TY  - JOUR
A1  - Wehrle, Esther
A1  - Liedert, Astrid
A1  - Heilmann, Aline
A1  - Wehner, Tim
A1  - Bindl, Ronny
A1  - Fischer, Lena
A1  - Haffner-Luntzer, Melanie
A1  - Jakob, Franz
A1  - Schinke, Thorsten
A1  - Amling, Michael
A1  - Ignatius, Anita
T1  - The impact of low-magnitude high-frequency vibration on fracture healing is profoundly influenced by the oestrogen status in mice
JF  - Disease Models & Mechanisms
N2  - Fracture healing is impaired in aged and osteoporotic individuals. Because adequate mechanical stimuli are able to increase bone formation, one therapeutical approach to treat poorly healing fractures could be the application of whole-body vibration, including low-magnitude high-frequency vibration (LMHFV). We investigated the effects of LMHFV on fracture healing in aged osteoporotic mice. Female C57BL/6NCrl mice (n=96) were either ovariectomised (OVX) or sham operated (non-OVX) at age 41 weeks. When aged to 49 weeks, all mice received a femur osteotomy that was stabilised using an external fixator. The mice received whole-body vibrations (20 minutes/day) with 0.3 g peak-to-peak acceleration and a frequency of 45 Hz. After 10 and 21 days, the osteotomised femurs and intact bones (contra-lateral femurs, lumbar spine) were evaluated using bending-testing, micro-computed tomography (mu CT), histology and gene expression analyses. LMHFV disturbed fracture healing in aged non-OVX mice, with significantly reduced flexural rigidity (-81%) and bone formation (-80%) in the callus. Gene expression analyses demonstrated increased oestrogen receptor β (ERβ, encoded by Esr2) and Sost expression in the callus of the vibrated animals, but decreased β-catenin, suggesting that ERβ might mediate these negative effects through inhibition of osteoanabolic Wnt/β-catenin signalling. In contrast, in OVX mice, LMHFV significantly improved callus properties, with increased flexural rigidity (+ 1398%) and bone formation (+637%), which could be abolished by subcutaneous oestrogen application (0.025 mg oestrogen administered in a 90-day-release pellet). On a molecular level, we found an upregulation of ER alpha in the callus of the vibrated OVX mice, whereas ERβ was unaffected, indicating that ERa might mediate the osteoanabolic response. Our results indicate a major role for oestrogen in the mechanostimulation of fracture healing and imply that LMHFV might only be safe and effective in confined target populations.
KW  - level mechanical vibrations
KW  - ovariectomized rats
KW  - bone formation
KW  - LMHFV
KW  - whole body vibration
KW  - receptor beta
KW  - replacement therapy
KW  - osteoblastic cells
KW  - early stage
KW  - alpha
KW  - Wnt
KW  - fracture healing
KW  - oestrogen receptor signalling
KW  - Wnt signalling
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-144700
VL  - 8
ER  - 
TY  - JOUR
A1  - Boschert, V.
A1  - Frisch, C.
A1  - Back, J. W.
A1  - van Pee,, K.
A1  - Weidauer, S. E.
A1  - Muth, E.-M.
A1  - Schmieder, P.
A1  - Beerbaum, M.
A1  - Knappik, A.
A1  - Timmerman, P.
A1  - Mueller, T. D.
T1  - The sclerostin-neutralizing antibody AbD09097 recognizes an epitope adjacent to sclerostin's binding site for the Wnt co-receptor LRP6
JF  - Open Biology
N2  - The glycoprotein sclerostin has been identified as a negative regulator of bone growth. It exerts its function by interacting with the Wnt co-receptor LRP5/6, blocks the binding of Wnt factors and thereby inhibits Wnt signalling. Neutralizing anti-sclerostin antibodies are able to restore Wnt activity and enhance bone growth thereby presenting a new osteoanabolic therapy approach for diseases such as osteoporosis. We have generated various Fab antibodies against human and murine sclerostin using a phage display set-up. Biochemical analyses have identified one Fab developed against murine sclerostin, AbD09097 that efficiently neutralizes sclerostin's Wnt inhibitory activity. In vitro interaction analysis using sclerostin variants revealed that this neutralizing Fab binds to sclerostin's flexible second loop, which has been shown to harbour the LRP5/6 binding motif. Affinity maturation was then applied to AbD09097, providing a set of improved neutralizing Fab antibodies which particularly bind human sclerostin with enhanced affinity. Determining the crystal structure of AbD09097 provides first insights into how this antibody might recognize and neutralize sclerostin. Together with the structure–function relationship derived from affinity maturation these new data will foster the rational design of new and highly efficient anti-sclerostin antibodies for the therapy of bone loss diseases such as osteoporosis.
KW  - phage display
KW  - Wnt signalling
KW  - sclerostin
KW  - neutralizing antibody
KW  - osteoporosis
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-177925
VL  - 6
ER  -