The authors would like to thank Prof. Naiming Zhou from Zhejiang University for his technical advice and for making the equipment of his laboratory available for use. This work was financially supported by the National Natural Science Foundation of China (grant numbers 41876154, 41606150, and 41406137) and the Fundamental Research Funds for Zhejiang Provincial Universities and Research Institutes [grant number 2019JZ00007].

1. Cell Culture Medium Preparation
<ol>
	<li>Coelomic fluid preparation
	<ol>
		<li>Coelomic fluid collection: Under sterile conditions, dissect a healthy sea cucumber (wet weight of 85-105 g), collect coelomic fluid, and store it in a sterile glass flask.</li>
		<li>Coelomic cell removal: Centrifuge the coelomic fluid in 50 mL centrifuge tubes at 1,700 x g for 5 min and transfer the supernatant into a new sterile glass flask; next, collect the cell-free coelo...

<ol>
	<li>Naganuma, T., Degnan, B. M., Horikoshi, K., Morse, D. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myogenesis+in+primary+cell+cultures+from+larvae+of+the+abalone,+Haliotis+rufescens.">Myogenesis in primary cell cultures from larvae of the abalone, Haliotis rufescens.</a> Molecular Marine Biology and Biotechnology. 3 (3), 131-140 (1994).</li><li>Reinardy, H. C., Emerson, C. E., Manley, J. M., Bodnar, A. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tissue+regeneration+and+biomineralization+in+sea+urchins:+role+of+Notch+signaling+and+presence+of+stem+cell+markers.">Tissue regeneration and biomineralization in sea urchins: role of Notch signaling and presence of stem cell markers.</a> Plos One. 10 (8), 0133860 (2015).</li><li>Schaffer, A. A., Bazarsky, M., Levy, K., Chalifa-Caspi, V., Gat, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+transcriptional+time-course+analysis+of+oral+vs.+aboral+whole-body+regeneration+in+the+Sea+anemone+Nematostella+vectensis.">A transcriptional time-course analysis of oral vs. aboral whole-body regeneration in the Sea anemone Nematostella vectensis.</a> Bmc Genomics. 17, 718 (2016).</li><li>Chiaramonte, M., Inguglia, L., Vazzana, M., Deidun, A., Arizza, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stress+and+immune+response+to+bacterial+LPS+in+the+sea+urchin+Paracentrous+lividus+(Lamarck,+1816).">Stress and immune response to bacterial LPS in the sea urchin Paracentrous lividus (Lamarck, 1816).</a> Fish and Shellfish Immunology. 92, 384-394 (2019).</li><li>Meng, J., Wang, T., Li, L., Zhang, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inducible+variation+in+anaerobic+energy+metabolism+reflects+hypoxia+tolerance+across+the+intertidal+and+subtidal+distribution+of+the+Pacific+oyster+(Crassostrea+gigas).">Inducible variation in anaerobic energy metabolism reflects hypoxia tolerance across the intertidal and subtidal distribution of the Pacific oyster (Crassostrea gigas).</a> Marine Environmental Research. 138, 135-143 (2018).</li><li>Han, G., Zhang, S., Dong, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anaerobic+metabolism+and+thermal+tolerance:+The+importance+of+opine+pathways+on+survival+of+a+gastropod+after+cardiac+dysfunction.">Anaerobic metabolism and thermal tolerance: The importance of opine pathways on survival of a gastropod after cardiac dysfunction.</a> Integrative Zoology. 12 (5), 361-370 (2017).</li><li>Zhang, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+sea+cucumber+genome+provides+insights+into+morphological+evolution+and+visceral+regeneration.">The sea cucumber genome provides insights into morphological evolution and visceral regeneration.</a> PLoS Biology. 15 (10), 2003790 (2017).</li><li>Sun, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=iTRAQ+reveals+proteomic+changes+during+intestine+regeneration+in+the+sea+cucumber+Apostichopus+japonicus.">iTRAQ reveals proteomic changes during intestine regeneration in the sea cucumber Apostichopus japonicus.</a> Comparative Biochemistry and Physiology Part D: Genomics and Proteomics. 22, 39-49 (2017).</li><li>Xu, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+loss+by+apoptosis+is+involved+in+the+intestinal+degeneration+that+occurs+during+aestivation+in+the+sea+cucumber+Apostichopus+japonicus.">Cell loss by apoptosis is involved in the intestinal degeneration that occurs during aestivation in the sea cucumber Apostichopus japonicus.</a> Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology. 216, 25-31 (2018).</li><li>Yang, H. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metabolic+characteristics+of+sea+cucumber+Apostichopus+japonicus+(Selenka)+during+aestivation.">Metabolic characteristics of sea cucumber Apostichopus japonicus (Selenka) during aestivation.</a> Journal of Experimental Marine Biology and Ecology. 