Tissue engineers are finding ways to grow living organs and tissues from cells, with the aim of replacing diseased and damaged counterparts in the body. Scientists have successfully grown artificial muscles, livers, kidneys, skin and other tissues. But there's been no reliable way to engineer precisely patterned networks of blood vessels, some of which can be finer than a human hair.
Without a vascular network to deliver nutrients, any artificial tissues, no matter how lifelike, can't function. Now MIT engineers have found they can engineer and control the growth of blood vessels by mechanically stretching them.
The team has built a human "blood vessel on a chip," composed of a central artery made from human endothelial cells, that is embedded in a gel that also contains a small magnet. The researchers studied how the main artery responded as they jostled the gel back and forth using an external magnet to move the magnet embedded within the gel.
They found that the simple mechanical action of repeatedly jostling the artery stimulated it to sprout other, smaller capillaries. By changing the direction in which the artery is jostled or stretched, the researchers could redirect the growing new vessels. Stretching the artery by varying degrees influenced how many new vessels sprouted.
Their results, published in the Proceedings of the National Academy of Sciences, offer scientists a new way to engineer artificial blood vessels and program the patterns in which they grow. The study's MIT co-authors include Sina Kheiri, Jessica Shah, Shashaank Venkatesh and Roger Kamm, along with Peiyuan Chai and Ryan Flynn at Harvard University.
"Healthy tissues depend on organized blood vessel networks, but state-of-the-art protocols don't make it possible to fabricate such networks within engineered tissues," says Ritu Raman, associate professor of mechanical engineering at MIT and the study's co-lead author. "The ability to program blood vessel growth with physical cues may enable reproducible and scalable fabrication of engineered tissues that can be implanted in the body to restore function after debilitating disease or injury."
Source: Phys.org
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