Blood vessels contribute to their own growth and oxygen delivery to tissues and tumors (w/ Video)

Sep 14, 2009

Researchers at the University of North Carolina at Chapel Hill School of Medicine and the College of Arts & Sciences have identified a new biological process that spurs the growth of new blood vessels.

Vascular networks form and expand by "sprouting," similar to the way trees grow new branches. The process allows fresh oxygen and nutrients to be delivered to tissues, whether in a developing embryo or a cancerous tumor. Up until now, scientists thought that the molecular signals to form new sprouts came from outside the vessel. But new research from UNC has shown that signals can also come from within the blood vessel, pushing new blood vessel sprouts outward.

The findings, published in the Sept. 15 issue of the journal Developmental Cell, could give important insights into the formation of the vasculature needed to feed new tumors.

This video is not supported by your browser at this time.
Victoria Bautch, Ph.D., discusses findings, published in the Sept. 15 issue of the journal Developmental Cell, that could give important insights into the formation of the vasculature needed to feed new tumors. Credit: Video produced by Courtney Potter for the UNC Medical Center News Office.

In experiments using mouse embryonic stem cells and mouse retinas, the researchers found that defects in a protein called Flt-1 lead to abnormal sprouts and poor vessel networks. Other research recently showed that levels of Flt-1 protein are particularly low in the dilated and leaky blood vessels that supply tumors with oxygen.

"The blood vessels themselves seem to participate in the process guiding the formation of the vascular network," said senior study author Victoria L. Bautch, Ph.D., professor of biology at UNC. "They do not just passively sit there getting acted upon by signals coming from the outside in. Rather, they produce internal cues that interact with external cues to grow."

The growth of new blood vessels can be stimulated by cascades of events within the cell - known as pathways - the most notable of which centers around the three proteins Flt-1, Flk-1 and VEGF. Scientists have known for years that Flk-1 is a positive regulator that responds to VEGF by pulling the emerging sprout outward from its parent blood vessel.

The role of its sister protein Flt-1, however, was not clearly understood. Bautch and colleagues hypothesized that Flt-1 is a negative regulator -- soaking up VEGF molecules so they are not available to interact with Flk-1 and signal for new blood vessels.

The researchers mixed two different types of mouse embryonic stem cells - one batch with normal Flt-1 protein levels, the other with no Flt-1 protein. They found that the genetic makeup of the area at the base of the sprout - rather than at the sprout itself - determined whether the sprout behaved normally or abnormally.

"The cells on each side of sprout produce and send out the soluble form of the protein, blocking the sprout from forming anywhere but in one spot and in one direction," says Bautch. "So when the sprout first forms, instead of flopping back onto its parent vessel, it has a corridor to push it forward away from the parent."

Bautch, who is also a member of the Program in Molecular Biology and Biotechnology, the UNC McAllister Heart Institute and UNC Lineberger Comprehensive Cancer Center, notes that the more scientists understand about the sophistication and complexity of the mechanisms guiding the formation of blood vessel sprouts, the better equipped they will be to develop therapeutic interventions to produce or to halt new .

Source: University of North Carolina School of Medicine (news : web)

Explore further: Hearing quality restored with bionic ear technology used for gene therapy

add to favorites email to friend print save as pdf

Related Stories

Precancerous stem cells can form tumor blood vessels

Feb 20, 2008

Tumors require a blood supply to grow, but how they acquire their network of blood vessels is poorly understood. A new study here shows that tumor blood vessels can develop from precancerous stem cells, a recently discovered ...

Recommended for you

LED exposure is not harmful to human dermal fibroblasts

5 hours ago

There was a time when no one thought about light bulbs—one blew, you screwed another one in. Nowadays, it's more complicated, as energy efficiency concerns have given rise to a slew of options, including ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

E_L_Earnhardt
not rated yet Sep 17, 2009
'Explains angiogenesis? On scene neurons detect high temperature of rapidly mitosing cells and attempt to lower the heat levels?

More news stories

Amazon Prime wins streaming deal with HBO

Amazon scored a deal Wednesday to distribute old shows from premium cable TV channel HBO to its monthly Prime subscribers, landing a blow on rival Netflix in the streaming video battle.