330 (2), 505-510 (2006).</li><li>Xiang, X. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glycolytic+regulation+in+aestivation+of+the+sea+cucumber+Apostichopus+japonicus:+evidence+from+metabolite+quantification+and+rate-limiting+enzyme+analyses.">Glycolytic regulation in aestivation of the sea cucumber Apostichopus japonicus: evidence from metabolite quantification and rate-limiting enzyme analyses.</a> Marine biology. 163 (8), 1-12 (2016).</li><li>Jiang, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+feedback+loop+involving+FREP+and+NF-kappaB+regulates+the+immune+response+of+sea+cucumber+Apostichopus+japonicus.">A feedback loop involving FREP and NF-kappaB regulates the immune response of sea cucumber Apostichopus japonicus.</a> International Journal of Biological Macromolecules. 135, 113-118 (2019).</li><li>Zhou, X., Chang, Y., Zhan, Y., Wang, X., Lin, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Integrative+mRNA-miRNA+interaction+analysis+associate+with+immune+response+of+sea+cucumber+Apostichopus+japonicus+based+on+transcriptome+database.">Integrative mRNA-miRNA interaction analysis associate with immune response of sea cucumber Apostichopus japonicus based on transcriptome database.</a> Fish and Shellfish Immunology. 72, 69-76 (2018).</li><li>Cai, X., Zhang, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Marine+invertebrate+cell+culture:+a+decade+of+development.">Marine invertebrate cell culture: a decade of development.</a> Journal of Oceanography. 70 (5), 405-414 (2014).</li><li>Maselli, V., Xu, F., Syed, N. I., Polese, G., Di Cosmo, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Novel+Approach+to+Primary+Cell+Culture+for+Octopus+vulgaris+Neurons.">A Novel Approach to Primary Cell Culture for Octopus vulgaris Neurons.</a> Frontiers in Physiology. 9, 220 (2018).</li><li>Pinsino, A., Alijagic, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sea+urchin+Paracentrotus+lividus+immune+cells+in+culture:+formulation+of+the+appropriate+harvesting+and+culture+media+and+maintenance+conditions.">Sea urchin Paracentrotus lividus immune cells in culture: formulation of the appropriate harvesting and culture media and maintenance conditions.</a> Biology Open. 8 (3), (2019).</li><li>Odintsova, N. A., Dolmatov, I. Y., Mashanov, V. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regenerating+holothurian+tissues+as+a+source+of+cells+for+long-term+cell+cultures.">Regenerating holothurian tissues as a source of cells for long-term cell cultures.</a> Marine Biology. 146 (5), 915-921 (2005).</li><li>Rastogi, R. P., Richa, R. P., Sinha, R. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Apoptosis:+Molecular+Mechanisms+and+Pathogenicity.">Apoptosis: Molecular Mechanisms and Pathogenicity.</a> Excli Journal. 8, 155-181 (2009).</li><li>Wan, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Apoptosis,+proliferation,+and+morphology+during+vein+graft+remodeling+in+rabbits.">Apoptosis, proliferation, and morphology during vein graft remodeling in rabbits.</a> Genetics and Molecular Research. 15 (4), (2016).</li><li>Kasibhatla, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Staining+of+suspension+cells+with+hoechst+33258+to+detect+apoptosis.">Staining of suspension cells with hoechst 33258 to detect apoptosis.</a> Cold Spring Harbor Protocols. 2006 (3), (2006).</li><li>Mikiewicz, M., Otrocka-Domagala, I., Pazdzior-Czapula, K., Rotkiewicz, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influence+of+long-term,+high-dose+dexamethasone+administration+on+proliferation+and+apoptosis+in+porcine+hepatocytes.">Influence of long-term, high-dose dexamethasone administration on proliferation and apoptosis in porcine hepatocytes.</a> Research in Veterinary Science. 112, 141-148 (2017).</li><li>Rinkevich, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+cultures+from+marine+invertebrates:+new+insights+for+capturing+endless+stemness.">Cell cultures from marine invertebrates: new insights for capturing endless stemness.</a> Marine Biotechnology. 13 (3), 345-354 (2011).</li><li>Bello, S. A., Abreu-Irizarry, R. J., Garcia-Arraras, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Primary+cell+cultures+of+regenerating+holothurian+tissues.">Primary cell cultures of regenerating holothurian tissues.</a> Methods in Molecular Biology. 1189, 283-297 (2015).</li><li>Yu, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impact+of+water+temperature+on+the+growth+and+fatty+acid+profiles+of+juvenile+sea+cucumber+Apostichopus+japonicus+(Selenka).">Impact of water temperature on the growth and fatty acid profiles of juvenile sea cucumber Apostichopus japonicus (Selenka).</a> Journal of Thermal Biology. 60, 155-161 (2016).</li></ol>

