“…Especially, we found that CD18 is highly expressed on the BMSSCs of the early passages after their purification from bone marrow. Given such a distinct pattern of expression, CD18 could be a useful surface marker for cell sorting to enrich the stromal stem cell population, because most of the other surface markers for stromal stem cells, including STRO-1, CD106͞VCAM-1, CD146͞MUC-18, HOP-26, CD49A͞integrin  1 , and SB-10͞ CD166 (20,22,28), are expressed both on progenitor and on differentiated mesenchymal cells. As proof of principle, we isolated BMSSCs from human bone marrow aspirates by cell sorting using both CD18 and STRO-1, a cell marker commonly used for stromal stem cells (12).…”