Challenges in cellular agriculture: lessons from Pacific white shrimp, Litopenaeus vannamei

The overall goal of this research was to develop an embryonic stem cell (ESC) line from the Pacific white shrimp, Litopenaeus vannamei, to support production of cell-based cultivated seafood products towards meeting a growing global demand for sustainable seafood. It was hypothesized that characteristics of ESCs, such as high proliferation and pluripotency, would facilitate development of a continuous cell line that could be triggered to differentiate into a muscle cell phenotype. The targeted approach was based on collection of ESCs from fertilized shrimp eggs at the blastomere stage. Various media, supplements, growth factors, and plate coatings were tested to achieve growth of the shrimp ESCs. Although successful in early culture, this manuscript describes substantial challenges encountered as cultures grew over time. The cell cultures were initially dominated by shrimp as indicated by 18S rDNA community analysis, but after multiple passages, thraustochytrids, a common contaminant of invertebrate cell culture, became the predominant cell type. Presence of shrimp cells was confirmed through species-specific primers for the cytochrome C oxidase subunit 1 gene. Presence of thraustochytrids was also confirmed using species-specific primers, morphological features, growth properties, and acriflavine staining. Unsuccessful attempts to eradicate thraustochytrid contamination prevented shrimp cells from thriving. The future of shrimp cell culture depends on eliminating culture contaminants while encouraging growth of shrimp ESCs.