In a significant advance for cosmetic and reconstructive medicine, scientists at Rice University have unveiled a new method for making synthetic collagen. The new material, which forms from a liquid in as little as an hour, has many of the properties of natural collagen and may prove useful as a scaffold for regenerating new tissues and organs from stem cells.
“Our work is significant in two ways,” said Rice’s Jeffrey Hartgerink, the lead author of a new paper about the research in Nature Chemistry. “Our final product more closely resembles native collagen than anything that’s previously been made, and we make that material using a self-assembly process that is remarkably similar to processes found in nature.”
Collagen, the most abundant protein in the body, is a key component of many tissues, including skin, tendons, ligaments, cartilage and blood vessels. Biomedical researchers in the burgeoning field of regenerative medicine, or tissue engineering, often use a combination of stem cells and collagen-like materials in their attempts to create laboratory-grown tissues that can be transplanted into patients without risk of immunological rejection.
Hartgerink said it’s too early to say whether the synthetic collagen can be substituted medically for human or animal-derived collagen, but it did clear the first hurdle on that path; the enzyme that the body uses to break down native collagen also breaks down the new material at a similar speed.
Replicating the multi-hierarchical self-assembly of collagen has long-attracted scientists, from both the perspective of the fundamental science of supramolecular chemistry and that of potential biomedical applications in tissue engineering. Many approaches to drive the self-assembly of synthetic systems through the same steps as those of natural collagen (peptide chain to triple helix to nanofibres and, finally, to a hydrogel) are partially successful, but none simultaneously demonstrate all the levels of structural assembly. Here we describe a peptide that replicates the self-assembly of collagen through each of these steps. The peptide features collagen’s characteristic proline–hydroxyproline–glycine repeating unit, complemented by designed salt-bridged hydrogen bonds between lysine and aspartate to stabilize the triple helix in a sticky-ended assembly. This assembly is propagated into nanofibres with characteristic triple helical packing and lengths with a lower bound of several hundred nanometres. These nanofibres form a hydrogel that is degraded by collagenase at a similar rate to that of natural collagen.