Extensive research efforts have been devoted to establishing cell lines in last decades, however, it is still difficult to make a progress on long-term culture of cells from marine invertebrates14,22. It has been reported that cultured cells from regenerating holothurian tissues were viable for a long period of time and high activity of proliferation can be detected in specific cells17,23. However, for th...

Culturing cells under artificially controlled conditions, and not in their natural environment, provides uniform experimental materials for biological studies, especially for species which cannot be easily cultured in a laboratory environment. Marine invertebrates account for more than 30% of all animal species1, and they provide numerous biological materials for undertaking research on the regulatory mechanisms of specific biological processes, such as regeneration2,3, stress response4, and environmental adaptation5,6.
The sea cucumber, Apostichopus japonicus, is one of the most studied echinoderm species inhabiting temperate waters along the North Pacific coast. It is well known as a commercially important species and maricultured on a large scale in East Asia, especially in China7. Numerous scientific questions regarding A. japonicus, including the regulatory mechanisms underlying intestinal regeneration after evisceration8 and degeneration in aestivation9, metabolic control10,11, and immune response12,13 under thermal or pathogenic stresses, have attracted the attention of researchers. However, compared with well-studied model animals, basic research, especially on the cellular level, is limited by technical bottlenecks, such as the lack of advanced cell culture methods.
Researchers have devoted much effort to establishing cell lines, but they have also faced many challenges and no cell line from any marine invertebrate has been established yet14. However, primary cell cultures from marine invertebrates have advanced in last decades15,16, and they have provided an opportunity for experimentation on the cellular level. For example, the regenerating intesine from A. japonicus has been utilized as a source of cells for long-term cell cultures which provided a practical method for primary cell culture of marine invertebrates17. This protocol combined and optimized invertebrate cell culture approaches and developed a widely suitable primary culture method for sea cucumber or other marine invertebrates.
Apoptosis is an intrinsic cell suicide program triggered by various exogenous and endogenous stimuli. Coordinated apoptosis is crucial to many biological systems18,19, and it has been implicated in the intestinal regression of sea cucumber during aestivation9. To investigate the apoptotic process in organisms of interest, a series of methods, including Hoechst staining and microscopy assays, have been established and successfully applied20. Here, we conducted apoptosis induction and detection in primary cultured intestinal cells of sea cucumber to assess the usability of primary cells in biological studies of marine invertebrates. Dexamethasone, one of the commonly used synthetic glucocorticosteroids21, was used to induce apoptosis in cultured intestinal cells from sea cucumber, and significant Hoechst 33258 signal was successfully detected in the stained cells by fluorescent microscopy.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>0.1 &#956;m filter</td>
