Tranylcypromine, or TCP, was found to able to trick the precursors of red blood cells into making a different form or hemoglobin, usually only found at the fetal stage, offering hope to people suffering from the disease.

According to the World Health Organization:

"Sickle Cell Disease is characterized by a modification in the shape of the red blood cell from a smooth, donut-shape into a crescent or half moon shape. The misshapen cells lack plasticity and can block small blood vessels, impairing blood flow. This condition leads to shortened red blood cell survival, and subsequent anaemia, often called sickle-cell anaemia. Poor blood oxygen levels and blood vessel blockages in people with sickle-cell disease can lead to chronic acute pain syndromes, severe bacterial infections, and necrosis (tissue death)."

Sickle Cell Disease is caused by a mutation in a certain gene for hemoglobin, the protein that is abundant in red blood cells that carries oxygen throughout one's body.  People with one copy of the mutated gene have no health effects, while those with both copies of the mutated gene have lie long health issues.

The study, published in Nature Genetics, tested the drug on human and mouse cells outside of the body and found that the drug stops a mechanism in place that blocks production of fetal hemoglobin, the protein LSD1. When this block is taken out, the cells start producing normal fetal hemoglobin proteins and not the defective adult hemoglobin genes (there is a switch of which gene is used during the transition from a baby residing in the uterus and surviving breathing air outside the womb).

"This is the first time that fetal hemoglobin synthesis was re-activated both in human blood cells and in mice to such a high level using a drug, and it demonstrates that once you understand the basic biological mechanism underlying a disease, you can develop drugs to treat it," says Doug Engel, Ph.D., senior author of the study. "This grew out of an effort to discover the details of how hemoglobin is made during development, not with an immediate focus on curing sickle cell anemia, but just toward understanding it."

Current treatment tries to boost fetal hemoglobin production using hydroxyurea, and other forms of treatment such as blood transfusions and bone marrow transplants are expensive and risky.  

Because the drug was used in the past, it has already been approved by the government and is no longer under patent, so it would be cheap to distribute. 

The research paper was published in the journal Nature Genetics can be found here