Christian Tessman is a rising senior at Johns Hopkins University in the Department of Materials Science and Engineering. This summer he is working with Dr. Murat Guvendiren’s lab to determine how surface patterning on hydrogel scaffolds affects the shape and alignment of cells cultured on hydrogel culture platforms. Christian plans to pursue a graduate degree in Materials Science and Engineering after graduating.
Patterning Surfaces for Inducing Cardiomyocyte Alignment
Christian Tessman, Joenid A. Colón-Mateo, Andrea N. Plaza-Castro
Wrinkles are a property found in many biological tissues. Scientists have tried to mimic these surface patterns to understand how cells mechanically interact with their microenvironment. Controlled surface patterns on gels have been shown to affect cell alignment, morphology, gene regulation, and differentiation. Here, wrinkle patterns were fabricated on polydimethylsiloxane (PDMS) substrates to regulate human cardiomyocyte (hCM) alignment, which is important for proper tissue function. PDMS sheets were subject to ultraviolet and ozone (UVO) treatment, with an initial strain of 20%, to form a thin film surface with a higher Young’s modulus than the bulk. Exposure time was modified to determine its effect on wrinkle wavelength, amplitude and film thickness. Analysis of microscope images of the PDMS sheets showed that wrinkle wavelength and amplitude increased linearly with UVO exposure time, and that critical strain decreased linearly with time. The effect of wrinkling on hCM nuclei alignment was also investigated by culturing hCMs on flat and patterned PDMS sheets. Analysis of microscope images of the hCMs showed the average direction of nuclei alignment was similar for both topographical conditions: 84.7±48.0 degrees for flat and 88.1±13.3 degrees for patterned on day 4. However, the standard deviation of nuclei alignment on flat substrates was approximately three times greater than for patterned substrates. This indicates more uniform cellular nuclei alignment on patterned substrates. Development of materials that can mimic surface topography of tissues promises a greater understanding of the morphological response of cells leading to more diverse biomedical applications.