable microenvironment for cells versus solid-walled scaffolds. In this study, an in vitro system was used to examine biological properties of the nano-fibrous scaffolds compared with those of solid-walled scaffolds for their potential use in bone tissue engineering. Biomineralization was enhanced substantially on the nano-fibrous scaffolds compared to solid-walled scaffolds, and this was confirmed by von Kossa staining, measurement of calcium contents, and transmission electron microscopy. In support of this finding, osteoblasts cultured on the nano-fibrous scaffolds exhibited higher alkaline phosphatase activity and an earlier and enhanced expression of the osteoblast phenotype versus solid-walled scaffolds. Most notable were the increases in runx2 protein and in bone sialoprotein mRNA in cells cultured on nano-fibrous scaffolds versus solid-walled scaffolds. At the day 1 of culture, alpha2 and beta1 integrins as well as alphav and beta3 integrins were highly expressed on the surface of cells seeded on nano-fibrous scaffolds, and linked to this were higher levels of phospho-Paxillin and phospho-FAK in cell lysates. In contrast, cells seeded on solid-walled scaffolds expressed significantly lower levels of these integrins, phospho-Paxillin, and phospho-FAK. To further examine the role of nano-fibrous architecture, we inhibited the formation of collagen fibrils by adding 3,4-dehydroproline to cultures and then assayed cells for expression of alpha2 integrin. Cells seeded on nano-fibrous scaffolds sustained expression of alpha2 integrin in the presence of dehydroproline, while suppression of alpha2 integrin was evident in cells seeded on solid-walled scaffolds. These results provide initial evidence that synthetic nano fibers may exhibit certain properties that are comparable to natural collagen fibers, and thus, the nano-fibrous architecture may serve as a superior scaffolding versus solid-walled architecture for promoting osteoblast differentiation and biomineralization.
authors.affiliation: School of Dentistry, Department of Cell and Developmental Biology, Seoul National University, Seoul 110-740, Republic of Korea.
authors.forename: Kyung Mi
authors.initials: KM
authors.lastname: Woo
authors.forename: Ji-Hae
authors.initials: JH
authors.lastname: Jun
authors.forename: Victor J
authors.initials: VJ
authors.lastname: Chen
authors.forename: Jihye
authors.initials: J
authors.lastname: Seo
authors.forename: Jeong-Hwa
authors.initials: JH
authors.lastname: Baek
authors.forename: Hyun-Mo
authors.initials: HM
authors.lastname: Ryoo
authors.forename: Gwan-Shik
authors.initials: GS
authors.lastname: Kim
authors.forename: Martha J
authors.initials: MJ
authors.lastname: Somerman
authors.forename: Peter X
authors.initials: PX
authors.lastname: Ma
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000378:metabolism; D040761:Biomimetic Materials / Q000737:chemistry*; D001861:Bone Regeneration / Q000502:physiology*; D002454:Cell Differentiation / Q000502:physiology*; D051379:Mice; D036103:Nanotechnology / Q000379:methods; D043942:Nanotubes / Q000737:chemistry / Q000648:ultrastructure; D010006:Osteoblasts / Q000166:cytology* / Q000502:physiology; D010012:Osteogenesis / Q000502:physiology; D023822:Tissue Engineering / Q000295:instrumentation / Q000379:methods*
chemical_list: D001672:Biocompatible Materials