Wound Healing Blood Cells May Promote Spread of Cancer

Researchers from the University of North Carolina at Chapel Hill said Tuesday that the body’s normal wound-healing blood cells may play a part in setting the conditions for the proliferation of cancer cells. 

The scientists said fibrocytes, blood cells that originate from bone marrow, might explain how healthy cells become cancer habitats.

"Cancer cells do not enter healthy tissue easily. We know that," Dr. Hendrik van Deventer of the University of North Carolina at Chapel Hill, who led the research, said in a telephone interview with Reuters.

"There has been sort of this movement to look for the cells that help prepare distant tissue to accept metastasis," he said.

"We don’t know what that cell is," van Deventer said. 

However, he suggested the cell might be a fibrocyte.

"It has characteristics that make it a nice cancer metastasis-promoting cell," he said.

Van Deventer began looking to fibrocytes during his work with genetically engineered mice that lacked the CCR5 cell receptor, a cellular gateway that controls the migration of cells throughout the body. CCR5 is the same entry point used by the AIDS virus to penetrate immune cells.

The genetically altered mice had the skin cancer melanoma, and showed a tendency to get fewer metastatic tumors than normal mice with melanoma. Van Deventer and his colleagues injected the altered mice with various types of cells from normal mice in an attempt to induce more tumors.

"We tried that with a bunch of different cells. The one that worked is this fibrocyte," van Deventer said.

When the mice were injected with 60,000 of the cells, the rate of metastases nearly doubled.

"That’s a big effect for a relatively small number of cells," van Deventer said in a statement about the research.

Fibrocytes normally travel through the bloodstream to injured areas, where they produce changes that help heal wounds. But Van Deventer believes these changes may also promote cancer growth.

In his research, he observed that mice injected with fibrocytes began producing matrix metallopeptidase 9, or MMP-9, an enzyme that is known to promote cancer. And although not proven, the research at least suggests a likely candidate, van Deventer said.

If fibrocytes are indeed involved, van Deventer said potential treatments already exist, such as drugs that block the MMP-9 enzyme.

"The problem is the side effects were awful. They have been abandoned," he said.

Since the MMP enzyme works together with CCR5, van Deventer believes a drug that blocks both could be developed, allowing doctors to reduce the dosage of the MMP-9 blocker.

"The combination of the drugs could be used at lower doses and have the same effect, and you wouldn’t have as many side effects," he said.

The study was published in the American Journal of Pathology. An abstract can be viewed here.