Optimizing the formation of in vitro sponge primmorphs from the Chinese sponge Stylotella agminata (Ridley)

Deep-Sea Sponges and Corals off the Western Coast of Florida-Intracellular Mechanisms of Action of Bioactive Compounds and Technological Advances Supporting the Drug Discovery Pipeline

The majority of natural products utilized to treat a diverse array of human conditions and diseases are derived from terrestrial sources. In recent years, marine ecosystems have proven to be a valuable resource of diverse natural products that are generated to defend and support their growth. Such marine sources offer a large opportunity for the identification of novel compounds that may guide the future development of new drugs and therapies. Using the National Oceanic and Atmospheric Administration (NOAA) portal, we explore deep-sea coral and sponge species inhabiting a segment of the U.S. Exclusive Economic Zone, specifically off the western coast of Florida. This area spans ~100,000 km2, containing coral and sponge species at sea depths up to 3000 m. Utilizing PubMed, we uncovered current knowledge on and gaps across a subset of these sessile organisms with regards to their natural products and mechanisms of altering cytoskeleton, protein trafficking, and signaling pathways. Since the exploitation of such marine organisms could disrupt the marine ecosystem leading to supply issues that would limit the quantities of bioactive compounds, we surveyed methods and technological advances that are necessary for sustaining the drug discovery pipeline including in vitro aquaculture systems and preserving our natural ecological community in the future. Collectively, our efforts establish the foundation for supporting future research on the identification of marine-based natural products and their mechanism of action to develop novel drugs and therapies for improving treatment regimens of human conditions and diseases.

Exploring Antimicrobials from the Flora and Fauna of Marine: Opportunities and Limitations

About 95% of earth living space lies deep below the ocean's surface and it harbors extraordinary diversity of marine organisms. Marine biodiversity is an exceptional reservoir of natural products, bioactive compounds, nutraceuticals and other potential compounds of commercial value. Timeline for the development of the drug from a plant, synthetic and other alternative sources is too lengthy. Exploration of the marine environment for potential bioactive compounds has gained focus and huge opportunity lies ahead for the exploration of such vast resources in the ocean. Further, the evolution of superbugs with increasing resistance to the currently available drugs is alarming and it needs coordinated efforts to resolve them. World Health Organization recommends the need and necessity to develop effective bioactive compounds to combat problems associated with antimicrobial resistance. Based on these factors, it is imperative to shift the focus towards the marine environment for potential bioactive compounds that could be utilized to tackle antimicrobial resistance. Current research trends also indicate the huge strides in research involving marine environment for drug discovery. The objective of this review article is to provide an overview of marine resources, recently reported research from marine resources, challenges, future research prospects in the marine environment.

Insights into the evolution of metazoan regenerative mechanisms: roles of TGF superfamily members in tissue regeneration of the marine sponge Chondrosia reniformis

Tissue repair is an adaptive and widespread metazoan response. It is characterised by different cellular mechanisms and complex signalling networks that involve numerous growth factors and cytokines. In higher animals, transforming growth factor-β (TGF-β) signalling plays a fundamental role in wound healing. In order to evaluate the involvement of TGF superfamily members in lower invertebrate tissue regeneration, sequences for putative TGF ligands and receptors were isolated from the transcriptome of the marine sponge Chondrosia reniformis We identified seven transcripts that coded for TGF superfamily ligands and three for TGF superfamily receptors. Phylogenetically, C. reniformis TGF ligands were not grouped into any TGF superfamily clades and thus presumably evolved independently, whereas the TGF receptors clustered in the Type I receptor group. We performed gene expression profiling of these transcripts in sponge regenerating tissue explants. Data showed that three ligands (TGF1, TGF3 and TGF6) were mainly expressed during early regeneration and seemed to be involved in stem cell maintenance, whereas two others (TGF4 and TGF5) were strongly upregulated during late regeneration and thus were considered pro-differentiating factors. The presence of a strong TGF inhibitor, SB431542, blocked the restoration of the exopinacoderm layer in the sponge explants, confirming the functional involvement of the TGF pathway in tissue regeneration in these early evolved animals.

