3D printer makes organs for transplant

In January 2011, we reported on the rapid growth of 3D design technology in product development and online consumer 3D print services, and the growing adoption of 3D software in architecture, interior design and manufacturing, resulting in a strong demand for 3D printers to produce these prototypes.

As of lately, we have had some more exciting announcements from Anthony Atala, M.D., who is a professor and director at the Wake Forest Institute for Regenerative Medicine.

In the near future, patients who need a kidney or heart transplant may be able to get a new organ designed and manufactured just for them. This work is extremely important due to shortages in the organ-donor program. The number of patients needing organ transplants has doubled in the last 10 years. Soon, it may be possible to custom-print a new organ, layer by layer, using a 3D organ inkjet printer.

“Instead of using ink in the inkjet cartridge, we use cells,” says Dr. Anthony Atala. Yet, the possibility of transplanting such organs is still years away. But researchers have already used printers to build quarter-sized two-chamber hearts, Atala told CBC Radio’s Quirks & Quarks. They spontaneously start beating about four to six hours later.

“All the cells in your body are already pre-programmed,” Atala said. “There’s a genetic code within all your cells that drives them to do what they are supposed to do if you place them in the right environment.”

Researchers have already taken advantage of that programming to build and implant simpler organs like urethras and bladders.

They layer the appropriate types of cells from the patient’s own body on a dissolvable scaffold. After implantation, the cells mature inside the body, connecting to blood vessels and nerves.

In an interview with Quirks & Quarks host Bob McDonald, Atala describes the state of technology to engineer human organs and how it works. Those who might be interested to learn more can see this live interview with Atala on www.ted.com. Simply look for Atala on the search button.

How does this 3D Organ Printer Work?

These new printers have already been developed by a couple of companies, Organovo, a company in San Diego that specializes in regenerative medicine; and Invetech, an engineering and automation firm in Melbourne, Australia.

Organovo’s 3D bio-printer works in a similar way to some rapid-prototyping machines used in industry, of which you can find in my previous articles. Current 3D printers used in building prototype models deposit droplets of polymer which fuse together to form a structure. With each pass of the printing heads, the base on which the object is being made moves down a notch. In this way, little by little, the object takes shape. Voids in the structure and complex shapes are supported by printing a “scaffold” of water-soluble material. Once the object is complete, the scaffold is washed away.

Though printing organs is new, growing them from scratch on scaffolds has already been done successfully (see May 2010 issue of GAM). In 2006, Anthony Atala and his colleagues at the Wake Forest Institute for Regenerative Medicine in North Carolina made new bladders for seven patients. These are still working today in these patients.

The advantage of using a bio-printer is that it eliminates the need for a scaffold. The Organovo machine uses stem cells extracted from adult bone marrow and fat as the precursors. These cells can be coaxed into differentiating into many other types of cells by the application of appropriate growth factors. The cells are formed into droplets 100-500 microns in diameter and containing 10,000 – 30,000 cells each. The droplets retain their shape well and pass easily through the inkjet printing process.

A second printing head is used to deposit scaffolding—a sugar-based hydrogel. This does not interfere with the cells or stick to them. Once the printing is complete, the structure is left for a day or two, to allow the droplets to fuse together. For tubular structures, such as blood vessels, the hydrogel is printed in the center and around the outside of the ring of each cross-section before the cells are added. When the part has matured, the hydrogel is peeled away from the outside and pulled from the center like a piece of string.

Invetech has developed a laser-based calibration system to ensure that both print heads deposit their materials accurately, and a computer-graphics system allows cross-sections of body parts to be designed.

Some researchers think 3D organ printers like this may one day be capable of printing tissues and organs directly into the body. Indeed, Dr. Atala is working on one that would scan the contours of the part of a body where a skin graft was needed and then print skin onto it. We wish them all the best of luck in their research.

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