Characterization of a new cell line from ornamental fish Amphiprion ocellaris (Cuvier, 1830) and its susceptibility to nervous necrosis virus

Establishment and characterization of a kidney cell line from hybrid snakehead (male Channa argus × female Channa maculata) and its susceptibility to hybrid snakehead rhabdovirus (HSHRV)

Hybrid snakehead (male Channa argus × female Channa maculata) is an emerging fish breed with increasing production levels. However, infection with hybrid snakehead rhabdovirus (HSHRV) critically affects hybrid snakehead farming. In this study, a fish cell line called CAMK, derived from the kidneys of hybrid snakehead, was established and characterized. CAMK cells exhibited the maximum growth rate at 28 °C in Leibovitz's-15 medium supplemented with 10% fetal bovine serum(FBS). Karyotyping revealed diploid chromosomes in 54% of the cells at the 50th passage (2n = 66), and 16S rRNA sequencing validated that CAMK cells originated fromhybrid snakehead, and the detection of kidney-specific antibodies suggested that it originated from kidney. .The culture was free from mycoplasma contamination, and the green fluorescent protein gene was effectively transfected into CAMK cells, indicating their potential use for in vitro gene expression investigations. Furthermore, qRT-PCR and immunofluorescence analysis revealed that HSHRV could replicate in CAMK cells, indicating that the cells were susceptible to the virus. Transmission electron microscopy revealed that the viral particles had bullet-like morphology. The replication efficiency of HSHRV was 107.33 TCID50/mL. Altogether, we successfully established and characterized a kidney cell line susceptible to the virus. These findings provide a valuable reference for further genetic and virological studies.

New parameters for in vitro development of cell lines of the species Astyanax bimaculatus (Linnaeus, 1758) and Geophagus proximus (Castelnau, 1855)

Intending to compare in vitro cell growth in different conditions, we established cell cultures using fin biopsies of two freshwater fishes, Astyanax bimaculatus and Geophagus proximus. Three different culture media (Leibovitz-L-15, Dulbecco's Modified Eagle Medium [DMEM], and 199) were employed, with or without the addition of AmnioMax, maintaining a standard temperature of 29°C. Based on the results obtained, we standardized a cell growth protocol in which medium 199 was less efficient for both species. Notably, G. proximus cells exhibited superior proliferation in DMEM and L-15 media, whereas A. bimaculatus cells demonstrated better parameters exclusively in the DMEM medium. Successful subculturing of cells with good proliferation index was observed, accompanied by preserved morphological characteristics. Therefore, the methodology outlined in this study represents an advancement in establishing fish cell cultures.

Establishment of a cobia (Rachycentron canadum) gill cell line: A valuable tool for immune response studies

Cobia (Rachycentron canadum), a commercially important marine fish, has been used to develop a novel gill cell line, designated CG, for the first time. The CG cell line was cultured in Leibovitz's-15 medium with 5% fetal bovine serum (FBS) and successfully sub-cultured more than 110 passages. It underwent verification through sequencing of the mitochondrial cytochrome C oxidase subunit I (COI) gene. Optimal growth rate was achieved when the CG cell line was cultured in a medium supplemented with 5% FBS, 1% Penicillin-Streptomycin (P/S), and 5 parts per thousand (ppt) of coral sea salt water, maintained at a temperature of 27 °C. The addition of 5 ppt of salt in the growth medium suggests that this cell line could be a viable in vitro tool for marine ecosystem toxicological studies or for culturing marine parasitic microorganisms. The CG cell line was also successfully transfected using the pTurbo-GFP plasmids, showing an 18% efficiency, with observable GFP expression. Furthermore, the cell line has been effectively cryopreserved. Gene expression analysis indicated that the CG cell line exhibits responsive regulation of immune gene expression when exposured to various stimulants, highlighting its potential as an in vitro platform for immune response studies. This makes it suitable for exploring dynamic immune signaling pathways and host-pathogen interactions, thereby offering valuable insights for therapeutic development.

Development and characterization of a new muscle cell culture system from Clarias magur (Hamilton, 1822)

The cell line has been used as a novel in vitro tool for executing several studies in life sciences. The current study aimed to develop and characterize a muscle cell culture system derived from Clarias magur. The primary muscle cell cultures derived from the caudal peduncle muscle have been successfully sub cultured up to 13 passages to establish a new muscle cell culture system known as CMM. At a temperature of 28 °C, L-15 medium supplemented with 20% FBS produced the maximum growth of muscle cells. However, muscle cells were optimized to grow at 10% FBS. To enhance the proliferation capacity of the CMM cells, a growth-promoting factor bFGF (10 ng/ml) was added, thereby reducing the time interval of passages for the subsequent cultures. DNA barcoding of the CMM cell culture system authenticated the species of origin. The cell culture system was successfully cryopreserved by a slow freezing procedure at - 80 °C with a revival efficiency of 60%.

