Featured Research

from universities, journals, and other organizations

How blood vessels regroup after stroke

Date:
February 11, 2013
Source:
Rice University
Summary:
Scientists have simulated "robot" cells to study the development of the microvascular systems in the brain. The goal is to find a way to direct the development of vessels that feed oxygen-starved cells in stroke and neurodegenerative disease patients.

Growth factors released by oxygen-starved cells prompt nearby endothelial cells, which line blood vessels, to grow into new networks. Researchers at Rice University are working to understand how to direct the process in the brains of stroke and disease patients.
Credit: Qutub Lab/Rice University

By thinking of cells as programmable robots, researchers at Rice University hope to someday direct how they grow into the tiny blood vessels that feed the brain and help people regain functions lost to stroke and disease.

Related Articles


Rice bioengineer Amina Qutub and her colleagues simulate patterns of microvasculature cell growth and compare the results with real networks grown in their lab. Eventually, they want to develop the ability to control the way these networks develop.

The results of a long study are the focus of a new paper in the Journal of Theoretical Biology.

"We want to be able to design particular capillary structures," said Qutub, an assistant professor of bioengineering based at Rice's BioScience Research Collaborative. "In our computer model, the cells are miniature adaptive robots that respond to each other, respond to their environment and pattern into unique structures that parallel what we see in the lab."

When brain cells are deprived of oxygen -- a condition called hypoxia that can lead to strokes -- they pump out growth factor proteins that signal endothelial cells. Those cells, which line the interior of blood vessels, are prompted to branch off as capillaries in a process called angiogenesis to bring oxygen to starved neurons.

How these new vessels form networks and the shapes they take are of great interest to bioengineers who want to improve blood flow to parts of the brain by regenerating the microvasculature.

"The problem, especially as we age, is that we become less able to grow these blood vessels," Qutub said. "At the same time, we're at higher risk for strokes and neurodegenerative diseases. If we can understand how to guide the vessel structures and help them self-repair, we are a step closer to aiding treatment."

First, they need to understand how individual cells respond to stimuli. To model the process in a computer requires rules, Qutub said. In these simulations, each cell is a "state machine," a unit that goes from one "state" to the next in time based on input. In the case of these endothelial cells, the input comes from vascular endothelial growth factor and/or brain-derived neurotrophic factor, proteins that encourage angiogenesis.

"There's a memory in each of these cells that helps define how they emerge into these very elaborate vasculature structures," she said. The cells that quickly differentiate into tip and stalk cells follow particular rules to advance, grow, divide and branch, depending on input from growth factors and from neighboring cells that can dictate how far and how fast they develop.

For instance, she said, in a chain of endothelial cells, a tip cell at its maximum length can only continue to migrate if the stalk cell immediately behind grows and pushes it forward. Similarly, the team set rules for branching and changes in direction, as well as an "idle" state, all based on observation of real vessel growth.

The researchers modeled a set of endothelial cells growing from a sphere and exposed them to simulated growth factors. They let them grow for what, in real life, would be a period of 24 hours, but in the computer took fractions of a second. They ran tens of thousands of simulations to see how the cells would migrate, proliferate and branch under various conditions.

The next step was to figure out which of the computer simulations matched actual behavior. Qutub's lab cultured spheres of human umbilical vein endothelial cells in collagen scaffolds, exposed them to growth factors and took microscope images as they developed networks over several days.

They compared these images with the simulations. The closest matches -- of which there are only a few amid thousands of simulations -- became the basis for a refined set of rules.

"We know how cells are connected as a function of the growth factors, and there are very distinct patterns to the way these networks are organized," Qutub said. "So when we compare the simulations with the assays, we find parallels that let us classify what we see in the real networks. This gives us a paradigm where we can start to think of actually programming real cells with chemical signaling.

"It opens up a lot of doors," she said. "Now we can think about changing things in the cells or giving them drugs that target pathways and growth factors to induce a particular vasculature structure."

Byron Long, a postdoctoral research associate in the Qutub Group, is lead author of the paper. Co-authors are Rice undergraduates Rahul Rekhi and Jiwon Jung and Amada Abrego, an undergraduate student at the Monterrey Institute of Technology, Mexico, who took part in the Rice Summer Undergraduate Research Program in Biosciences and Bioengineering, funded by the Howard Hughes Medical Institute, and has a complimentary appointment to the Qutub Lab.

The research was funded in part by a National Academies Keck Future Initiatives grant, a Hamill Innovation Award and a National Science Foundation CAREER award.


Story Source:

The above story is based on materials provided by Rice University. The original article was written by Mike Williams. Note: Materials may be edited for content and length.


Journal Reference:

  1. Byron L. Long, Rahul Rekhi, Amada Abrego, Jiwon Jung, Amina A. Qutub. Cells as state machines: Cell behavior patterns arise during capillary formation as a function of BDNF and VEGF. Journal of Theoretical Biology, 2012; DOI: 10.1016/j.jtbi.2012.11.030

Cite This Page:

Rice University. "How blood vessels regroup after stroke." ScienceDaily. ScienceDaily, 11 February 2013. <www.sciencedaily.com/releases/2013/02/130211102310.htm>.
Rice University. (2013, February 11). How blood vessels regroup after stroke. ScienceDaily. Retrieved December 20, 2014 from www.sciencedaily.com/releases/2013/02/130211102310.htm
Rice University. "How blood vessels regroup after stroke." ScienceDaily. www.sciencedaily.com/releases/2013/02/130211102310.htm (accessed December 20, 2014).

Share This


More From ScienceDaily



More Health & Medicine News

Saturday, December 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

The Best Tips to Curb Holiday Carbs

The Best Tips to Curb Holiday Carbs

Buzz60 (Dec. 19, 2014) It's hard to resist those delicious but fattening carbs we all crave during the winter months, but there are some ways to stay satisfied without consuming the extra calories. Vanessa Freeman (@VanessaFreeTV) has the details. Video provided by Buzz60
Powered by NewsLook.com
Sierra Leone Bikers Spread the Message to Fight Ebola

Sierra Leone Bikers Spread the Message to Fight Ebola

AFP (Dec. 19, 2014) More than 100 motorcyclists hit the road to spread awareness messages about Ebola. Nearly 7,000 people have now died from the virus, almost all of them in west Africa, according to the World Health Organization. Video provided by AFP
Powered by NewsLook.com
Researchers Test Colombian Village With High Alzheimer's Rates

Researchers Test Colombian Village With High Alzheimer's Rates

AFP (Dec. 19, 2014) In Yarumal, a village in N. Colombia, Alzheimer's has ravaged a disproportionately large number of families. A genetic "curse" that may pave the way for research on how to treat the disease that claims a new victim every four seconds. Duration: 02:42 Video provided by AFP
Powered by NewsLook.com
The Best Protein-Filled Foods to Energize You for the New Year

The Best Protein-Filled Foods to Energize You for the New Year

Buzz60 (Dec. 19, 2014) The new year is coming and nothing will energize you more for 2015 than protein-filled foods. Fitness and nutrition expert John Basedow (@JohnBasedow) gives his favorite high protein foods that will help you build muscle, lose fat and have endless energy. Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins