Gel instrumental in 3D bioprinting biological tissues

Date:
October 16, 2020
Source:
Penn State
Summary:
The eventual creation of replacement biological parts requires
fully three-dimensional capabilities that two-dimensional and
three-dimensional thin-film bioprinting cannot supply. Now, using
a yield stress gel, engineers can place tiny aggregates of cells
exactly where they want to build the complex shapes that will be
necessary to replace bone, cartilage and other tissues.



FULL STORY ==========================================================================
The eventual creation of replacement biological parts requires fully
three- dimensional capabilities that two-dimensional and three-dimensional thin-film bioprinting cannot supply. Now, using a yield stress gel,
Penn State engineers can place tiny aggregates of cells exactly where
they want to build the complex shapes that will be necessary to replace
bone, cartilage and other tissues.


==========================================================================
"The reason why this is important is that the current cell aggregate bioprinting techniques can't make complicated configurations and is
mostly in 2D and 3D thin films or simple configurations," said Ibrahim
T. Ozbolat, Hartz Family Career Development Associate Professor of
Engineering Science and Mechanics. "If we want complicated 3D, we need a supportive field." That supportive field, the researchers report today
(Oct. 16) in Communication Physics is a yield stress gel. Yield stress
gels are unusual in that without stress they are solid gels, but under
stress, they become liquid.

The researchers are using an aspiration-assisted bioprinting system
that they demonstrated earlier this year to pick up aggregates of
cells and place them precisely inside of the gel. The stress of the
aspiration nozzle against the gel liquefies it, but once the aspiration
nozzle releases cell aggregates and withdraws, the gel returns to solid
again, self-healing. The tiny balls of cells rest upon each other and self-assemble, creating a solid tissue sample within the gel.

The researchers can place different types of cells, in small aggregates, together to form the required shape with the required function. Geometric shapes like the cartilage rings that support the trachea, could be
suspended within the gel.

"We tried two different types of gels, but the first one was a little
tricky to remove," said Ozbolat. "We had to do it through washing. For
the second gel, we used an enzyme that liquefied the gel and removed
it easily." "What we are doing is very important because we are trying
to recreate nature," said Dishary Banerjee, postdoctoral researcher
in engineering science and mechanics. "In this technology it is very
important to be able to make free- form, complex shapes from spheroids."
The researchers used a variety of approaches, creating theoretical models
to get a physical understanding of what was happening. They then used experiments to test if this method could produce complex shapes.


========================================================================== Story Source: Materials provided by Penn_State. Original written by
A'ndrea Elyse Messer.

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Bugra Ayan, Nazmiye Celik, Zhifeng Zhang, Kui Zhou, Myoung Hwan Kim,
Dishary Banerjee, Yang Wu, Francesco Costanzo, Ibrahim T. Ozbolat.

Aspiration-assisted freeform bioprinting of pre-fabricated tissue
spheroids in a yield-stress gel. Communications Physics, 2020; 3
(1) DOI: 10.1038/s42005-020-00449-4 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201016090213.htm

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