Angiogenesis

What is angiogenesis?

Angiogenesis is the process that forms new capillaries out of existing blood vessels in your body. Angiogenesis helps your body heal from wounds and perform other vital functions. This process begins before you’re born and continues throughout your life.

Capillaries are tiny blood vessels that do important work in your body. They deliver blood, nutrients and oxygen to your organs and tissues. If some tissues aren’t receiving enough oxygen (hypoxia), cells in the affected area send out chemical signals that cause angiogenesis to begin. It’s like an SOS call for help. In response, cells that line your blood vessels (called endothelial cells) arrange themselves in ways that allow new capillaries to develop. There are two ways this process can occur.

Sprouting and intussusceptive angiogenesis

There are two main types of angiogenesis:

• Sprouting angiogenesis: This is when sprouts (new growths) of endothelial cells emerge from your blood vessel. They grow toward a chemical stimulus such as vascular endothelial growth factor (VEGF). These sprouts turn into blood vessels that can reach areas of your tissue that have no other blood supply.
• Splitting (intussusceptive or nonsprouting angiogenesis): This is when a capillary forms without sprouting. Rather, one blood vessel splits into two to form the new capillary. Instead of sprouting outward, endothelial cells move into the blood vessel’s opening (lumen) and form pillars. These pillars lead to the growth of new capillary branches.

Angiogenesis vs. vasculogenesis

Angiogenesis and vasculogenesis are both medical terms that refer to the formation of new blood vessels inside of your body. What makes them different is the type of cells that give rise to the new blood vessels.

In vasculogenesis, new blood vessels form out of a type of cell called an angioblast. Angioblasts are cells that haven’t fully matured into endothelial cells.

In angiogenesis, new capillaries form out of blood vessels that already exist in your body. These blood vessels are lined with endothelial cells. The endothelial cells move and grow in number to allow the new capillaries to form.

Is angiogenesis good or bad?

Angiogenesis is a bodily process that can be either good or bad. It depends on what the new blood vessels are feeding. In a healthy state, your body sometimes needs new capillaries to form so your tissues and organs can receive enough oxygen. That’s when angiogenesis kicks into gear (thanks to your body’s dynamic chemical signaling process). So, normally, angiogenesis is vital to keeping you alive and healthy.

But angiogenesis can become harmful if it supports the growth and spread of tumors inside of your body. This is what happens if you have cancer. So, it’s helpful to take a closer look at how angiogenesis functions in a person who has cancer.

The function of angiogenesis in cancer

Cancer happens when cells in your body malfunction and start to reproduce uncontrollably. Those faulty cells form solid tumors that require a constant supply of blood in order to grow and spread. Like your body’s healthy tissues, tumors also need to be “fed” through blood vessels to sustain themselves. To receive the blood they need, tumors (like other cells in your body) can send out chemical signals that cause angiogenesis to begin.

In this case, angiogenesis is harmful to you. It’s creating new blood vessels that feed the tumor with oxygen and nutrients. The tumor then grows bigger, and cancer cells can spread elsewhere in your body. This is why you may hear that angiogenesis relates to cancer. It’s a process that tumors can use for purposes you don’t want or intend.

Angiogenesis inhibitors

Researchers know that tumors can send signals that trigger angiogenesis to begin. Current research explores ways to inhibit (block) blood supply to tumors. One such way is through medications called angiogenesis inhibitors.

These medications interrupt the process of new blood vessel formation that would feed tumors. They do this in many ways. For example, they can interfere with the chemical signaling process that supports angiogenesis. Like static that garbles a phone call, these drugs block communication between cells that would lead to angiogenesis.

The U.S. Food and Drug Administration (FDA) has approved a long list of angiogenesis inhibitors for use in cancer treatment. Researchers continue to look for ways to make these drugs more effective in helping people who need them. Ask your healthcare provider if you have questions about angiogenesis inhibitors or their role in cancer treatment.

A note from Cleveland Clinic

Angiogenesis is a process that takes place inside of your body on a microscopic level. It’s easy to forget that such processes happen because you can’t see them going on. But learning about the inner workings of your body can help you understand diagnoses, treatments and other aspects of your care. Talk with your healthcare provider to learn more about angiogenesis and how it affects your body.