• Scientists developed technique that uses a solvent to make organs such as the brain and kidneys transparent
• Organ scanned by lasers in microscope that allows researchers to capture structure, including blood vessels
• They load 3D printer with stem cells which act as ‘ink,’ injected into correct position making organ functional

Researchers in Germany have created transparent human organs using a new technology that could pave the way to print three-dimensional body parts such as kidneys for transplants.

Scientists led by Ali Erturk at Ludwig Maximilians University in Munich have developed a technique that uses a solvent to make organs such as the brain and kidneys transparent.

The organ is then scanned by lasers in a microscope that allows researchers to capture the entire structure, including the blood vessels and every single cell in its specific location.

Using this blueprint, researchers print out the scaffold of the organ. 

They then load the 3D printer with stem cells which act as ‘ink’ and are injected into the correct position making the organ functional.

While 3D printing is already used widely to produce spare parts for industry, Erturk said the development marks a step forward for 3D printing in the medical field.

Until now 3D-printed organs lacked detailed cellular structures because they were based on images from computer tomography or MRI machines, he said.

‘We can see where every single cell is located in transparent human organs. And then we can actually replicate exactly the same, using 3D bioprinting technology to make a real functional organ,’ he said.

‘Therefore, I believe we are much closer to a real human organ for the first time now.’

Erturk’s team plan to start by creating a bioprinted pancreas over the next 2-3 years and also hope to develop a kidney within 5-6 years.

The researchers will first test to see whether animals can survive with the bioprinted organs and could start clinical trials within 5-10 years, he said.

WHAT OTHER BODY PARTS CAN SCIENTISTS PRINT?

3D printing has become increasingly common in the medical world and researchers have already used it to try and create skin, spinal cells and corneas.

At Newcastle University scientists last year printed the first ever human corneas – the fronts of the eyes. 

Researchers used human stem cells combined with collagen and alginate, which together turn into a strong gel, which could be used by a printer.

They say the technology could be used to produce an unlimited supply of corneas to combat a global shortage for people who need transplants.

Experts at the University of California in San Diego restored the walking ability of paralysed mice by printing a spinal cord. 

They created a scaffolding for the spine, loaded with neural stem cells, into sites of severe spinal cord injury in rats.

The implants then grew new nerves and tissue which attached to the existing spine to repair it and restore muscle control.

Researchers at the University of Toronto created a skin gun. 

The glue gun-like device can 3D print three layers of skin on demand to quickly treat severe flesh wounds, such as burns and gashes, which need skin grafts to repair.

Stem cells taken from a patient are plugged into the device and used to generate three sheets composed of proteins including fibrin – which helps to heal wounds, and collagen.