Feb.20, 2014

3D bioprinting, the process of creating human tissues through 3D printing, is in the early stages of development. But bioprinting will advance far faster than general understanding and acceptance of the ramifications of this technology, according to analyst firm Gartner.

Scientists at the Harvard Wyss Institute for Biologically Inspired Engineering announced Wednesday that they have used multiple print heads and customized "inks" to create complex living tissue constructs, complete with tiny blood vessels.

The method represents an early but important step toward creating human tissue constructs realistic enough to test drug safety and effectiveness and building fully functional replacements for injured or diseased tissue.

"Tissue engineers have been waiting for a method like this," said Don Ingber, M.D., Ph.D., Wyss Institute Founding Toward Printed Living Tissues: Harvard team 3D prints blood vessel-lined tissue Director. "The ability to form functional vascular networks in 3D tissues before they are implanted not only enables thicker tissues to be formed, it also raises the possibility of surgically connecting these networks to the natural vasculature to promote immediate perfusion of the implanted tissue, which should greatly increase their engraftment and survival".

Tissue engineers have tried for years to print human tissue, but they have been limited to thin slices of tissue about a third as thick as a dime. When scientists try to print thicker layers of tissue, cells on the interior starve for oxygen and nutrients, and have no good way of removing carbon dioxide and other waste. So they suffocate and die.

Nature gets around this problem by permeating tissue with a network of tiny, thin-walled blood vessels that nourish the tissue and remove waste, so researchers set out to mimic this key function.

To print 3D tissue constructs with a predefined pattern, the researchers developed several "bio-inks" - tissue-friendly inks containing extracellular matrix and living cells, the key ingredients of living tissues.

Video above: Building intricate structures. The team first designed a custom printer that can precisely co-print multiple materials in 3D to create intricate heterogeneous patterns.

Video above: Building in blood vessels. Then they addressed a big challenge in tissue engineering: embedding 3D vascular networks.

To create blood vessels, they developed a third ink with an unusual property: it melts as it is cools, rather than as it warms. The team first printed an interconnected network of filaments, then melt them by chilling the material and suction the liquid out to create a network of hollow tubes, or vessels. The scientists then injected human endothelial cells into the vascular network, those cells regrew the blood-vessel lining.

Video above: Building with bio-inks. Using their custom-built printer, the fugitive ink for the vasculature, and other biological inks containing extracellular matrix and human cells, the researchers printed a 3D tissue construct.

Keeping cells alive and growing in the tissue construct represents a "foundational step toward creating 3D living tissue," said Jennifer Lewis, Ph.D., senior author of the study. Along with lead author David Kolesky, a graduate student in SEAS and the Wyss Institute, her team reported the results February 18 in the journal Advanced Materials.

The result

Scientists are now focused on creating functional 3D tissues that are realistic enough to screen drugs for safety and effectiveness. They could also use the printed tissue constructs to shed light on activities of living tissue that require complex architecture, such as wound healing, blood vessel growth, or tumor development.

Posted in 3D Printing Technology



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alvaro wrote at 2/21/2014 11:34:10 AM:

Amazing! i believe that in a near future they will print limbs to replace the missed ones.

Matt wrote at 2/20/2014 5:30:49 PM:

This is awesome. I have never seen someone print cells and blood vessels together.

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