Vitamin C-sulfate inhibits mineralization in chondrocyte cultures: a caveat

Differentiating chick limb-bud mesenchymal cell micro-mass cultures routine ly mineralize in the presence of 10% fetal calf serum, antibiotics, 4 mM in organic phosphate (or 2.5 mM beta -glycerophosphate), 0.3 mg/ml glutamine a nd either 25 mug/ml vitamin C or 5-12 mug/ml vitamin C-sulfate. The failure of these cultures to produce a mineralized matrix (assessed by electron mi croscopy, Ca-45 uptake and Fourier transform infrared microscopy) led to th e evaluation of each of these additives. We report here that the 'stable' v itamin C-sulfate (ascorbic acid-2-sulfate) causes increased sulfate incorpo ration into the cartilage matrix. Furthermore, the release of sulfate from the vitamin C derivative appears to be responsible for the inhibition of mi neral deposition, as demonstrated in cultures with equimolar amounts of vit amin C and sodium sulfate. (C) 2001 Elsevier Science B.V./International Soc iety of Matrix Biology. All rights reserved.