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Mild Heat Shock Induces Proliferation, Alkaline Phosphatase Activity, and Mineralization in Human Bone Marrow Stromal Cells and Mg‐63 Cells In Vitro
Author(s) -
Shui Chaoxiang,
Scutt Andrew
Publication year - 2001
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1359/jbmr.2001.16.4.731
Subject(s) - alkaline phosphatase , stromal cell , osteoblast , chemistry , bone marrow , in vitro , cell culture , microbiology and biotechnology , heat shock , hsp70 , heat shock protein , endocrinology , andrology , medicine , biology , biochemistry , immunology , enzyme , genetics , gene
Bone formation has been shown to be stimulated by local diathermy in vivo; however, the mechanisms involved in this heat‐induced osteogenesis are unclear. In this study, we investigated the direct effect of temperature on human bone marrow‐derived stromal cells (BMSCs) and the human osteoblast‐like, osteosarcoma‐derived MG‐63 cells in culture conditions. Both cell types were shown to tolerate the transient exposure to mild heat shock conditions (1 h at 39–41°C), and long‐term (96 h) exposure at 39°C stimulated DNA synthesis in BMSC but caused growth arrest in MG‐63 cells. Furthermore, 1‐h exposure to higher temperatures (42.5–45°C) or continuous 96‐h exposure to 40°C or 41°C inhibited the proliferation of both BMSCs and MG63 cells. The level of alkaline phosphatase (ALP) in these cells linearly correlated with the increase in temperature, and the ALP expression, either at the basal level or in response to 1,25‐dihydroxyvitamin D 3 [1,25(OH) 2 D 3 ], was enhanced after a single 1‐h exposure to 42.5°C. In addition, continuous incubation at 39°C or repeated transient exposure to 39/41°C greatly enhanced the ability of BMSCs to form mineralizing nodules. The heat shock protein HSP70, which was expressed constitutively by BMSCs, was found to be up‐regulated by hyperthermia (39°C) and down‐regulated at 33°C. The expression of HSP70 could be induced in MG‐63 cells by both low‐ and high‐temperature conditions. These data suggest that treatment with a mild heat shock induces the proliferation and differentiation of osteoprogenitor cells, and the direct effects of temperature on bone‐forming cells might be one of the mechanisms involved in heat‐induced bone formation in vivo.