Overview of Red Blood Cell (RBC) Role in Oxygen Generation

Biree Andemariam, MD: Hello, and welcome to this HCPLive® Peer Exchange titled “Understanding Red Blood Cell Health and the Management of Sickle Cell Disease.” I’m Dr Biree Andemariam, a professor of medicine and the American Red Cross endowed chair in transfusion medicine at the University of Connecticut Health [in Farmington, Connecticut]. I’m also the director of the New England Sickle Cell Institute. I have the pleasure of having several colleagues joining me in this discussion. Can you introduce yourself, Dr Nirmish Shah?

Nirmish Shah, MD: Thanks for the invitation. I’m the director of the sickle cell transition program at Duke University [School of Medicine]. I’m a life span hematologist. I care for kids and adults in my clinics, and I’m looking forward to the conversation.

Biree Andemariam, MD: Thank you, Dr Shah. Next, we have Dr Elna Saah.

Elna Saah, MD: Hello, my name is Dr Elna Saah, and I’m a pediatric hematologist. I direct the transition program, from pediatrics to adults, at Children’s Healthcare of Atlanta. I’m also an assistant professor of pediatrics at the at Emory University School of Medicine in Atlanta, Georgia.

Biree Andemariam, MD: Thank you. Welcome, Dr Saah. Last but not least, Dr Matthew Heeney.

Matthew M. Heeney, MD: Thanks, Biree. My name is Dr Matthew Heeney. I’m a pediatric hematologist also and the associate chief of hematology at Boston Children’s Hospital [in Boston, Massachusetts], where I direct the sickle cell program. And I’m the Orah Platt chair for in pediatric hematology.

Biree Andemariam, MD: As you’ll see, we have a breadth of knowledge across the life span of individuals affected by sickle cell disease. Our discussion will focus on providing an overview of red blood cells, and the factors that contribute to their health. We’ll also take a deep dive into the management of sickle cell disease. Welcome, everyone. Let’s get started.

The first thing we’re going to do is focus on red blood cells. As hematologists, we all know that our colleagues often think of red cells as being this inert bystander. Everything it needs to do is propelled by the heart and the lungs, circulates for 120 days, does its job, and then goes away. But as hematologists, we know that the red blood cells are a lot more complex than that. First, I’d like to focus our discussion on what a healthy red blood cell is. Elna, could you provide us an overview of the role that red blood cells play in oxygen transport and the generation of energy?

Elna Saah, MD: Absolutely. You started that very well. All hematologists get excited about red blood cells. We can talk about this for the whole session. First, the way they were designed is a very intelligent design. Red blood cells structurally have a membrane and have hemoglobin inside the content. The structure of it gives a biconcave disk, meaning it’s a little denser on the outside and a little lighter inside, giving it that biconcave disk structure. That anatomical design helps it conduct and perform all its functions very elegantly. The main function of the red blood cell is to transport oxygen from the lungs, dump them to the tissues, and release them at the appropriate time. Then they carry carbon dioxide from the tissues back into circulation to the lungs. On the flip side, the red blood cells don’t have many organelles, mitochondria, and other things. They’re supposed to be self-sustaining in a very energy-efficient manner. They cannot rely on generation of energy by the Krebs cycle, like other organelles, cardiac muscles, and myocytes. They couldn’t rely on the Krebs cycle, so they have their own pathway, which generates ATP [adenosine triphosphate], and the Embden-Meyerhof-Parnas pathway, which is very energy efficient.

Back to the structure and function of why there’s a biconcave disk. The micro capillaries that the red blood cells have to squeeze into could be as small as 3 µm, which is very small. If the red blood cells are much denser or not flexible, and the protein membranes don’t allow it to slowly squish, deform, and emerge without being destroyed, they won’t be efficient in performing that function. Also, that biconcave disk allows for a much larger surface area for it to carry the oxygen and for release of gases to across a much larger surface area. Otherwise, we would have needed much larger red cells, which won’t be efficient in physiologically maneuvering through the microcirculation. That’s what makes red blood cells fascinating.

Transcript edited for clarity