Molecular analysis of the hematopoiesis supporting osteoblastic cell line U2-OS

Objective. Osteoblasts play an important role in regulating hematopoiesis i n the bone marrow. Here we show that U2-OS, a widely used osteoblastic cell Line derived from an osteosarcoma, has the capacity to support proliferati on of human hematopoietic progenitor tells in vitro. In this study, U2-OS c ells are characterized at the molecular level to unravel the molecular mech anisms underlying the support of hematopoiesis. Materials and Methods. U2-OS was analyzed in great detail using RT-PCR and flow cytometry. In addition, a cDNA library was constructed and randomly se quenced to obtain insight in the repertoire of expressed molecules. Results. A broad panel of growth factors and cytokines is expressed by U2-O S, TGF-beta, GM-CSF, c-kit ligand, and IL-7 are produced constitutively and IL-1 beta, IL-6, IL-8, TNF-alpha, IFN-gamma, and MIP1-alpha are upregulate d upon stimulation. In addition to those, mRNAs of the CC chemokine LARC an d leukemia inhibitory factor were identified. U2-OS cells express high leve ls of beta 1-integrins at the cell surface: VLA-2, VLA-3, VLA-4, VLA-5, VLA -6, and the integrin alpha v beta 3. Besides integrins, ALCAM and NCAM are detected on the cell surface of U2-OS. Interestingly, we show that CD34(+) progenitor cells expressing ALCAM are highly proliferative when compared wi th CD34(+) ALCAM(low) cells, hinting at a role for ALCAM in anchoring proge nitor cells to the bone marrow stroma, Interestingly, random sequencing of an U2-OS cDNA library yielded almost 10% of novel cDNAs with a potential ro le in hematopoiesis, The involvement of these novel molecules in hematopoie sis is an interesting target fur future investigations. Conclusions. We conclude that U2-OS supports outgrowth of hematopoietic pro genitor cells and accordingly expresses adhesion molecules and growth facto rs and a number of novel, as get uncharacterized potentially interesting ge nes. (C) 2000 International Society for Experimental Hematology. Published by Elsevier Science Inc.