title: Sdf-1 (CXCL12) induces CD9 expression in stem cells engaged in muscle regeneration.
abstract: BACKGROUND
  Understanding the mechanism of stem cell mobilization into injured skeletal muscles is a prerequisite step for the development of muscle disease therapies. Many of the currently studied stem cell types present myogenic potential; however, when introduced either into the blood stream or directly into the tissue, they are not able to efficiently engraft injured muscle. For this reason their use in therapy is still limited. Previously, we have shown that stromal-derived factor-1 (Sdf-1) caused the mobilization of endogenous (not transplanted) stem cells into injured skeletal muscle improving regeneration. Here, we demonstrate that the beneficial effect of Sdf-1 relies on the upregulation of the tetraspanin CD9 expression in stem cells.
  
  
  METHODS
  The expression pattern of adhesion proteins, including CD9, was analysed after Sdf-1 treatment during regeneration of rat skeletal muscles and mouse Pax7-/- skeletal muscles, that are characterized by the decreased number of satellite cells. Next, we examined the changes in CD9 level in satellite cells-derived myoblasts, bone marrow-derived mesenchymal stem cells, and embryonic stem cells after Sdf-1 treatment or silencing expression of CXCR4 and CXCR7. Finally, we examined the potential of stem cells to fuse with myoblasts after Sdf-1 treatment.
  
  
  RESULTS
  In vivo analyses of Pax7-/- mice strongly suggest that Sdf-1-mediates increase in CD9 levels also in mobilized stem cells. In the absence of CXCR4 receptor the effect of Sdf-1 on CD9 expression is blocked. Next, in vitro studies show that Sdf-1 increases the level of CD9 not only in satellite cell-derived myoblasts but also in bone marrow derived mesenchymal stem cells, as well as embryonic stem cells. Importantly, the Sdf-1 treated cells migrate and fuse with myoblasts more effectively.
  
  
  CONCLUSIONS
  We suggest that Sdf-1 binding CXCR4 receptor improves skeletal muscle regeneration by upregulating expression of CD9 and thus, impacting at stem cells mobilization to the injured muscles.
authors.affiliation: Department of Cytology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096, Warsaw, Poland. edbrzoska@biol.uw.edu.pl.
authors.forename: Edyta
authors.initials: E
authors.lastname: Brzoska
authors.affiliation: Department of Cytology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096, Warsaw, Poland. k.kowalski@biol.uw.edu.pl.
authors.forename: Kamil
authors.initials: K
authors.lastname: Kowalski
authors.affiliation: Department of Cytology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096, Warsaw, Poland. markowska@biol.uw.edu.pl.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Markowska-Zagrajek
authors.affiliation: Department of Molecular and Translational Oncology, Maria Skłodowska-Curie Memorial Cancer Center and Institute of Oncology, Roentgena 5, 02-781, Warsaw, Poland. magdalena.kowalewska@wum.edu.pl.|Department of Immunology, Biochemistry and Nutrition, Medical University of Warsaw, Banacha 1b, 02-097, Warsaw, Poland. magdalena.kowalewska@wum.edu.pl.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Kowalewska
authors.affiliation: Departament of Systems Biology, Faculty of Biology, University of Warsaw, Pawińskiego 5a, 02-106, Warsaw, Poland. rafa@ibb.waw.pl.
authors.forename: Rafał
authors.initials: R
authors.lastname: Archacki
authors.affiliation: Department of Cytology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096, Warsaw, Poland. kipk@interia.pl.
authors.forename: Izabela
authors.initials: I
authors.lastname: Plaskota
authors.affiliation: Department of Cytology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096, Warsaw, Poland. krymar@biol.uw.edu.pl.
authors.forename: Władysława
authors.initials: W
authors.lastname: Stremińska
authors.affiliation: Department of Cytology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096, Warsaw, Poland. kilach@biol.uw.edu.pl.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Jańczyk-Ilach
authors.affiliation: Department of Cytology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096, Warsaw, Poland. ciemerych@biol.uw.edu.pl.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Ciemerych
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D054377:Chemokine CXCL12 / Q000494:pharmacology*; D018920:Coculture Techniques; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D000066450:Mouse Embryonic Stem Cells / Q000166:cytology; D018482:Muscle, Skeletal / Q000293:injuries / Q000502:physiology*; D032446:Myoblasts / Q000166:cytology / Q000378:metabolism; D051763:PAX7 Transcription Factor / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D054387:Receptors, CXCR / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D019718:Receptors, CXCR4 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D012038:Regeneration; D032496:Satellite Cells, Skeletal Muscle / Q000166:cytology; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D060245:Tetraspanin 29 / Q000378:metabolism*
chemical_list: D054377:Chemokine CXCL12; C501897:Cmkor1 protein, mouse; D051763:PAX7 Transcription Factor; C497322:Pax7 protein, mouse; D034741:RNA, Small Interfering; D054387:Receptors, CXCR; D019718:Receptors, CXCR4; D060245:Tetraspanin 29