In vitro establishment of continuous cell cultures and cell lines from ten colonial cnidarians

Continuous cell cultures from the ten taxa of sedentary colonial marine cnidarians Stylophora pistillata, Porites lutea, Favia favus (Anthozoa, Hexacorallia, Madeporaria), Parerythropodium fulvum fulvum, Dendronephthya hemprichi, Nephthya sp. Heteroxenia fuscescence (Anthozoa, Octocorallia, Alcyonacea), Clathraria rubrinoides, Plexaura A (Anthozoa, Octocorallia, Gorgonacea) and Millepora dichotoma (Hydrozoa) were established in vitro. Primary cultures of various cell types (5 to 20 μm) were obtained from colony fragments and/or planula larvae (collected in 1993 from coral reefs at Eilat, Red Sea and from the San Blas islands, Panama) using three dissociation approaches: a mechanical approach, chemical approach and a novel approach, spontaneous dissociation. Cells were cultured in a modified Leibowitz L15 medium, with 5 to 10% heat-inactivated fetal bovine serum, diluted in seawater. Cell proliferation was observed in primary cultures within 7 to 20 d following dissociation. When developed to secondary cultures, spindle-shaped cells (5 to 10 μm) gradually replaced all other cell types seen in primary cultures of S. pistillata, C. rubrinoides, P.f. fulvum and M. dichotoma. The spindle-shaped cells differentiated to several cell types when the diluted medium was replaced with a concentrated one, or when microbial contamination occurred. Secondary cultures of spindle-shaped cells from three species (S. pistillata, C. rubrinoides and M. dichotoma) were cloned. They gave rise to continuously proliferating cell lines (NIO-SPP-1, NIO-CR-1 and NIO-MD-1, respectively). A clone from Plexaura planula, originated from one rounded cell, started to differentiate and gave rise to a heterogeneous culture. Samples of the above four cultures were frozen for future work. Rounded cells of various sizes (5 to 30 μm) dominated secondary cell cultures of H. fuscescence, D. hemprichi, Nephthya sp., P. f. fulvum and F. favus. Several cell cultures from P. lutea developed flattened cell interconnected by ectoplasmic networks characteristic of the eukaryotic unicellular organisms of the phylum Labyrinthulomycota. We propose that this culture methodology may be used as a ubiquitous protocol for producing tissue cultures from other cnidarians. The established cell lines may be used in a variety of disciplines in cnidarian biology and ecology.