Manipulation of signalling to promote reprogramming of pig cells into a naïve pluripotent state.

Abstract

For years and years, attempts have been made to isolate porcine embryonic stem cells (ESCs). Although porcine ESCs would be invaluable, – since the pig represents an attractive large animal model that could be used in human medicine , derivation of authentic porcine ESCs has proven to be elusive. Induced pluripotent stem cells (iPSCs) provide a unique resource of pluripotent cells and are a useful alternative to embryo-derived cells. The Burdon lab has generated pig iPSCs by transducing foetal fibroblasts with retroviruses expressing c-Myc, Klf4, Sox2 and Oct4. The resulting lines expressed core pluripotency factors and embryoid bodies (EBs) could be formed. Interestingly, all of the pig cell lines the Burdon lab has screened retained expression of the four retroviral transgenes, which consequently indicates that these cells are not fully reprogrammed. Lack of transgene silencing is thought to be indicative of incomplete reprogramming. It has previously been reported that culturing mouse and human stem cells at a low oxygen concentration instead of the atmospheric 21% oxygen concentration, may also aid reprogramming. The aim of this project is to investigate whether manipulation of signalling by modifying the culture conditions will enhance reprogramming of porcine iPSCs as well. The major finding from this project is a consistent difference in the growth rate between the two Oշ concentrations. Additional differences between 5% and 21% Oշ – which were likely caused by the Oշ concentrations – were exclusively found in cell line A1 and included a difference in colony morphology, AP-staining and the appearance of the plated EBs.