Story URL: http://news.medill.northwestern.edu/chicago/news.aspx?id=217613
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EARS.BONASSAR

Lindsay France/University Photography

Lawrence Bonassar shows the collagen ear replacement.


Human ears printed 3D could lead the way to transplants

by Conner Forrest
March 05, 2013


EARS.EAR

Lindsay France/University Photography

A 3D printer prints the mold for the ear.

The age of the cyborgs is upon us! Well….soon. Scientists at Cornell University in New York have successfully “printed” a human ear, and hope to adapt it to transplants within the next few years.

Bioengineers Dr. Jason Spector and Lawrence Bonassar used 3D printing technology to print an artificial ear to help combat microtia, a congenital defect where a child is born with an undeveloped ear. The printed ears are made of collagen, which then grows a cartilage matrix over a few months.

The success lies in the fact that cartilage doesn't need a blood supply to grow, so researchers do not need to print blood vessels within the ear. The process begins with a high-resolution 3D photograph of the patient’s developed ear, and offers a replica that is matches the healthy ear.

”That image is then digitized and based upon that image a computer directs a fabrication device to make a [3D] mold, and the mold represents an exact negative image of the child’s ear. Into that mold, we inject collagen, which is seeded with ear chondrocytes, or cartilage cells. So, what we take out of the mold a half an hour later is an exact three-dimensional replica of that child’s ear, which is seeded with cartilage cells, ear cartilage cells,” said Spector.

But, once the ear is removed from the mold, it needs a natural environment to promote cellular growth. To achieve that, the ear incubates in an animal where it remains for several months. After that time, the ear will have developed a sufficient amount of type-II cartilage and elastin, a protein, and will be ready for placement on a patient.

“We need the body [of the animal] to provide nutrients for the cells,” Bonassar said. He added that hosting the ear in vivo (in an animal) helps the scientists to determine if the ear is stable and biocompatible.

The researchers pulled cartilage cells from cows, a good source for the amount of cells needed for an ear. Spector said the critical number is 250 million, and they have seen the experiment work with this number of cells. Now, they are looking for ways to obtain and culture that amount of cells from a human subject.

The field of cartilage engineering has grown rapidly over the past few years, due to the unique nature of it not needing its own blood supply, but bioengineering other parts of the body might be a little ways out. “We will not see bio-printing of any [other] body parts until someone figures out how to incorporate a blood supply within the bio-printed tissues,” said Spector.

Currently, ears can be fabricated from the patient’s rib cartilage. The rib cartilage is usually harvested when a child is 5 or 6 years old, and this is a very painful surgery. The rib cartilage cannot fully mimic the real thing, as it is not as pliable as natural ear cartilage. Fully synthetic replacements are also available. The printed ears, if successful, will provide a replacement that is more alike its natural counterpart.