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Finally, another mystery humans have yet to solve is the fact that living
cells need a “start” button. Today, no one knows exactly how to jump start
seeded cells, even if the cells were placed into the right spot in a perfectly
shaped scaffolding. Nature knows how to make an organ start working. We
don't.
A team of researchers at the University of Missouri and Yale coined the terms
bioink particles
(multicellular spheroids) and
biopaper
(biocompatible gel).
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In
an article in
Nature
magazine, Dr. Gabor Forgacs, a researcher at the University
of Missouri, describes his approach, “You give us your cells: we grow them, we
print them, the structure forms and we are ready to go.”
His team used a custom-made 3D printer originally intended to make
microelectronics:
The printer has three heads, each of which is controlled by an
attached computer, that can lay down spheroids of cells much as a
desk printer would lay down ink.
Two of the heads print out tissue cells (mixtures including, for example,
cardiac and endothelial cells), while the third prints a “gap-filler”
(such as collagen) that fills a space temporarily until the other cells
have fused. So to make a blood vessel, for example, lines of cells are
laid down with lines of collagen in the middle, which will later be
extracted to make way for blood.
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To understand why bioprinting holds such potential, it helps to briely
compare it to established methods of tissue engineering.
For several decades, living tissue has been made using a two-phase
approach. The irst step is to engineer a tissue's scaffolding from some kind
of biodegradable material. To make engineered scaffolding using the tradi-
tional approach, researchers would stamp its shape from a mold, carve it, or
use chemicals to etch out a porous shape. The second phase is to seed the
scaffolding with living cells.
Compare this approach to just 3D printing living cells into a precise shape
and letting them form their own matrix and eventually supportive scaffolding.
Traditional tissue engineering techniques have helped thousands of patients
gain back lost soft tissues. Yet, limitations are aplenty.
