Axial strain enhances osteotomy repair with a concomitant increase in connexin43 expression.
The mechanical environment is known to influence fracture healing. We speculated that connexin43 (Cx43) gap junctions, which impact skeletal homeostasis, fracture healing and the osteogenic response to mechanical load, may play a role in mediating the response of the healing bone to mechanical strain. Here, we used an established rat fracture model, which uses a 2 mm osteotomy gap stabilized by an external fixator, to examine the impact of various cyclical axial loading protocols (2%, 10%, and 30% strain) on osteotomy healing. We examined the presence of Cx43 in the osteotomy-healing environment and assessed how mechanical strain modulates Cx43 expression patterns in the callus. We demonstrated that increased cyclical axial strain results in increased radiographic and histologic bone formation. In addition, we show by immunohistochemistry that Cx43 is abundantly expressed in the healing callus, with the expression most robust in samples exposed to increased cyclical axial strain. These data are consistent with the concept that an increase in Cx43 expression by mechanical load may be part of the mechanisms by which mechanical forces enhances fracture healing.
Department of Orthopaedics, University of Maryland , Baltimore, MD, USA.
Rishi R
RR
Gupta
Fischell Department of Bioengineering, University of Maryland , College Park, MD, USA.
Hyunchul
H
Kim
Department of Orthopaedics, University of Maryland , Baltimore, MD, USA.
Yu-Kwan
YK
Chan
Department of Orthopaedics, University of Maryland , Baltimore, MD, USA.
Carla
C
Hebert
Department of Orthopaedics, University of Maryland , Baltimore, MD, USA.
Leah
L
Gitajn
Department of Orthopaedics, University of Maryland , Baltimore, MD, USA.
David J
DJ
Yoo
Department of Orthopaedics, University of Maryland , Baltimore, MD, USA.
Robert V
RV
O'Toole
Fischell Department of Bioengineering, University of Maryland , College Park, MD, USA.
Adam H
AH
Hsieh
Department of Orthopaedics, University of Maryland , Baltimore, MD, USA.
Joseph P
JP
Stains