Imagine if you could take living cells, load them into a printer, and
squirt out a 3D tissue that could develop into a kidney or a heart.
Scientists are one step closer to that reality, now that they have
developed the first printer for embryonic human stem cells.
In a new study, researchers from the University of Edinburgh have created a
cell printer
that spits out living embryonic stem cells. The printer was capable of
printing uniform-size droplets of cells gently enough to keep the cells
alive and maintain their ability to develop into different cell types.
The new printing method could be used to make 3D human tissues for
testing new drugs,
grow organs, or ultimately print cells directly inside the body.
Human embryonic stem cells (hESCs) are obtained from human embryos and
can develop into any cell type in an adult person, from brain tissue to
muscle to bone. This attribute makes them ideal for use in regenerative
medicine — repairing, replacing and regenerating damaged cells, tissues
or organs. [
Stem Cells: 5 Fascinating Findings]
In a lab dish, hESCs can be placed in a solution that contains the
biological cues that tell the cells to develop into specific tissue
types, a process called differentiation. The process starts with the
cells forming what are called "embryoid bodies." Cell printers offer a
means of producing embryoid bodies of a defined size and shape.
In the new study, the cell printer was made from a modified CNC machine
(a computer-controlled machining tool) outfitted with two "bio-ink"
dispensers: one containing stem cells in a nutrient-rich soup called
cell medium and another containing just the medium. These
embryonic stem cells
were dispensed through computer-operated valves, while a microscope
mounted to the printer provided a close-up view of what was being
printed.
The two inks were dispensed in layers, one on top of the other to
create cell droplets of varying concentration. The smallest droplets
were only two nanoliters, containing roughly five cells.
The cells were printed onto a dish containing many small wells. The
dish was then flipped over so the droplets now hung from them, allowing
the stem cells to form clumps inside each well. (The printer lays down
the cells in precisely sized droplets and in a certain pattern that is
optimal for differentiation.)
Tests revealed that more than 95 percent of the cells were still alive
24 hours after being printed, suggesting they had not been killed by the
printing process. More than 89 percent of the cells were still alive
three days later, and also tested positive for a marker of their
pluripotency — their potential to develop into different cell types.
Biomedical engineer Utkan Demirci, of Harvard University Medical School
and Brigham and Women's Hospital, has done pioneering work in printing
cells, and thinks the new study is taking it in an exciting direction.
"This technology could be really good for high-throughput drug testing,"
Demirci told LiveScience. One can
build mini-tissues
from the bottom up, using a repeatable, reliable method, he said.
Building whole organs is the long-term goal, Demirci said, though he
cautioned that it "may be quite far from where we are today."
Others have created printers for other types of cells. Demirci and
colleagues made one that printed embryonic stem cells from mice. Others
have printed a kind of human stem cells from connective tissues, which
aren't able to develop into as many cell types as embryonic stem cells.
The current study is the first to print embryonic stem cells from
humans, researchers report in the Feb. 5 issue of the journal
Biofabrication.
