Scaffolding for Growth

STEM-SI student Santiago Lazarte builds connections among cells and tissues–and for his future

For STEM-SI student and rising senior Santiago Lazarte, spending the summer in a research lab at Lehigh University is the next rung on his educational ladder. A native of Panama, Santiago spent his first two undergraduate years on Florida State University’s Republic of Panama campus before transferring to the Tallahassee campus. Once there, the biomedical engineering major landed in mechanical engineering professor Brandon Krick’s lab and eventually became part of a joint project conducted by Krick and Lehigh’s Materials Science and Engineering and Bioengineering professor Lesley Chow, focusing on osteochondral tissue regeneration. Santagio worked remotely with Chow for two semesters, then came to the Chow Lab as part of STEM-SI.

In the Chow Lab, Santiago spends his days building 3D scaffolds. Think “scaffold” means a large-scale construction project? Think again. The scaffolds Santiago builds are tiny, just 6mm x 6mm and 1mm thick. He builds them from the ground up, including writing the blueprint code for the 3D printer, combining the polymers and other materials (mixed for 48 hours in a device that shakes them continuously like a hardware-store paint mixer), and finally printing the scaffolds.

Chow’s lab focuses on tissue engineering, so the scaffolds are more like a garden lattice that vines grow on, supporting cells as they grow into tissue such as bone and cartilage. Unlike a garden lattice, though, Santiago’s scaffolds contain the “seeds” of the tissues that will grow on them. And the scaffolds are designed to be short-lived. Some of the polymers used to build them disappear in a volatile solvent after the scaffold is built, leaving behind a solid filament. If the test is successful, these filaments grow into healthy tissues.

Like the native tissues in your knee, for example, these tissues aren’t all the same: Some are bone and some are cartilage. Santiago’s scaffold tells them which type to become. He notes that the lab-grown tissue has to have the properties of the natural tissue. “An interesting thing about this project,” he says, “is that the researchers can spatially tune the scaffolds to have different properties.” Specialized cells are arranged on the scaffold and as they grow and differentiate themselves into bone or cartilage, they reflect the composition of native tissues.

Another component of the research, Santiago says, is printing several scaffolds to fit together so they’re offset and can have elastic properties. He compares them to a stress ball, because “after you remove the load, or the squeeze, it recovers its shape.” Creating lab-grown tissues with such a property mimics the resilience of natural tissues, able to stretch and return to their original position. The lab-grown tissues can also be built to fit specific requirements. “Your knee is going to experience higher loads than your elbow, for example,” says Santiago. “Or like a scaffold that goes in a horse, it's going to probably undergo higher loads. We could tailor the scaffold to whatever requirements we need, and we can make the chemistry match, which is one of the important factors for cellular differentiation, and then we can change the other parameters to get the stiffness that we desire.”

One of Santiago’s tasks for the summer is testing the scaffolds and tissues, sometimes hundreds of times, until the samples demonstrate the qualities the researchers want. With the offset scaffolds, he says, the researchers noticed a “viscose behavior.” That behavior is time dependent, unlike the elastic qualities of the previous samples, so Santiago’s testing needs to account for the extra time. This factor has bumped the testing time to about eight minutes, he says, making for long days in the lab.

If the research Santiago, Krick, and Chow are working on succeeds—and it’s an “if” that will take a long time to turn into a “when,” Santiago notes—patients with conditions such as osteoarthritis will be able to have the tissues in their joints repaired in a less surgically invasive manner.

For Santiago, his time at STEM-SI this summer has not only allowed him to continue contributing to the Krick-Chow project, but also to grow as a researcher. Arriving in Professor Krick’s mechanical engineering lab as a biomedical major, he has also worked with bioengineering and materials science. He plans to attend graduate school, as he “feels that curiosity” about research, and wants to find out where his multidisciplinary skill set might take him. Like the tissues he’s growing in The Chow Lab, he is building connections that he hopes will grow into a successful career.