Fracture healing in osteoporotic mice

Genome-wide comparative gene expression analysis of callus tissue of osteoporotic mice (Col1a1-Krm2 and Lrp5-/-) and wild-type were performed to identify candidate genes that might be responsible for the impaired fracture healing observed in Col1a1-Krm2 and Lrp5-/- mice. To investigate bone healing in osteoporosis, we performed fracture healing studies in wild-type mice (C57BL/6 genetic background) and the low bone mass strains Col1a1-Krm2 and Lrp5-/- (Schulze et al., 2010; Kato et al., 2002). Osteotomy was set in femora of female mice and stabilized by a semi-rigid fixator to allow fast bone healing (Röntgen et al., 2010). 21 days post surgery we analyzed the fracture calli by biochemical/histological methods, as well as micro-computed tomography, and observed impaired fracture healing in Col1a1-Krm2 and Lrp5-/- mice in comparison to wild-type. To identify genes that may be responsible for the impaired healing in osteoporotic mice, we performed microarray analysis of three independent callus samples of each genotype. The callus tissue was taken 10 days after surgery, because extensive bone formation took place at this point.