Cohousing Male Mice with and without Segmental Bone Defects

Area of Science:

• Spaceflight research
• Bone healing studies
• Animal models in research

Background:

• Spaceflight induces bone loss similar to osteoporosis and trauma.
• The International Space Station (ISS) offers a unique environment to study bone healing.
• Previous spaceflight bone healing study designs required optimization due to potential animal welfare concerns.

Purpose of the Study:

• To determine if operated and non-operated male mice can be successfully cohoused during spaceflight.
• To address concerns about potential aggression between male mice with and without surgical bone defects.
• To optimize housing strategies for future surgical studies in microgravity.

Main Methods:

• Male C57BL/6 mice were used, with some undergoing surgery for a segmental bone defect.
• Operated and non-operated mice were cohoused from birth under identical conditions.
• Quantitative behavioral scoring, body weight, and organ weight analyses were employed.

Main Results:

• Cohoused operated and non-operated male mice did not exhibit aggressive behavior.
• No evidence of stress was observed through veterinary assessment.
• Body weight and proportional organ weights remained unchanged in all mice.

Conclusions:

• Operated and non-operated male mice can be successfully cohoused, mitigating aggression concerns.
• This finding validates the housing strategy for the ISS bone healing mission.
• The results may inform future surgical study designs, enhancing housing flexibility in spaceflight research.