Osteoclasts are involved in the maintenance of dormant leukemic cells

Osteoclasts (OCs) are specialized cells for the resorption of bone matrix that have also been recently reported to be involved in the mobilization of hematopoietic progenitor cells. WhenBa/F3 cells expressing wild-type bcr-abl were co-cultured with osteoblasts (OBs), OCs, and bone slices, their proliferation was significantly suppressed, and the Ki-67 negative population, which is believed to be in G(0) phase, was increased. The results of our in vitro experiments suggest that OCs could be involved in the maintenance of dormant leukemic cells in the bone marrow (BM) microenvironment through the release of soluble factors, one of which could be TGF-beta. (C) 2009 Elsevier Ltd. All rights reserved.