Structure and quantification of microvascularisation within mouse long bones: what and how should we measure?

Area of Science:

• * Bone Biology and Vascular Biology
• * Preclinical Imaging and Histomorphometry

Background:

• * Bone marrow vascularization is integral to skeletal remodeling and hematopoiesis.
• * Accurate imaging and quantification of bone vasculature are essential for understanding skeletal diseases and development in mouse models.

Purpose of the Study:

• * To compare barium sulfate and lead chromate-loaded silicon for mouse bone marrow vascular imaging.
• * To assess the compatibility of imaging agents with histological and immunohistochemical staining.
• * To characterize bone marrow vascular heterogeneity and establish reproducible quantification methods.

Main Methods:

• * Infusion of contrast agents (barium sulfate, lead chromate-loaded silicon) into mouse hind limb long bones.
• * Imaging via histology, low-resolution, and synchrotron-radiation microtomography.
• * Validation of barium sulfate technique with CD31 immunohistochemistry, histomorphometry, and ovariectomy model.

Main Results:

• * Barium sulfate provided superior vascular imaging compared to lead chromate-loaded silicon.
• * Barium sulfate infusion is compatible with bone histomorphometry and CD31 immunohistochemistry.
• * Bone marrow vascularization exhibits significant spatial heterogeneity, including lobular sinusoids and distal capillaries.
• * A reproducible method for quantifying microvascularization in barium-infused long bones was established.

Conclusions:

• * Barium sulfate is an effective contrast agent for high-quality mouse bone marrow vascular imaging.
• * Understanding vascular heterogeneity is critical for unbiased assessment of bone vascular changes.
• * The developed technique enables reproducible quantification of microvascularization and can be applied to study bone diseases.