Project description:Experimental cell therapies for skeletal muscle conditions have shown little success, primarily because they used committed myogenic progenitors rather than true muscle stem cells, known as satellite cells. Here we present a method to generate in vitro–derived satellite cells (idSCs) from skeletal muscle tissue. When transplanted in small numbers into mouse muscle, mouse idSCs fuse into myofibers, repopulate the satellite cell niche, self-renew, support multiple rounds of muscle regeneration, and improve force production on par with freshly isolated satellite cells. in damaged skeletal muscle. We profiled the epigenomic and transcriptional differences between idSCs and satellite cells, and used these differences to identify core signaling pathways and genes that confer idSC functionality. Finally, fromhuman muscle biopsies we successfully generated satellite cell–like cells in vitro. After further development, idSCs may provide a scalable source of cells for the treatment of genetic muscle disorders, trauma-induced muscle damage and age-related muscle weakness.
Project description:The satellite cell of skeletal muscle provides a paradigm for quiescent and activated tissue stem cell states. We have carried out transcriptome analyses by comparing satellite cells from adult skeletal muscles, where they are mainly quiescent, with cells from growing muscles, regenerating (mdx) muscles, or with cells in culture, where they are activated. Our study gives new insights into the satellite cell biology during activation and in respect with its niche. We used microarrays to study the global programme of gene expression underlying adult satellite cell quiescence compared to activation states and to identify distinct classes of up-regulated genes in these two different states Skeletal muscle satellite cells were isolated by flow cytrometry using the GFP fluorescence marker from Pax3GFP/+ mice skeletal muscle. The transcriptome of quiescent satellite cells from adult Pax3GFP/+ muscle was compared to the transcriptome of activated satellite cells obtained from three different samples: 1) regenerating Pax3GFP/+:mdx/mdx muscle (Ad.mdx) , 2) growing 1 week old Pax3GFP/+ muscle (1wk), and 3) adult Pax3GFP/+ cells after 3 days in culture (Ad.cult).
Project description:Skeletal muscle aging results in a gradual loss of skeletal muscle mass, skeletal muscle function and decreased regenerative capacity, which can lead to sarcopenia and increased mortality. While the mechanisms underlying sarcopenia remain unclear, the skeletal muscle stem cell, or satellite cell, is required for muscle regeneration. Therefore, identification of signaling pathways affecting satellite cell function during aging may provide insights into therapeutic targets for combating sarcopenia. Here, we show that a cell-autonomous loss in self-renewal occurs via novel alterations in FGF and p38αβ MAPK signaling in old satellite cells. We further demonstrate that pharmacological manipulation of these pathways can ameliorate age-associated self-renewal defects. Thus, our data highlight an age-associated deregulation of a satellite cell homeostatic network and reveals potential therapeutic opportunities for the treatment of progressive muscle wasting. Satellite cells were isolated from young (3-6mo) and aged (20-25mo) adult mice; individual date files represent 2 independent pools of RNA from 4-8 mice at each timepoint.
Project description:In response to skeletal muscle injury, adult myogenic stem cells, known as satellite cells, are activated and undergo proliferation and differentiation to regenerate new muscle fibers. The skeletal muscle-specific microRNA, miR-206, is up-regulated in satellite cells following muscle injury, but its role in muscle regeneration has not been defined. Here we show that skeletal muscle regeneration in response to cardiotoxin injury is impaired in mice lacking miR-206. Loss of miR-206 also accelerates and exacerbates the dystrophic phenotype of mdx mice, a model for Duchenne muscular dystrophy. MiR-206 promotes satellite cell differentiation and fusion to form multinucleated myofibers by suppressing a collection of negative regulators of myogenesis. Our findings reveal an essential role for miR-206 in satellite cell differentiation during skeletal muscle regeneration and as a modulator of Duchenne muscular dystrophy. total RNA obtained from TA muscle of mdx and 3 miR-206 KO; mdx mice at 3 months of age.
Project description:Transcriptomic analysis of FACS-sorted Pax7nGFP quiescent skeletal muscle satellite cells cells from young, and old mice. Results provide knowledge about the molecular mechanisms underlying age-related skeletal muscle satellite cells homeostasis.
Project description:High regenerative capacity of adult skeletal muscle relies on a self-renewing depot of adult stem cells, termed muscle satellite cells (MSCs). A novel MSC line was isolated from the rat levator ani muscle and termed Levator Ani Satellite Cells (LASCs). Androgen, a known mediator of overall body composition and specifically skeletal muscle mass, has been shown to regulate MSCs. The use of non-steroidal androgen receptor agonists (NARA) aims to retain the beneficial influence of androgen on skeletal muscle, while circumventing undesirable cardiovascular and prostate-related side-effects. Primary objectives: 1) Identify biomarkers of satellite cell growth and differentiation, 2) Characterize a novel muscle satellite cell line, 3) Understand the effects of androgen (NARA) on rat satellite cell activation and recruitment. LASCs will be treated with one of the following conditions (N=4 for all groups): 1) 0.2% DMSO, 4 hours; 2) 10 nM NARA, 4 hours; 3) 0.2% DMSO, 48 hours; 4) 10nM NARA, 48 hours
Project description:Utilizing glycerol intramuscular injections in M. musculus provide a models of skeletal muscle damage followed by skeletal muscle regeneration. In particular, glycerol-induced muscle injury triggers accute activation of skeletal muscle stem cells, called satellite cells. However, aging dramatically impairs the regenerative capacity of satellite cells. We characterized genome-wide expression profiles of young and old satellite cells in the non-proliferative and activated state, freshly isolated to non-injured or damaged muscles, respectively. Our goal was to uncover new regulatory signaling specific to satellite cells entry into the activation and myogenic program that are affected with age. Satellite cells were isolated in either quiescent / non-proliferative or activated state from uninjured or 3 days after glycerol-induced injury of tibialis anterior, gastrocnemius and quadriceps, respectively. Young (2-4 months old) and old (20-24 months old) wildtype C57BL/6J male were used, with five to six biological replicates per group.