In vitro osteoblastic differentiation of human bone marrow cells in the presence of metal ions

For periods up to 21 days human bone marrow was cultured in control conditi ons that favor the proliferation and differentiation of osteoblastic cells. The effect of AISI 316L corrosion products and the corresponding major sep arate metal ions (Fe, Cr, and Ni) were studied in three different phases of the culture period in order to investigate the effects of metal ions in ce ll populations representative of osteoblastic cells in different stages of differentiation Toxicity consequences of the presence of metal ions in bone marrow cultures were evaluated by biochemical parameters (enzymatic reduct ion of MTT, alkaline phosphatase activity, and total protein content), hist ochemical assays (identification of ALP-positive cells and Ca and phosphate s deposits), and observation of the cultures by light and scanning electron microscopy. Culture media were analyzed for total and ionized Ca and P and also for metal ions (Fe, Cr, and Ni). The presence of AISI 316L corrosion products and Ni salt in bone marrow cultures during the first and second we eks of culture significantly disturbs the normal behavior of these cultures , interfering in the lag phase and exponential phase of cell growth and ALP expression. However, the presence of these species during the third week o f culture, when expression of osteoblastic functions occurs (mineralization process), did not result in any detectable effect. Fe salt also disturbs t he behavior of bone marrow cell cultures when present during the lag phase and proliferation phase, and a somewhat compromised response between the no rmal pattern (control cultures) and intense inhibition (AISI 316L corrosion products and Ni salt-added cultures) was observed. Fe did not affect the p rogression of the mineralization phase. Osteogenic cultures exposed to Cr s alt (Cr3+) presented a pattern similar to the controls, indicating that thi s element does not interfere, in the concentration studied, in the osteobla stic differentiation of bone marrow cells. Quantification of metal ions in the culture media showed that Cr (originated from AISI 316L corrosion produ cts but from not Cr3+ salt) and Ni (originated from AISI 316L corrosion pro ducts and Ni salt) appear to be retained by the bone marrow cultures. (C) 1 999 John Wiley & Sons, Inc.