			<td>Millipore</td>
			<td>SLVV033RS</td>
			<td></td>
		</tr>
		<tr>
			<td>0.22 &#956;m filter</td>
			<td>Millipore</td>
			<td>SLGP033RB</td>
			<td></td>
		</tr>
		<tr>
			<td>0.25% Trypsin</td>
			<td>Genom</td>
			<td>GNM25200</td>
			<td></td>
		</tr>
		<tr>
			<td>100 &#956;m filter</td>
			<td>Falcon</td>
			<td>352360</td>
			<td></td>
		</tr>
		<tr>
			<td>4 cm dishes</td>
			<td>ExCell Bio</td>
			<td>CS016-0124</td>
			<td></td>
		</tr>
		<tr>
			<td>4% paraformaldehyde solution</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>80096618</td>
			<td>in PBS</td>
		</tr>
		<tr>
			<td>Benchtop Centrifuges</td>
			<td>Beckman</td>
			<td>Allegra X-30R</td>
			<td></td>
		</tr>
		<tr>
			<td>BeyoClick EdU-488 kit</td>
			<td>Beyotime</td>
			<td>C0071S</td>
			<td></td>
		</tr>
		<tr>
			<td>CaCl2</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>10005817</td>
			<td></td>
		</tr>
		<tr>
			<td>Constant temperature incubator</td>
			<td>Lucky Riptile</td>
			<td>HN-3</td>
			<td></td>
		</tr>
		<tr>
			<td>Dexamethasone</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>XW00500221</td>
			<td></td>
		</tr>
		<tr>
			<td>Electric thermostatic water bath</td>
			<td>senxin17</td>
			<td>DK-S28</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>80176961</td>
			<td>75%</td>
		</tr>
		<tr>
			<td>Fibroblast Growth Factor(FGF)</td>
			<td>PEPROTECH</td>
			<td>100-18B</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescent microscope</td>
			<td>Leica DMI3000B</td>
			<td>DMI3000B</td>
			<td></td>
		</tr>
		<tr>
			<td>Garamycin</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>XW14054101</td>
			<td></td>
		</tr>
		<tr>
			<td>Glucose</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>63005518</td>
			<td></td>
		</tr>
		<tr>
			<td>Hoechst33258 Staining solution</td>
			<td>Beyotime</td>
			<td>C1017</td>
			<td></td>
		</tr>
		<tr>
			<td>Insulin</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>XW1106168001</td>
			<td></td>
		</tr>
		<tr>
			<td>Insulin like Growth Factor(IGF)</td>
			<td>PEPROTECH</td>
			<td>100-11</td>
			<td></td>
		</tr>
		<tr>
			<td>KCl</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>10016308</td>
			<td></td>
		</tr>
		<tr>
			<td>Leibovitz&#39;s L-15</td>
			<td>Genom</td>
			<td>GNM41300</td>
			<td></td>
		</tr>
		<tr>
			<td>L-glutamine (100 mg/mL)</td>
			<td>Genom</td>
			<td>GNM-21051</td>
			<td></td>
		</tr>
		<tr>
			<td>MgCl2</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>XW77863031</td>
			<td></td>
		</tr>
		<tr>
			<td>Na2SO4</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>10020518</td>
			<td></td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>10019308</td>
			<td></td>
		</tr>
		<tr>
			<td>NaOH</td>
			<td>Sinopharm Chemical Reagent</td>
			<td>10019718</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS</td>
			<td>Solarbio</td>
			<td>P1020</td>
			<td>pH7.2-7.4</td>
		</tr>
		<tr>
			<td>Penicillin-Streptomycin</td>
			<td>Genom</td>
			<td>GNM15140</td>
			<td></td>
		</tr>
		<tr>
			<td>PH meter</td>
			<td>Bante</td>
			<td>A120</td>
			<td></td>
		</tr>
		<tr>
			<td>Taurine</td>
			<td>SIGMA</td>
			<td>T0625</td>
			<td></td>
		</tr>
		<tr>
			<td>VE</td>
			<td>Seebio</td>
			<td>185791</td>
			<td></td>
		</tr>
	</tbody>
</table>

