Muscle stem cells (MuSCs) contribute extensively to muscle tissue regeneration following injury and transplantation. Consequently, MuSCs offer much promise for treating skeletal muscle diseases, including genetic defects and muscle wasting conditions such as sarcopenia and cachexia. The therapeutic utility of MuSCs is limited by the rarity of these cells in adult tissues and the inability to propagate them in culture to therapeutic numbers without loss of their stem cell properties. MuSCs readily give rise in culture to abundant myogenic progenitors called myoblasts, but these cells have extremely limited regenerative potential upon transplantation, as evidenced by failures in myoblast-based clinical trials for the treatment of Duchenne Muscular Dystrophy (DMD). The inability to generate therapeutic levels of MuSCs is due, in part, to a lack of understanding of the molecular mechanisms that regulate the maintenance or induction of the MuSC phenotype. Since MuSC isolation and characterization methods have only been fully validated within the last few years, this paucity of knowledge is not surprising. Here we propose to generate MuSCs from more abundant somatic cells by nuclear reprogramming.
In Aim 1, two abundant and culture- expandable human somatic cell types present in muscle tissue, myoblasts and pre-adipocytes, will be reprogrammed to a muscle stem cell phenotype by cell fusion with mouse MuSCs to form non-dividing bi- species heterokaryons. Heterokaryons will allow elucidation of the earliest steps in reprogramming to a MuSC fate and identification of the mechanisms regulating the reversion (myoblast-to-MuSC) or conversion (pre-adipocyte-to-MuSC) of a phenotype.
In Aim 2, genetic manipulations of critical reprogramming genes identified in heterokaryons and microarrays of MuSCs (encoding transcription factors and epigenetic regulators) will be tested for their potential to direct reprogramming of myoblasts and pre-adipocytes to functional MuSCs. Reprogrammed phenotypes will be assessed for in vitro MuSC gene expression and epigenetic profiles, and, ultimately, in vivo function following transplantation.
In Aim 3, myoblast-to-MuSC and pre-adipocyte-to-MuSC reprogramming will be compared for cells isolated from young and old mice to provide greater understanding of the effects of clinically relevant parameters of age. The proposed studies to investigate maintenance and generation of MuSCs using myoblasts and pre-adipocytes benefit from several recent advances in our laboratory: (a) development of novel techniques to assess global transcriptional and epigenetic changes essential to distinguishing nuclear reprogramming contributions of each cell type in bi-species heterokaryons, (b) a hydrogel-based cell culture substrate that maintains muscle stem cells in vitro, and (c) a noninvasive imaging assay of in vivo MuSC function following transplantation. The molecular insights gained will increase the clinical utility of muscle stem cells and increase our understanding of muscle biology and aging.

Public Health Relevance

A rare but highly functional population of specialized cells, muscle stem cells, is essential to effective skeletal muscle regeneration. Transplantation of muscle stem cells has the potential to treat numerous muscle diseases but is currently impractical due to the limited quantities of these cells that can be isolated from human muscle tissue. We propose to generate clinically sufficient quantities of muscle stem cells from more abundant mature muscle and fat cells through nuclear and cellular reprogramming involving the manipulation of expression of genes associated with muscle stem cell generation.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Project (R01)
Project #
5R01AG009521-27
Application #
8456997
Study Section
Skeletal Muscle and Exercise Physiology Study Section (SMEP)
Program Officer
Williams, John
Project Start
1997-06-01
Project End
2015-04-30
Budget Start
2013-06-01
Budget End
2014-04-30
Support Year
27
Fiscal Year
2013
Total Cost
$455,355
Indirect Cost
$172,146
Name
Stanford University
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
009214214
City
Stanford
State
CA
Country
United States
Zip Code
94305
Cosgrove, Benjamin D; Gilbert, Penney M; Porpiglia, Ermelinda et al. (2014) Rejuvenation of the muscle stem cell population restores strength to injured aged muscles. Nat Med 20:255-64
Maška, Martin; Ulman, Vladimír; Svoboda, David et al. (2014) A benchmark for comparison of cell tracking algorithms. Bioinformatics 30:1609-17
Chenouard, Nicolas; Smal, Ihor; de Chaumont, Fabrice et al. (2014) Objective comparison of particle tracking methods. Nat Methods 11:281-9
Chu, Jun; Haynes, Russell D; Corbel, Stéphane Y et al. (2014) Non-invasive intravital imaging of cellular differentiation with a bright red-excitable fluorescent protein. Nat Methods 11:572-8
Mourkioti, Foteini; Kustan, Jackie; Kraft, Peggy et al. (2013) Role of telomere dysfunction in cardiac failure in Duchenne muscular dystrophy. Nat Cell Biol 15:895-904
Oliver, Stefan L; Brady, Jennifer J; Sommer, Marvin H et al. (2013) An immunoreceptor tyrosine-based inhibition motif in varicella-zoster virus glycoprotein B regulates cell fusion and skin pathogenesis. Proc Natl Acad Sci U S A 110:1911-6
Brady, Jennifer J; Li, Mavis; Suthram, Silpa et al. (2013) Early role for IL-6 signalling during generation of induced pluripotent stem cells revealed by heterokaryon RNA-Seq. Nat Cell Biol 15:1244-52
Bhutani, Nidhi; Decker, Matthew N; Brady, Jennifer J et al. (2013) A critical role for AID in the initiation of reprogramming to induced pluripotent stem cells. FASEB J 27:1107-13
Pomerantz, Jason H; Blau, Helen M (2013) Tumor suppressors: enhancers or suppressors of regeneration? Development 140:2502-12
Gilbert, Penney M; Corbel, Stephane; Doyonnas, Regis et al. (2012) A single cell bioengineering approach to elucidate mechanisms of adult stem cell self-renewal. Integr Biol (Camb) 4:360-7

Showing the most recent 10 out of 83 publications