London:Researchers have successfully identified the four keys that unlock the genetic code of skin cells and reprogramme them to start producing red blood cells instead. The findings could lead to personalised red blood cells for those in need of blood transfusion, for instance, people suffering from chronic anemia -- a condition in which the patient has an insufficient amount of red blood cells. "This is the first time anyone has ever succeeded in transforming skin cells into red blood cells, which is incredibly exciting," said the lead author of the study Sandra Capellera from Lund University in Sweden. "We have performed this experiment on mice, and the preliminary results indicate that it is also possible to reprogramme skin cells from humans into red blood cells,” Johan Flygare, who is also from Lund University, noted. The study was published in the journal Cell Reports. Every individual has a unique genetic code, which is a complete instruction manual describing exactly how all the cells in the body are formed. This instruction manual is stored in the form of a specific DNA sequence in the cell nucleus. All human cells -- brain, muscle, fat, bone and skin cells -- have the exact same code. The thing that distinguishes the cells is which chapter of the manual the cells are able to read. The research team wanted to find out how the cells open the chapter that contains instructions on how to produce red blood cells. Here is how the researchers got the skin cells to open the chapter describing red blood cells. With the help of a retrovirus, they introduced different combinations of over 60 genes into the skin cells' genome, until one day they had successfully converted the skin cells into red blood cells. The study showed that out of 20,000 genes, only four are necessary to reprogramme skin cells to start producing red blood cells. Also, all four are necessary in order for it to work.