Effects of Gadodiamide on cell proliferation and collagen production in cultured human dermal fibroblasts

Nephrogenic systemic fibrosis (NSF) is a disease characterized by fibrosis of the systemic organs in patients with renal failure. Following the findings of recent epidemiological studies and the finding of gadolinium (Gd) in the skin tissue of NSF patients, it is now definitely known that the use of Gd contrast agents can trigger NSF. To date, however, the exact mechanism underlying the induction of fibrosis in various organs by Gd remains unexplained. This study was undertaken to evaluate the influence of Gd on the proliferation activity and collagen production of cultured fibroblasts. Normal human dermis-derived fibroblasts were incubated in the presence of gadodiamide (GA) in the concentration range of 5 × 10⁻⁷ to 5 × 10⁻³ M. The proliferation activity of the cells was assessed on the basis of the cell counts in the fibroblast growth curve and the DNA-synthetic activity of the cells (indicator; level of ³H-thymidine uptake by cells). The collagen production was evaluated by densitometric measurement of the quantity of collagen through electrophoresis and fluorography after incorporation of ³H-proline into the procollagens. Furthermore, the expression levels of the genes for type I and III collagen were measured by real-time reverse transcription polymerase chain reaction (RT-PCR) assay. The cell count tended to be higher when the fibroblasts were incubated in medium containing GA in the concentration range of 5 × 10⁻⁷ to 5 × 10⁻⁴M as compared to that in the GA-free control cultures; furthermore, the DNA-synthetic activity also rose in a concentration-dependent manner in the GA-treated group as compared to that in the control group. No significant changes in either the collagen production or the collagen gene expression levels were noted in cultures containing GA at concentrations between 5 × 10⁻⁷ and 5 × 10⁻³ M. These results suggest that the formation of sclerosing lesions in patients with NSF may be attributable to the effect of GA of enhancing the growth activity of fibroblasts.