In vitro, In silico and In vivo Antitumor Activity of Crude Methanolic Extract of Tetilla dactyloidea (Carter, 1869) on DEN Induced HCC in a Rat Model

Tetilla dactyloidea (Carter, 1869) is a marine sponge classified under Demospongia and recent studies have demonstrated that active constituents of Demospongia class have exhibited several potential medical applications. However, no preliminary pharmacological studies have been reported so far. The present investigation was carried out to evaluate the zoo-chemical status, antioxidant potential and anticancer activity of Crude Methanolic Extract of Tetilla dactyloidea (CMETD). Hepatocellular Carcinoma (HCC) was induced in the liver of male Sprague Dawley (SD) rats by treating with diethylnitrosamine (DEN). Nodule incidence, body weight, liver marker enzymes, enzymatic and non-enzymatic antioxidant, phase I metabolizing and liver macromolecular damaging enzymes and immuno-histopathological changes were assessed in DEN and DEN+CMETD treated rats. Oral administration of CMETD at a dose of 400mg/kg body weight to DEN treated rats restored the above parameters to near normal levels compared to control. The biochemical results were consistent with histopathological observations suggesting marked hepatoprotective effect of CMETD in a dose dependent manner. The GCMS of CMETD analysis showed the presence of six compounds. In in silico analysis 9-Octadecenoic acid (Z)-, 2-hydroxy-1-(hydroxymethyl) ethyl ester ligand showed an effective binding energy of -7.1kcal/mol against Cox-2 receptor. The compounds showed desirable pharmacokinetic properties and significant molecular interactions with the HCC receptors. To conclude, our results clearly suggested that CMETD treatment prevented liver damage, protected the antioxidant defense system and possessed anti-carcinogenic potential in DEN induced hepatic carcinoma.

Cytotoxic Natural Products from Marine Sponge-Derived Microorganisms

A growing body of evidence indicates that marine sponge-derived microbes possess the potential ability to make prolific natural products with therapeutic effects. This review for the first time provides a comprehensive overview of new cytotoxic agents from these marine microbes over the last 62 years from 1955 to 2016, which are assorted into seven types: terpenes, alkaloids, peptides, aromatics, lactones, steroids, and miscellaneous compounds.

Identification of okadaic acid binding protein 2 in reconstituted sponge cell clusters from Halichondria okadai and its contribution to the detoxification of okadaic acid

Okadaic acid (OA) and OA binding protein 2 (OABP2) were previously isolated from the marine sponge Halichondria okadai. Because the amino acid sequence of OABP2 is completely different from that of protein phosphatase 2A, a well-known target of OA, we have been investigating the production and function of OABP2. In the present study, we hypothesized that OABP2 plays a role in the detoxification of OA in H. okadai and that the OA concentrations are in proportional to the OABP2 concentrations in the sponge specimens. Based on the OA concentrations and the OABP2 concentrations in the sponge specimens collected in various places and in different seasons, however, we could not determine a positive correlation between OA and OABP2. We then attempted to determine distribution of OA and OABP2 in the sponge specimen. When the mixture of dissociated sponge cells and symbiotic species were separated with various pore-sized nylon meshes, most of the OA and OABP2 was detected from the same 0-10 μm fraction. Next, when sponge cell clusters were prepared from a mixture of dissociated sponge cells and symbiotic species in the presence of penicillin and streptomycin, we identified the 18S rDNA of H. okadai and the gene of OABP2 in the analysis of genomic DNA but could not detect OA by LC-MS/MS. We thus concluded that the sponge cells express OABP2, and that OA was not apparently present in the sponge cells but could be colocalized with OABP2 in the sponge cells at a concentration less than the limit of detection.

Primmorphs cryopreservation: a new method for long-time storage of sponge cells

The possibility to cryopreserve cells allows for wide opportunities of flexible handling of cell cultures from different sponge species. Primmorphs model, a multicellular 3D aggregate formed by dissociated sponge cells, is considered one of the best approaches to establish sponge cell culture but, in spite of the available protocols for freezing sponge cells, there is no information regarding the ability of the latter to form primmorphs after thawing. In the present work, we demonstrate that, after a freezing and thawing cycle using dissociated Petrosia ficiformis cells as a model, cells viability was high but it was not possible to obtain primmorphs. The same protocol for cryopreservation was then used to directly freeze primmorphs. In this second case, after thawing, viability and the cellular proliferative level were similar to unfrozen standard primmorphs. Spiculogenesis in thawed primmorphs was evaluated by quantifying the silicatein gene expression level and by assaying the silica amount in the newly formed spicules, then compared with the correspondent values obtained in standard unfrozen primmorphs. Results indicate that the freezing cycle does not affect the spiculogenesis rate. Finally, the expression level of heat shock protein 70, a well-known stress marker, was assayed and the results showed no differences between frozen and unfrozen samples. These findings are likely to promote relevant improvements in sponge cell culture technique, allowing for a worldwide exchange of living biological material, paving the way for cell banking of Porifera.

