In vitro effects of combination chemotherapy on osteoblasts: implications for osteopenia in childhood malignancy.

Clinical studies suggest that combination chemotherapy adversely affects bone metabolism and in vitro studies have demonstrated that a reduction in osteoblast numbers results in diminished bone formation. The aim of this study was to investigate the in vitro effects of combinations of chemotherapeutic agents on primary human osteoblast-like (hOB) cell numbers and apoptosis, and to assess the ability of hOBs and osteoprogenitor (HCC1) cells to recover from prior treatment with chemotherapy. As glucocorticoids are frequently administered during treatment with cytotoxic agents, we evaluated whether glucocorticoids influence the chemosensitivity of hOB and human osteosarcoma (MG63) cells. Culture with clinically relevant concentrations of the individual chemotherapeutic agents reduced hOB cell numbers compared with control (p < 0.01) and also increased the numbers of apoptotic cells (p < 0.05). Potentiation of cytotoxicity was observed when agents were given in combination, thus further reducing cell numbers, and this effect was greatest when vincristine was given in combination with asparaginase. Following culture with a chemotherapeutic agent, there was greater recovery of hOB compared with HCC1 cell numbers (p < 0.01). Pretreatment with glucocorticoids ameliorated the adverse effects of chemotherapeutic agents on hOB and MG63 cell numbers and apoptosis (p < 0.05). We conclude that the use of combination chemotherapy contributes to osteopenia in childhood malignancy by a reduction in osteoblast numbers. However, this effect may be attenuated by the concomitant use of glucocorticoids.