title: Mice lacking pten in osteoblasts have improved intramembranous and late endochondral fracture healing.
abstract: The failure of an osseous fracture to heal (development of a non-union) is a common and debilitating clinical problem. Mice lacking the tumor suppressor Pten in osteoblasts have dramatic and progressive increases in bone volume and density throughout life. Since fracture healing is a recapitulation of bone development, we investigated the process of fracture healing in mice lacking Pten in osteoblasts (Ocn-cre(tg/+;)Pten(flox/flox) ). Mid-diaphyseal femoral fractures induced in wild-type and Ocn-cre(tg/+;)Pten(flox/flox) mice were studied via micro-computed tomography (µCT) scans, biomechanical testing, histological and histomorphometric analysis, and protein expression analysis. Ocn-cre(tg/+;)Pten(flox/flox) mice had significantly stiffer and stronger intact bones relative to controls in all cohorts. They also had significantly stiffer healing bones at day 28 post-fracture (PF) and significantly stronger healing bones at days 14, 21, and 28 PF. At day 7 PF, the proximal and distal ends of the Pten mutant calluses were more ossified. By day 28 PF, Pten mutants had larger and more mineralized calluses. Pten mutants had improved intramembranous bone formation during healing originating from the periosteum. They also had improved endochondral bone formation later in the healing process, after mature osteoblasts are present in the callus. Our results indicate that the inhibition of Pten can improve fracture healing and that the local or short-term use of commercially available Pten-inhibiting agents may have clinical application for enhancing fracture healing.
authors.affiliation: Center for Skeletal Disease Research, Van Andel Research Institute, Grand Rapids, Michigan, United States of America.
authors.forename: Travis A
authors.initials: TA
authors.lastname: Burgers
authors.forename: Martin F
authors.initials: MF
authors.lastname: Hoffmann
authors.forename: Caitlyn J
authors.initials: CJ
authors.lastname: Collins
authors.forename: Juraj
authors.initials: J
authors.lastname: Zahatnansky
authors.forename: Martin A
authors.initials: MA
authors.lastname: Alvarado
authors.forename: Michael R
authors.initials: MR
authors.lastname: Morris
authors.forename: Debra L
authors.initials: DL
authors.lastname: Sietsema
authors.forename: James J
authors.initials: JJ
authors.lastname: Mason
authors.forename: Clifford B
authors.initials: CB
authors.lastname: Jones
authors.forename: Heidi L
authors.initials: HL
authors.lastname: Ploeg
authors.forename: Bart O
authors.initials: BO
authors.lastname: Williams
mesh_terms: D000818:Animals; D002146:Bony Callus / Q000000981:diagnostic imaging / Q000502:physiology*; D002113:Calcification, Physiologic / Q000502:physiology; D002454:Cell Differentiation; D005264:Femoral Fractures / Q000000981:diagnostic imaging / Q000473:pathology; D005269:Femur / Q000293:injuries*; D017102:Fracture Healing / Q000235:genetics*; D017353:Gene Deletion; D051379:Mice; D008822:Mice, Transgenic; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism*; D010012:Osteogenesis / Q000235:genetics*; D051059:PTEN Phosphohydrolase / Q000172:deficiency / Q000235:genetics*; D011859:Radiography; D020127:Recovery of Function
chemical_list: D051059:PTEN Phosphohydrolase; C487757:Pten protein, mouse