Engineering a 3D bone marrow adipose composite tissue loading model suitable for studying mechanobiological questions

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Mechanobiology

Background:

• Bone marrow microenvironment research is crucial for understanding healthy and pathological conditions.
• Mechanical stimulation significantly impacts bone function, but its effect on the bone marrow niche, particularly bone marrow adipose tissue (BMAT), remains poorly understood.
• Existing in vitro models lack the capability to replicate the biomechanical stimuli crucial for studying BMAT.

Purpose of the Study:

• To engineer a biomimetic bone marrow adipose tissue (BMAT) analog.
• To develop an innovative bioreactor capable of applying mechanical loading to BMAT analogs.
• To investigate the effects of biomechanical stimuli on BMAT adipogenesis and adipokine secretion.

Main Methods:

• Fabrication of a GelMA (gelatin methacryloyl) hydrogel/mPCL (medical-grade polycaprolactone) scaffold composite to mimic the BMAT microenvironment.
• Utilizing a novel bioreactor for long-term intermittent mechanical stimulation (1 Hz, 2 h/day, 3 days/week, 3 weeks).
• Assessing cellular proliferation, lipid accumulation, and adipokine secretion (leptin, adiponectin) in response to mechanical loading.

Main Results:

• Reproducible BMAT analogs supported successful adipogenesis of human mesenchymal bone marrow stem cells.
• Mechanical stimulation did not significantly alter cellular proliferation or lipid accumulation compared to unloaded controls.
• A significant reduction in leptin and adiponectin secretion was observed following mechanical loading, consistent with clinical findings related to physical activity.

Conclusions:

• The engineered GelMA/mPCL BMAT analog effectively mimics key aspects of the bone marrow microenvironment.
• The novel bioreactor platform allows for the study of mechanical loading effects on BMAT in a controlled in vitro setting.
• This system provides a valuable tool for investigating bone marrow physiology within the context of its dynamic mechanical microenvironment.