The impact of fluoride on in vitro cultured human chondrocytes

Objective To study the cell vitality and ultra-structure of in vitro cultured fetus chondrocytes exposed to different doses of fluoride.Methods Primary chondrocytes were obtained from articular cartilage of the 24-27 weeks,aborted and dead fetuses.The third generation of primary cultured chondmcytes were exposed to concentrations of 0,10-2,5 × 10-3,10-3,10-4,10-5,10-6,10-7 and 10-8 mol/L fluoride for 24,48 and 72 h.Cell vitality was detected with Cell Counting Kit-8 (CCK-8) and ultra-structure of chondrocytes was observed by transmission electron microscope.Results The cell vitalities of chondrocytes exposed to doses of fluoride (10-2,5 ×10-3,10-3,10-4,10-5,10-6,10-7 and 10-8 moL/L) for 24,48 and 72 h were(15.04 ± 0.55)％,(62.53 ± 1.03)％,(100.34 ± 5.19)％,(111.40 ± 3.69)％,(121.47 + 6.09)％,(129.95 ± 4.96)％,(121.81 ± 4.97)％,(111.00 ± 1.63)％;(10.35 ± 0.64)％,(35.23 ± 2.41)％,(110.30 ± 2.07)％,(113.66 ± 6.98)％,(120.36 ± 6.23)％,(133.40 ± 5.80)％,(126.06 ± 5.40)％,(115.62 ± 7.33)％; (6.19 ± 0.16)％,(18.44 ± 0.21)％,(120.83 ± 4.93)％,(123.77 ± 4.82)％,(129.09 ± 5.21)％,(140.44 + 4.18)％,(131.99 ± 7.00)％,(124.10 ± 3.68)％,respectively.The cell vitalities of 10-2,5 × 10-3 mol/L fluoride groups were significantly lower than that of the control group (all P ＜ 0.05).The cell vitality of 10-2 mol/L group was significantly lower than that of the 5 × 10-3 mol/L group (P ＜ 0.05).Doses of fluoride (10-2,5 × 10-3 mol/L) could inhibit the cell vitality and promote the apoptosis of chondrocytes in vitro with increasing doses and prolonged time.The cell vitalities of 10-3,10-4,10-5,10-6,10-7,10-8 mol/L of fluoride groups were significantly higher than that of the control group (except the 24 h 10-3 mol/L,P ＜ 0.05).Between 10-4 and 10-3 mol/L groups(the vitalities of 48 h and 72 h were higher,but not significantly); 10-5 and 10-4 mol/L groups (the vitality of 72 h was higher,but not significantly); 10-6 and 10-5 mol/L groups,the cell vitalities were significantly higher than that of the control group(all P ＜ 0.05).Between 10-7 and 10-6 mol/L groups,10-8 and 10-7 mol/L groups (the vitality of 72 h was lower,but not significantly),the cell vitalities were significantly lower than that of the control group(all P ＜ 0.05).Doses of fluoride(10-3-10-8 mol/L) could promote the cell vitality of chondrocytes in vitro with prolonged time.The optimal concentration for the promotion was 10-6 mol/L.The cells of the control group were characterized as regular morphology,the abnormal surface microvillis,abundant cytoplasm and mitochondrial,abundant and slightly expanded rough endoplasmic reticulums and low electron-dense materials.The cells of 10-6 mol/L fluoride group had the following changes,increased and swell mitochondrial,hypertrophy and expanded rough endoplasmic reticulums.The cells of 5 × 10-3 mol/L fluoride group had the following changes,decreased microvillis,invaginated cell membrane,pyknosis and apoptotic body.Conclusion Doses of fluoride (10-3-10-8 mol/L) can promote the proliferation of human chondrocytes cultured in vitro.Doses of fluoride (10-2,5 × 10-3 mol/L) can promote the apoptosis of human chondrocytes cultured in vitro. Key words: Fluoride ;  Chondrocytes;  Apoptosis ;  Cell proliferation