Running along side your blood vessels are thousands of tiny capillaries that collect your body’s trash from blood and tissue, and carry it away.
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This system of vessels called the lymphatic system is an integral part of the body’s immune system, which is why researchers are now looking at the lymphatic system’s role in cancer.
Dr. Ricardo Saban, a researcher at the University of Oklahoma Health Sciences Center and a member of the OU Cancer Institute, studies bladder inflammation, including bladder cancer.
Thanks to a recent discovery, Saban also is one of few researchers looking at the lymphatic-cancer connection.
“We have 30 years of research in blood vessels. We don’t have the same thing for lymphatics,” Saban said.
Scientists hope research will lead to new medicines to stop cancer growth and effectively treat the disease.
Saban stumbled onto the lymphatic problem while studying a mouse model sent from France. He noticed on the image of the mouse’s bladder a series of blue dots that formed a network he hadn’t seen before.
After other cancer specialists were stumped by the structure, he sent a message to scientists at other facilities worldwide.
On the other end of one message was Dr. David Jackson from Oxford University, a leader in the field of lymphatics. Jackson explained he had found the same structure by creating an antibody that re- vealed the system under the microscope.
Saban put the two together and realized what he had was a mouse model that showed the location of the lymphatic system. It was a new way to track lymphatic vessels in diseased organs, which is an invaluable tool for researchers looking for answers about how the lymphatic system interacts with cancer and helps it spread.
“It was just a happy accident,” Saban said.
“I saw this beautiful thing and it took me one year to figure out what it was.”
Scientists already knew that blood vessels form on a cancerous tumor to feed it and help it grow. If the tumor’s food supply is cut off, it stops growing.
Since lymphatic vessels are always near blood vessels, Saban figured he could use his new method to spot the lymphatic system near a tumor and determine what happens when it forms.
He found the bladder of a normal mouse covered about 25 percent with a lymphatic system. A cancerous mouse bladder was 45 percent.
The next step was to determine whether it was the cancer or the inflammation associated with cancer that caused more lymphatic vessels to grow.
He looked at a normal mouse given a bladder cancer drug that causes significant inflammation. New vessels grew, even though the mouse was cancer-free, suggesting inflammation was the cause, not cancer.
Saban is concentrating on a growth factor that causes lymphatic vessels to grow. The growth factor is brought into the tissue by inflammation.
Surprisingly, further study showed no lymphatic vessels growing in the tumor, just a marked increase around the tumor and in the rest of the organ.
Without this direct connection between the tumor and the lymphatic system, researchers must find how cancer cells get into the lymphatic vessels to spread.
Saban also is studying the overall function of the lymphatic system by using a special molecule to watch in a mouse how the lymphatic system picks up “trash” and delivers it to the lymph nodes.
So far, he has learned the system works rapidly with a squeezing action that pushes lymph fluid from tiny vessels deep in the tissue to larger collecting vessels on the surface and eventually to the lymph nodes.
“What I am trying to discover is I want to see how lymphatics grow, how to stop the growth and how they function,” he said.
He hopes to devise a way to keep cancer cells from using the system to spread, which can occur in nearly all types of cancer.
Saban is presenting his work in September at an international conference in Switzerland.
