Silk fibers improve bioink for 3D-printed artificial tissues and organs


Date:
October 8, 2020
Source:
Osaka University
Summary:
Researchers processed silk fibers into a versatile component of
bioink for 3D cell printing technology. Printed objects retain
their shape better than those produced without the silk additive,
and the cells are not further damaged. This development will help
advance regenerative medicine and drug discovery, and potentially
reinvigorate the silk industry.



FULL STORY ==========================================================================
How do you test, in early-stage research, whether a potential
pharmaceutical effectively targets a human tumor, organ, or some
other part of the body? How do you grow a new hand or some other body
part? Researchers are in the early stages of using 3D cell printing
technology to make developments like these happen. A standard way --
currently unavailable -- to fix the cells in place after printing
would help researchers avoid having to 'reinvent the wheel' in every
new investigation.


==========================================================================
In a study recently published in Materials Today Bio, researchers
from Osaka University have used silk nanofibers obtained by mechanical disintegration to enhance the printing process without damaging the cells
or cell assemblies. An attractive point of silk for this application is
that silk is believed to be a safe material for humans. This development
will help bring 3D cell printing research out of the laboratory and into real-world biomedical use.

To obtain the fibers, the researchers started with virgin silk,
then removed the protein sericin from it because this protein causes inflammation in patients. Next, the researchers ground the remaining biocompatible material into nanofibers. The fibers can be sterilized
-- without damaging them -- for medical use, with common laboratory
equipment.

"Our silk fibers are excellent additives to bioink cell printing media,"
says lead author Shinji Sakai. "They are compatible with many media,
such as those containing gelatin, chitosan, or hyaluronic acid, giving
them a broad range of potential applications." The main purpose of
the fibers was to ensure that the cells in the bioink retained their 3D positioning after printing without damaging the cells. The fibers fulfill
this purpose by enhancing the integrity of the bioink and minimizing the damaging high mechanical stresses often placed on cells during printing.

"Various mechanical experiments say the same thing: the nanofibers
enhanced the properties of the printing media," explains Professor
Sakai. "For example, Young's modulus -- a measure of stiffness --
increased several-fold and remained enhanced for over a month."
The fibers help printed configurations retain their structural integrity
after printing. For example, a nose-shaped configuration retained its
shape only when printed with bioink containing the silk fibers. Over 85%
of the cells in the bioink remained alive after a week in the printed
bioink with or without the added fibers, indicating that adding the
fibers did not damage the cells.

Current cell printing technology often heavily damages cells or does not
retain the intended shape for long. The research here helps overcome these limitations in a way that will help advance drug discovery, regenerative medicine, and many other ongoing high-impact biomedical research fields,
and has the potential added economic benefit of reinvigorating the
silk industry.


========================================================================== Story Source: Materials provided by Osaka_University. Note: Content may
be edited for style and length.


========================================================================== Journal Reference:
1. S. Sakai, A. Yoshii, S. Sakurai, K. Horii, O. Nagasuna. Silk fibroin
nanofibers: a promising ink additive for extrusion three-dimensional
bioprinting. Materials Today Bio, 2020; 8: 100078 DOI: 10.1016/
j.mtbio.2020.100078 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201008091626.htm

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