The biological complexity of bone marrow is driven by the diverse array of hematopoietic and non-hematopoietic cells that orchestrate intricate biological activities, such as immune and tumor regulation, as well as hematopoiesis. Observing and tracking the complex cellular interactions and activities within the bone marrow niche are limited by currently available techniques, such as blood counts and histology, which use a “snapshot” of static evidence to infer such dynamics in vivo.
Researchers from the Princess Margaret Cancer Centre, University of Toronto, have developed a novel pre-clinical technique to visualize and quantitate the in vivo activities of bone marrow cells in real-time using a femur window chamber model. This new model, intended to complement current standard methods, was used in conjunction with intravital multiphoton fluorescence microscopy, a powerful technique for imaging living tissue. The researchers describe the protocol for surgical implantation of the window chamber in the murine femur and demonstrate the use of this approach for imaging and tracking neutrophils within the femur vasculature. In this case, the femur window chamber model enabled the dynamic imaging of three constituents of the femoral bone marrow: neutrophils, vasculature, and collagen matrix.
The current model provides valuable proof of principle that serial visualization and quantification of immune cell movement and regulation is feasible within the highly complex bone marrow compartment. Long-term optical access to the bone marrow niche is an important advancement that has future applications in studying stem cells transplantation, hematopoiesis and immune regulation in various pathologies, including cancer.
Study in journal JOVE: Femur Window Chamber Model for In Vivo Cell Tracking in the Murine Bone Marrow