apoptosis induction and detection in a primary culture of sea cucumber intestinal cells

Primary cultured cells are used in a variety of scientific disciplines as exceptionally important tools for the functional evaluation of biological substances or characterization of specific biological activities. However, due to the lack of universally applicable cell culture media and protocols, well described cell culture methods for marine organisms are still limited. Meanwhile, the commonly occurring microbial contamination and polytropic properties of marine invertebrate cells further impede the establishment of an effective cell culture strategy for marine invertebrates. Here, we describe an easy-to-handle method for culturing intestinal cells from sea cucumber Apostichopus japonicus; additionally, we provide an example of in vitro apoptosis induction and detection in primary cultured intestinal cells. Moreover, this experiment provides details about the appropriate culture medium and cell collection method. The described protocol is compatible with a variety of widely available tissue samples from marine organisms including Echinodermata, Mollusca, and Crustacea, and it can provide sufficient cells for multiple in vitro experimental applications. This technique would enable researchers to efficiently manipulate primary cell cultures from marine invertebrates and to facilitate the functional evaluation of targeted biological materials on cells.

Here, we established primary intestinal cell culture of A. japonicus and passaged the cells. Figure 1 shows round cells in different stages of culturing. And the EdU staining assays provide direct evidences to reveal the proliferative activity of these round cells in later stage (Figure 2). We also slightly adjusted the protocol, culturing minced tissue blocks instead of filtrated cells; furthermore, a spindle cell type could be cultured successfully. T...

Watch this Scientific Journal Video about Apoptosis Induction and Detection in a Primary Culture of Sea Cucumber Intestinal Cells at JoVE.com

Apoptosis Induction and Detection in a Primary Culture of Sea Cucumber Intestinal Cells

This protocol provides an easy-to-handle method to culture the intestinal cells from sea cucumber Apostichopus japonicus and is compatible with a variety of widely available tissue samples from marine organisms including Echinodermata, Mollusca, and Crustacea.

Primary cultured cells are used in a variety of scientific disciplines as exceptionally important tools for the functional evaluation of biological ...