Establishment and Characterization of Continuous Satellite Muscle Cells from Olive Flounder (Paralichthys olivaceus): Isolation, Culture Conditions, and Myogenic Protein Expression

Olive flounder (Paralichthys olivaceus) muscle satellite cells (OFMCs) were obtained by enzymatic primary cell isolation and the explant method. Enzymatic isolation yielded cells that reached 80% confluence within 8 days, compared to 15 days for the explant method. Optimal OFMC growth was observed in 20% fetal bovine serum at 28 °C with 0.8 mM CaCl2 and the basic fibroblast growth factor (BFGF) to enhance cell growth. OFMCs have become permanent cell lines through the spontaneous immortalization crisis at the 20th passage. Olive flounder skeletal muscle myoblasts were induced into a mitogen-poor medium containing 2% horse serum for differentiation; they fused to form multinucleate myotubes. The results indicated complete differentiation of myoblasts into myotubes; we also detected the expression of the myogenic regulatory factors myoD, myogenin, and desmin. Upregulation (Myogenin, desmin) and downregulation (MyoD) of muscle regulation factors confirmed the differentiation in OFMCs.

Development of a cell line from skeletal trunk muscle of the fish Labeo rohita

Labeo rohita is a widely cultivated tropical freshwater carp and found in rivers of South Asian region. A new cell line, designated LRM, has been developed from the muscle tissue of L. rohita. Muscle cells were subcultured up to 38 passages in a Leibovitz's-15 (L-15) supplemented with 10% FBS (Fetal Bovine Serum) and 10 ng/ml bFGF. The LRM cells exhibited fibroblastic morphology with a doubling time of 28 h, and a plating efficiency of 17%. A maximum growth rate was observed for LRM cells at 28 °C, 10% FBS and 10 ng/ml bFGF. A cytochrome C oxidase subunit I (COI) gene sequence was used to authenticate the developed cell line. Chromosome analysis revealed 50 diploid chromosomes. The fibroblastic characteristics of the of the LRM cells was confirmed by immunocytochemistry. The expression of MyoD gene in LRM cells was analyzed by quantitative PCR in comparison with passages 3, 18 and 32. The expression of MyoD was higher at passage 18 compared to the passages 3 and 32. The LRM cells attached properly onto the 2D scaffold and the expression of the F-actin filament protein was confirmed by phalloidin staining followed by counter staining with DAPI to observe the distribution of the muscle cell nuclei and the cytoskeleton protein. A revival rate of 70-80% was achieved when the LRM cells were cryopreserved at - 196 °C using liquid nitrogen. This study would further contribute to understanding the in vitro myogenesis and progress toward cultivated fish meat production.

Functional characterization of Labeo rohita muscle cell line for in vitro research

BACKGROUND

Labeo rohita represents the most dominant fish species in Indian aquaculture and the fish cell lines have been used as an excellent in vitro platform for performing various biological research.

METHODS AND RESULTS

The LRM cell culture developed from the muscle tissue of L. rohita was used to study the in vitro applications. The developed muscle cells were maintained in a Leibovitz's-15 (L-15) supplemented with 10% FBS (Fetal Bovine Serum) and 10 ng/ml bFGF at 28 ^oC temperature. The LRM cells showed fibroblastic-like morphology and was authenticated by sequencing mitochondrial gene 16S rRNA. The expression of myogenic regulatory factors (MRFs) was studied in different stages of LRM cells; however, the expression patterns varied at different passages. The MEF2A, Mrf-4, and Myogenin expressions were higher in passage 25, while the expression of MyoD was maximum in passage 15, and the expression of Myf-5 was highest in passage 1. The transfection efficiency of LRM cells revealed 14 % of the GFP expression with a pmaxGFP vector DNA. The LRM cells were susceptible to the extracellular products prepared from Aeromonas hydrophilla and Edwardsiella tarda. The acute cytotoxicity of six heavy metals (Hg, Cd, Zn, Cu, Pb, Ni) was assessed in LRM cells by a dose-dependent manner in comparison to IC₅₀ values obtained from MTT and NR assays. A revival rate of 70-75% was achieved when the LRM cells were cryopreserved at - 196 °C using liquid nitrogen.

CONCLUSION

The developed muscle cells serve as an functional in vitro tool for toxicological and biotechnological studies.

