Cadmium in vitro induces apoptosis to human fibroblast

Abstract

The heavy metal cadmium is a common environmental pollutant associated with industrial processes. Cadmium can be taken up into the human body by eating, drinking, breathe. Cadmium accumulation can produce damage to humans. For example, cadmium decreases cell density in some human organs such as ovaries, testis, or cadmium can induce disorders of enzyme function in the human body. In this study, we examined effects of cadmium on human fibroblast during in vitro proliferation. The result showed that cell densities were decreased by inducing with medium supplemented cadmium in various concentrations (1 µM, 10 µM, 100 µM), whereas cell density increased in the control group. Densities of fibroblast induced 10 µM cadmium were examined at 2 days, 4 days, 6 days, 8 days. There was no change of cell density at 2-day induced (98 ´ 103/dish) compared to thecontrol group (100 ´ 103/dish). Cell densities were significantly decreased in 4-day, 6-day and 8-day cadmium induced cells. Cadmium not only reduced cell density in vitro, it also induced apoptotic charactericstics of human fibroblast. Firstly, cadmium induced cytoplasmic fragments and apoptotic formation of fibroblast whereas fibroblasts were long and flat with elongated nucleus morphology in the control group. To detect morphologic changes in chromatin and nucleus, cadmium induced fibroblast were stained with acridine orange. Chromatin condensation was observed in 2-day cadmium induced cells but no nucleus fragment. In 4-day, 6-day, 8-day cadmium induced cells, there were not only chromatine condensation but also nucleus fragments. Reversed transcription polymerase chain reaction was applied to access the transcript expression of bcl-2 (anti-apoptosis gene) and bax (pre-apoptosis gene). The transcript expression of bcl-2 was decreased during cadimium inducing while the transcript expression of bax was increased. In the control group, bcl-2 transcript expression was higher than bax transcript but this balance in bcl-2 and bax expression was lost in cadmium induced fibroblast leading to apoptosis. In conclusion, cadmium in vitro can induce apoptotic characteristics of human fibroblast.