Induced pluripotency is the conversion of a differentiated cell to an undifferentiated state, such as a pluripotent stem cell, which can give rise to every other cell type in the body. Although the most sought-after aspect of the induced Pluripotent Stem Cell (iPSC) research, regenerative medicine, is not so relevant on fish, many other applications of iPSC, like disease modelling, genetic engineering, and drug and toxicity testing still are!
Furthermore, there is a lot of ongoing research to improve traits of farmed fish within genetic engineering, where the researchers make a tailored change in the gene, hoping that this will lead to a beneficial change in a trait (phenotype). Unfortunately, with the traditional methods, it takes a long time before such changes are observable. The required time for this type of research can be shortened significantly using iPSCs and their differentiation into a wide range of tissue-specific cell types, including germ cells. However, there is a lack of commercially available cell lines and information on the early development of the Atlantic Salmon compared to other model organisms, which makes this research even more challenging. Starting with a better understanding of the molecular mechanisms in the embryonic development of the Atlantic Salmon, we are working towards developing methods of iPSC culture for Atlantic Salmon.
As an initial step towards this goal, we have established a skin-fibroblast cell line and a Sertoli cell-like cell line isolated from the testis of Atlantic Salmon. Our ongoing characterization confirms the morphological and transcriptional stability of our cultured fibroblasts over 40 passages. Both cell lines are susceptible to infection by Infectious pancreatic necrosis virus (IPNV) and Infectious salmon anaemia (ISA) virus, pathogens of high importance for the aquaculture. Our cell lines are amenable to cryopreservation thus can be preserved for a long time. More importantly, both are permissible to transduction of Plasmid DNA and mRNA, providing us with the opportunity of genetic engineering.
Figure 1: Fibroblast(left) and Sertoli cells(right) stained with α-smooth muscle actin and DAPI.
Figure 2: Skin fibroblast (left to right) Passage 3, 15, 39.
Figure 3: Sertoli cells(left) and fibroblast(right), CMV-GFP Plasmid transfection.
Our next step is to analyze our new early embryonic developmental stage transcriptomic data to identify native de-differentiation factors with the ultimate goal of expressing them to establish iPSC.
PhD candidate Prabin Sharma Humagain is undertaking this pioneering work supervised by CIGENE Researcher Victor Boyartchuk while AquaGen Senior Scientist Jacob Torgersen provides invaluable guidance.
From left to right: Prabin Humagain, Victor Boyartchuk and Jacob Torgersen.