High glucose (HG) concentrations impair cellular functions and induce apoptosis. Exposition of mesenchymal stem cells (MSC) to HG was reported to reduce colony forming activity and induce premature senescence. We characterized the effects of HG on human MSC in vitro using telomerase-immortalized MSC (hMSC-TERT) and primary MSC (hMSC). FIG (25 mM) enhanced hMSC-TERT proliferation in long-term studies in contrast to hMSC where proliferation was unchanged. Thioredoxin-interacting protein, which is involved in apoptosis regulation, was stimulated by glucose in hMSC-TERT. However, apoptosis was not influenced by FIG in both cell types. MSC treatment with HG favored osteogenic differentiation. MSC are resistant to HG toxicity, depending on the sternness of MSC. Proliferation and osteogenic differentiation are stimulated by HG. Effects of HG on the transient amplifying compartment of MSC may differ from those in mature cells. Further research is needed to unravel the molecular mechanisms of HG resistance of MSC. (C) 2007 Elsevier Inc. All rights reserved.