Cultivation of sponges, sponge cells and symbionts: achievements and future prospects

Marine sponges are a rich source of bioactive compounds with pharmaceutical potential. Since biological production is one option to supply materials for early drug development, the main challenge is to establish generic techniques for small-scale production of marine organisms. We analysed the state of the art for cultivation of whole sponges, sponge cells and sponge symbionts. To date, cultivation of whole sponges has been most successful in situ; however, optimal conditions are species specific. The establishment of sponge cell lines has been limited by the inability to obtain an axenic inoculum as well as the lack of knowledge on nutritional requirements in vitro. Approaches to overcome these bottlenecks, including transformation of sponge cells and using media based on yolk, are elaborated. Although a number of bioactive metabolite-producing microorganisms have been isolated from sponges, and it has been suggested that the source of most sponge-derived bioactive compounds is microbial symbionts, cultivation of sponge-specific microorganisms has had limited success. The current genomics revolution provides novel approaches to cultivate these microorganisms.

A journey under the sea: the quest for marine anti-cancer alkaloids

The alarming increase in the global cancer death toll has fueled the quest for new effective anti-tumor drugs thorough biological screening of both terrestrial and marine organisms. Several plant-derived alkaloids are leading drugs in the treatment of different types of cancer and many are now being tested in various phases of clinical trials. Recently, marine-derived alkaloids, isolated from aquatic fungi, cyanobacteria, sponges, algae, and tunicates, have been found to also exhibit various anti-cancer activities including anti-angiogenic, anti-proliferative, inhibition of topoisomerase activities and tubulin polymerization, and induction of apoptosis and cytotoxicity. Two tunicate-derived alkaloids, aplidin and trabectedin, offer promising drug profiles, and are currently in phase II clinical trials against several solid and hematologic tumors. This review sheds light on the rich array of anti-cancer alkaloids in the marine ecosystem and introduces the most investigated compounds and their mechanisms of action.

Long-term cultivation of primmorphs from freshwater Baikal sponges Lubomirskia baikalensis

The work was aimed at performing long-term cultivation of primmorphs in vitro from freshwater sponge Lubomirskia baikalensis (Pallas 1776), collected from Lake Baikal, obtaining its long-term primmorph culture in both natural (NBW) and artificial (ABW) Baikal water and at identifying the impact of different environmental factors on formation and growth of primmorphs. The first fine aggregates of L. baikalensis are formed in vitro 10-15 min after dissociation of sponge cells. Epithelization of aggregates begins 4 h later after the dissociation. Young primmorphs are formed 1 or 2 days later. The surface of primmorphs is covered with a layer of exopinacocytes. The primmorphs remain viable for more than 10 months at 3-6 °C. Over 50% of primmorphs in NBW and 25% in ABW are attached to the substrate and grow like adult sponges. Thus, the long-term primmorph cultivation in vitro allows the creation of a controlled live model system under experimental conditions. The results of this work will allow the creation of a cell culture collection of Baikal freshwater sponges for studying morphogenesis of primmorphs during cultivation at different stages and transdifferentiation of their cells, physiological functions of sponge cells, processes of spiculogenesis, identification of proteins involved in biomineralization process, decoding of their genes, as well as a spectrum of secondary metabolites.

