title: Calvarial Defect Healing Induced by Small Molecule Smoothened Agonist.
abstract: Hedgehog (Hh) signaling positively regulates both endochondral and intramembranous ossification. Use of small molecules for tissue engineering applications poses several advantages. In this study, we examined whether use of an acellular scaffold treated with the small molecule Smoothened agonist (SAG) could aid in critical-size mouse calvarial defect repair. First, we verified the pro-osteogenic effect of SAG in vitro, using primary neonatal mouse calvarial cells (NMCCs). Next, a 4 mm nonhealing defect was created in the mid-parietal bone of 10-week-old CD-1 mice. The scaffold consisted of a custom-fabricated poly(lactic-co-glycolic acid) disc with hydroxyapatite coating (measuring 4 mm diameter × 0.5 mm thickness). Treatment groups included dimethylsulfoxide control (n = 6), 0.5 mM SAG (n = 7) or 1.0 mM SAG (n = 7). Evaluation was performed at 4 and 8 weeks postoperative, by a combination of high-resolution microcomputed tomography, histology (H & E, Masson's Trichrome), histomorphometry, and immunohistochemistry (BSP, OCN, VEGF). In vivo results showed that SAG treatment induced a significant and dose-dependent increase in calvarial bone healing by all radiographic parameters. Histomorphometric analysis showed an increase in all parameters of bone formation with SAG treatment, but also an increase in blood vessel number and density. In summary, SAG is a pro-osteogenic, provasculogenic stimulus when applied locally in a bone defect environment.
authors.affiliation: 1 Division of Growth and Development and Section of Orthodontics, School of Dentistry, University of California , Los Angeles, Los Angeles, California.|2 Department of Orthopaedic Surgery, CHA Bundang Medical Center, CHA University , Republic of Korea.|3 Department of Orthopaedic Surgery and the Orthopaedic Hospital Research Center, University of California , Los Angeles, Los Angeles, California.
authors.forename: Soonchul
authors.initials: S
authors.lastname: Lee
authors.affiliation: 1 Division of Growth and Development and Section of Orthodontics, School of Dentistry, University of California , Los Angeles, Los Angeles, California.
authors.forename: Jia
authors.initials: J
authors.lastname: Shen
authors.affiliation: 1 Division of Growth and Development and Section of Orthodontics, School of Dentistry, University of California , Los Angeles, Los Angeles, California.
authors.forename: Hsin Chuan
authors.initials: HC
authors.lastname: Pan
authors.affiliation: 3 Department of Orthopaedic Surgery and the Orthopaedic Hospital Research Center, University of California , Los Angeles, Los Angeles, California.
authors.forename: Swati
authors.initials: S
authors.lastname: Shrestha
authors.affiliation: 1 Division of Growth and Development and Section of Orthodontics, School of Dentistry, University of California , Los Angeles, Los Angeles, California.
authors.forename: Greg
authors.initials: G
authors.lastname: Asatrian
authors.affiliation: 1 Division of Growth and Development and Section of Orthodontics, School of Dentistry, University of California , Los Angeles, Los Angeles, California.
authors.forename: Alan
authors.initials: A
authors.lastname: Nguyen
authors.affiliation: 4 Department of Pathology, Johns Hopkins University , Baltimore, Maryland.
authors.forename: Carolyn
authors.initials: C
authors.lastname: Meyers
authors.affiliation: 1 Division of Growth and Development and Section of Orthodontics, School of Dentistry, University of California , Los Angeles, Los Angeles, California.
authors.forename: Vi
authors.initials: V
authors.lastname: Nguyen
authors.affiliation: 5 Section of Biomaterials, School of Dentistry, University of California , Los Angeles, Los Angeles, California.
authors.forename: Min
authors.initials: M
authors.lastname: Lee
authors.affiliation: 3 Department of Orthopaedic Surgery and the Orthopaedic Hospital Research Center, University of California , Los Angeles, Los Angeles, California.|6 Division of Plastic and Reconstructive Surgery, Department of Surgery, David Geffen School of Medicine, University of California , Los Angeles, Los Angeles, California.
authors.forename: Chia
authors.initials: C
authors.lastname: Soo
authors.affiliation: 2 Department of Orthopaedic Surgery, CHA Bundang Medical Center, CHA University , Republic of Korea.|3 Department of Orthopaedic Surgery and the Orthopaedic Hospital Research Center, University of California , Los Angeles, Los Angeles, California.
authors.forename: Kang
authors.initials: K
authors.lastname: Ting
authors.affiliation: 3 Department of Orthopaedic Surgery and the Orthopaedic Hospital Research Center, University of California , Los Angeles, Los Angeles, California.|4 Department of Pathology, Johns Hopkins University , Baltimore, Maryland.
authors.forename: Aaron W
authors.initials: AW
authors.lastname: James
mesh_terms: D000818:Animals; D003514:Cyclohexylamines / Q000494:pharmacology*; D016503:Drug Delivery Systems / Q000379:methods*; D017102:Fracture Healing / Q000187:drug effects*; D008297:Male; D051379:Mice; D010294:Parietal Bone / Q000000981:diagnostic imaging / Q000293:injuries* / Q000378:metabolism* / Q000473:pathology; D013876:Thiophenes / Q000494:pharmacology*; D054457:Tissue Scaffolds / Q000737:chemistry*
chemical_list: D003514:Cyclohexylamines; C468918:SAG compound; D013876:Thiophenes
keywords: bone healing; hedgehog signaling; osteogenesis; small molecule; smoothened agonist; vasculogenesis