PURIFICATION OF HUMAN MUSCLE SATELLITE CELLS BY FLOW-CYTOMETRY

To purify satellite cells directly from human muscle biopsies, we have developed a method based on size separation of dissociated cells by flow cytometry. Immediately after tryptic dissociation of human muscle biopsies and elimination of erythrocytes, microscopic observation and flow cytometry analysis of cell suspensions revealed two populations of cells differing in size and nucleocytoplasmic ratio. Clonal cultures of these two cell types with a manual procedure demonstrated that only the small cells were myogenic satellite cells. Flow cytometry-sorting and analysis of the small cell population showed that (1) all sorted cells contained desmin immediately after dissociation and plating; (2) more than 98% of the cells expressed the 5.1.H11 epitope after 2 weeks of proliferation in culture; and (3) 90% of the sorted cells were able to form myotubes when cultivated at low density or in clonal cultures. Thus, human muscle satellite cells can be directly purified from human muscle samples using flow cytometry.