Induction of apoptosis accompanying with G(1) phase arrest and microtubule disassembly in human hepatoma cells by jaspolide B, a new isomalabaricane-type triterpene

Jaspolide B is a novel isomalabaricane-type triterpene isolated from sponge Jaspis sp. We investigated its effects on human hepatoma cells in this study. After 48 h of incubation, jaspolide B inhibited the growth of Bel-7402 and HepG2 cells with IC(50) values of 29.1 and 29.5 μM, respectively. Incubation with 0.5 μM of jaspolide B caused time-dependent induction of apoptosis in up to 66.8% of Bel-7402 cells for 48 h, and the induction of apoptosis was confirmed by the enhancement of mitochondrial masses and cell membrane permeability, and nuclear condensation in Bel-7402 and HepG2 cells. Moreover, jaspolide B arrested cell cycle progression at G(1) phase of human hepatoma cells in a dose- and time-dependent manner. In addition, treatment of the compound caused dose-dependent disassembly of microtubule cytoskeleton in Bel-7402 cells at indicated concentrations, and this effect being similar but weaker than that of colchicine, a well-known microtubule-disassembly agent. We conclude that the anti-cancer effect of jaspolide B relates to the apoptosis induction, cell cycle arrest and microtubule disassembly, and these multiple mechanisms of jaspolide B, especially the induction of apoptosis, open interesting perspectives for further exploration of the isomalabaricane-type terpenes and compounds of marine sponge origin as potential anticancer agents.

Possible taxonomic trends in the success of primary aggregate formation in marine sponge cell cultures

A large number of novel compounds with significant medical potential have been isolated from sponges, motivating efforts to develop techniques for the sustainable cultivation of sponge biomass. To date, 33 sponges from nine different orders have been examined to assess their ability to be cultured in vitro. However, little consideration has been given to the relationships between these sponges; only one report has considering the phylogenetic relationships between the species. On the basis of morphological data, no taxonomic specificity was apparent as an indicator for the successful cultivation of the sponges. As the systematic classification of the Demospongiae is poorly understood, we collated available information on the success of in vitro sponge cell cultivation reports and examined the phylogenetic relationships of these sponges through the use of 18S and 28S rDNA sequence data. Based on molecular data, the ability of sponges to form primary aggregates from the dissociated cells of marine demosponges indicates that taxonomic trends may exist, emphasizing the need to better characterize sponges being investigated for biotechnological applications.

Sponge-associated microorganisms: evolution, ecology, and biotechnological potential

Marine sponges often contain diverse and abundant microbial communities, including bacteria, archaea, microalgae, and fungi. In some cases, these microbial associates comprise as much as 40% of the sponge volume and can contribute significantly to host metabolism (e.g., via photosynthesis or nitrogen fixation). We review in detail the diversity of microbes associated with sponges, including extensive 16S rRNA-based phylogenetic analyses which support the previously suggested existence of a sponge-specific microbiota. These analyses provide a suitable vantage point from which to consider the potential evolutionary and ecological ramifications of these widespread, sponge-specific microorganisms. Subsequently, we examine the ecology of sponge-microbe associations, including the establishment and maintenance of these sometimes intimate partnerships, the varied nature of the interactions (ranging from mutualism to host-pathogen relationships), and the broad-scale patterns of symbiont distribution. The ecological and evolutionary importance of sponge-microbe associations is mirrored by their enormous biotechnological potential: marine sponges are among the animal kingdom's most prolific producers of bioactive metabolites, and in at least some cases, the compounds are of microbial rather than sponge origin. We review the status of this important field, outlining the various approaches (e.g., cultivation, cell separation, and metagenomics) which have been employed to access the chemical wealth of sponge-microbe associations.

Purification and in vitro cultivation of archaeocytes (stem cells) of the marine sponge Hymeniacidon perleve (Demospongiae)

Marine sponges (Porifera) are the best source of marine bioactive metabolites for drug discovery and development, although the sustainable production of most sponge-derived metabolites remains a difficult task. In vitro cultivation of sponge cells in bioreactors has been proposed as a promising technology. However, no continuous cell line has as yet been developed. Archaeocytes are considered to be toti/multipotent stem cells in sponges and, when purified, may allow the development of continuous sponge cell lines. As a prerequisite, we have developed a novel four-step protocol for the purification of archaeocytes from a marine sponge, Hymeniacidon perleve: (1) differential centrifugation to separate large sponge cells including archaeocytes; (2) selective agglomeration in low-Ca(2+)/Mg(2+) artificial seawater in which living archaeocytes form small loose aggregates with some pinacocytes and collencytes; (3) differential adherence to remove anchorage-dependent pinacocytes, collencytes and other mesohyl cells; (4) Ficoll-Vrografin density gradient centrifugation to purify archaeocytes. The final purity of archaeocytes is greater than 80%. The proliferation potential of the archaeocytes has been demonstrated by high levels of BrdU incorporation, PCNA expression and telomerase activity. In 4-day primary cultures, the purified archaeocytes show a 2.5-fold increase in total cell number. This study opens an important avenue towards developing sponge cell cultures for the commercial exploitation of sponge-derived drugs.

