Skeletal muscle-derived CD34+/45- and CD34-/45- stem cells are situated hierarchically upstream of Pax7+ cells

Stem Cells Dev. 2008 Aug;17(4):653-67. doi: 10.1089/scd.2008.0070.

Abstract

The hierarchical relationship of skeletal muscle-derived multipotent stem cells sorted as CD34(+)/CD45(-) (Sk-34) and CD34(-)/CD45(-) (Sk-DN) cells, which have synchronized reconstitution capacities for blood vessels, peripheral nerves, and muscle fibers, was examined. Expression of Sca-1 and CD34 (typical state of freshly isolated Sk-34 cells) in Sk-DN cells was examined using in vitro culture and in vivo cell implantation. Sk-DN cells sequentially expressed Sca-1 and CD34 during cell culture showing self-maintenance and/or self-renewal-like behavior, and are thus considered hierarchically upstream of Sk-34 cells in the same lineage. Sk-34 and Sk-DN cells were further divided into small and large cell fractions by cell sorting. Immunocytochemistry using anti-Pax7 was performed at the time of isolation (before culture) and revealed that only 1% of cells in the large Sk-DN cell fraction were positive for Pax7, while Sk-34 cells and 99% of Sk-DN cells were negative for Pax7. Therefore, putative satellite cells were possibly present in the large Sk-DN cell fraction. However, serial analysis of Pax7 expression by RT-PCR and immunocytochemistry for single and 2 to >40 clonally proliferated Sk-34 and Sk-DN cells revealed that both cell types expressed Pax7 after several asymmetric cellular divisions during clonal-cell culture. In addition, production of satellite cells was seen after muscle fiber formation following Sk-34 or Sk-DN cell transplantation into damaged muscle, and even in the nonmuscle tissue environment (beneath the renal capsule). Thus, Sk-DN cells are situated upstream of Sk-34 cells and both cells can produce Pax7+ cells (putative satellite cells) after cellular division.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, CD34* / biosynthesis
  • Antigens, Ly / biosynthesis
  • Cell Separation / methods
  • Cells, Cultured
  • Immunohistochemistry
  • Leukocyte Common Antigens*
  • Membrane Proteins / biosynthesis
  • Mice
  • Mice, Transgenic
  • Muscle, Skeletal / cytology*
  • Muscle, Skeletal / metabolism
  • PAX7 Transcription Factor* / biosynthesis
  • Stem Cells / cytology*

Substances

  • Antigens, CD34
  • Antigens, Ly
  • Ly6a protein, mouse
  • Membrane Proteins
  • PAX7 Transcription Factor
  • Pax7 protein, mouse
  • Leukocyte Common Antigens
  • Ptprc protein, mouse