Development, characterization and in vitro applications of a thymus cell line from Pangasianodon hypophthalmus (Sauvage 1878)

Pangasianodon hypophthalmus is an economically important catfish species cultured in India. In the present study, a continuous cell line from the thymus of P. hypophthalmus (PHT) was established using the explant method and subcultured 52 times since development. PHT cells showed optimal growth in L-15 medium containing 20% fetal bovine serum at 28°C. The species of the cell line from striped catfish was confirmed through PCR amplification and sequencing of 16S, and COI genes. The cell line was found to be Mycoplasma free. The modal chromosome number of PHT cells was 60 (2n). Immunophenotyping using different antibodies showed the epithelial nature of the cells. Cytotoxicity of arsenic and mercury was assessed using Neutral red and MTT assay, which revealed reduced cell survival with an increase in toxicant concentration. Cells transfected successfully with the GFP reporter gene using lipofectamine reagent indicated the suitability of the cell line for expression studies. The cell line has been submitted to NRFC, Lucknow with accession no. NRFC-078 at ICAR-NBFGR, Lucknow. The developed cell line will have applications in suspected viral disease investigation, transgenic, and immunological studies.

Establishment of an in vitro model from the vulnerable fish species Coregonus maraena (maraena whitefish): Optimization of growth conditions and characterization of the cell line

In this study, a cell line of the fish species Coregonus maraena was produced for the first time. C. maraena is an endangered species, and studies indicate that this fish species will be affected by further population declines due to climate change. This cell line, designated CMAfin1, has been maintained in Leibovitz L-15 supplemented with 10% fetal bovine serum over 3 years. Both subculturing and storage (short-term storage at -80°C and long-term storage in liquid nitrogen) was successful. Cell morphology and growth rate were consistent from passage 10 onwards. Immunocytochemical examination of cellular proteins and matrix components confirmed the mechanical stability of the cells. Actin, fibronectin, vinculin, vimentin, and tubulin are present in the cells and form a network. In addition, the transport of molecules is ensured by the necessary proteins. Gene expression analysis showed a shift in the expressions of stem cell markers between younger and higher passages. While SOX2 and IGF1 were more highly expressed in the seventh passage, SOX9 and IGF2 expressions were significantly increased in higher passages. Therefore, the stable cell culture CMAfin1 can be used for applied analysis to further understand the cell physiology of C. maranea.

Derivation and characterization of new cell line from intestine of turbot (Scophthalmus maximus)

A continuous intestine cell line from turbot (Scophthalmus maximus) designated as SMI was established utilizing the tissue explant technique. Primary SMI cell was cultured at 24 °C in a medium with 20% fetal bovine serum (FBS), then subcultured in 10% FBS after 10 passages. Impacts of medium or temperature on the growth of SMI were examined and the results indicated it grew well in DMEM supplemented with 10% FBS at 24 °C. The SMI cell line was subcultured more than 60 times. Karyotyping, chromosome number, and ribosomal RNA genotyping analysis revealed that SMI had a modal diploid chromosome number of 44 and originated from turbot. After being transfected with pEGFP-N1 and FAM-siRNA, a large number of green fluorescence signals were observed in SMI, indicating that SMI could be used as an ideal platform to explore gene function in vitro. In addition, the expression of epithelium-associated genes such as itga6, itgb4, gja1, claudin1, zo-1, and E-cadherin in SMI suggested the SMI had some characteristics of epidermal cells. The upregulation of immune-associated genes such as TNF-β, NF-κB, and IL-1β in SMI after stimulation with pathogen-associated molecular patterns suggested the SMI might exhibit immune functions similar to the intestinal epithelium in vivo.

Cell line derived from muscle of Gymnocypris przewalskii, a species of Schizothoracinae in Qinghai Lake, Qinghai-Tibet Plateau

Gymnocypris przewalskii (naked carp), a native teleost, plays an important role in the ecosystem of Qinghai Lake (altitude, 3.2 km) on the Qinghai-Tibet Plateau in China. We developed a new cell line from the muscle of G. przewalskii using the explant technique and named the cell line GPM. This cell line was maintained in DMEM medium (high glucose) supplemented with 15% fetal bovine serum (FBS). The cell line was successfully subcultured up to 32 passages and was authenticated by immunofluorescence assay, sequencing the mitochondrial cytochrome C oxidase subunit I (COI) and 16S rRNA genes, and by chromosome analysis. In the medium containing 15% FBS, the cell line could be passaged stably at 25 °C. The GPM cell line could express green fluorescent protein (GFP) with a CMV promoter with about 5% transfection efficiency. MTT tests showed that Clostridium botulinum toxin (BTX) was toxic to the cell line. The cell line could be successfully cryopreserved in liquid nitrogen with a revival efficiency of over 70%. This study demonstrated that the GPM cell line can be used as an important tool for understanding the physiological characteristics of G. przewalskii, and it can provide a resource for studying gene function and toxicological reactions in vitro.

