Artistic rendering of Lesley Chow's new method to create continuous, highly organized scaffolds to regenerate two different tissues

Illustration by Roman Bratschi

A New Approach to Tissue Engineering: Lesley Chow Creates Scaffolds for Tissue Regeneration

Chow and her team have demonstrated a new method to create continuous, highly organized scaffolds for tissue regeneration.

Story by

Lori Friedman

Photography by

Illustrations by Roman Bratschi

Organs, muscles and bones are composed of multiple types of cells and tissues that are carefully organized to carry out a specific function. Articular cartilage, for example, exists where bones meet at the joints. This type of cartilage protects the ends of bones and is tightly integrated with bone through a region known as the osteochondral interface.

When articular cartilage is absent or damaged, debilitating pain results. Unlike some tissues, cartilage cannot regenerate after an injury. Instead, it degenerates, leading to osteoarthritis, which affects approximately 27 million Americans.

“Medical intervention is the only way to regenerate osteochondral tissue,” says Lesley Chow, an assistant professor of materials science and engineering and bioengineering. “To successfully regenerate this cartilage and make it functional, we must consider the fact that function is related to both the cartilage and the bone. If the cartilage doesn’t have a good anchor, it’s pointless. You could regenerate beautiful cartilage, but it won’t last if it isn’t anchored to that bone immediately beneath it.”

It’s difficult to create one organ made of two very different tissues, says Chow, so the problem requires a tissue-engineering method that respects the multi-component and organizational nature of how tissues form in nature.

Chow has taken a major step in the field’s efforts to address such a challenge. She and her team have demonstrated a new method to create continuous, highly organized scaffolds to regenerate two different tissues, such as those found in the osteochondral interface. Their proof-of-concept paper, published in Biomaterials Science, is titled “3D printing with peptide-polymer conjugates for single-step fabrication of spatially functionalized scaffolds.” This work was led by Lehigh graduate students Paula Camacho and Hafiz Busari, with co-authors Kelly Seims, Peter Schwarzenberg and Hannah L. Dailey, an assistant professor of mechanical engineering and mechanics.

Artistic rendering of Lesley Chow's method of scaffolding for tissue regeneration

Chow’s lab creates biomaterial scaffolds made of biodegradable polymers, which are long chains of molecules that can degrade over time in the body. Scaffolds are widely used in tissue engineering to provide cells with structural support, as well as chemical cues that “tell” the cells what type of cell to become or tissue to form. Used in the early stages of tissue regeneration, scaffolds are designed to be implanted in the body and then degrade as new tissue forms.

The team uses 3D-printing technology to control the deposition of “inks” with different material compositions. These inks are prepared by mixing a biodegradable polymer with peptide-modified polymers. The peptides, composed of amino acids, provide the chemical cues to the cells.

“We know from literature and nature what amino acid sequences we want,” says Chow. “We can take a peptide segment that we know plays a specific and important role in telling cells to grow new tissue and, in a sense, steal from nature. We take a peptide and attach it onto a polymer and add that in while we are constructing our scaffolds. We use 3D printing as a way to control the organization of these peptide-functionalized polymers as well as the scaffold’s architecture.”

Once the team fabricates the scaffolds, they “seed” them with cells such as human mesenchymal stem cells that can, in response to the peptides, be “coaxed” into becoming different cell types.

Changing the scaffold’s properties is simply a matter of changing the inks loaded in the printer, Chow explains. The team can modify peptide concentration as well as location, and they can do this with more than one ink composition.

“What we are doing is creating an environment that fosters the regeneration of two different tissues simultaneously in one scaffold,” says Chow. “We make a scaffold that has the correct cues—one that promotes cartilage, one that promotes bone—all in one material. You then have a single scaffold where you don’t have to worry about mechanical failure at the interface because you have a single material rather than ‘gluing’ two separate scaffolds together and just hoping for the best.”

Story by

Lori Friedman

Photography by

Illustrations by Roman Bratschi

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