title: Hematopoietic contribution to skeletal muscle regeneration by myelomonocytic precursors.
abstract: Adult bone marrow-derived cells can participate in muscle regeneration after bone marrow transplantation. In recent studies a single hematopoietic stem cell (HSC) was shown to give rise to cells that not only reconstituted all of the lineages of the blood, but also contributed to mature muscle fibers. However, the relevant HSC derivative with this potential has not yet been definitively identified. Here we use fluorescence-activated cell sorter-based protocols to test distinct hematopoietic fractions and show that only fractions containing c-kit(+) immature myelomonocytic precursors are capable of contributing to muscle fibers after i.m. injection. Although these cells belong to the myeloid lineage, they do not include mature CD11b(+) myelomonocytic cells, such as macrophages. Of the four sources of mature macrophages tested that were derived either from monocytic culture, bone marrow, peripheral blood after granulocyte colony-stimulating factor mobilization, or injured muscle, none contributed to muscle. In addition, after transplantation of bone marrow isolated from CD11b-Cre-transgenic mice into the Cre-reporter strain (Z/EG), no GFP myofibers were detected, demonstrating that macrophages expressing CD11b do not fuse with myofibers. Irrespective of the underlying mechanisms, these data suggest that the HSC derivatives that integrate into regenerating muscle fibers exist in the pool of hematopoietic cells known as myelomonocytic progenitors.
authors.affiliation: Baxter Laboratory in Genetic Pharmacology and Department of Molecular Pharmacology, Stanford University School of Medicine, 269 Campus Drive, Stanford, CA 94305, USA.
authors.forename: Regis
authors.initials: R
authors.lastname: Doyonnas
authors.forename: Mark A
authors.initials: MA
authors.lastname: LaBarge
authors.forename: Alessandra
authors.initials: A
authors.lastname: Sacco
authors.forename: Carol
authors.initials: C
authors.lastname: Charlton
authors.forename: Helen M
authors.initials: HM
authors.lastname: Blau
mesh_terms: D000818:Animals; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism; D018845:CD11 Antigens / Q000378:metabolism; D002454:Cell Differentiation; D019070:Cell Lineage; D002478:Cells, Cultured; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000378:metabolism; D008264:Macrophages / Q000166:cytology; D051379:Mice; D008810:Mice, Inbred C57BL; D018482:Muscle, Skeletal / Q000166:cytology* / Q000378:metabolism; D022423:Myeloid Cells / Q000166:cytology* / Q000378:metabolism; D012038:Regeneration
chemical_list: D015214:Antigens, Differentiation, Myelomonocytic; D018845:CD11 Antigens