A Mouse Model for Skeletal Structure and Function Changes Caused by Radiation Therapy and Estrogen Deficiency.

Area of Science:

• Bone biology
• Radiation oncology
• Endocrinology

Background:

• Radiation therapy and estrogen deficiency are known risk factors for bone damage and increased fracture risk.
• Developing accurate animal models is crucial for understanding these skeletal pathologies.

Purpose of the Study:

• To establish a mouse model simulating fractionated radiation therapy for cervical cancer treatment.
• To investigate the combined effects of radiation and estrogen deficiency (ovariectomy) on bone health in mice.

Main Methods:

• Thirty-two female C57BL/6 mice were divided into four groups: Sham+Non-irradiated, Sham+Irradiated, Ovariectomy+Non-irradiated, and Ovariectomy+Irradiated.
• Irradiated mice received a fractionated 18 Gy dose of X-rays to the hindlimbs.
• Bone structure and function were quantified using DEXA, microCT, and Finite Element Analysis (FEA) at various skeletal sites.

Main Results:

• Both irradiation and ovariectomy significantly reduced trabecular bone volume fraction (BV/TV) in the proximal tibia.
• Ovariectomy induced a systemic decline in bone microarchitecture, while radiation damage was localized to the irradiated trabecular bone.
• FEA revealed increased whole bone stiffness with irradiation but decreased stiffness with ovariectomy.

Conclusions:

• Fractionated irradiation and ovariectomy independently exert detrimental effects on skeletal microarchitecture.
• Ovariectomy has a systemic impact on bone, whereas radiation-induced bone damage is largely confined to the irradiated area.
• This mouse model effectively replicates key aspects of radiation-induced bone damage and estrogen deficiency relevant to cancer treatment outcomes.