Lab-grown organs for transplant are one step closer thanks to a technique for making artificial blood vessels using 3D printers and liquid metal.
One challenge in developing organs in the lab is to reproduce the microscopic structure of blood vessels that permeate the tissue. In the body, cells are supported by the extracellular matrix (ECM), a gel-like network of proteins such as collagen that acts as a natural scaffolding, giving structure to tissues and organs.
3D printing offers an easy way to create moulds into which cells can be placed, but it is difficult to print directly in an ECM due to its softness and vulnerability to high temperatures.
Advertisement
Now, at Harvard University and his colleagues have developed a process for making an ECM mould with fine channels resembling blood vessels.
First, they 3D printed a template of a branched channel system in plastic and used it to create a silcone mould. They filled the mould with liquid gallium, an unusual metal that melts at around 30掳C (86掳F). Once the gallium solidifies, the silicone can be removed to leave a rigid template of the branching channels.
They encapsulated the gallium template in a soft collagen gel, then warmed it up to melt the gallium and drain it out of the gel, leaving behind channels in the desired shape. Gallium鈥檚 surface tension is 10 times as high as that of water, so it can be drained quickly and cleanly from the gel, and at a low temperature that does no damage.
Unlike other metals, like mercury, with similar melting points, gallium seems to present no health risk. In tests, Sundaram and his team found that human cells grew faster on gallium than off it. 鈥淚 remember thinking that maybe we鈥檝e found the killer app for gallium here,鈥� he says. 鈥淭his is really the perfect material.鈥�
Sundaram says the technology takes us one step closer to creating a wide range of artificial organs for human transplant, although much remains to be done. 鈥淭hings like this take a lot of time,鈥� he says. 鈥淚 think that every small step counts, and I think that this will be one of those key steps.鈥�
at Carnegie Mellon University in Pittsburgh, Pennsylvania, who has developed methods to create moulds of blood vessels with 3D-printed ice, says the problem of creating blood vessels in artificial organs has stumped scientists for the past 30 years.
鈥淐reating 3D vascular systems with this type of sacrificial material approach that can have many different shapes is excellent and pushes the field forward in exciting directions,鈥� says LeDuc. 鈥淲hile there are still many other areas to address to get to fully vascularised tissue systems in the future, this work shows the ability to create 3D vascular systems down to the tens of micrometres, which is an excellent advancement.鈥�
Nature
