title: A novel osteogenic oxysterol compound for therapeutic development to promote bone growth: activation of hedgehog signaling and osteogenesis through smoothened binding.
abstract: Osteogenic factors are often used in orthopedics to promote bone growth, improve fracture healing, and induce spine fusion. Osteogenic oxysterols are naturally occurring molecules that were shown to induce osteogenic differentiation in vitro and promote spine fusion in vivo. The purpose of this study was to identify an osteogenic oxysterol more suitable for clinical development than those previously reported, and evaluate its ability to promote osteogenesis in vitro and spine fusion in rats in vivo. Among more than 100 oxysterol analogues synthesized, Oxy133 induced significant expression of osteogenic markers Runx2, osterix (OSX), alkaline phosphatase (ALP), bone sialoprotein (BSP), and osteocalcin (OCN) in C3H10T1/2 mouse embryonic fibroblasts and in M2-10B4 mouse marrow stromal cells. Oxy133-induced activation of an 8X-Gli luciferase reporter, its direct binding to Smoothened, and the inhibition of Oxy133-induced osteogenic effects by the Hedgehog (Hh) pathway inhibitor, cyclopamine, demonstrated the role of Hh pathway in mediating osteogenic responses to Oxy133. Oxy133 did not stimulate osteogenesis via BMP or Wnt signaling. Oxy133 induced the expression of OSX, BSP, and OCN, and stimulated robust mineralization in primary human mesenchymal stem cells. In vivo, bilateral spine fusion occurred through endochondral ossification and was observed in animals treated with Oxy133 at the fusion site on X-ray after 4 weeks and confirmed with manual assessment, micro-CT (µCT), and histology after 8 weeks, with equal efficiency to recombinant human bone morphogenetic protein-2 (rhBMP-2). Unlike rhBMP-2, Oxy133 did not induce adipogenesis in the fusion mass and resulted in denser bone evidenced by greater bone volume/tissue volume (BV/TV) ratio and smaller trabecular separation. Findings here suggest that Oxy133 has significant potential as an osteogenic molecule with greater ease of synthesis and improved time to fusion compared to previously studied oxysterols. Small molecule osteogenic oxysterols may serve as the next generation of bone anabolic agents for therapeutic development.
authors.affiliation: Department of Orthopedic Surgery, University of California, Los Angeles (UCLA), Los Angeles, CA, USA.
authors.forename: Scott R
authors.initials: SR
authors.lastname: Montgomery
authors.forename: Taya
authors.initials: T
authors.lastname: Nargizyan
authors.forename: Vicente
authors.initials: V
authors.lastname: Meliton
authors.forename: Sigrid
authors.initials: S
authors.lastname: Nachtergaele
authors.forename: Rajat
authors.initials: R
authors.lastname: Rohatgi
authors.forename: Frank
authors.initials: F
authors.lastname: Stappenbeck
authors.forename: Michael E
authors.initials: ME
authors.lastname: Jung
authors.forename: Jared S
authors.initials: JS
authors.lastname: Johnson
authors.forename: Bayan
authors.initials: B
authors.lastname: Aghdasi
authors.forename: Haijun
authors.initials: H
authors.lastname: Tian
authors.forename: Gil
authors.initials: G
authors.lastname: Weintraub
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Inoue
authors.forename: Elisa
authors.initials: E
authors.lastname: Atti
authors.forename: Sotirios
authors.initials: S
authors.lastname: Tetradis
authors.forename: Renata C
authors.initials: RC
authors.lastname: Pereira
authors.forename: Akishige
authors.initials: A
authors.lastname: Hokugo
authors.forename: Raed
authors.initials: R
authors.lastname: Alobaidaan
authors.forename: Yanlin
authors.initials: Y
authors.lastname: Tan
authors.forename: Theodor J
authors.initials: TJ
authors.lastname: Hahn
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Wang
authors.forename: Farhad
authors.initials: F
authors.lastname: Parhami
mesh_terms: D000818:Animals; D050071:Bone Density Conservation Agents / Q000737:chemistry / Q000494:pharmacology; D001846:Bone Development / Q000187:drug effects* / Q000235:genetics; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D053823:Hedgehog Proteins / Q000502:physiology*; D008297:Male; D051379:Mice; D015394:Molecular Structure; D010012:Osteogenesis / Q000187:drug effects* / Q000235:genetics; D051381:Rats; D011917:Rats, Inbred Lew; D015398:Signal Transduction / Q000187:drug effects*; D013261:Sterols / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D050071:Bone Density Conservation Agents; D053823:Hedgehog Proteins; C000603092:Oxy133; D013261:Sterols
keywords: ADIPOGENESIS; BMP2; OSTEOGENESIS; OXYSTEROL; SPINAL FUSION