Right now, trillions of donut-shaped red blood cells are whizzing through your arteries, ferrying oxygen from your lungs to the tips of your fingers and toes and everywhere in between. But if you’re one of the millions of people around the world who have sickle cell disease, this constant shuttle is constantly getting disrupted.
The moment the hemoglobin molecules inside a sickle cell patient’s red blood cells release their oxygen cargo, they start to stick to each other, adhering into long, twisting braids that stretch and distort the cells, deforming them into the eponymous “sickle” shape. When those red blood cells pass back through the lungs and pick up a new oxygen load, their hemoglobin molecules snap back into solitary suspension. This can happen up to four times every minute. And that repeated cycle makes the red blood cells hard and brittle, causing them to break apart and block blood vessels, resulting in painful crises, and if left untreated, death. A normal red blood cell can survive in circulation for up to four months. For patients with sickle cell disease, their cells might not last a week.