Measurement of [18F] -fluorodeoxyglucose incorporation into human osteoblast : An experimental method

An evaluation of human osteoblast metabolism usually involves measurements of the by-products of bone matrix elaboration. The assessment of glycolytic activity of osteoblasts is not a standard tool in most of the reports, but might be of value by providing a direct indicator of cellular metabolism. Measurement of the incorporation of [(18)F]-fluorodeoxyglucose, which is not further degradable following its conversion into glycose-6-phosphate during glycolysis and is trapped in this form within the cells, can be used as an effective research tool for estimation of osteoblast metabolism. In order to estimate the [(18)F]-fluorodeoxyglucose incorporation we used cultured human osteoblast-like cells. Following incubation of the culture samples in a glucose free medium with 5 mu Ci [(18)F]-fluorodeoxyglucose we measured the radioactivity of the cell fraction, as a percent from the initial dose, and compared to the incorporation values in cells treated by protoporphyrine IX (10(-5) M), an endogenous pro-apoptotic agent. To compare the response of [(18)F]-fluorodeoxyglucose incorporation studies, following treatment of cells with the protoporphyrine IX, to other experimental cell metabolism evaluation methods, we performed a parallel comparison of alkaline phospatase activity, which is a standard measurement tool of osteoblast metabolism, in the control and treatment groups. A narrow range of 0.22-1.36% of [(18)F]-fluorodeoxyglucose incorporation per million cells was found. Additionally in the protoporphyrine IX treated cells a significant 62% decrease of [(18)F]-fluorodeoxyglucose incorporation was observed (p < .05). A parallel significant decrease in alkaline phosphatase activity (p < .001) was found in the cells treated by the protoporphyrine IX. Therefore we suggest that the presented method of [(18)F]-fluorodeoxyglucose incorporation measurement can be utilized as an effective research tool for estimation of the cellular glycolitic activity in human osteoblast-like cells in vitro.