Biology of the Porifera: cell culture

The discovery that dissociated sponge cells will reaggregate to form a functional organism was the basis for the establishment of sponge cell cultures that have been used as a model for the study of fundamental processes in developmental biology and immunology. More recent is the discovery of unique bioactive compounds in marine sponges, and the feasibility of in vitro production of these chemicals is being evaluated. Techniques are well established for cell dissociation; development of several nutrient media formulations has resulted in improvements in viability and cell division; and molecular approaches to identification of genes responsible for regulation of cell cycling may provide unique perspectives in culture optimization. The use of novel substrates for immobilization of cells offers alternatives for proliferation and scale-up. All of these results support the potential for development of a model system for the study of basic metabolic processes involved in cell differentiation, as well as an in vitro production system for sponge-derived bioactive compounds. Perhaps more important, however, is the development of cell lines of these "simple" metazoans to facilitate basic cell physiology and molecular biology research that may be applied to understanding more complex metazoan systems, including humans.

Formulation of a basal medium for primary cell culture of the marine sponge Hymeniacidon perleve

Marine sponge cell culture is a potential route for the sustainable production of sponge-derived bioproducts. Development of a basal culture medium is a prerequisite for the attachment, spreading, and growth of sponge cells in vitro. With the limited knowledge available on nutrient requirements for sponge cells, a series of statistical experimental designs has been employed to screen and optimize the critical nutrient components including inorganic salts (ferric ion, zinc ion, silicate, and NaCl), amino acids (glycine, glutamine, and aspartic acid), sugars (glucose, sorbitol, and sodium pyruvate), vitamin C, and mammalian cell medium (DMEM and RPMI 1640) using MTT assay in 96-well plates. The marine sponge Hymeniacidon perleve was used as a model system. Plackett-Burman design was used for the initial screening, which identified the significant factors of ferric ion, NaCl, and vitamin C. These three factors were selected for further optimization by Uniform Design and Response Surface Methodology (RSM), respectively. A basal medium was finally established, which supported an over 100% increase in viability of sponge cells.

Marine invertebrate cell cultures: new millennium trends

This review analyzes activities in the field of marine invertebrate cell culture during the years 1999 to 2004 and compares the outcomes with those of the preceding decade (1988 to 1998). During the last 5 years, 90 reports of primary cell culture studies of marine organisms belonging to only 6 taxa (Porifera, Cnidaria, Crustacea, Mollusca, Echinodermata, and Urochordata) have been published. This figure represents a 2-fold increase in the annual number of publications over the decade 1988 to 1998. Three other trends distinguish the two reviewed periods. First, in recent years studies attempting to improve cell culture methodologies have decreased, while interest in applications of already existing methodologies has increased. This reflects the effects of short-term cultures in attracting new researchers and scientific disciplines to the field. Second, only 17.8% of the recent publications used long-term cultures, compared with 30.0% of the publications in the previous decade. Third, during recent years research in cell cultures has studied fewer model species more extensively (mainly, Botryllus schlosseri, Crassostrea, Mytilus, Penaeus, and Suberites domuncula), signifying a shift from previous investigations that had studied a more diverse range of organisms. From 1988 to 1998 the phylum Mollusca was the most studied taxon (34.4%), but recent years have seen more studies of Porifera and Crustacea (30.0% and 32.2% of publications) than of Mollusca (21.1%). Still, not even a single established cell line from any marine invertebrate has yet been made available. However, the use of new cellular, genomic, and proteomic tools may fundamentally change our strategy for the development of cell cultures from marine invertebrates.

Large-scale production of pharmaceuticals by marine sponges: sea, cell, or synthesis?

