One of the hurdles to longevity is that bodies seemed designed to break down. It's a part of aging. It might be a part of evolution. Transplants and implants aren’t painless and can be risky. Now, researchers are saying that you won’t have to worry about bodies breaking down when you can just print a new part.

Nature Magazine reports that scientists are using 3D bioprinting technology that can print everything from new knees and bones to eyes and ears.

Penn State biological engineer Ibrahim Ozbolat, who is studying how to use 3D bioprinting to repair cartilage and other tissue types, tells Nature that one day a patient could lay under a machine that would inject cells into a trick knee to repair it.

“In the future, we can have the patient under the bioprinter,” says Ozbolat.

Ozbolat ads that this bioprinter machine could fix any body part, not just knees.

How Bioprinting Works

3D Bioprinting is a little different than the 3D printers that you see whip up plastic Star Wars figures in a few minutes. Bioprinters takes cells and mixes them in with a gooey mess that are typically hydrogels. They are polymers that hold water but are solid enough to temporarily maintain shapes.

A nozzle sprays the material in place and then solidify. Different methods use different ways to solidify the material. Temperature changes, added pressure, chemicals, and even light waves can help the solution solidify, according to Nature. Then the cells, with a boost of nutrients and growth factors, can take over, becoming the correct tissue for the operation.

This may sound like it would happen in the far future -- about the time we start holding debates on whether phasers are protected by the Second Amendment -- but indications are these treatments are on the way to clinical trials now. The simpler forms of 3D bioprinted tissue might be in use within a few years, according to Anthony Atala, director of the Wake Forest Institute for Regenerative Medicine in Winston-Salem, North Carolina. (Watch Dr. Atala give a TED Talk on printing a kidney below).

Since it’s flat and a relatively simple cellular mix, operations involving 3D-printed cartilage will be first. In fact, operations with cartilage and bones have already been performed in mice.

Designs for an artery and urethra might be next.

Organs may be a little more difficult. They are cellularly complex and need a way to bring nutrients and food to the cells -- or a vascular system. But Harvard is already taking steps to cross that hurdle. The Harvard team mixed two types of materials -- a gel called Pluronic and pluripotent stem cells -- to make the tissue. Pluronic, which goes in as a solid, but cools to a liquid, makes channels in the tissue. When it cools, the liquid drains and the channels, which can serve as vessels, remain.

According to Jennifer Lewis, a bioengineer who led the team, they printed tissue that was a centimeter thick and it remained alive for over six weeks.

“There's really no limitation. We could go thicker,” she adds.

Although the vascular system in this case was pretty simple, this research -- as well as Ibrahim and other researchers’ work -- suggests that 3D bioprinting could help us switch from replacing body parts with rebuilding and maybe even regrowing them.