ABSTRACT Numerous technological advances and scientific insights have had profound effects on our understanding of skeletal muscle growth and development. The objective of this review is to highlight a new technology and recent findings on the functional responses of skeletal muscle/satellite cells to physiological stimuli. First, recent technological advances have facilitated global gene expression profiling experiments. This type of research has, for the first time, provided researchers with insights into cell/tissue-wide response to a given treatment. These experiments have dramatically increased our understanding of the extent to which cells/tissues respond. Furthermore, these experiments have implicated previously underappreciated genes as playing potentially vital roles in biological events. Secondly, recent advances have suggested that the cell culture model utilized can greatly influence the results and conclusions obtained from an experiment. Under standard culture conditions, satellite cells obtained from aged rats are capable of only a few rounds of replication before becoming senescent. Under conditions of reduced oxygen content, the number of rounds of replication is greatly increased. These results demonstrate that experiments using traditionally accepted in vitro culture conditions might be flawed. Finally, recent studies have identified a population of pluripotent stem cells in skeletal muscles termed side population cells. These cells possess the ability to efflux Hoechst dye, which distinguishes them from all other cells that cannot efflux the dye. These cells are capable of differentiating into many other tissue types in vitro and in vivo. With these new technologies and insights, our portrait of skeletal muscle growth and development continues to evolve.
Implications
Great strides have been made in our understanding of skeletal muscle growth and development. These advancements have come about because of technological innovations and scientific discovery. It is our belief that microarray analysis of gene expression, atmospheric culture conditions, and skeletal muscle-derived stem cells are advances that will have profound influences on our understanding of skeletal muscle growth and development. However, future advances will be necessary if we are to successfully develop new strategies to enhance lean tissue deposition in livestock and/or prevent muscle loss in at risk individuals.
Key Words: Cells, Cell Cultures, Differentiation, Gene Expression, Skeletal Muscle
© 2003, by the American Society of Animal Science. All rights reserved.
J. Anim. Sci. 2003. 81(E. Suppl. 1):E1-E8
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