Methods for the reliable induction of heterotopic ossification in the conditional Alk2 mouse
Haichun Pan1, Nicole Fleming2, Charles C Hong2,3,4,5
1University of Michigan School of Dentistry, Ann Arbor, MI.
Objectives:
Conditional Alk2 (caALK2) mice have previously been used as a model of heterotopic ossification (HO). However, HO formation in this model can be highly variable, and it is unclear which methods reliably induce HO. Hence, these studies report validated methods for reproducibly inducing HO in caALK2 mice.
Methods:
Varying doses of Adex-cre and cardiotoxin (CTX) were injected into the calf muscles of 9, 14, or 28-day-old caALK2 or caALK2 mice. HO was measured by planar radiography or microCT at 14-28 days post-injury.
Results:
In 9-day-old caALK2 or caALK2 mice, single injections of 109 PFU Adex-cre and 0.3 μg of CTX were sufficient to induce extensive HO within 14 days post-injury. In 28-day-old mice, the doses were increased to 5 x 109 PFU Adex-cre and 3.0 μg of CTX to achieve similar consistency, but at a slower rate versus younger mice. Using a crush injury, instead of CTX, also provided consistent induction of HO. Finally, the Type 1 BMPR inhibitor, DMH1, significantly reduced HO formation in 28-day-old caALK2 mice.
Conclusions:
These data illustrate multiple methods for reliable induction of localized HO in the caALK2mouse that can serve as a starting point for new laboratories utilizing this model.
