Researchers led by mechanical engineering professor Boris Rubinsky and graduate student Gideon Ukpai have developed a technique that may be key to the viability of bioprinting, an extension of 3D printing that could allow whole organs — as well as living tissue, bone and blood vessels — to be printed on demand.
There have been two major hurdles standing in the way of organ printing. Because living cells and functioning organs require specialized temperature and chemical conditions to survive, cells deteriorate during the actual 3D printing of a large organ, as the process is too slow. And even if the organ can be printed in 3D, the logistics of transporting it requires storage, which has always been a bottleneck for transplants.
To minimize cell death during the 3D printing of an organ, the researchers developed a technique that employs parallelization, in which multiple printers produce 2D layers of tissues simultaneously. These 2D layers are then stacked layer-by-layer to form 3D structures.
To overcome the storage problem of these manufactured organs, their technique freezes each 2D layer immediately after it is merged into the 3D structure. This process of freezing a single layer of cells provides optimal conditions for surviving the process of freezing, storage and transportation.
By printing tissues in 2D first and then assembling them into a 3D object at a different station, the team significantly sped up production. After the assembly line of bioprinters creates, in parallel, multiple 2D layers of tissue, a robotic arm — which was augmented by students from the master of engineering program — picks up each layer and carries it to another station. There, the tissues are stacked together to create a 3D object and fused via freezing.
In addition to bioprinting, this technique has other applications, such as the industrial scale manufacturing of frozen foods.