Sponge cell cultivation: Optimization of the model Petrosia ficiformis (Poiret 1789)

Sponge cells represent a unique model for the study of the molecular evolution of animal metabolism and of the ancestral processes of biomineralization. Among various sponge culture models, the most promising ones are based on the primmorph technique, which allows the production of 3D sponge cell aggregates, easily reared in a laboratory setting. The effects of three supplements (silicate, iron, RPMI medium) on cell proliferation, silicatein β production and HSP70 activation in Petrosia ficiformis primmorphs were investigated, as well as the relevance of endogenous spicule retention during the early phases of primmorph formation. The results show that retention of endogenous spicules together with cells during the re-aggregation phase dramatically improves primmorph formation, very likely acting as an “interactive scaffold” for cell homing and/or mediating cell adhesion signals. Furthermore, in contrast to the standard technique whose yield in terms of biomass growth is significantly lower, the addition of silicate, iron and RPMI in the early phases of primmorph formation in a restricted concentration range, as well as their maintenance during long time cultivation, gives a dramatic boost to primmorph growth. In conclusion, our examination highlights certain aspects of the P. ficiformis primmorph preparation protocol, whose implementation improves the yield and growth of sponge cells.