Wade Stewart, Biomedical Engineering.

Doctoral Dissertation Defense – Wade Stewart

BME PhD Candidate Wade Stewart will be defending their dissertation:


Implementation of static and dynamic culture substrates to control maturation of human induced pluripotent stem cell cardiomyocytes through tunable manipulation of topographical roughness and bulk stiffness.


  • Location: BPI, Room 140
  • Zoom Link: https://udel.zoom.us/j/91260781103
  • Date: Thursday, August 31, 2023
  • Time: 10:30 a.m.
  • Committee: Elise Corbin, Christopher Price, Megan Killian, Robert Akins


In the pursuit of understanding and treating heart disease, many have turned to induced pluripotent stem cell derived cardiomyocytes (iPSC-CMs). While iPSCs provide a nearly unlimited source of cardiomyocytes, iPSC-CMs exhibit a fetal-like phenotype including rounded morphology, atypical beating pattern, and disorganized underdeveloped sarcomeres. Prior to their use as effective in vitro models of in vivo human heart tissue, these iPSC-CMs must undergo a maturation process which has previously utilized spatial patterning of integrins and constant static stiffness of the extracellular matrix. However, these mono-mechanical static environments do not recapitulate the complex and dynamic forces that influence growth, remodeling, and function in cardiac tissue. Therefore, we attempt to model the complex interconnected nature of two key mechanical regulators of morphology and maturation through collective, independent, and dynamic regulation of topographical roughness and substrate stiffness.

To study collective static and dynamic regulation of roughness and stiffness, we implement the use of our magnetorheological elastomers (MREs). MREs provide magnetically and dynamically tunable stiffness (10-50 kPa) and roughness (smooth – rough) control for cell and tissue culture. Using MREs we statically and dynamically drive phenotypic changes in cell spreading, elongation, alignment of sarcomeres, sarcomere length, sarcomere width, and Z-ratio of iPSC-CMs. However, to understand how these different mechanical properties play a role in CM maturation, we have developed an agarose molding technique to fabricate elastomers with independent roughness (40, 440, 740nm) and stiffness (17, 25, 45, 60kPa) characteristics. We show that morphologic and sarcomeric shifts toward maturation are linked to changes in collective, independent, and dynamic roughness and stiffness. These studies demonstrate that iPSC-CMs respond to temporal static and dynamic culture by various phenotypic maturation responses, and independent static cultures. Similarly, by decoupling roughness and stiffness we show that surprisingly a higher-than-normal physiologic stiffness (45kPa) and moderate roughness (440nm) are the ideal parameters to maximize maturation of CM phenotypic markers. These results compel the consideration and adoption of a systems level approach by the implementing mechanical co-cultures and dynamic environments that are more biomimetic of CM tissues in all future studies. This work provides new insights into multi-mechanical culture of CMs and utilizes novel techniques to regulate stiffness and roughness both collectively and independently in biomimetic culture platforms for future maturation and therapeutic research.