An in vitro, serum-free organ culture technique for the study of development and growth of the dermal skeleton in fish

To develop a serum-free, chemically defined in vitro organ culture system enabling the study of epithelial-mesenchymal interactions in development and growth of fish dermal skeleton, we investigated in vitro continuation of scale regeneration in the cichlid fish Hemichromis bimaculatus. The culture medium in our system is based an Leibovitz medium (L-15) supplemented with vitamin C, additional amino acids, and HEPES. With this basis medium, we examined the effects of all trans-retinoic acid, dexamethasone, and prostaglandin-E2 (PG-E2), factors known to exert an effect on development and growth of teeth and bone in mammalian culture systems on the in vitro regeneration of scales. These effects were compared with those obtained by supplementation of the basis medium with newborn and fetal call serum. To evaluate our culture system, the medium that allowed to mimick in the best possible way the in vivo regeneration of scales (i.e., the basis medium plus dexamethasone and PG-E2) was also tested on the in vitro development of teeth in the same fish species. Our serum-free, chemically defined organ culture system enables in vitro development and growth of both scales and teeth. With this model culture system, it is possible to evaluate the in vitro effects of hormones, growth factors, and other substances on growth and development of dermal skeleton in fish.