Characterization of the continuous skin fibroblastoid cell line, WE-skin11f, from walleye (Sander vitreus)

Novel Eel Skin Fibroblast Cell Line: Bridging Adherent and Suspension Growth for Aquatic Applications Including Virus Susceptibility

Suspension growth can greatly increase the cell density and yield of cell metabolites. To meet the requirements of aquatic industries, a culture model derived from Anguilla anguilla skin was developed using the explant outgrowth and enzyme-digesting passaging methods. These cells were kept in vitro continuously for over 12 months and subcultured 68 times. This heteroploid cell line, designated as ES, can naturally adapt to adherent and suspension growth reversibly under certain temperatures, serum percentages, and inoculum densities, without the need for any microcarriers or special medium additives. The ES cells can continue being highly productive under a temperature range of 15-37 °C and a serum percentage ranging from 3 to 15%. An inoculum density higher than 5 × 105 cells·mL-1 is necessary for the ES cells to turn into suspension efficiently. The green fluorescent protein (GFP) reporter gene was successfully expressed in the ES cells. The ES cells demonstrated susceptibility to Anguillid herpesvirus (AngHV) and red-spotted grouper nervous necrosis virus (RGNNV). ES is the first natural suspension growth model of aquatic origin; it does not require the processes of suspension domestication and carrier dissolution, making it a promising and cost-effective model for vaccine production, bio-pharmaceutical manufacturing, and cellular agriculture.

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.

Regulation of endogenous antigen presentation in response to suboptimal temperatures in a walleye skin fibroblast cell line

A skin fibroblast cell line WE-skin11f from walleye (Sander vitreus) was used to study the impact of temperature (26 °C, 20 °C, 14 °C, or 4 °C) on the transcript levels of genes involved in the endogenous antigen processing and presentation pathway (EAPP), which is an important antiviral pathway of vertebrates. Partial coding sequences were found for 4 previously unidentified walleye EAPP members, calreticulin, calnexin, erp57, and tapasin, and the constitutive transcript levels of these genes in WE-skin11f was unchanged by culture incubation temperature. The viral mimic poly (I:C) and viral haemorrhagic septicaemia virus (VHSV) IVb were used to study possible induction of EAPP transcripts (b2m, mhIa, and tapasin). The walleye cells were exquisitely sensitive to poly (I:C), losing adherence and viability at concentrations greater than 100 ng/mL, particularly at suboptimal temperatures. VHSV IVb viral particles were produced from infected WE-skin11f cells at 20 °C, 14 °C, and 4 °C but with much lower production at 4 °C. Under conditions where their impact on the viability of WE-skin11f cultures was slight, poly (I:C) and VHSV IVb were shown to induce b2m, mhIa, and tapasin transcript°s at 26 °C and 20 °C respectively. However, at 4 °C, the up-regulation of EAPP transcript levels was either delayed or completely impaired when compared to the 26 °C and 20 °C control temperatures of the respective experiments. These in vitro results suggest that suboptimal temperatures may be capable of modulating the regulation of the EAPP in walleye cells during viral infection.