This past spring semester, I undertook an independent study project to develop tissue engineered constructs for neuroregeneration. However, after the one-semester course, much more development was necessary for these constructs to be proven successful. This summer, I was fortunate to continue pursuing this area of tissue engineering by the support of the Jumpstart for Juniors Research Grant.
Trauma or disease to the peripheral nervous system (PNS) can cause neurodegeneration, leading to life-changing complications from loss of motor function and sensory input. After peripheral nerve injury, axons distal (farther from the spinal cord) to the injury are broken down and cleared, known as Wallerian degeneration. The remaining distal Schwann cells rapidly multiply to form hollow tubes, known as bands of Bungner, which provide a route to encourage surviving proximal axons (closer to the spinal cord) to grow distally to the nerve’s original targets. However, if the injury is too large, the surviving proximal axons cannot reach the natural bands of Bungner on the distal side of the injury.
With the help of the Cullen laboratory, I worked on improving a technique for making agarose micro-columns filled with Schwann cells, essentially mimicking the bands of Bungner that naturally occur after peripheral nerve injury. The micro-columns that I make are extremely small, with an inner diameter (ID) of 160 μm and a length of 5 mm. I hope to find that the micro-column environment encourages the Schwann cells to align along the length of the micro-column core, forming a long bundle of aligned Schwann cells.
By manipulating independent variables, including micro-column ID and Schwann cell concentration, I have found that the Schwann cell growth is dependent on these changes. For example, by altering the micro-column ID from 350 μm to 160 μm, I observed an increase in Schwann cell process alignment using phase-contrast microscopy. Although more trials are necessary to form a conclusion, this observation is important for future testing. In addition, I noticed that using a cell density of 8.7x105 cells/mL did not completely fill the micro-column core with cells. By gradually increasing the cell concentration, I determined that 6x106 cells/mL sufficiently fills the micro-column and can be used as a control to test other independent variables. The next step is to determine the ideal extracellular matrix (ECM) to incorporate in the Schwann cell structures. Thus far, I have used collagen ECM in every micro-column to encourage Schwann cell growth. However, it is possible that a different ECM, such as laminin or fibronectin, will best support the extension and alignment of Schwann cell processes within the micro-column.
Overall, I have gained a lot from conducting research as an undergraduate because research allows me to learn and apply knowledge outside of the classroom. I believe this type of hands-on learning in a real-world setting has been essential for me to better understand and apply the knowledge that I have learned from other sources, specifically in peripheral nerve injury. This summer research experience has been a great opportunity to dive deeper into an application of tissue engineering that really interests me. I have enjoyed the freedom and independence to test conditions and set variables in a way that I see fit, and I have been able to further improve on techniques such as cell culture, phase-contrast microscopy, and immunocytochemistry. Although my project hit a few bumps along the way, I have learned to view each complication as a learning lesson, allowing me to adapt and improve my technique in the future.