A novel in vitro model for studying quiescence and activation of primary isolated human myoblasts

PLoS One. 2013 May 23;8(5):e64067. doi: 10.1371/journal.pone.0064067. Print 2013.

Abstract

Skeletal muscle stem cells, satellite cells, are normally quiescent but become activated upon muscle injury. Recruitment of resident satellite cells may be a useful strategy for treatment of muscle disorders, but little is known about gene expression in quiescent human satellite cells or the mechanisms involved in their early activation. We have developed a method to induce quiescence in purified primary human myoblasts isolated from healthy individuals. Analysis of the resting state showed absence of BrdU incorporation and lack of KI67 expression, as well as the extended kinetics during synchronous reactivation into the cell cycle, confirming arrest in the G0 phase. Reactivation studies showed that the majority (>95%) of the G0 arrested cells were able to re-enter the cell cycle, confirming reversibility of arrest. Furthermore, a panel of important myogenic factors showed expression patterns similar to those reported for mouse satellite cells in G0, reactivated and differentiated cultures, supporting the applicability of the human model. In addition, gene expression profiling showed that a large number of genes (4598) were differentially expressed in cells activated from G0 compared to long term exponentially proliferating cultures normally used for in vitro studies. Human myoblasts cultured through many passages inevitably consist of a mixture of proliferating and non-proliferating cells, while cells activated from G0 are in a synchronously proliferating phase, and therefore may be a better model for in vivo proliferating satellite cells. Furthermore, the temporal propagation of proliferation in these synchronized cultures resembles the pattern seen in vivo during regeneration. We therefore present this culture model as a useful and novel condition for molecular analysis of quiescence and reactivation of human myoblasts.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Cell Culture Techniques
  • Cell Cycle Checkpoints
  • Cell Differentiation
  • Cell Proliferation
  • Cells, Cultured
  • DNA Replication
  • Female
  • Humans
  • Ki-67 Antigen / metabolism
  • Male
  • Myoblasts / physiology*
  • Myogenic Regulatory Factors / metabolism
  • Paired Box Transcription Factors / metabolism
  • Primary Cell Culture
  • Resting Phase, Cell Cycle
  • Signal Transduction
  • Transcriptome
  • Young Adult

Substances

  • Ki-67 Antigen
  • Myogenic Regulatory Factors
  • Paired Box Transcription Factors

Grants and funding

This work was supported by the Lundbeck Foundation (HDS), grant from Institute of Clinical Research, University of Southern Denmark (JS, HDS), grant from Institute for Clinical Pathology, Odense University Hospital, Denmark (JS, HDS), grant from the Govt of India, Dept of Biotechnology (JD) and a collaborative Indo-Denmark grant from the Govt of India, Dept of Biotechnology and the Danish Council for Strategic Research (HDS, JD). SC was supported by a doctoral fellowship from the Council of Scientific and Industrial Research. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.