Three-Dimensional Printing of Living Tissues with Stem Cell Bioink

A recent paper described an advance in the use of three-dimensional printing that enables the use of the technique to print living tissues from a bioink that contains stem cells and nutrients.

Investigators at the University of Bristol (United Kingdom) compounded the bioink from two different polymer components. The first component was a seaweed extract that provided structural support, while the second component was a synthetic polymer – already approved for medical applications – that produced a liquid to solid-state change when the temperature of the medium was raised.

The paper, which was published in the June 22, 2016, online edition of the journal Advanced Healthcare Materials, described the differentiation of stem cells into osteoblasts and chondrocytes) and the use of this material to generate three-dimensional printed tissue structures over a period five weeks, including a full-size tracheal cartilage ring.

Senior author Dr. Adam Perriman, a senior research fellow at the University of Bristol, said, "Designing the new bioink was extremely challenging. 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 special bioink formulation was extruded from a retrofitted benchtop three-D printer, as a liquid that transformed to a gel at 37 degrees Celsius, which allowed construction of complex living three-D architectures."

Dr. Perriman said, "What was really astonishing for us was when the cell nutrients were introduced, the synthetic polymer was completely expelled from the three-D structure, leaving only the stem cells and the natural seaweed polymer. This, in turn, created microscopic pores in the structure, which provided more effective nutrient access for the stem cells.

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