The protocol provide a easy-to-handle and widely compatible primary cell culture method for marine invertebrates. This technique gives researchers a way to culture the marine invertebrate cells for comparatively long time. A culture of cells should be provided with consistent genetic background for different further biological experimental applications in marine biology research.To the new research to this field, we believe that the indicated simplified protocol should be the good choice to exercise. After anesthetization, dissect and collect the anterior intestines, then section the tissue samples vertically and remove the inner contents. Wash the tissue samples in PBS twice and disinfect them by immersion in a 75%ethanol solution for no longer than two seconds.Then wash the tissue samples in PBS three times to remove the ethanol, and transfer about 100 milligrams of tissue sample into a two milliliter sterile micro centrifuge tube. Add 1.5 milliliters of pre-optimized culture medium to the sea cucumber intestinal tissue block and mince the block with sterilized surgical scissors until the solution is cloudy. Add 400 microliters of 0.25%trypsin.Mix the solution by inversion and incubate it for five minutes at room temperature. Then filter the solution using a 100 micron cell strainer and collect the filtrate in a new sterile two milliliter micro centrifuge tube. For optional simplified protocol, tissue blocks cut in cultured media can be directly transferred into dishes and subsequently incubated.Centrifuge the tube at 1700xG for three minutes, discard the supernatant, then re-suspend the pellet in culture medium with antibiotics, and wash it with culture medium twice. Pre-set the incubator for cell culture, and run it in advance for at least 24 hours with the temperature of 18 degrees Celsius and saturated humidity. Then re-suspend the cells using 200 microliters of indicated medium, and transfer them into four centimeter dishes.Culture the cells in an incubator. After six hours, take them out of the incubator and add two milliliters of indicated medium to the cell culturing dishes. Every 12 hours, change half of the medium.After five to seven days, the cells start to divide. Reduce the adverse effects of antibiotics by reducing the concentration of indicated antibiotics, penicillin, streptomycin, and gentamicin in the culture medium by half. Every two to three days, replace the cell culture medium.When the primary cell density reaches 60%conduct cell passaging. First, wash the cultured cells twice using PBS at room temperature. Add 200 microliters of 0.25%trypsin solution to each dish, and manually agitate the dishes, ensuring the whole bottom is covered.Discard the trypsin solution, and incubate the cells for five minutes at room temperature. Wash the cells with one milliliter of fresh culture medium by pipetting and re-suspending the cells. Transfer 0.5 milliliters of cell suspension to a new dish.Add 1.5 milliliters of fresh medium, and incubate the cells at 18 degrees Celsius. After 12 hours, change the medium, and observe the cells under a microscope to evaluate the conditions. Prepare three experimental groups, including a control, and two groups of solutions, with one micromolar and 100 micromolar deximethazone.After incubation with or without deximethazone for zero, 24, or 48 hours, wash the cells three times with PBS. After turning off the light, add 300 microliters of hoechst 33258 solution per well to a 12 well plate, and gently agitate the plate to cover all cells, ensuring their staining. Incubate at 18 degrees Celsius for 30 minutes.Then remove the hoechst staining solution and fix the cells by adding 300 microliters of four percent paraformaldehyde solution in PBS to each well. Gently agitate for 15 minutes. After that, wash the fixed cells three times in PBS.Keep the PBS after the last washing to keep the cells covered. Turn on the fluorescent microscope hardware, including the mercury lamp power, the fluorescent light power, and the PC.Log into the operating system account, launch the software, and check its configuration. Place the prepared plate on the microscope stage.Position the sample over the objective lens using the stage controller. Find the cells of interest under the light microscope. Switch to fluorescent microscopy and adjust the parameters of the excitation and emission to approximately 352 and 461 nanometers, respectively, for nuclei DNA observation.Capture the images. In this study, primary intestinal cell culture of sea cucumber was established and passaged. Round cells in different stages of culturing are shown here.Here are cells attached to the bottom of dishes on the third day, after being seeded. Here is cell proliferation on the seventh day. Here are cells attached to the bottom of the dishes after passaging.And cells that lost activity and were dying after 10 passages. The EDU stating assays provide direct evidence to reveal the proliferative activity of these round cells in later stages. The stimulation with one micromolar deximethazone increased the apoptotic cell rate most rapidly, compared with the control and the 100 micromolar deximethazone stimulation.The cultured cells were treated with deximethazone for different time periods, followed by hoechst 33258 staining for apoptotic cell detection. Cell treatments before incubating is critical for longterm control. It is a reminder to try the optional simplified protocol when the cell don't grow well.Paraformaldehyde is moderately toxic by skin contact or inhalation, and it is documented as a probably human carcinogen.

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Research

JoVE Journal

Biology

6.7K vistas.  Zhejiang Ocean University. El protocolo proporciona un método de cultivo de células primarias fácil de manejar y ampliamente compatible para los invertebrados marinos. Esta técnica ofrece a los investigadores una manera de cultivar las células invertebradas marinas durante un tiempo relativamente largo. Se debe proporcionar un cultivo de células con antecedentes genéticos consistentes para diferentes aplicaciones experimentales biológicas adicionales en la investigación de la biología marina.Para la nu...