Establishment of a cell line derived from the gills of Gymnocypris przewalskii, an endemic Schizothoracine fish from Qinghai Lake of Tibet Plateau

Gymnocypris przewalskii (Naked carp), a native teleost, plays an important role in maintaining the ecological balance of Lake Qinghai (altitude, 3.2 km), the largest saline lake in China. In this study, a new gill cell line from G. przewalskii was developed using the explant technique and named as GPG. This cell line was maintained in Dulbecco's Modified Eagle Medium (DMEM) (high glucose), supplemented with 15% fetal bovine serum (FBS), and was successfully subcultured up to 32 passages. Meanwhile, this cell line was also authenticated by sequencing the mitochondrial cytochrome C oxidase subunit I (COI) and 16S rRNA genes and by chromosome analysis. With the Cytomegalovirus (CMV) promoter, the GPG cell line could express green fluorescent protein (GFP) at about 5% transfection efficiency. MTT test showed that Clostridium botulinum toxin (BTX) was toxic to the cell line. After cryopreservation with 10% dimethyl sulfoxide (DMSO), this cell line could be successfully revived at an efficiency over 70%. This study revealed that the GPG cell line could be used as materials for physio-chemical investigation of G. przewalskii and also provided a tool for gene function study and toxicological reaction in vitro.

Reprocessing seafood waste: challenge to develop aquatic clean meat from fish cells

Fish consumption has been increasing worldwide as per capita consumption of fish rises along with population growth. At the same time, overfishing is increasing all over the world, causing enormous damage to the ecosystem. There is an urgent need to secure sustainable fishery resources to meet the expanding demand for fish. The present study focused on the cells obtained from fish fins, which were often discarded as food waste, and which had the potential to change their morphology with simple treatments, creating the possibility of processing fish fin cells into clean meat (i.e., meat produced in vitro; artificial, lab-cultured meat using tissue engineering techniques). The fin-derived fibroblast-like cells demonstrated an interesting characteristic; changing the sera or culture media supported differentiation of the fibroblast-like cells to various cell morphologies, such as neurofilaments and adipocytes, etc., without genetic manipulation. Furthermore, it was possible to culture the cells in multi-layered and three-dimensional forms that were suitable for processing and shaping. Taking advantage of the cells' characteristics, 'aquatic clean meat' was produced successfully at the prototype stage. Our results suggest that fish fins, which are often treated as waste material, thus, are easy to procure, simple to process, and could be used to create a sustainable food resource.

Role and relevance of fish cell lines in advanced in vitro research

Introduction

Cell line derived from fish has been established as a promising tool for studying many key issues of aquaculture covering fish growth, disease, reproduction, genetics, and biotechnology. In addition, fish cell lines are very useful in vitro models for toxicological, pathological, and immunological studies. The easier maintenance of fish cell lines in flexible temperature regimes and hypoxic conditions make them preferable in vitro tools over mammalian cell lines. Great excitement has been observed in establishing and characterizing new fish cell lines representing diverse fish species and tissue types. The well-characterized and authenticated cell lines are of utmost essential as these represent cellular functions very similar to in vivo state of an organism otherwise it would affect the reproducibility of scientific research.

Conclusion

The fish cell lines have exhibited encouraging results in several key aspects of in vitro research in aquaculture including virology, nutrition and metabolism, production of vaccines, and transgenic fish production. The review paper reports the cell lines developed from fish, their characterization, and biobanking along with their potential applications and challenges in in vitro research.

The Development and Evaluation of Brain and Heart Cell Lines from a Marine Fish for Use in Xenobiotic-Induced Cytotoxicity Testing

Two cell lines derived from the brain and heart of a Pacific white snook specimen (Centropomus viridis) were developed and evaluated in terms of their responsiveness to glyphosate-induced cytotoxicity. The cells were grown in Leibovitz-15 (L-15) medium supplemented with 10% fetal bovine serum (FBS) and were passaged 36 times. Growth was tested at different concentrations of FBS (5, 10 and 20%) at 27°C. The cell lines were cryopreserved at different passages and were successfully thawed, with a survival rate greater than 80% without detectable contamination. At passage 36, the cells were used to assess the deleterious effects of glyphosate, and cell proliferation was measured by direct counting and with the MTT assay. Similar LC₅₀ values were obtained with both methods. Although the principles behind these two assessment methods differ, our results show that both are suitable for evaluating glyphosate toxicity. In addition, heart- and brain-derived cells showed similar sensitivity, suggesting that the same mode of action might be responsible for the toxicity of glyphosate at the cellular level. The newly developed Pacific white snook brain and heart cell lines could be useful to investigate cellular and molecular mechanisms of toxicity, satisfying the need to reduce the use of animals in experiments. Glyphosate-related toxicological data obtained in the present study will allow us to continue investigating the effects of this herbicide directly on brain and heart fish cells since similar studies have only been carried out on either live organisms or on human cell lines such as neuroblastoma, which are immortalised by oncogenes or similar.