Robert Hyldahl from Brigham Young University, USA, the Lonza CytoSMART Lab for myoblast proliferation and differentiation

Robert Hyldahl, Brigham Young University, Department of Exercise Sciences






Human Primary Myoblast Differentiation in the Presence of a Novel JAK/STAT Inhibitor

Research Interest

Our laboratory seeks to characterize the molecular mechanisms that underlie age-related skeletal muscle dysfunction, and use this information to develop effective treatments. Stress to skeletal muscle initiates the release of cytokines, hormones, and growth factors that activate the JAK/STAT pathway. JAK is a family of tyrosine kinases that auto-phosphorylate and attract cytoplasmic binding of STAT proteins. The STAT family proteins can stimulate multiple pathways or dimerize and translocate to the nucleus, induce mRNA transcription, and promote synthesis of myogenic proteins (1). Marked increases in basal levels of STAT3 have been identified in aging muscle and have been shown to contribute to muscle stem cell dysfunction by over activating myogenic differentiation pathways and prohibiting cell quiescence (2,3). Importantly, inhibition of STAT3 activity reduces stem cell differentiation, restores muscle stem cell function, and improves the quality of aged skeletal muscle (2,3).

The Experiment

We used the CytoSMART™ System to observe the differentiation response of human primary myoblasts to various concentrations of our newly developed small molecule JAK/STAT inhibitor. The simple to use cell imaging platform allowed us to collect wonderful time lapse images to track differentiation and cell coverage of the myoblasts under various treatment conditions.

Image of primary Myoblasts taken with the CytoSMART System

Graph showing growth curves of human myoblast in presence or absence of inhibitor recorded with the CytoSMART System
Video of human primary myoblasts in the presence of the new small molecule JAK/STAT inhibitor (recorded with the CytoSMART™ System for 12 days at an image frequency of one image every 15 min).             Analysis of cell confluency data recorded with the CytoSMART™ System. Human primary myoblasts were left untreated (control, blue line) or treated with 500µM of the new small molecule JAK/STAT inhibitor (with compound, grey line).           


The CytoSMART™ System is a compact, relatively inexpensive and easy to use solution for live cell imaging. We found the software to be user friendly and provide a number of useful analysis tools.  



  1. Jang Y-N, Baik EJ. JAK-STAT pathway and myogenic differentiation. Jak-Stat. 2013;2(2):e23282.
  2. Price FD, von Maltzahn J, Bentzinger CF, Dumont NA, Yin H, Chang NC, et al. Inhibition of JAK-STAT signaling stimulates adult satellite cell function. Nature medicine. 2014;20(10):1174-81.
  3. Tierney MT, Aydogdu T, Sala D, Malecova B, Gatto S, Puri PL, et al. STAT3 signaling controls satellite cell expansion and skeletal muscle repair. Nature medicine. 2014;20(10):1182-6.


Find out more about Dr. Hyldahl’s research