Marine sponges are known to produce an overwhelming array of secondary metabolites with pharmaceutical potential. The technical and economical potential of using marine sponges for large-scale production of these compounds was assessed for two cases: the anticancer molecule halichondrin B from a Lissodendoryx sp., and avarol from Dysidea avara for its antipsoriasis activity. An economic and technical analysis was done for three potential production methods: mariculture, ex situ culture (in tanks), and cell culture. We concluded that avarol produced by mariculture or ex situ culture could become a viable alternative to currently used pharmaceuticals for the treatment of psoriasis. Production of halichondrin B from sponge biomass was found to not be a feasible process, mainly due to the extremely low concentration of the compound in the sponge. Technical feasibility was also analyzed for five alternatives: chemical synthesis, wild harvest, primmorph culture, genetic modification and semi-synthesis. It was concluded that the latter two approaches could prove to be valuable methods for the production of pharmaceuticals, based on chemical structures of secondary metabolites present in trace amounts in marine sponges.

Molecular cloning of silicatein gene from marine sponge Petrosia ficiformis (Porifera, Demospongiae) and development of primmorphs as a model for biosilicification studies

In some sponges peculiar proteins called silicateins catalyze silica polymerization in ordered structures, and their study is of high interest for possible biotechnological applications in the nanostructure industry. In this work we describe the isolation and the molecular characterization of silicatein from spicules of Petrosia ficiformis, a common Mediterranean sponge, and the development of a cellular model (primmorphs) suitable for in vitro studies of silicatein gene regulation. The spicule of P. ficiformis contains an axial filament composed of 2 insoluble proteins, of 30 and 23 kDa. The 23-kDa protein was characterized, and the full-length cDNA was cloned. The putative amino acid sequence has high homology with previously described silicateins from other sponge species and also is very similar to cathepsins, a cystein protease family. Finally, P. ficiformis primmorphs express the silicatein gene, suggesting that they should be a good model for biosilicification studies.

Application of a MTT assay for screening nutritional factors in growth media of primary sponge cell culture

Marine sponges (Porifera) are producers of the largest variety of bioactive compounds among benthic marine organisms. In vitro culture of marine sponge cells has been proposed for the sustainable production of these pharmacologically interesting compounds from marine sponges but with limited success. The development of a suitable growth medium is an essential prerequisite for sponge cells grown in vitro. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was adapted to screen for potential nutritional factors in formulating a growth medium for primary cell culture of Suberites domuncula. In 96-well plates, the effects of nutritional factors including glutamine, pyruvate, iron citrate, silicon, RPMI 1640, and Marine Broth 2216 on the viable cell density were examined in primary cell culture of S. domuncula 36 h after inoculation. Ferric iron (Fe(3+)) and pyruvate were found to significantly improve cell viability in a dose-dependent manner. Silicon and glutamine showed limited improvements at certain concentrations. The supplement of RPMI 1640 and Marine Broth 2216 did not increase cell viability. As a result, several improved media able to maintain higher cell viability in a short-term culture of primary sponge cells could be formulated.

Primmorphs from archaeocytes-dominant cell population of the sponge hymeniacidon perleve: improved cell proliferation and spiculogenesis

Marine sponges (Porifera) possess an extraordinary diversity of bioactive metabolites for new drug discovery and development. In vitro cultivation of sponge cells in a bioreactor system is very attractive for the sustainable production of sponge-derived bioactive metabolites; however, it is still a challenging task. The recent establishment of sponge primmorphs, multicellular aggregates from dissociated mixed-cell population (MCP), has been widely acknowledged to hold great promise for cultivation in vitro. Here we present a new method to establish an in vitro sponge primmorph culture from archaeocyte-dominant cell population (ADCP) enriched by a Ficoll gradient, rather than a mixed-cell population (MCP). Our rationale is based upon the totipotency (the ability of a cell to differentiate into other cell types) of archaeocyte cells and the different biological functions of various sponge cell types. A sponge, Hymeniacidon perleve collected from the China Yellow Sea was used as a model system for this investigation. Distinct dynamics of primmorph formation were observed while significant increases in DNA synthesis, cell proliferation (up to threefold), and cell growth (up to fourfold) were achieved. Furthermore, a time-dependent spiculogenesis was clearly demonstrated in our longterm culture, indicating high metabolic activity of primmorphs from the ADCP. This new method represents an important step forward to advance sponge cell culture in vitro that may lead to commercial exploitation of sponge-derived drugs.