Bio-ink made with stem cells could be used to 3-D print living tissue

An artist's impression of bio-printing.--Courtesy of the University of Bristol

A new stem cell-containing bio-ink could be used to create living tissue through 3-D printing, called "bio-printing." The ink was developed by scientists at the University of Bristol, and it could eventually produce complex tissues for surgical implants.

"Designing the new bio-ink was extremely challenging," said lead researcher Adam Perriman of the School of Cellular and Molecular Medicine in an announcement. "You need a material that is printable, strong enough to maintain its shape when immersed in nutrients, and that is not harmful to the cells. We managed to do this, but there was a lot of trial and error before we cracked the final formulation."

The bio-ink used contains a natural polymer from seaweed and a sacrificial synthetic polymer used in the medical industry. The seaweed polymer offers structural support when cell nutrients are introduced, and the synthetic polymer changes the bio-ink from a liquid to a solid as temperature is raised.

"The special bio-ink formulation was extruded from a retrofitted benchtop 3-D printer, as a liquid that transformed to a gel at 37°C, which allowed construction of complex living 3-D architectures," Perriman explained in the announcement.

According to the announcement, the team managed to differentiate stem cells into osteoblasts and chondrocytes. Osteoblasts are cells that secrete bone substance and chondrocytes are cells that have secreted the matrix of cartilage and are then embedded in it. With that, tissue structures including a tracheal cartilage ring were 3-D printed over 5 weeks.

Perriman made note of a particular finding: The synthetic polymer was completely expelled from the printed structure as cell nutrients were introduced. Only stem cells and the natural seaweed polymer remained. Microscopic pores were created in the process, offering even more effective nutrient access for the stem cells.

The announcement explained that these findings could eventually lead to patients' own stem cells being used to print complex tissues such as surgical bone or cartilage implants, which could be used in knee or hip surgeries.

The full findings were published in Advanced Healthcare Materials.

- here's the press release
- and here are the full findings