A team of scientists have engineered auxotrophic cells that are dependent on an externally supplied compound to survive. In research presented today at the American Society of Gene & Cell Therapy Annual Meeting (29 April–May 2, Washington, DC, USA), researchers from Stanford University (CA, USA), Auxolytic Ltd (UK) and Rice University (TX, USA) developed cells with disruptions to a gene meaning that an external source of uridine was required for the cells to proliferate. This mechanism could act as a ‘kill switch’ to avoid abnormal differentiation, as in the case of tumorigenesis.
The authors commented in the abstract: “The ability to use an external compound to influence proliferation and survival of human cells and the possibility to deplete residual non-auxotrophic cells enable the development of this approach for a range of applications where a pure population of externally controllable cells is necessary.”
In the study, human cell lines, pluripotent cells and primary T cells were engineered to have disruptions in UMPS, a gene encoding a uridine 5'-monophosphate synthase protein which catalyzes the final two steps of the de novo pyrimidine biosynthetic pathway. Withdrawal of the external source of uridine, inhibited growth of the cells.
This mechanism was also tested in vivo in a xenograft model in immunodeficient mice. In the murine model, the uridine was administered via a prodrug, with withdrawal of the prodrug from the mouse diet also leading to inhibited cell growth. Off-target analysis found no detectable insertion–deletion mutation activity anywhere other than the on-target site.
“Genetically engineered auxotrophy provides an addition and alternative to current safety mechanisms for cell therapies that offers several potential advantages,” the authors concluded.
Source: Wiebking V, Patterson JO, Martin R et al. Can’t Live without “U”: Genetic Engineering of UMPS to Create Auxotrophy in Human Cells. Presented at: American Society of Gene & Cell Therapy Annual Meeting. Washington, DC, USA. 2019