Satellite cell-mediated angiogenesis in vitro coincides with a functional hypoxia-inducible factor pathway

• Published in: American Journal of Physiology: Cell Physiology Vol. 296; no. 6; pp. C1321 - C1328
• Main Authors: Rhoads, R. P, Johnson, R. M, Rathbone, C. R, Liu, X, Temm-Grove, C, Sheehan, S. M, Hoying, J. B, Allen, R. E
• Format: Journal Article
• Language: English
• Published: United States American Physiological Society 01.06.2009
• Subjects: Adipose Tissue - blood supply; Angiogenesis; Animals; Cell culture; Cell growth; Cell Hypoxia; Cells, Cultured; Culture Media, Conditioned - metabolism; Gene expression; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit - genetics; Hypoxia-Inducible Factor 1, alpha Subunit - metabolism; Male; Microvessels - metabolism; Muscle Cell Biology and Cell Motility; Musculoskeletal system; Neovascularization, Physiologic; Paracrine Communication; Proteins; Rats; Rats, Sprague-Dawley; RNA, Messenger - metabolism; Rodents; Satellite Cells, Skeletal Muscle - metabolism; Signal Transduction; Stem cells; Time Factors; Tissue Culture Techniques; Vascular Endothelial Growth Factor A - metabolism
• ISSN: 0363-6143; 1522-1563
• DOI: 10.1152/ajpcell.00391.2008

1 Muscle Biology Group, Department of Animal Sciences; 2 Department of Physiology; and 3 Biomedical Engineering Program/Arizona Research Laboratories, University of Arizona, Tucson, Arizona Submitted 31 July 2008 ; accepted in final form 14 April 2009 Muscle regeneration involves the coordination of myogenesis and revascularization to restore proper muscle function. Myogenesis is driven by resident stem cells termed satellite cells (SC), whereas angiogenesis arises from endothelial cells and perivascular cells of preexisting vascular segments and the collateral vasculature. Communication between myogenic and angiogenic cells seems plausible, especially given the number of growth factors produced by SC. To characterize these interactions, we developed an in vitro coculture model composed of rat skeletal muscle SC and microvascular fragments (MVF). In this system, isolated epididymal MVF suspended in collagen gel are cultured over a rat SC monolayer culture. In the presence of SC, MVF exhibit greater indices of angiogenesis than MVF cultured alone. A positive dose-dependent effect of SC conditioned medium (CM) on MVF growth was observed, suggesting that SC secrete soluble-acting growth factor(s). Next, we specifically blocked VEGF action in SC CM, and this was sufficient to abolish satellite cell-induced angiogenesis. Finally, hypoxia-inducible factor-1 (HIF-1 ), a transcriptional regulator of VEGF gene expression, was found to be expressed in cultured SC and in putative SC in sections of in vivo stretch-injured rat muscle. Hypoxic culture conditions increased SC HIF-1 activity, which was positively associated with SC VEGF gene expression and protein levels. Collectively, these initial observations suggest that a heretofore unexplored aspect of satellite cell physiology is the initiation of a proangiogenic program. skeletal muscle Address for reprint requests and other correspondence: R. E. Allen, Dept. of Animal Sciences, Univ. of Arizona, Tucson, AZ 85721 (e-mail: rallen{at}ag.arizona.edu )