The heart is a complex three-dimensional structure with mechanical properties that are inhomogeneous, non-linear, time-variant and anisotropic. These properties affect major physiological factors within the heart, such as the pumping performance of the ventricles, the oxygen demand in the tissue and the distribution of coronary blood flow.
During the cardiac cycle the heart muscle tissue is deformed as a consequence of the active contraction of the muscle fibers and their relaxation respectively. A mapping of this deformation would give increased understanding of the mechanical properties of the heart. The deformation induces strain and stress in the tissue which are both mechanical properties and can be described with a mathematical tensor object.
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Chicago: Injecting stem cells into injured mice made their muscles grow back twice as big in a matter of days, creating mighty mice with bulky muscles that stayed big and strong for the rest of their lives, U.S. researchers said on Wednesday.
If the same applies to humans, the findings could lead to new treatments for diseases that cause muscles to deteriorate, such as muscular dystrophy. It may even help people resist the gradual erosion of muscle strength that comes with age, Bradley Olwin, of the University of Colorado at Boulder, and colleagues reported in the journal Science Translational Medicine.
“This was a very exciting and unexpected result,” Olwin, who worked on the study, said.“We found that the transplanted stem cells are permanently altered and reduce the aging of the transplanted muscle, maintaining strength and mass,” he added.
Olwin’s team experimented on young mice with leg injuries, injecting them with muscle stem cells taken from young donor mice. Stem cells are unique in that they can constantly renew themselves, and form the basis of other specialized cells. These cells not only repaired the injury, but they caused the treated muscle to increase in size by 170%.
Olwin’s team had thought the changes would be temporary, but they lasted through the lifetime of the mice, which was about two years.
Olwin and colleagues said when they injected the cells into a healthy leg, they did not get the same effect, suggesting there is something important about injecting the cells into an injured muscle that triggers growth. REUTERS