Insulin and IGF-I effects on the proliferation of an osteoblast primary culture from sea bream (Sparus aurata).

Bone deformities in several fish species, like gilthead sea bream (Sparus aurata), are currently a major problem in aquaculture. To gain knowledge of fish skeletal development, a primary cell culture has been established from sea bream vertebra. The initial fibroblastic phenotype of the cells changed to a polygonal shape during the culture, and the addition of an osteogenic medium promoted the deposition of minerals in the extracellular matrix. Cell proliferation was analyzed using the MTT assay in control and mineralizing conditions at different culture days, up to day 20. The capacity of the cells to differentiate into osteoblasts was evaluated using Alizarin red stain. The cells showed slightly increased proliferation and differentiation in the presence of osteogenic medium. Furthermore, pluripotentiality of these cells was demonstrated by inducing them to differentiate into adipocytes, and the accumulation of lipids into the cells was detected with Oil Red O staining. Subsequently, the effects of insulin (1, 10, 100 and 1000 nM) and IGF-I (0.1, 1 and 10nM) on cell proliferation were evaluated with the MTT assay at day 3. Both peptides significantly stimulated the proliferation of the cells in a dose-dependent manner after either 24 or 48 h of incubation, with IGF-I apparently being more potent than insulin. In summary, a primary culture of sea bream osteoblasts has been characterized. This cellular system can be a good model to study the process of osteoblastogenesis in fish and its endocrine regulation, which may help to improve the quality of the product in aquaculture.