Efforts to develop a cultured sponge cell line: revisiting an intractable problem

Abstract

Residents of the marine environment, sponges (Porifera) have the ability to produce organic compounds known as secondary metabolites, which are not directly involved in the normal growth, development, or reproduction of an organism. Because of their sessile nature, the production of these bioactive compounds has been interpreted as a functional adaptation to serve in an important survival role as a means to counter various environmental stress factors such as predation, overgrowth by fouling organisms, or competition for limited space. Regardless of the reasons for this adaptation, a variety of isolated compounds have already proven to demonstrate remarkable anticancer, fungicidal, and antibiotic properties. A major obstacle to the isolation and production of novel compounds from sponges is the lack of a large, reliable source of sponge material. Sponge collection from the sea would be environmentally detrimental to the already stressed and sparse sponge populations. Sponge production in an aquaculture setting might appear to be an ideal alternative but would also be cost-ineffective and sponge growth is extremely slow. A third approach involves the development of a sponge cell culture system capable of producing the necessary cell numbers to harvest for research purposes as well as for the eventual commercial-scale production of promising bioactive compounds. Unfortunately, little progress has been made in this direction other than the establishment of temporary cultures containing aggregates and fragments of cells. One impediment toward successful sponge cell culture might be ascribed to a lack of published knowledge of failed methodologies, and thus, time and effort is wasted on continued reinvention of the same methods and procedures. Consequently, we have undertaken here to chart some of our unsuccessful research efforts, our methodology, and results to provide the sponge research community with knowledge to assist them to better avoid taking the same failed pathways.

Sponge cell aggregation: checkpoints in development indicate a high level of organismal complexity

“…In recent years, sponge dissociation experiments have largely been aimed at obtaining cell cultures for the production of bioactive compounds (Pomponi & Willoughby ; Grasela et al. ). These primary cultures are not usually a single cell type.…”

Marine Microorganism-Invertebrate Assemblages: Perspectives to Solve the “Supply Problem” in the Initial Steps of Drug Discovery

“…Scientists have substantially increased their efforts to develop culture techniques for marine sponges, which include in situ aquaculture (reviewed by [68]) and ex situ culture approaches, such as aquarium culture, primmorphs and cell cultures (reviewed by [67,69]). While sea-based culture techniques (Figure 2) have proven to be feasible for products, such as halichondrin [70], avarol [61] and discodermolide [71], ex situ approaches have not yet been very successful, mostly due to the lack of scientific knowledge on sponge biology.…”

Modelling sponge-symbiont metabolism

“…Cell culture would present conditions that could be controlled and combined with the ability to engineer the metabolic network to improve yields. Currently this approach is limited by the difficulties in sustaining long-term cultures of either sponge cells or their associated bacteria (De Rosa et al, 2003;Grasela et al, 2011;Osinga et al, 2003;Rinkevich, 2011;Schippers et al, 2012). We simply do not know enough about the metabolism of sponges, or their bacterial symbionts, to establish and maintain long-term and sustainable cultures.…”

“…Reconstructing the amino acid synthesis pathways in A. queenslandica revealed that it has the same essential dietary amino acid requirements as other metazoans (section 5.4.3) (Payne & Loomis, 2006;Rose et al, 2003). This has implications for sponge cell culture where commercial mammalian cell culture media has been used (De Rosa et al, 2003;GarciaCamacho et al, 2006;Grasela et al, 2011;Zhang et al, 2008;Zhao et al, 2008). The inclusion off the essential amino acids for A. queenslandica in mammalian cell culture media indicates that the lack of developing a primary culture is not due to an amino acid deficiency and other metabolites may be essential nutrients.…”