Matching Items (3)
Description
Skeletal muscle injury may occur from repetitive short bursts of biomechanical strain that impair muscle function. Alternatively, variations of biomechanical strain such as those held for long-duration are used by clinicians to repair muscle and restore its function. Fibroblasts embedded within the unifying connective tissue of skeletal muscle experience these multiple and diverse mechanical stimuli and respond by secreting cytokines. Cytokines direct all stages of muscle regeneration including myoblasts differentiation, fusion to form myotubes, and myotube functionality. To examine how fibroblasts respond to variations in mechanical strain that may affect juxtapose muscle, a myofascial junction was bioengineered that examined the interaction between the two cell types. Fibroblasts were experimentally shown to increase myoblast differentiation, and fibroblast biomechanical strain mediated the extent to which differentiation occurred. Intereleukin-6 is a strain-regulated cytokine secreted by fibroblasts was determined to be necessary for fibroblast-mediated myoblast differentiation. Myotubes differentiated in the presence of strained fibroblasts express greater number of acetylcholine receptors, greater acetylcholine receptor sizes, and modified to be more or less sensitive to acetylcholine-induced contraction. This study provides direct evidence that strained and non-strained fibroblasts can serve as a vehicle to modify myoblast differentiation and myotube functionality. Further understanding the mechanisms regulating these processes may lead to clinical interventions that include strain-activated cellular therapies and bioengineered cell engraftment for mediating the regeneration and function of muscle in vivo.
ContributorsHicks, Michael (Author) / Standley, Paul R (Thesis advisor) / Rawls, Jeffrey (Committee member) / Lake, Douglas (Committee member) / Hinrichs, Richard (Committee member) / Arizona State University (Publisher)
Created2014
Description
Satellite cells are adult muscle stem cells that activate, proliferate, and differentiate into myofibers upon muscle damage. Satellite cells can be cultured and manipulated in vitro, and thus represent an accessible model for studying skeletal muscle biology, and a potential source of autologous stem cells for regenerative medicine. This work summarizes efforts to further understanding of satellite cell biology, using novel model organisms, bioengineering, and molecular and cellular approaches. Lizards are evolutionarily the closest vertebrates to humans that regenerate entire appendages. An analysis of lizard myoprogenitor cell transcriptome determined they were most transcriptionally similar to mammalian satellite cells. Further examination showed that among genes with the highest level of expression in lizard satellite cells were an increased number of regulators of chondrogenesis. In micromass culture, lizard satellite cells formed nodules that expressed chondrogenic regulatory genes, thus demonstrating increased musculoskeletal plasticity. However, to exploit satellite cells for therapeutics, development of an ex vivo culture is necessary. This work investigates whether substrates composed of extracellular matrix (ECM) proteins, as either coatings or hydrogels, can support expansion of this population whilst maintaining their myogenic potency. Stiffer substrates are necessary for in vitro proliferation and differentiation of satellite cells, while the ECM composition was not significantly important. Additionally, satellite cells on hydrogels entered a quiescent state that could be reversed when the cells were subsequently cultured on Matrigel. Proliferation and gene expression data further indicated that C2C12 cells are not a good proxy for satellite cells. To further understand how different signaling pathways control satellite cell behavior, an investigation of the Notch inhibitor protein Numb was carried out. Numb deficient satellite cells fail to activate, proliferate and participate in muscle repair. Examination of Numb isoform expression in satellite cells and embryonic tissues revealed that while developing limb bud, neural tube, and heart express the long and short isoforms of NUMB, satellite cells predominantly express the short isoforms. A preliminary immunoprecipitation- proteomics experiment suggested that the roles of NUMB in satellite cells are related to cell cycle modulation, cytoskeleton dynamics, and regulation of transcription factors necessary for satellite cell function.
ContributorsPalade, Joanna (Author) / Wilson-Rawls, Norma (Thesis advisor) / Rawls, Jeffrey (Committee member) / Kusumi, Kenro (Committee member) / Newbern, Jason (Committee member) / Stabenfeldt, Sarah (Committee member) / Arizona State University (Publisher)
Created2020
Description
The behavior of animals is an intrinsically fascinating topic for students from a wide array of backgrounds. We describe a learning experience using animal behavior that we created for middle school students as part of a graduate-student outreach program, Graduate Partners in Science Education, at Arizona State University in collaboration with a K-8 public school. This activity capitalizes on the interest that animal behavior can generate to introduce and reinforce student understanding of the scientific method. Specifically, our activity highlights the general utility of the scientific method and uses this method to examine ant social behavior, with emphasis on generating and testing hypotheses. Furthermore, this activity introduces the idea of animal societies and encourages students to apply the concepts they learn to other species, including humans. By collecting ants locally, from schoolyards or nearby habitats, this experience situates learning in the context of students' own communities. We also provide optional assessment materials that teachers can use to assess learning objectives and standard mastery.
ContributorsLigon, Russell (Author) / Hicks, Michael (Author) / Dolezal, Adam G. (Author) / Butler, Michael W. (Author) / Morehouse, Nathan I. (Author) / Ganesh, Tirupalavanam (Author) / College of Liberal Arts and Sciences (Contributor)
Created2014-10-01