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Annals of Biomedical Engineering, Vol. 36, No. 12, December 2008 ( 2008) pp. 19781991 DOI: 10.1007/s10439-008-9577-x
The Mechanical Environment of Bone Marrow: A Review
UMUT ATAKAN GURKAN and OZAN AKKUS
Weldon School of Biomedical Engineering, Purdue University, 206 S. Martin Jischke Drive, West Lafayette, IN 47907-2032, USA
(Received 29 December 2007; accepted 29 September 2008; published online 15 October 2008)
AbstractBone marrow is a viscous tissue that resides in the connes of bones and houses the vitally important pluripo-tent stem cells. Due to its connement by bones, the marrow has a unique mechanical environment which has been shown to be affected from external factors, such as physiological activity and disuse. The mechanical environment of bone marrow can be dened by determining hydrostatic pressure, uid ow induced shear stress, and viscosity. The hydrostatic pressure values of bone marrow reported in the literature vary in the range of 10.7120 mmHg for mammals, which is generally accepted to be around one fourth of the systemic blood pressure. Viscosity values of bone marrow have been reported to be between 37.5 and 400 cP for mammals, which is dependent on the marrow composition and temperature. Marrows mechanical and compositional properties have been implicated to be changing during common bone diseases, aging or disuse. In vitro experiments have demonstrated that the resident mesenchymal stem and progenitor cells in adult marrow are responsive to hydrostatic pressure, uid shear or to local compositional factors such as medium viscosity. Therefore, the changes in the mechanical and compositional microenvironment of marrow may affect the fate of resident stem cells in vivo as well, which in turn may alter the homeostasis of bone. The aim of this review is to highlight the marrow tissue within the context of its mechanical environment during normal physiology and underline perturbations during disease.
KeywordsMesenchymal stem cells, Marrow progenitor cells, Physiological activity, Osteoporosis, Disuse, Aging, Pressure, Fluid shear, Rheology, Viscosity.
INTRODUCTION
Bone marrow is the soft tissue residing in the cavities of the bones housing the essential pluripotent precursor cells for the living organism. It is the major source of hematopoietic stem cells (HSCs) which have the role of renewing the elements (monocytes, macrophages, neutrophils, eosinophils, erythroblasts,
erythrocytes, megakaryocytes, platelets) in the blood.12
Adult bone marrow also contains the mesenchymal stem...