EVERY year about 120,000 organs, mostly kidneys, are transplanted from one human being to another. Sometimes the donor is a living volunteer. Usually, though, he or she is the victim of an accident, stroke, heart attack or similar sudden event that has terminated the life of an otherwise healthy individual. But a lack of suitable donors, particularly as cars get safer and first-aid becomes more effective, means the supply of such organs is limited. Many people therefore die waiting for a transplant. That has led researchers to study the question of how to build organs from scratch.
One promising approach is to print them. Lots of things are made these days by three-dimensional printing, and there seems no reason why body parts should not be among them. As yet, such “bioprinting” remains largely experimental. But bioprinted tissue is already being sold for drug testing, and the first transplantable tissues are expected to be ready for use in a few years’ time.
Just press “print”
Bioprinting originated in the early 2000s, when it was discovered that living cells could be sprayed through the nozzles of inkjet printers without damaging them. Today, using multiple print heads to squirt out different cell types, along with polymers that help keep the structure in shape, it is possible to deposit layer upon layer of cells that will bind together and grow into living, functional tissue. Researchers in various places are tinkering with kidney and liver tissue, skin, bones and cartilage, as well as the networks of blood vessels needed to keep body parts alive. They have implanted printed ears, bones and muscles into animals, and watched these integrate properly with their hosts. Last year a group at Northwestern University, in Chicago, even printed working prosthetic ovaries for mice. The recipients were able to conceive and give birth with the aid of these artificial organs.