Feb 13, 2019 | By Cameron

Corneal transplantation is one of the primary treatments for loss of corneal function, but only one in 70 people who need corneal transplants receive them, leaving some 12.5 million people suffering from vision loss because there simply aren’t enough corneal donors to go around. Attempts to replicate the perfectly-spherical, collagen-based protective layer of the eye have come up short. But last year we reported on a 3D bioprinted cornea out of Newcastle University that looked (pun intended) very promising.

Now, Martina Miotto, a post-doctoral researcher in tissue engineering at the same Newcastle University has created a self-assembling cornea fabricated from 4D biomaterials. 4D biomaterials are materials comprised of biocompatible substrates and living tissue cells that change shape, composition, and/or function when exposed to specific external stimuli. Collagen gels that contain corneal cells (CCCGs) exhibit a contracting shrinkage, and Miotto and her team previously discovered that the presence of peptide amphiphile molecules inhibits the contracting behavior. So they created concentric circles using two CCCGs, one with the peptide amphiphiles and one without, “producing a 4D biomaterial with an internal mechanism of stimulus, using contractile cells as bio‐actuators to change tissue shape and structure,” according to the paper abstract.

Over five days, the CCCGs curved into cornea shapes. Miotto explains the emergent 4D behavior: “Each cell’s force is tiny but together they can shape a one-inch-wide block of tissue into a cornea-like structure.”

She also describes how 4D biomaterials could enhance current 3D bioprinting efforts, stating that it’s ”possible to take this technology one step further with the invention of 4D printing, the printing of structures that can self-assemble by folding after the manufacturing process is done, just like our corneas. Printing biological structures that can arrange themselves into an even more complex shape would mean you wouldn’t need to produce scaffolds to print the cells on, or remove them afterwards. The accuracy of the printing process would be extremely useful in precisely positioning the peptide-based molecules that make the cells contract within the bio-material.”

3D bioprinting entire organs with 4D biomaterials may be a ways off, but the technology can still be used for therapeutic applications in the immediate future. Miotto provides a possible example: “The process could be used to create shape-changing stents to keep clogged blood vessels open. A closed stent could easily be injected into the bloodstream and then made to open up by the contracting force of cells at a site of injury, avoiding the need for surgery.” Researchers are already exploring 3D printed arterial stents, so this is a realistic expectation.



Posted in 3D Printing Application



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