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Current Research of Dr. Glen Niebur

Mechanobiology of Bone Marrow

We are using multi-scale experimental and computational approaches to better understand the mechanobiology of bone marrow. Marrow is a complex tissue composed of a heterogeneous cell population and a loose connective tissue, or stroma. Most of the cells have been shown to respond to mechanical stimuli in 2-D culture. Our experiments and models demonstrate that typical activities of daily living can sufficiently deform the bone and the encased marrow to impart mechanical stimuli to these cells through adheren junctions and cell-cell contact. We are developing novel bioreactor culture systems using native and artificial tissue to study these interactions in a controlled environment.

Explant Culture of Trabecular Bone

Trabecular bone explants were harvested from bones immediately after slaughter, then placed in culture in custom bioreactors that imparted mechanical loading to the explant. Bone marrow morphology was assessed to demonstrate its viability after long term culture. Future studies will investigate bone marrow adaptation and response to mechanical stimuli.

This research was conducted at The National University of Ireland, Galway in collaboration with Peter McHugh, Laosie McNamara, Evelyn Birmingham, Frank Barry, and the Regenerative Medicine Institute, and supported by Science Foundation Ireland.

Microdamage formation and propagation in trabecular bone

The role of microdamage in osteoporosis and age related fractures is being studied. We are currently studying the damage behavior of trabecular bone subjected to multiple sequential loading scenarios. Changes in loading mode cause microcracks in trabecular bone to propagate, while a single loading mode results in increased numbers of cracks without propagation. The mechanical consequences of this behavior are currently being investigated.

The figures show fluorescent labeled micrographs of trabecular bone following a sequence of on-axis compressive and torsional overloads. Damage due to each loading mode is differentiated by the labeling color.