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. Last Updated: 07/27/2016

Umbilical Cord Provides New Breakthrough for Leukemia

SINGAPORE -- Singapore doctors have used blood from umbilical cords to replace cancerous bone marrow cells in leukemia patients without destroying existing cells in a new technique offering hopes of a cure.

Doctors at the Singapore General Hospital successfully transplanted cord blood from unrelated donors into two adult patients in the past three months by suppressing the patient's host cells.

Previously, the existing blood cells were killed to make way for the replacement cells.

"The cord blood will slowly grow and displace the host cells over a period of weeks and in some cases you may get a total replacement between 90 to 100 days," Dr. Patrick Tan, who headed the medical team, said Tuesday.

"If you really remove 100 percent then there's no more leukemia at all."

The new cells were believed to form an immune network that kept the cancer at bay, Tan said.

One patient received cord blood from two separate samples in what was believed to be a world's first and was expected to achieve complete replacement of his bone marrow cells soon, Tan said.

But patients would have to wait three years before they could be considered fully cured of leukemia.

Patients suffering from leukemia currently have to undergo chemotherapy, which often kills both cancerous and healthy cells, or find a suitable donor for a bone marrow transplant.

By suppressing the bone marrow host cells instead of killing them off via chemotherapy, patients have a much higher chance of survival as their own cells can still take over if the transplant fails as compared to conventional bone marrow or cord blood transplants, which kill existing cells to make way for the replacement, Tan said.

"The [cord blood] transplant may fail, but people don't die. There's a safety net. But if you do the myeloablative [removal of bone marrow] method, you're not providing that safety net: If the transplant fails, the patient dies," said Tan.

The use of umbilical cord blood also reduced the risk of the new graft cells attacking the host body, which is a major concern in bone marrow transplants, he said.

Tan and his team plan to try the new technique on more leukemia patients who fail to respond to chemotherapy.