Researchers are prepared to begin the first human trials of lab-produced blood within two years.

This man-made red blood  cells could help treat complex blood conditions, and are created using stem cells from both adult and umbilical cord blood, the University of Bristol reported.

"This announcement is an important stage in progressing this pioneering research.  There are a small number of patients with complex blood disorders for who NHSBT sometimes finds it difficult to find matched blood. We hope to enable NHSBT to provide these patients with an alternative compatible blood product in the future," said Ashley Toye, from Bristol's School of Biochemistry.

These blood cells can only be produced in small batches at this time, but the researchers are hopeful they will be able to scale it up in the future. If this feat is achieved, the method could be used to treat diseases such as sickle cell anaemia and thalassemia. Patients who suffer from these diseases often require blood transfusions, but struggle to find donors.

The clinical trial of the manufactured red blood cells will compare the survival of these cells to those provided by a blood donor. It will involve a group of 20 participants who will each receive a small volume transfusion of the lab-produced blood.

"Scientists across the globe have been investigating for a number of years how to manufacture red blood cells to offer an alternative to donated blood to treat patients. We are confident that by 2017 our team will be ready to carry out the first early phase clinical trials in human volunteers," said Nick Watkins, NHS Blood and Transplant Assistant Director of Research and Development. "These trials will compare manufactured cells with donated blood. The intention is not to replace blood donation but provide specialist treatment for specific patient groups."

The research will be conducted in part by NHS Blood and Transplant.