Traditional transfusions using donor blood are life-saving and routine treatments. Especially rich countries have effective blood donor corps where the collected blood is both in abundance, and safe to use. However, blood transfusions in general are associated with several risks, including but not limited to; infectious diseases, insufficient screening, donor incompatibility, and strict storage requirements. These issues call for a donor-independent blood supply, either for the production of fully synthetic whole blood, or as a supplement for use during emergencies.The oxygen-carrying molecule of blood is called haemoglobin (Hb); a tetrameric metalloprotein situated on the red blood cells. Hb can be subdivided into heme; a prosthetic group containing ferrous iron, and globin chains. The model organism and industrial workhorse, Saccharomyces cerevisiae is a potential candidate for the production of recombinant human haemoglobin due to its native production of heme and well-understood metabolism.Our engineering philosophy focuses on upregulating, and de-repressing of heme metabolism, recombinant production of human haemoglobin, better understanding of iron regulation, and growth media optimization through minimal engineering using native genes, promotors, and terminators. The target of the overall project is to reach 25% active rHb of total cell protein. Currently, our best candidates for a production strain are producing 15x total heme compared to the wildtype, and 10.67±0.67% active human haemoglobin of the total cell protein, respectively. Free heme as well as 22.52±1.09nM/mgCell accumulated intracellular iron allow room for improvement in rHb titers, making it realistic to reach 25% active rHb at lab-scale within years.With the ongoing task of further genetic engineering and media optimization we do believe that recombinant human haemoglobin can serve as artificial oxygen carriers in humans in the future to allow for a safer and more readily available treatment for anemia
