Printing the Body: How 3D Printers Are Changing Medicine

by Wellness Editor – MH

People associate printers with things like photographs and office documents, but can you imagine special printers used to produce physical replicas of body parts? That wasn’t a typo – there may come a time when doctors are able to print out bones, organs and other key parts of the human body. As unbelievable as this technology might seem, medical researchers have recently made strides towards achieving this goal.

Creating Bones and Ears

Over the last several years, medical science has sought to use 3D printing technology to recreate complex and crucial body parts. In late 2011, Washington State University faculty announced that they had printed material that closely resembled human bones. The WSU team created this object by modifying a 3D printer typically used to make metal objects.

The end result of this experiment was the creation of cylinder-shaped item. Roughly the size of a pencil eraser, this object was subsequently transferred to a controlled environment. The researchers then monitored the cylinder’s interactions with real human bone cells. Within a week, the bone cells had attached themselves to this cylindrical scaffolding, using it as a supporting structure for the creation of new bone cells.

This research may eventually have a major impact in how bone-related injures are conditions are treated. Ideally, doctors will one day be able to routinely print bone-growing scaffolding for their patients. These implants would then dissolve on their own when no longer needed. The study can be found in the November 29, 2011 issue of the journal Dental Materials.

Scientists at Cornell University have also explored the medical possibilities of three dimensional printers. Rather than print bone-like material, this group recently used this technology to produce human ears. Because human cartilage is often difficult to come by, samples from cows were used instead. The researchers also needed to provide the printer with an accurate depiction of a human ear. Fortunately, they didn’t have to look very far for a model; the five year old twin daughters of one of the study’s co-authors agreed to have their ears scanned with a 3D camera. A soft mold based on this data ear was then printed.

The final step was to create scaffolding for the ear cells to grow on. To do this, the researchers injected a special collagen gel into their ear mold. This gel contained cartilage-growing cells taken from cows. In all, the ear mold took a half a day to design and a full day to print. Applying the gel required only thirty minutes. Afterwards, the ear was trimmed and placed in a controlled area to finish growing.

The injected gel proved to be very effective at facilitating tissue growth. Over the following weeks, the gel was steadily replaced by ear cartilage. The researchers then implanted these printed appendages into the backs of laboratory rats. This would determine how the ears would hold up when attached to living test subjects. After a period of three months, the research team found that the procedure had not altered the shape of the ears.

The Cornell team hopes to build on the success of this experiment. The next step will be to make an ear using a patient’s own cells. By achieving this goal, the researchers believe they may be able to attach printed ears to young patients (the recipients would be children aged five to six. At this age, ears have grown to eighty percent of their adult size). In February 2013, the study was published in the online journal PLoS One.

Printing Organs – The Next Step?

While the prospect of printing ears and bone-like substances certainly makes for an interesting read, 3D printing’s biggest contribution to medicine might involve the production of vital organ tissues. Organovo, a San Diego based 3-D biotechnology company, has recently undertaken such a project. The firm has begun to print realistic and functional strips of liver tissue. In the coming years, Organovo hopes to develop organ tissues with cell samples taken directly from patients. Such tissues would be used to repair organs crippled by disease or injury.

Organovo’s ultimate goal is to produce entire replacement organs with 3D printing technology. Needless to say, such a breakthrough could save numerous lives. It is estimated that 18 people die each day waiting in vain for organ transplants. In January 2014, the company achieved one of the project’s first milestones, shipping a sample of printed liver tissue to an outside laboratory. Though this tiny sample cannot be implanted in human patients, researchers do plan on using it to test the effectiveness of new medications. Considering that it usually takes 12 years and $1.2 billion to bring a drug to market, these tissue samples could prove very useful to medical researchers.

How 3D Printing Works

There are multiple ways in which 3D printers are able to print physical copies of specific objects. One such method is direct 3D printing, which involves using fluid-dispensing nozzles to create the desired object. While such nozzles have long been used in conventional 2D printers, they are used somewhat differently in direct 3D printing. Rather than simply moving back and forth, the nozzles in direct 3D printers also move vertically during the printing process. Thick waxes and plastic polymers are released instead of ink. This method allows for multiple layers of printing material to be applied to the same surface area. The waxes and polymers harden immediately after being released, coalescing into a fully three dimensional product.

Alternatively, some 3D printers create objects by using an approach known as binder 3D printing. Once again, inkjet nozzles are used to dispense liquids, moving up and down when needed to produce each new layer. Unlike direct 3D printers, the printing materials used to make the end product are released separately. First, the printer creates a thin layer of fine, white powder using a cylindrical roller. The printer then applies a type of liquid glue known as a binder, allowing predetermined sections of the powder to harden into a solid layer. With this cross section finished, the building platform is lowered and the printer sets about making the next layer. The printer repeats this process until the requested item is finished.

Photopolymerization and selective laser sintering (SLS) are two other types of 3D printing technology. The former involves using ultraviolet light to transform liquid drops into solid material. The latter uses lasers to meld together particles of powder, ceramic or glass into as solid whole.

Three dimensional printing is not only a reality, but appears poised to have a major impact on the future of medicine. Years from now, doctors may have the ability to produce body parts of all shapes and sizes with the push of a button.

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