Earlier 3D printers only print plastic articles,scientists say 3D-printed objects stuffed with embryonic stem cells may enable doctors print micro-organs for transplant patients in the nearest future.
Embryonic stem cells,collected from human embryos, can grow into any type of cell in the body like brain tissue, heart cells or bone. This ability makes them good for use in regenerative medicine — repairing and replacing damaged cells, tissues and organs.
Scientists usually experiment with embryonic stem cells by loading them with biological instructions that makes them develop into specific type tissues — a process known as cell differentiation. This process starts with the cells forming spherical masses called embryoid bodies — an activity that resembles early stages of embryonic development. [7 Cool Uses of 3D Printing in Medicine]
Earlier research revealed that the best way to grow embryonic stem cells is not in flat lab dishes, but in 3D environments that resembles how these cells develop in human bodies. Recently, scientists developed 3D printers for embryonic stem cells. A 3D printer operates by depositing layers of material, just as ordinary printers lay ink, only it can also lay flat layers on top of one another to make 3D objects.
Before now, 3D printers used for embryonic stem cells only produced flat arrays or simple mounds known as "stalagmites," of cells. Recently,researchers said,for the first time,they were able to develop a way to print 3D structures loaded with embryonic stem cells.
"We were able to use a 3D-printing method to grow embryoid bodies in a controlled manner to make highly uniform blocks of embryonic stem cells," study co-author Wei Sun, a professor of mechanical engineering at Tsinghua University in Beijing and Drexel University in Philadelphia,told Live Science.
In theory, these blocks can be used as Lego bricks to build tissues"and even micro-organs," Sun added.
In experiments, the researchers simultaneously printed out mouse embryonic stem cells with a hydrogel, the same type of substance from which soft contact lenses are made from. Since embryonic stem cells are relatively fragile, the scientists made sure to protect the cells as much as possible — for example, by locating the most comfortable temperature for them and increasing the size of the nozzle used to print them.
Nearly all the cells survived the printing process, according to the new study. The cells combined to form embryoid bodies within the hydrogel scaffolds and generated the kind of proteins that would be expected from healthy embryonic stem cells, the researchers said. The scientists also noticed that they could dissolve the hydrogel to harvest the embryoid bodies.
The size and uniqueness of embryoid bodies can greatly affect the types of cells they turn into. The researchers said their new technology resulted in better control of embryoid body size and uniformity than previous methods could achieve.
"The grown embryoid body is uniform and homogenous, and serves as [a] much better starting point for further tissue growth," Sun said in a statement. "It was really exciting to see that we were able to grow embryoid bodies in such a controlled manner."
"Our next step is to find out more about how we can vary the size of the embryoid body by changing the printing and structural parameters, and how varying the embryoid body size leads to 'manufacture' of different cell types," study co-lead author Rui Yao an assistant professor at Tsinghua University in Beijing, said in a statement.
In the long term, the researchers would like to print different kinds of embryoid bodies side by side. "This would promote different cell types developing next to each other, which would lead the way for growing micro-organs from scratch within the lab," Yao said in a statement.
The scientists detailed their findings online Nov. 4 in the journal Biofabrication.
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