Peptide 3D-printing inks could advance regenerative medicine
Lab opens new door to creating cell scaffolds for growing tissue,
studying disease

Date:
February 7, 2023
Source:
Rice University
Summary:
How do you build complex structures for housing cells using a
material as soft as jelly? Researchers have the answer with a new
3D-printing ink.


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FULL STORY ==========================================================================
How do you build complex structures for housing cells using a material
as soft as jelly? Rice University scientists have the answer, and it
represents a potential leap forward for regenerative medicine and medical research in general.


========================================================================== Researchers in the lab of Rice's Jeffrey Hartgerink have figured out
how to 3D- print the well-defined structures using a self-assembling
peptide ink.

"Eventually, the goal is to print structures with cells and grow mature
tissue in a petri dish. These tissues can then be transplanted to treat injuries, or used to learn about how an illness works and to test drug candidates," said Adam Farsheed, a Rice bioengineering graduate student
and lead author of the study, which appeared in Advanced Materials.

"There are 20 naturally occurring amino acids that make up proteins
in the human body," Farsheed said. "Amino acids can be linked together
into larger chains, like Lego blocks. When amino acid chains are longer
than 50 amino acids, they are called proteins, but when these chains are shorter than 50 amino acids they are called peptides. In this work, we
used peptides as our base material in our 3D-printing inks." Developed by Hartgerink and collaborators, these "multidomain peptides" are designed
to be hydrophobic on one side and hydrophilic on the other. When placed
in water, "one of the molecules will flip itself on top of another,
creating what we call a hydrophobic sandwich," Farsheed said.

These sandwiches stack onto one another and form long fibers, which then
form a hydrogel, a water-based material with a gelatinous texture that
can be useful for a wide range of applications such as tissue engineering,
soft robotics and wastewater treatment.

Multidomain peptides have been used for nerve regeneration, cancer
treatment and wound healing, and have been shown to promote high levels
of cell infiltration and tissue development when implanted in living
organisms.

"We know that the multidomain peptides can safely be implanted in the
body," Farsheed said. "But what I was looking to do in this project was
to go in a different direction and show that these peptides are a great 3D-printing ink.

"It might be counterintuitive since our material is so soft, but I
recognized that our multidomain peptides are an ideal ink candidate
because of the way they self-assemble," he continued. "Our material can reassemble after being deformed, similar to how toothpaste forms a nice
fiber when pushed out of a tube." Farsheed's mechanical engineering
background allowed him to take an unconventional approach when testing
his hypothesis.

"I had more of a brute-force engineering approach where instead of
chemically modifying the material to make it more amenable to 3D printing,
I tested to see what would happen if I simply added more material,"
he said. "I increased the concentration about fourfold, and it worked
extremely well.

"There have been only a handful of attempts to 3D-print using other self- assembling peptides, and that work is all great, but this is the first
time that any self-assembling peptide system has been used to successfully 3D-print such complex structures," Farsheed continued.

The structures were printed with either positively charged or negatively charged multidomain peptides, and immature muscle cells placed on the structures behaved differently depending on the charge. Cells remained
balled up on the substrate with a negative charge, while on the positively charged material the cells spread out and began to mature.

"It shows that we can control cell behavior using both structural and
chemical complexity," Farsheed said.

Hartgerink is a professor of chemistry and bioengineering and associate
chair for undergraduate studies. Farsheed is a bioengineering graduate
student and lead author on the study. Additional study co-authors are undergraduate student Adam Thomas and graduate student Brett Pogostin.

The National Institutes of Health (R01 DE021798) and the National Science Foundation Graduate Research Fellowships Program supported the research.

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========================================================================== Story Source: Materials provided by Rice_University. Original written
by Silvia Cernea Clark.

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Adam C. Farsheed, Adam J. Thomas, Brett H. Pogostin, Jeffrey D.

Hartgerink. 3D Printing of Self‐Assembling Nanofibrous
Multidomain Peptide Hydrogels. Advanced Materials, 2023; 2210378
DOI: 10.1002/ adma.202210378 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/02/230207191606.htm

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